The Refraction of the Human Eye. A Critical Study of the Statistics obtained by Examinations of the Refraction, especially among School Children. BY B. ALEX. RANDALL, A. M., M. D., Ophthalmic and Aural Surgeon to the Episcopal and the Children's Hospitals, Philadelphia. FROM THE AMERICAN JOURNAL OF THE MEDICAL SCIENCES. July, 1885. Extracted from the American Journal of the Medical Sciences for July, 1885. THE REFRACTION OF THE HUMAN EYE. A CRITICAL STUDY OF THE STATISTICS OBTAINED BY TIONS OF THE REFRACTION, ESPECIALLY AMJTNfjT SCHOOL CHILDREN. / * By B. ALEX. RANDALL, A.M., M.D., Ophthalmic and Aural Surgeon to the Episcopal and the Children’s Hospitals, Philadelphia. The great importance of full sharpness of vision is a matter which is steadily obtaining wider-spread recognition, and is demanding still more earnest consideration of all thinking persons. Defective sight is growing more notable for a variety of reasons, and the means of amending it are progressively improving and are more widely employed, thus furnishing con- stant reminders of the need of such help ; yet they are making only the more distinct those classes of cases which are but partially, if at all, remediable, and driving us to the more thorough study of the causes of these defects and the means for their prevention. The progress which has been made in all branches of knowledge, especially the natural sciences, is constantly increasing the field to be covered in the usual educational process. The demands made upon children at their lessons have steadily increased; while the assumption of the matter of education by the state, as a duty owing to itself and its citizens, has carried the influence of the schools, sometimes by compulsion, into every rank of life. Conditions, therefore, which not long since invested only the few, are now the environment of the community. Census reports point to a steady and rapid decrease, in every country making claim to civilization, of that portion of its inhabitants unable to read and write; while means and attractions to the exercise of these powers are offered by veritable floods of literary productions and reproductions, by postal facilities which would have been deemed a few decades since utterly beyond belief, and by an immense broadening, for almost every one, of the field of every-day interest. Some information on almost all points is expected of every one; and the most abstruse dis- 2 coveries of modern science in revealing new worlds, measuring the globe, or investigating its components and the creatures which live or have lived upon it, are quickly absorbed into the fund of general information, and go to widen or to modify that stock of knowledge of which all are expected to be cognizant. And the means to the attainment of the major part of all this is the eye. Most children begin to study the alphabet and its combinations before the fifth year, and a few years more finds them all readers. School tasks surround and occupy them much of the time, and of what remains not a little is given to amusements hardly less exacting in their demands for the use of the eyes in accurate vision. The general spread of the employment of artificial illumination has lengthened greatly the hours during which the eyes can be rigorously exercised, and the child whose school work is finished turns to other reading for recreation. In the general walks of life vision, and good vision at that, is being more and more strictly required—how much we are hardly likely to appreciate at first. Yet if we think of any one, of whatever age or rank, suddenly deprived of vision, we will, perhaps, in some measure realize how essen- tial to almost every employment is the lacking sense. How few are the paths now open to the blind, and in them, how difficult it is that they should at all cope with seeing competitors ! The disadvantages of those with defective vision differ in degree rather than in kind. In every one of our eye clinics the cases are numerous where persons reject with alarm the advice that they should wear glasses, knowing, as they do, that such an assumed confession of visual defect may cost them a present situation, and will certainly count to their prejudice in seeking any new place. All this is but a fraction of the evidence showing how much is required, even outside of the schools, of the visual powers of those who have them in the usual measure. The present century has seen the introduction of methods and instruments of precision into almost every branch of study, most notably in all which would lay any claim to scientific value. The inductive method is almost universal, and each advance is a generalization from extended observations. The observer works for the instruction of the community as well as him- self ; his results must receive confirmation in order to meet general accep- tance ; and to this end standards of comparison more or less constant and methods free as far as possible from the personal equation have become essentials. Advancing with the general realization of the importance of good vision, ophthalmology has furnished means more and more exact for the determination of the visual acuity and for the measurement and cor- rection of its defects; until we are now in position to obtain data in these matters as strictly accurate as any in the whole range of natural science. In the mean time, investigation after investigation has been made in the 3 matters of vision and refraction, embracing enormous numbers of indi- viduals, in the endeavor to answer the numerous hygienic and social ques- tions involved in the subject of defective vision. Early realizing that, to obtain results of general applicability, eyes presumably normal must be the objects of study, and that in youth many of the causes of defect have not yet come into play, the eyes of school children have been most fre- quently examined, both to obtain information as to the important subject of the special hygiene of schools, and also to gain data as to what is to be regarded as the standard eye, the typical form, the normal, which the various conditions of imperfection have failed to attain. This standard determined, and the statistics of the primary variations from it once settled, we will be in position to study the questions of the general preva- lence of defective vision, the causes which are effective in evoking it, and the measures to be employed in combating the evil. The foundations of such a wide-reaching study must, of course, be broad. Furthermore, they must be sure; lest the crumbling of some of the constituents should imperil the stability of all that is built upon them. The first condition would seem well answered, since no student of the subject, not even Prof. Cohn, has up to the present time had the patience to collect all the statistics of the matter already in print; yet arrays of scores of investigations, based upon thousands of individuals, are to be found in the summaries which have been given by various authorities. In the other direction much remains to be desired in not a few of these studies, so much, indeed, that some of them can be employed in any sum- marizing of results only within the narrowest limits. Setting out in many instances with some single object in view, such as the question of the prevalence of myopia, attention has been given to it alone, and their negative showings in other directions are often valueless, even where the positive results are reliable. Yet they are often grouped as all equal and competent portions of evidence, and advantage is taken of their wide divergence on many important points, either to employ the convenient ones in the support of any fallacy, or else, by holding them up into view in their apparent contradiction, to throw discredit upon all such investi- gations and the so-called science which they in some measure represent. There has been almost no attempt to combine a critical examination of the methods, details, and results of this extensive series of investigations, with a summary embracing all that are accessible. No light work nor a pleasant one, dealing as it must with comparisons more or less odious, yet a task which the writer here undertakes in the belief that valuable results are thus to be attained. That these results will display any striking novelty is not to be hoped; but that they may give added weight to con- current testimony derived from other sources, and perhaps widen the ac- ceptance of views not yet receiving their due appreciation, seems abundant 4 reason for the labor necessary to educe them. Where a hundred investi- gators have expended years of study in gathering statistics on so weighty a subject, surely there is place for one to combine the data thus gathered. If only to show that much of the labor has been wasted in the past, and to give indication of the points to-day demanding elucidation and the methods by which they are to be studied out, this study would appear to be called for. That it can give or disseminate mucli other valuable infor- mation will, it is hoped, be made to appear. A comparison of the numerous investigations which have been made in the field before us shows the utmost variation in their aims, methods, and results. Great as are the differences, however, the studies will repay careful scrutiny, and in few instances will we fail to find reason for dis- crepancies. In most of the examinations the question of the occurrence of myopia and its increase was paramount; in many, it alone was studied. Indeed, the earliest investigators knew of nothing else in our field to seek, and the methods at their command were hardly sufficient for its discovery. Even after hypermetropia and astigmatism became well known they were rarely sought with any care, and vision equal to normal was considered, sometimes even defined, as synonymous with emmetropia. In many of the investigations each eye was not separately tested, so that practically only the better eye was studied, and any difference between the two over- looked. Investigating the subject with rather vague hygienic views, the individual was quite naturally the centre of interest. If he could see with normal sharpness, whether with one eye or both, he was not a myope, and the requirements of the matter were considered to be satisfied. Among the later examinations such oversights are, naturally, rarer; yet often the meagre reports available either give no information on such points, or afford it in such indefinite terms as to leave them still in doubt. In many of the studies the nature of the refraction has been carefully determined; but the degrees of the anomalies found have either not been determined or not reported. Others state these important details for the class, the age or the year of school life ; yet, omitting the mention of the actual numbers of individuals or eyes embraced under each heading, the results, valuable as they may be in themselves, cannot be combined with those of others. In some of the cases where the ophthalmoscope was employed in the examination of every eye (and in the many where it was not used, a most important aid to accuracy was omitted), it was used to seek for lesions and not to measure the refraction. It is needless here to repeat that in the aims held by some of the investigators such details had no place; and that in studies so comprehensive in the matter of numbers examined, the introduction of the methods of extreme refinement would have been impracticable. What most concerns us is the stability, the cor- rectness, of our foundations. The subject here taken up is the informa- tion which these examinations can afford as to the usual refraction of the 5 human eye; in health, as far as we may exclude pathological conditions in youth and in age, if the data are to be found : to extract all that is ger- mane to our purpose. And when grave omissions or vexatious errors, generally typographical, have to be pointed out, it will be with full reali- zation from the writer’s own experience, of how hard it is to avoid error in statistical reports, and how impossible for one man to comprehend in his investigation all those points that to another may seem most interest- ing or essential. And if, in passing, we cannot conceal a regret that some study, most valuable in some respects, gives us no information in others, it will be with no thought of adverse criticism—rather in testimony to the value of that which is given. To begin this study with a series of definitions, where the subject has been so much written about, may seem unnecessary, if not presumptuous. Yet, since loose employment of technical terms constitutes the principal ground of fallacy in statistics, the cardinal vice, which can make figures the most lying of witnesses, it is essential that some points be absolutely defined, and then the data of various observers be marshalled under these headings with the strictest accuracy which the details at hand will permit. Waiving technicalities as far as possible: the refraction of the eye is the relation of the situation of the percipient retina to the focus of the lens system of the passive eye, for rays of light coming from distant ob- jects. When, without any effort, the focus for such rays falls on the per- ceiving layer of the retina, the eye is emmetropic. When the eye is rela- tively too long to meet this condition, it is myopic ; its retina is in position to receive the focus only of rays coming from some point not remote ; it is nearsighted. When relatively too short, the eye is hypermetropic; without accommodative effort, or its equivalent, the eye can focus no rays of light that occur in nature ; distant objects form undefined images upon the retina; near objects form images still less clear. Vision is the perception of external objects through the agency of the rays of light coming from them and impressing the retina. Its acuity depends upon the formation of a sharp image upon this membrane, and upon the capacity of it, and the visual centres behind it, to take cogni- zance of the image so found. Granted the latter conditions in full mea- sure, the acuity of vision depends upon the transparency of the ocular media and the refraction, primary or fictitious, of the eye. By fictitious refraction is meant every deviation from its primary condition above de- fined, whether produced by accommodative effort or by optical appliances, such as lenses. Conditions of imperfect retinal perception and of non- transparency of the media before it, may for our purposes be grouped under the heading amblyopia, and practically laid aside, and we have before us the subject of the visual acuity of the human eye as dependent upon its refraction, this last being divisible into real or primary, and ficti- tious or apparent, refraction. The real or primary refraction is the 6 object of our present search ; and we will endeavor to winnow out of the mass of results furnished by a long series of investigations those which have bearing upon it, and try to solve with their aid the question—What is the normal refraction of the human eye ? Since we have at our command easy methods of determining with the utmost accuracy the visual acuity in any case ; this, the most salient prac- tical point of our study, can be directly measured ; and as by wide obser- tion we have obtained reliable data as to the average sharpness of vision, we can make ready use of it as a means to our end, only noting that the tests must be strictly applied. The farthest point of distinct vision for the myopic eye is not remote, hence normal vision at a distance without lenses at once excludes myopia: but the opposite condition of hyperme- tropia is far more difficult to exclude. Exercise of the accommodative power, which in the myope only makes distant vision worse, can in the hypermetropic eye cover up the defect of refraction and raise vision to the normal; nay, more, the small pupil, and probably the tension of accommo- dation and its effects, may raise vision above that which we hold to be the average. Vision above the normal is rather indicative of liypermetropia. The accommodation must be set aside in order to reveal the real refrac- tion, above defined. A convex lens held before the eye will render the rays coming from distant objects convergent, and only a hypermetropic eye can focus such rays, and see normally at a distance through a convex lens. The accommodation used to render the eye apparently emmetropic is now unnecessary, and can only impair vision ; it may, therefore, be laid aside, and the eye then manifests its hypermetropia. But a lifelong habit will not always yield in an instant. The accommodative tension may be maintained, distant vision is made worse by a convex lens, even the weakest; and we are driven to other methods to attain our aim. Dark surroundings are conducive to relaxation of accommodation, and the glare of light reflected into the eye by the ophthalmoscopic mirror may aid, or at least not counteract, the influence. This method, then, in expert hands, may as it were surprise the eye into a revelation of its de- fect. Yet all such measures may fail, and nothing short of absolute paralysis of accommodation by a mydriatic will tell the whole story. Irritative causes have perhaps set up a cramp of the ciliary muscle, a spasm of accommodation, which will yield but obstinately to the most powerful mydriatic. The accommodation, then, is the factor which introduces uncertainty into the investigation ; study of it can sometimes clear away doubts. The range of accommodation is at each age approximately a constant: if a part of it be called into play to cover up hypermetropia, by thus much will the range be shortened. Here we have not only a clue to the existence of such a condition, but also some indication of the amount of accommoda- tion thus rendered latent; and hence of the amount of liypermetropia 7 neutralized. Where astigmatism is absent, very accurate results may often be thus obtained. Similar measures may be employed to determine the presence and also the degree of myopia, and to exclude the cases where nearsight is simulated by accommodative spasm ; but the same difficulties may be met and nothing less than total paralysis of accommodation will enable us to claim absolute accuracy. Still more is this the case with astigmatism; and although we can in addition to other methods, get ab- solute results by ophthalmometric measurements as to corneal asymmetry, we have only one—the most important—of the series of factors involved. To turn, now', to the practical workings of an examination, let us see what information we can obtain, and how we may prove the existence of emmetropia, or other conditions of refraction. Testing of the visual acuity will show it to be normal or subnormal—the former excluding myopia. If subnormal, the use of convex or concave lenses may show the presence and degree of absolute hypermetropia or apparent myopia, respectively. In all these tests each eye must be separately tried; but sometimes the testing of both together may be also advantageously employed. Convex glasses held before eyes with normal vision may reveal hypermetropia (“H. facultative manifest” of Bonders), or in case of their rejection will speak for apparent emmetropia. The various tests for astigmatism may show the presence of this defect, and indicate, perhaps correctly, the meri- dians of greatest and least refraction in the media of the eye. These data may be confirmed by the ophthalmoscopic examination, most especially in the direct method and in retinoscopy; the cornea may be measured with the ophthalmometer, and the range of the accommodation may be deter- mined and compared w ith the standard furnished by Donders. Concur- rence of these various tests will greatly enhance the confidence which would be due to the findings of any one of them alone; and the presumption will be strong that eyes, which by all tests appear emmetropic, are so in fact. Only by paralysis of the accommodation, howrever, can this be absolutely settled, and the emmetropic eye be proven to be actually such; then no latency of hypermetropia could enlarge the list of seeming emmetropes, and no spasm of the accommodation could decrease it by causing apparent myopia. Then, too, the degree of any error of refraction could be exactly measured—all previous tests claiming to furnish but an approximation. One principle must rule in all these tests. Accommodation is to be done away if possible. It can increase temporarily the refraction of the eye, lessening or covering hypermetropia, increasing the degree of myopia, or making apparent myopes of those really emmetropic or hypermetropic. There is nothing tending to the contrary—no counter-force to oppose it or to introduce error in the other direction. The lowest grade of myopia, therefore, or the highest grade of hypermetropia, obtainable by any method of competent accuracy, is the nearest approximation to the real refraction. All data in this direction are positive; all to the contrary, merely nega- 8 tive. Hypermetropia proven by any one test, for example, is to be con- sidered as the true refraction of the eye, although every other test points to the contrary. The one test, to stand thus in conflict with all others, must be well based; it should be repeated to obtain confirmation from itself; but standing still, it is to be accepted as correct—all the others are pro- bably vitiated by the deceiving activity of the accommodation. Of the various methods of examining the eye with unparalyzed accommodation, that by the ophthalmoscope is most frequently able to act such a part. The conditions of accuracy must be fulfilled and the observer must be competent; then its findings can be maintained against any array of others, which point towards myopia, i. e., in the direction in which accommodative activity would tend. In the abstracts which follow, the original reports of the examinations have been strictly followed in every case where they have been accessible; the source of information actually employed being given in the appended bibliography, to which the numbers refer. Abstracts and reviews have also been studied to obtain all possible collateral information ; in this regard, and also as a source of most quotations which have had to be made at second-hand, use having been most frequently made of the “ Jahres- bericht liber die Leistungen und Fortschritte im Gebiete der Ophtlmlmo- logie.” Our study being of eyes and not individuals, this as well as con- venience or conciseness has here and there dictated a recasting of the forms in which the results have been given ; but effort has been made to do the least violence consistent with our needs to the observer’s own arrangement, and none whatever to his actual results. Occasionally, palpable error in the summing up given by the examiner has driven us to work over his detailed results, and figures have been thus obtained dif- fering (rarely in notable degree) from his totals. Information as to the actual numbers being more important to our ends than percentages, these numbers have been worked out when not given—always with the proviso that they are merely approximations. All results which are not in perfect accord with those of the investigator cited are indicated by parentheses, or, if derived by the writer from percentages, etc., by bx*ackets. The varying nomenclature and standard of the schools in which many of the investi- gations have been made, and of their classes, makes uniform arrangement in this regard well-nigh impossible. The designation of the equivalent American school has been sometimes given, but the untranslatable “Ileal- schule” and other similar terms, have been retained. Age, being looked upon as the best basis of comparison for our purposes, has been so employed whenever the data permitted. As to the “ Gymnasium,” it may be re- marked that its curriculum extends generally from the fourth year of school-life about as far as the Sophomore studies of our American colleges ; while in the “ Realschule” the course is approximately parallel, but with lighter stress upon the classical studies. 9 No. Date. Examiner. Character of examined. Age. Persons. Eyes. Em. per ct. M. per ct. H.m. per ct. H. per ct. As. and | Amb. 1 1813 Ware . Foot guards, England .... 10,000 0 =0? Chelsea Military scholars, England . 1,300 3 0.25? University students, Oxford 127 32 25.2? 2 1848 Szokalski . Primary scholars, Paris 6 300 0 0? «• College and Lyceum pupils, Paris 977+ 114 [11.6] 3 1856 Schiirmayer Grammar-school pupils, Baden . 930 46 4.9 “ Normal school, etc., pupils, Baden 2172 392 18.4 4 1861 v. Jaeger . Infants, children, and soldiers, Vienna 9d. 25y. (800) 700 223= =31.8 416 59.4 61=8.7 ? 5 1866 Ruete . Free and charity school pupils, Leipsic 213(2514)1 fl21 48 [22.5] 55= L25.8] 6 1867 Reck . School-children, Brunswick . 2250 ? 7 Alexander . Primary scholars, Aix .... 869 ? 8 Gaertner Theological graduates, Tiibingen ±i9 138 276 41=14.9 231 83.7 ? 9 Cohn . Village primary pupils, Breslau, etc. 6-13 1486 1408 94.7 22 1.4 16- = 1.1 Am. 34 City elementary pupils, Breslau 6-14 4978 4245 85.3 334 6.7 127 2.5 222 Secondary and Grammar pupils, Bres. 7-17 1260 995 78.9 109 8.65 52 4.12 90 it Realscliule and Gymnasium, Breslau 9-22 2336 1682 72. 539 23. 44 1.9 oO 10 University students, Breslau 17-27 410 134 32.7 244 59.5 15 3.7 17 11 1868 Tvpe-setters, Breslau .... 20-71 132 51 38.7 68 51.5 10 7.6 3 12 Thilenius . Gymnasium scholars, Rostock 314 175 55.7 96 30.6 9 2.9 13 1S70 Schultz Gymnasium scholars, Upsala 12^i<3 431 159 36.9 ? 14 1871 Erismann . Pupils of various schools,St.Petershurg 8-24 4358 1132 26. 1317 30.2 1S89 43.3 TApp. Em.671 (Atropine) 15 << Cohn . Village scholars, Silesia 6-13 240 480 14 3. 4 0.9 370 77. 438=91.2 24 16 *« Maklakoff . School children, Russia 759 482 63.5 254 33.5 23 3. 17 1872 Cohn . Gymnasium pupils, Breslau 6-22 361 187 52. 125 35. 25 7. 24 18 « Kruger Gymnasium pupils, Frankfort 9-19 203 406 159 39. 162 40. (72 17.7) 83 20.6 19 1873 v. Hoffmann Gymnasium pupils, Wiesbaden . 91-19 256 512 140 27.3 187 36.5 [101 19.7] 171 33.8 9 Girls prep. & gram, pupils, Wiesbaden 61-15 403 203 50.4 S3 20.6 87 21.5 (94 23?) 23 «* ti Boys prep. & gram, pupils, Wiesbaden 6j-16 568 321 56.5 67 12. 37 6.5 145 25.5 35 20 v. Reuse Gymnasium pupils (1872), Vienna 409 818 243 29.7 375 45.8 158 19.3 [184] 42 Gymnasium pupils (1873), Vienna 389 144 37. 166 42.7 69 17.7 4 21 1874 Ott & Ritzmann Gymnasium pupils, Schaffhausen 122 244 124 51. 96 39.3 24 10. ? 22 «« Ott Realschule pupils, Schaffhausen 12^ii? 164 324 146 45. 37 11.1 122 37.7 ? As. 19 23 Cohn . Old villagers, Silesia .... 60-84 100 200 49 24.5 25 12.5 114 57. 114 57. 12? 24 Gayat . Pupils of various schools, Lyons 6-14 600 440 73.3 52 8.7- 108 18. = or >1. D. 25 Burgl . Girls Grammar school, Munich . 10-17 179 [721 40. 88 49.2 19 10.7 26 Dor Realschule pupils, Berne 10-18 430 279 64.9 125 29. 18 4.18 27 1875 Callan . Negro prim. & grammar school, N.York 5-19 457 81 17.7? 12 2.6 2S9 67. 350 7 6 5 28 v. Reuss Gymnasium pupils, Vienna . 480 159 33.1 177 34.6 49 10.5 132 28.3 i Only those having eve-trouble were sent for examination. 10 No. Date.1 Examiuer. Character of examined. Age. Persons. Eyes. Em. per ct. M. per ct. H.m. per ct. H. per ct. As. and Amb. 29 1875 Pfliiger Teacher recruits, Switzerland 20-25 529 112= =21.2 30 1876 Conrad Gymnasium pupils, KOnigsberg . 6-20 1518 3036 909= =29.94 678 22.33 357= =11.76 1441=47.47 31 Adler . Deaf-mute pupils, Vienna . 8-19 100 200 64 32. 10 5. 126 63. 32 Spalding Primary and Grammar pupils, Portland 5-15 2372 244 11.? 33 “ Pfliiger Pupils of various schools, Lucerne . 7-23 1S46 862 46. 184 10. 800 44. 34 Emmert Pupils of various schools, Berne, etc. 5-55 214S 4296 422 9.82 542 12.61 3308 77. 35 it Loring & Derby. R. H. Pupils of various schools, New York . 6-21 2265 1531 67.59 448 19.78 286 12.63 ? 36 (4 Sclieiding . Gymnasium pupils, Erlangen 8- 746 187 25.1 371 49.7 188 25.2 [166 12.4] _[224 18.8] 37 Koppe . Pupils of various schools, Dorpat 661 1332 279 20.9 270 20.3 687 51.5 [904 67.8] As. 92 38 1S77 Kotelmaun . Normal scholars, Hamburg . 8-20 413 240 58. 157 38. 8 2. 39 44 44 Realschule pupils, Hamburg 232 reoi 26. 44 4» Grammar scholars, Hamburg 310 l'/vj 25. 44 44 Pupils of girls private school,Hamburg 104 |18| 17. “ 44 Pupils of girls private school, Hamburg 218 1431 22. 44 Girls’ normal school pupils, Hamburg 45 |19| 42. 44 44 Primary scholars, Hamburg 296 1361 12. 40 Classen Realschule pupils, Hamburg 402 165 41. 34 5.5 41 11 aeon . District scholars, Hartford . 7—17 308 616 464 75.3 102 16.5 42 Steven District scholars, Hartford . 7-17 675 fl20] 18. 43 44 Becker Gymuasium pupils, Heidelberg . 287 154 53. 100 35. 33 12. 4* 1 # Grammar pupils, Heidelberg 261 [34] 13. 44 44 Agnew fWilliams & Ayresj Primary district pupils, Cincinnati . 630 507 80.5 85 13.5 37 6. “ rCheat ham! College students, New York 549 1097 651 59. 333 30 3 105 9.6 “ [Prout & Mathewson] Tech. Institute pupils, Brooklyn 3(0 600 372 62. 79 12.5 126 21. 45 44 Derby, Basket . College freshmen (Harvard) Boston . 122 [361 29.5 46 44 Nieruaun Gymnasium pupils, Magdeburg . 325 [156] 49. “ Grammar school pupils, Magdeburg . 3S8 Li 71] 44. 47 *» Cohn . Watchmakers, jewelers, lithogra- [phers, Breslau. 19-71 172 116 67.4 28 16.2 25 14.5 As. 3 48 1878 Dor Lyceum pupils, Lyons .... 5-23 1016 2026 1300 64. 568 28. - or >1 D. 49 Ott Gymnasium pupils, 1876, Schaffhausen 120 240 90 37.5 98 40.8 87 4.2 50 Seggel Recruits, grad. ofGymn. etc., Munich. 18-24 284 164 58. 52 21.6 51 44 Reich2 Pupils of various schools, Caucasus . 1259 [529] 42.? [365] 29.? [42S] 34.? =5. 44 61 122 76 62.3 53 Roosa3 . Med. Students and graduates, N. York 21-31 14 3 22. 0 0 11 78. 54 Gymnasium pupils (II & I), Hesse 177 354 ? [209 59.3] 55 *4 Haenel District school, boys, Dresden 6-ij> 432 854 [470 55. 182 21.3 202 23.7] 44 District school, girls, Dresden 6-14 382 764 [317 41.5 209 27.3 23S 31.2] 44 44 City school, boys, Dresden . 6-14 368 736 [429 58.3 186 25.3 121 16.4] 44 City school, girls, Dresden . 5-14 364 726 [409 56.3 166 22.9 151 20 8] “ Girls school pupils, Dresden. 7-16 171 337 [187 55.5 95 28.2 55 16.3] Perhaps the same as No. 112. 2 The percentages foot up 110 per cent, through a typographical error. 3 Atropine. 11 No. Date. Examiner. Character of examined. Age. Persons. Eyes. Em. per ct. M. per ct. H. per ct. H. per ct. As. and A mb. 1878 Realscliule, Dresden .... 8-17 209 417 [204= =48.5 161 = =38.5 52- =12.4] Kreuzschnle, Dresden .... 9-21 554 1100 [460 41.5 554 50. 86 7.8] t< it Gymnasium, Dresden .... 9-21 480 953 [450 46.9 449 46.8 54 5.62] it 575 1150 283 24.6 865 75.2 2 0 17 9;> Derby, Hasket . College graduates, Amherst 21-26 254 87 34.3 120 47.2 47 18.5 96 Dobrowolsky High school pupils, Ural 212 [26] 12.0 (Homatropia) 97 Durr Lyceum pupils, Hanover [9-19] 345 46 13.3(7) 121 35.(7) 107 33.6 192 60.4 (Homatropia) 44 Seminary students, Hanover [16-20] 96 9 9.37 32 33.3 36 37.5 55 57.3 98 “ Real-Gymnasium pupils, Hanover [9-19] 271 81 30.4 (Homatropia) 99 Hansen .... Country school pupils, Kiel 10-14 80S 1610 26 1.58 51 3.4 1522 94.12 Amb. 6 100 Reich Girls’ institute pupils, Tiflis 173 40 23.1 57 33. 63 36.4 As. 13 “ Intantry school pupils, Tiflis 292 52 17.8 “ Military gymnasium pupils, Tiflis 252 61 24.2 49 19.4 129 51.2 As. 10 101 Motais Type-setters, Paris .... 97 10 10.3 31 31.9 21 21.6 As. 30 102 U Schtschepotjeff . Middle school pupils, Astrachan . 600 [4S2] 80.33 [99] 16.5 [17] 2.83 As. [3] 103 Schadow .... Primary scholars, Islaud of Borkuih . 6-14 146 292 44 15.1 2 0.7 240 82.2 104 Hadlow .... Naval training sch’l pupils, Greenwich 15 1074 60 5.8(7) (+2. 2.A ( >2- 105 Tscherning.... Recruits (educated), Copenhagen, etc. 2336 V.1825 78.12 / \420 18. ) v 91 3.9 ) /+2— -2\ ( >2‘ ( >+2' “ • • . . Recruits (uneducated), Copenhagen . 5187 V.4770 91.96/ V207 4. ) V.210 4.05/ 106 v. fieuss .... Railway employes, clerks, etc , Vienna 273 150 54.94 86 31.50 37 13.55 “ “ “ engineers, etc., Vienna 280 188 67.14 11 3.92 81 28.93 44 “ “ trainmen, Vienna 421 307 72.92 25 5.93 89 21.13 <« “ “ “ stationmen, Vienna . 554 376 67.87 30 5.41 148 26.71 \ 107 1884 Schleich .... Infants (newborn), Tubingen . '2h.-8d. s150 300 •o- 0'.- .0; 0. 300 >100. \ 1 Received too late for inclusion in summaries. 2 Re-examination, vide H 3 Corneal astigmatism was measured with the ophthalmometer of Java! & SchiOtz. 13 No. Date. Examiner. Character of examined. Age. Persons. Eyes. Em. per ct. M. per ct. H.m. per ct. H. per ct. As. and Amb. 108 1884 Schiifer Deaf-mute pupils, Heidelberg 9-18 95 21 = 22.1 7= 7.3 41=43.1 62=65.2 109 44 Seggel. Recruits (common soldiers), Munich . 20-24 1526 3052 1425 46.7 347 11.4 1239 40.6 41 il Recruits (volunteers), Munich 20-24 284 668 128 22.5 341 60. 71 12.5 (Atropine) 28 110 Cl Ulrich . # Infants (newborn), KOnigsberg . 4h.-14d. 102 204 0 0. 0 0. 204 100. (Atropine) 111 “ Bjerrum Infants (newborn) .... 7h.-14d. 87 23 26.5 3 3.4 61 70.1 ( + 1.- -1.) (> 1.) (>+!•) 112 Beselin [Becker] Girls’ school pupils, Heidelberg . 8-18 250 500 348 69.6 61 12.2 ? 75 15. As. 16 (+1— -1.) (> 1.) (•'” 4- !•) 44 44 Girls’ school pupils, Heidelberg . 5-18 369 738 482 65.3 62 8.4 r 154 20.8 As 40 113 44 Kotelrnan . Kalmucks, Hamburg .... 15-35 17 34 9 26.5 0 0. 25 73.5 114 44 Seggel Soldiers (militia), Munich 1118 2236 [11 SO 52.7] 44 44 Military cadets, Munich 350 700 [ 176 25.1] 44 44 Gymnasium pupils, Munich 208 416 [ 208 50.] 44 44 Girls, boarding school pupils, Munich 174 348 [ 141 40.5] (Atropine) 115 ii Horstmann. Infants (newborn), [Berlin] 7-21d. 50 100 10 10. 6 2. 88 88. (Atropine) 44 Ci Young children, [Berlin] l-2y. 50 100 10 10. 6 6. 84 S4. (Atropine) a 44 Young children, [Berlin] 4-5y. 50 100 13 13. 13 13. 74 74. 116 44 Fox Indian girls, pupils, [Carlisle] . 60 110 36 32.7 13 11.8 48 43.6 6 117 44 Van Anrooy • University students, Leyden 17-33 470 939 527 56.23 291 31. 114 12.15 Mix. As. 5 118 •< Del Carlo & PardinD Municipal scholars, Lucca 6-16 266 532 (224 ) 142 26.7 7 1.2 119 Cl Scellingo Boys, elementary scholars, Rome 5-10 76 152 ( 73) 6 4.— 5 0. 44 44 Boys, municipal scholars, Rome . 6-15 350 700 ( 515) 91 13. 10 1.4 it Girls, municipal scholars, Rome. 6-13 220 440 ( 295) 67 15.2 30 7. 120 44 Masini. Boys, municipal scholars, Sienna 7-15 352 704 ( 422) 81 11.5 2 0.3 44 it Boys, mun. scholars, Castelflorentino 7-12 102 204 ( 168) 16 7.8 2 1. 44 44 Boys, elementary scholars, Certaldo . 7-14 148 296 ( 221) 19 6.4 0 0. 121 44 Moyne . Girls, element, etc., Naples, etc. 3-30 722 1444 (1133) 190 13.1 14 1. 44 44 Boys, element, etc., Naples, etc. 6-22 1037 2074 (1752) 226 10.9 7 0.3 44 Boys, Lyceum, etc., Naples, etc. 7-19 415 830 ( 660) 131 15.8 1 0.1 122 44 Brignoui Girls, elementary scholars, Trapani . 8-15 156 312 ( 226) 57 15.+ 2 0.6 44 44 Boys, elementary scholars, Trapani . 6-17 389 778 ( 575) 95 12.2 0 0. 123 44 Hoffmann, A.2 . Lyceum pupils, Strassburg . 9-20 517 246 47.4 190 36.6 (81 15.6)? 121 1885 Schleich Upper Gymnasium pupils, Tubingen . 14-18 60 120 16 13.3 86 71.6 14 11.6 125 | “ Randall Medical students, Philadelphia . 19-34 90 ISO 32 18.8 17 9.44 (37 26.) 131 72.77 1 In this group of Italian investigations the optometer of Moyne seems to have been used and note made of only the absolute H. if any. 2 The II. was measured with the ophthalmoscope, whether it was sought with this means among the apparent Em. does not appear. 14 Let us now see how far the methods above sketched have been applied in the investigations which have been made; what results, positive and negative, have been obtained ; and how far we can formulate corrections for such as are incomplete, and by their application bring also the inferen- tial results to the elucidation of our subject :x— Beginning our study of the data given in the preceding tables by a summing up of all that can be employed on the subject of the frequency of Myopia, we find that we have available records of 115 investigations or groups of investigations :— Of 146,522 examinations (individuals or eyes) M. 28,483 = 19.44 p. c. Separating, now, those investigations giving us data as to all conditions of refraction, we have as the result of 88 investigations or groups of studies:— 90,886 exam.: Em. 43,174 = 47.73 p. c., M. 19,750 = 21.87 p. c., H. 25,635 = 28.46 p. c. In not a few of these cases the M. designates only apparent myopia, the Em. comprises all with normal vision, or at best those without mani- fest ametropia ;2 wThile under H. are included, for the most part, only the H. manifest—the cases where the H. total was sought being about coun- terbalanced by those in which only the H. absolute is given. Turning now to that series of studies in which H. total was sought and noted with care sufficient to obtain some approximation to it, and to exclude from M. the cases of spasm of accommodation simulating that anomaly, we gain the following results from 27 studies :— 16,160 examinations : Em. 3297 = 20.40 p. c., M. 2918 = 18.01 p. c., H. 9717 = 60.13 p. c. This is excluding Erismann’s 1889 = 43.3 per cent. H. m., Emmert’s 3308 = 77 per cent. H. m., Pfliiger’s 800 = 44 per cent. H. m., Seggel’s 1239=40.6 per cent. H. m., and many others with even higher percent- ages of II. m. It is also exclusive of Just’s work, since the 1660= 67. per cent, non-myopic eyes, although “almost all” hypermetropic are not with sufficient clearness stated to have been H.; and Weber’s, Tscherning’s, and Beselin’s work, although doubtless accurately done, is excluded for lack of full data as to the results obtained. 1 Lack of space excludes the detailed accounts of the methods and results of the individual investigations which were prepared to form the body of this paper: so also as to the tables of curves which would in some measure have supplied their place as to class-results, etc. The school totals are given in the tabulation which follows. Under Em. are included all not proven ametropic ; under M. all whose apparent myopia was not shown to be fictitious ; under H. m. all cases of hypermetropia mani- fest, whether absolute, facultative, or relative ; and under H. all, where any attempt 6eems to have been made to discover the total hypermetropia, as well as those where the methods employed are not given. Astigmatic eyes are included under H. and M. respectively, when recorded as H. As. or M. As.; under As. when not so specified. 2 Gardner found among 1082 pupils of Springfield, Mass., 81=7.5 p. c. M., 291 = 26.9 p. c. H. m. and 69 = 6.35 As. Report of School Committee, 1884. 15 Combining the cases where we obtain data as to the relations of normal vision, apparent Em. (t. e., absence of H. in.), and Em. probably such, we find:— 5347 examinations : V = 1. 4362 = 81.58 p. c., App. Em. 2578 = 48.21 p. c., Em. 147 = 27.51 p. c. although among the Em. here noted, are still many not adequately tested, if at all, for latent H. A similar comparison as to H. abs., H. m., and H. (generally ophthal- moscopically determined) gives :— 1378 examinations: H. abs. 59=4.29 p. c., H. m. 784 = 56.9 p.c., H. 1031 = 74.8 p. c. while in— 9344 examinations : App. Em. 4383 = 47. p. c., Em. 1742 = 18.6 p. c., H. m. 2076 = 22.2 p. c., H. 5284 = 56.5 p. c. if we include Just’s work, as well as others more definite. In 6873 ex- aminations where App. M. constituted 1911 =27.8 per cent., these figures were reduced to 1415 = 20.6 percent, by measures calculated to eliminate more or less completely the accommodative spasm. Similar comparisons could be made on many points ; but this is sufficient to show the direction and extent of the corrections which would have to be applied to many of the studies before us in order to approximate accurate results. The actual application of such corrections can hardly be profitably made, except to very extensive summaries, and even then with great reserve; yet we will probably be fully justified in claiming that, among the whole number thus far examined, more than 145,000 in all, not more than 20,000, or 14 per cent., were actually myopic. Similarly, of about 90,000 examined as to the relative frequency of the various conditions of refraction, some 22,000 were approximately Em. (25 per cent.), 13,000 M. (14 per cent.), 30,000 H. m. (33 per cent.), and 55,000 H. (60 per cent.).1 Leaving this field of conjecture, and turning to the data showing the refraction at various ages, we will first study the question of the refraction of the new-born infant. Eight investigations are on record :— Infants. Eyes. Em. M. H. 1861. v. Jaeger, (100+) 100 5 = 5 p. c. 78 = 78 p. c. 17 = 17 p. c. 1880. Ely, 111 154 21 14 “ 27 18 “ 106 69 “ “ Horstmann, 20 40 8 20 “ 4 10 “ 28 70 “ 1881. Konigstein, 281 562 10 2 “ 0 0 “ 552 98.2 “ 1884. Schleich, 150 300 0 0 “ 0 0 “ 300 100 “ “ Ulrich, 102 204 0 0 “ 0 0 “ 204 100 “ “ Bjerrum, 87 (87) 23 26.4 “ 3 3.4“ 61 70.1 “ “ Horstmann, 50 100 10 10 “ 2 2 “ 88 88 “ 901+ 1547 77 = 5 p. c. 114 = 7.3 p. c. 1356 = 87.6 p. c. All authorities are agreed that full paralysis of the accommodation by a mydriatic is an absolute essential in this difficult field of investigation ; and vve must accept Horstmann’s statement that this is attainable with 1 Study of the degree of refraction error, of anisometropia and of many other points of cardinal importance must be reserved for a later paper. 16 difficulty, even when employing a solution of atropim sulph. 1 :100. Jaeger’s work, done in the earliest days of the ophthalmoscope, probably lacked that exquisite skill in the use of the instrument which later distin- guished this master of ophthalmoscopy; and, further, was done without employment—certainly without the complete employment—of a mydriatic. His parallel work in the study of the dimensions of 70 eyes of infants after death, showed no instance of axial myopia; and the later studies force us to decide against his assumption of an undeveloped suspensory ligament or of a usual forward displacement of the lens, causing a tempo- rary myopia of the new-born—a view negatived also by the rest of his examinations of the eyes of older children. We must, therefore, exclude Jaeger’s study (albeit with much hesitation) as incompetent evidence in the matter before us. The need of “ full paralysis of accommodation” leaves room for questioning of the results obtained by weak mydriatic solutions, since Horstmann failed in at least 7 instances to secure even full dilatation of the pupil with 1 per cent, solution of atropine repeatedly used. Bjerrum’s finding of 23 Em. and 3 M. after (a single?) employ- ment of atropine (0.25 per cent, solution) cannot be considered conclusive; and Ely’s results of 17 per cent. Em. and 11 per cent. M. among 105 eyes under the influence of a solution (gr. ij ad fgj) of atropine, and 8.2 per cent. Em. and 32.6 per cent. M. among 49 eyes under a weak atropine solution (gr. j ad Oj) must be similarly viewed. Accepting them condi- tionally, however, and doubling Bjerrum’s figures to obtain the number of eyes studied by him (a procedure apparently justifiable), we gain as the result of these studies, exclusive of v. Jaeger’s :— Of 1534 eyes of infants, Em. 95 = 6.19 p. c., M. 39 = 2.54 p. c., H. 1400 = 91.26 p. c. Only the 6 myopic eyes of Ilorstmann’s two studies can be considered as well-established cases of M.; yet the success of Konigstein and Ulrich with atropine (0.1 per cent.), and of Schleich with 0.5 per cent., in doing away with all apparent M. in their studies, lends confirmation to other results where weak mydriatic solutions were employed. Passing on to the consideration of the refraction of children more developed, but not yet of school-age, we find, exclusive of v. Jaeger’s work, only four investigations. Eyes. Em. p.c. M. p. c. H. p.c. Koppe, Kindergarten pupils, 30 Horstmann, children : 60 1 = = 1.7 0 = 0 59 = 98.3 (8-24 months), 57 96 13 13.5 9 9.4 74 77 (1-2 years), 50 100 10 10.10 6 6 84 84 (4-5 years), 50 100 13 13 13 13 74 74 Total children (8m.-5yrs.), 187 356 37 = 10.4 28 = 7.86 291 = 81.75 1 Koppe’s results in the Kindergarten are impeached by himself, since he may have been measuring his own hypermetropia and not that of the observed eye. All but 18 17 Proceeding now to the other end of the scale of life, we find the one study of Cohn on the eyes of aged persons, mountaineer villagers in Silesia:— 100 persons (60-84 years), 200 eyes, Em. 49 = 24.5 p. c., M. 25 = 12.5 p. c., H. (m.) 114 = 57 p. c. ? 12 = 6 p. c. A study of much interest, but of insufficient extent to be conclusive, while the individuals tested were within the region of the “ hypermetropia aquisita,” and of myopia due to the cataractous swelling of the lens, the “second sight” of common parlance. The other investigations of the eyes of adults have generally more bearing upon the question of the ophthalmic hygiene of various handicrafts than upon our subject, until we reach the investigations of the eyes of recruits, almost invariably young men from 20 to 24 years of age. Considering only the common soldier, whose eyes have been subjected to primary school-work alone, examinations as to visual acuity have been extensive and interesting. Thus Herzenstein found among 27,682 men of various arms, binocular vision above normal with Junge’s test-types in from 71.6 per cent, to 76.6 per cent, of various garrisons about Orel and Cracow ; while Rumschewitsch among 9882 recruits in the Kiew district, found 70 per cent, with V. = — to XL XL 26.4 per cent, with — to — 4 per cent, with V. = — to — and 0.6 XL XL XL XL 1 20 with Y — to —-,1 The examinations bearing more strictly upon the refrac- XL XL tion are numerous, but rarely of both convincing accuracy and fulness.2 Seggel’s study of the common soldiers of the Munich garrison is about the only one fully competent in its testimony, and from its extent it can well stand alone. 1526 common soldiers, 3052 eyes, Em. 1425 = 46.7 p. c., M. 347=11.4 p. c., H. m. 1239 = 40.6 p. c., Amb. 41. Allowance must, of course, be made for the cases with latent H. among those noted as Em. in order to approximate full accuracy; a correction which cannot, however, be accurately formulated. eyes, however, appeared H. >1. D., the amount which he estimates that he mani- fested in this investigation, and only 2, including the 1 Em., were H < 1. D. The Kindergarten and El. pupils were examined by the ophthalmoscope alone. In the other schools he obtained (counting As. with M. and H.) :— by glasses, 989 pupils, Em. 219=22.1 p. c. M. 269 = 27.8 H. m. 501 = 50.7 p. c. by ophthal. 1059 “ “ 188=17.7 “ M. 240 = 22.6 H. 606 = 57.2 “ by oph. and gl., 1059 “ “ 112 = 10.6 “ M. 220 = 20.8 H. 711 = 67.1 “ 1 The question as to the illumination under which these results were obtained is all- important ; yet many investigators are strangely silent in this regard. In sunlight 120 20 — would indicate no sharper vision than in a well-lighted room. XL xv 2 Ljubinsky is cited (Nagel’s Jahresbrt. xiv. p. 195) as having found, among 7312 sailors, Em. 48.7 p. c., M. 28 p. c., II. 43.1 p. c., and As. 2.2 p. c. (120. p. c.). 18 Of the data that remain all are complicated by the question of “ school myopia,” into which it is impossible here to enter. The persons examined were pupils of schools of every grade, generally fully engaged with their school-work, and showing at once the temporary and the permanent marks of its effect upon their eyes. Yet much information can be obtained from their study, and we will proceed to a rapid review of the refraction in the schools of various gradesr-— Summing up, as before, the results of the twenty-six investigations as to myopia, we learn that in 23,315 examinations 1582 = 6.79 per cent. M. were found. A discrimination between the real and the apparent M. in these results would lower somewhat the M. percentage, although the figures of the first two studies on the list contain no myopes below 1. D. in grade, and the last study, only those greater than 1. D. Passing to the other conditions of refraction we find— In 22 investigations 13,929 examinations : Em. 857 = 63.59 p. c., M. 1582 = 11.36 p. c. H. 3764 = 27.01 p. c. “10 “ 3,358 “ Em. 491=14.62 p.c., M. 137= 4.08 p. c. H. 2564 = 76.06 p. c. In the second series are placed those studies in which the H. t. was sought, although in Beselin’s work only the II. > 1. D. is reported, and here are also included Just’s results, although not entirely definite in their statement—any error in the one being probably neutralized by the other. From five investigations, exclusive of Just’s, we obtain:— 1835 examinations: App. Em. 767 = 41.79 p. c., Em. 371=20.22 p. c., App. M. 126 = 6.86 p. c., M. 58 = 3.16 p. c., H. m. 970 = 52.86 p. c., II. 1368 = 74.55 p. c. These figures comprehend the results of Cohn’s study in the mountain village of Schreiberhau, in Silesia, when atropine (in substance) was em- ployed in most of the eyes. As various critics take diverse views of the question of the refraction under mydriatics, a few remarks upon the subject seem in place. Donders’s definition of refraction fittingly opens the sub- ject : “ By refraction of the eye, we understand its refraction in a state of rest; that is, the refraction which the eye possesses in virtue of its form and of that of its component parts, independently of muscular action, inde- pendently of accommodation. The term, therefore, applies to the refrac- tion of the eye whose muscles of accommodation are inactive or paralyzed (for example under the influence of atropia), to the refraction also of the dead but as yet otherwise unaltered eye.”1 In discussing emmetropia, how- ever, Donders assumes a 11 tone of accommodation” which can be done away only by a mydriatic, and concludes with the often-quoted expression: “ Consequently, the actually emmetropic vision requires in a certain sense a minimum of H., and that minimum is capable of no accurate taxation, because to the tone itself a certain latitude, perhaps from to must be allowed.” Whether his view on this point remains unchanged we do 1 Donders, Accommodation and Refraction of the Eye, p. 80. (Italics ours.) 19 Examiner. Examined. Age. Pupils. Eyes. Em. per ct. M. per ct. Hm. per ct. H. per ct. Cohn Cohn Erismann Cohn v.Hoffmann . Callan . Conrad . Spalding Pfliiger . Emmert. Loring & Derby Koppe . Koppe . Haenel . Just Smith . . Netoliczka Dennett . Florscliiitz Florschiitz v. Reus6. Risley * . Borthen . Mitteudorf & Derby Nordenson Schadow Beselin . Country Primary City Elementary City Preparatory Village Primary City Preparatory Negro Primary City Preparatory City Primary . City Primary . Elementary City Primary . City Elementary City Preparatory City Primary (classes) . City Primary . City Board School . City and Village Primary Village Primary City Primary, 1873 . City Primary, 1877 . City Primary . City Primary . Common .... City Primary . City Primary . Country Primary City Primary . 6-13 6-14 6-13 ey2-9y2 6- [6-9] 6-10 7- 6-12 6-12 7-13 4- 6- [6-15] 6-11 5- 7- 7-13 6- 5-9 1486 4978 59 (240) 249 270 1200(-f) 808 367 (103) (136) 682 (281) 1636 4934 530 1476 1616 257 (164) 133 203 79 (146) 131 480 568 "734 410 206 272 1364 562 328 192 1408=94.7 4245 85.3 11 18.6 14 3. 147 59. 18 6.6 155 27.3 383 84.9 103 14. 348 84.9 53 25.7 37 14. 784 57.47 (433 77. \ VO? ' 430 81.1 1053 71.3 129 40.4 23 7.01 64 48.1 [162 80.] 61 77.2 44 15.1 70 53.4 22= 1.4 334 6.7 8 13.6 4 0.9 4 1.6 2 0.84 28 5. 84 7. 27 3.35 32 4.86 28 6.8 5 2.4 20 7.5 226 16.68 59 10.5 86 5.3 493 10. 21 3. 198 13.4 90 5.57 29 11.2 13 4. 8 6. 6 3. 5 6.3 2 0.7 4 16= 1.1 127 2.5 40 67.8 370 77. 13 5.2 213 78.9 101 17.6 409 50.6 596 81.2 34 8.3 173 70. 348 25.49 59 10.5 58 10.9 60 4.1 99 37.1 61 45.8 35 17. 13 15.2 438=91.2 88 31.3 250 92. 383 67.4 126 61.1 209 78.5 [492 87.5] 289 88.1 240 82. 49 37.4 M. > 1. D. M. > 1. D. Atropine. ( Am. > 1, ( Em.=+1.—1. Elementary Schools, etc. 20 not1 know; but can hardly imagine so careful an observer to be still in error on this simple point. The question before us is whether this com- mon residual tension is an organic tonicity or an habitual action. That no such “ tone” is ascribed to the myopic eye is curious, if the first suppo sition holds good. Is there, then, in the eye, a tension of the accommoda- tion which cannot be voluntarily relaxed ? It may be confidently asserted that an emphatic negative will be given by every observer who has care- fully tested the matter. The assumption of such a “ tone,” like the hypothesis of negative accom- modation—really another phase of the same question—lacks the first posi- tive proof in its support. Negative evidence alone, cases of habitual spasm of the accommodation, can be adduced in its favor; and a single positive fact, did it stand alone, would scatter such support to the winds. The investigation before us fully answers the question, although its testimony has been generally overlooked. Cobn states: “ In 34 cases with If. m. in degree from to there was no slightest increase of the H. after atropi- nization.” It may be remarked that full paralysis of accommodation was proven to have been attained in these cases, although in four others who remained apparently emmetropic, Acc. = T15, and respectively* was found remaining. Similar proof, were any needed, would be found in the investigations of Roosa (53) and Durr (98). How two opinions on the subject can exist is the only matter of surprise to the writer, who has in hundreds of cases given the full correcting-glass as determined under a mydriatic pushed to complete paralysis of accommodation (and seen it done in thousands), and has rarely seen it necessary to reduce the strength of the glass because of persisting recurrence of the habitual spasm.1 His own low II., twice measured under full mydriatic paralysis, is entirely relaxed at will, and always taken into account in ophthalmoscopic mea- surements. The only noteworthy point, therefore, as to the admission of Cohn’s atropine work in our present study, is that especial weight is to be given to its showings, since in it was employed a means of accuracy lack- ing in others. The group of schools in which were found the results which have been given, practically represent the first three years of school-life; and it is from this point that the course of the German Gymnasium takes its start. Intermediate schools exist in Germany as well as elsewhere, but they differ as to the upper limit of their curriculum, and in the aims and the class of the pupils attending them, rather than in the age of their scholars. While the distinction between these and the gymnasia is, therefore, very important in its bearing on the question of school-myopia, to our investi- 1 The necessity, or, indeed, the advisability, of carrying this matter in practice to its extreme logical conclusion is a point which most ophthalmologists are by no means prepared to admit. Its practicability is the only question here raised, and is, in he writer’s opinion, too fully demonstrated to need more extended proof. 21 Examiner. Schools. Age. Per- sons. Eyes. Em. p.c. M. p.c. VIII. VII. VI. V. IV. III. II. I. Hm. p. c. H. p. c. 10-22 1141 816- =75.9 225=19.7 16= = 9. 44=16.7 51=19.2 50= =25.1 41=26.4 23= =44. j44 9 =1.9 2.9 Gymnasia, Gymnasium, Gymnasium, Various, Gymnasium, Gymnasium, Gymnasium, Gymnasium, Gymnasium, 9-22 1195 866 72.5 314 2«.2 31 12.5 41 18.2 52 23.7 73 31. 61 41.3 54 55.8 41. Thilenius ... 314 431 175 55.7 96 30.6 159 36.9 11. 16. 33. 36. 40. 1=14.3 16= =26.2 10 15.4 22 36.7 13 26. 20 44.4 45 53.6 32 54.2 Erismann ... 6-22 4239 361 203 1110 187 25.6 52. 1284 29.7 125 35. 124 5 15.8 13. 197 13 22.4 21. 262 14 30.7 27. 228 21 38.4 55. 206 33 41.3 52.4 157 27 42. 60. no 12 42.8 42. 1825 43. 25 7. 83—20.6 9J-I9 9i-19 406 159 39. 162 40. 6.7 22.2 51.7 26. 37.5 55. 71. 25 53 22 [101 158 69 19.7] 19.3 17.7 171 33.8 [184 ] v. Hoffmann, v. Reuss .... v. Reuss .... 256 409 389 512 818 140 243 144 27.3 29.7 37. 187 36.5 375 45.8 166 42.7 •••• 16 19. 41. 37. 28 23.7 49. 42. 21 28.4 48. 46. 22 32. 40. 45. 52.1 50. 55. 63.3 61. 69. 52.5 58. 75. Ott & Ritz- Gymnasium, Realschule, 122 164 430 244 124 51. 96 39.3 [15] 19 26.8 [25] 40.3 [161 30. [IS] 47. [14] 54. [7] 58. 24 10. ? 12-14? 10-19 324 146 279 45. 64.9 37 11.1 125 29. 14 13 8 5 14.5 4 12.9 122 37.7 ? 5 11.6 17.1 19 28.1 19 26.4 23 34 9 23 41.1 12 40. 11 58. 18 4.18 1058 42.9 Gymnasium, Grammar, 9-20 1234 2468 754 30.55 650 26.34 36 8.7 54 14.3 SI 18.6 200 34. 155 37.4 124 51.7 256 10.37 Spalding.... 10-15 inonc-i-t [160] 16. 151 15.1 11-23 1005 439 43.9 14 6.3 12 5.8 20 10. 22 14.4 26 26.6 23 34.5 34 67. 404 2712 40.4 Various, Various, Latin classes Gymn. “ Gymn. Gymn. Realschule, Realschule, Gymnasium, College, Techn. Inst. Coll. Freshm. Coll. Freshm. Gymnasium, Paedagogium Lyceum, Gymnasium, Gymnasium, Gymnasium, 1781 3562 1855 448 298 792 319 1183 134 53 75 8.95 63.8 29.9 17.8 9.7 510 14.3 420 22.6 155 34.6 216 72.5 200 26. 76.1 Loring & 252 13.6 ? Scheiding.... Scheiding 224 199 396 21 21.8 30 25.8 44 41.5 46 42.6 14 63.6 59.6 28 6.25 56 57 75. 50 80.6 53 80.3 29 9.7 18 14 32 31 41 33 31 61.2 328 44.2 502 64.5 s-2i 413 232 402 287 549 300 122 240 58. 157 38. 14.7 22. 45.3 40.2 48.2 10 2.4 Kotelmann.. [60] 26. [166] 41.29 >1. D.? 100 35. 333 30.3 79 12.5 36 29.5 16 21. 32 29. 45. 45. 29. 24. 40. 46. 71. 50. 154 651 372 53. 59. 62. 4. 100. >1. D? 33 12. Agnew [Cheatham] [Prout & Mathewson] Derby, Has- ket 1097 600 179 26.7 71 35. 35 30.7 30 60. 18 37.5 105 9.6 ? 126 21. ? 15-24 321 325 388 145 45.2 114 35.9 [318] 49. [340] 44. 568 28. 67 20.9 ? Niemann.... Niemann.... 650 776 2032 23. 29. 39. 63. 58. 75. 23. 27. 42. 47. 56. 70. 7-21 1300 64. 22 10.3 51 19.6 69 21.3 1S5 42.6 175 39.6 63 18.1 87 4.2 120 177 480 240 354 960 90 37.5 nifi 40 91 98 40.8 209 59.3 52 21.6 ? 55. 65. 1 9-21 450 46.9 449 46.8 44 31. 59 33.7 83 47.9 75 48.1 46 54.8 89 62.2 53 68.8 54 5.62 9-21 554 1108 460 41.5 554 50. 24 29.6 47 35.1 73 47.4 78 51.3 72 46.7 152 61.5 10S 60.7 86 7.76 Realschule, Seminary, 8-17 13-21 209 218 418 436 204 164 48.5 37.6 161 38.5 23 63.9 8 25. 23 25.8 73 56.1 28 31.1 13 26. 16 61.5 52 12.4 Haenel 49 47.6 57 67. 42 50.6 31 59.6 32 64. 25 56.8 32 7.6 22 Examiner. Schools. Age. Per- sons. Eyes. Em. p. c. M. p. c. VIII. VII. VI. V. IV. III. II. I. Hm. p. c. H. p. c. 13-20 131 262 103 = -39.3 134= -51.1 22= -37 9 23= -40.3 24= -54.5 16= -40. 21= -SO.8 28= -77.7 24- - 9.2 8-16 1035 2060 1028 49.9 612 29.7 76= =25.2 139= =24.4 109 22 8 156 36 2 132 39.5 420 20.4 194 388 (167 40.4) 195 50 3 37 1 23 32 8 21 39 48 52. 38 76. 39 67.2 27 7. [193-49.7] 293 586 (264 45 ) 266 45.4 °3 28 31 29 2 35 38-8 46 52.3 87 58. 44 62. 24 4.1 [296 54.6] Kotelmann.. Gymnasium, 8-17 2S3 566 1S2 31.6 no 19.4 12 9.5 23 18.2 27 22.1 32 22.2 14 35. 2 25. 273 48.8 1S-23 357 72 20 10-19 603 424 70.3 74 12.3 23 9.8 19 10.5 18 16.5 10 19.6 3 33.3 76 12.6 ? 6-18 203 406 36 8.9 52 12.8 318 78.3 Florschfltz .. Gymnasium, 9-20 177 72 40.7 91 51.4 24.2 37. 49. 69.7 12 85.7 7 77. 6 3.4 Florschiitz .. Realschule, 10-18 260 122 47. 110 42.53 33. 33.3 47.5 37.5 55.5 62. 5 1.9 “ 1877, 290 101 34.8 19 65.5 Gymn. 1877, 182 90 49.4 18 66.6 Florschiitz .. Seminary, 17-20 44 16 36.4 472 242 51 2 69 14.6 161 34.1 509 1018 355 34.8(4- 403 39.6(? 72 7.07 [105 + ] 354 70S 3/i.3/-L 245 34.6(7 50 7.06 [ 70 + ] 9-21 1048 2094 249 11.4 319 15.2 1505 71.9 Westphal... Gymnasium, 149 298 133 44.6 149 50. 11 32. 23 .35. 27 54. 38 54. 28 54. 22 85. 16 5.3 Netoliczka .. Realschule, 254 136 53.5 75 29.5 15 26.8 7 16.3 8 21. 12 29.2 7 31.8 15 46.9 11 50. 35 13.8 Netoliczka .. “ &Gvmn. 1225 376 30.7 49 51 38 47 54 53 58 26 “ &Gymn. 417 183 43.9 88 21.1 147 35.2 Mittendorf & 698 [162 80] 60 8.5 [84] 12. Mittendorf & S96 119 13.5 Mittendorf & 201 [111 55.] 69 35. [20] 10. Nordenson... Lyceum, 10-20 147 97 66? 32 21.8 2 8.3 3 13. 2 11.7 6 23. 4 23.5 5 25. 10 75. 18 12.2 [487] 141 29. 5 6.8 14 IS. 13 16. 45 33.1 39 50. 25 54.3 [280] 52 18.5 7 11. 13 17. 11 19. 6 17. 11 36 4 24. Secondary', [603] 74 12.2 0 0. 10 4.7 23 12.1 21 17.1 20 25.6 Dobrowolsky l212j [23] 12. Homatr’p Durr Lyceum, [9-19] 318 25 7.86 101 31.7 9 15.5 12 8 11 22 33 23 107 33.6 192 60.4 Homatr’p Seminary. [16-20] 96 9 9.4 32 33.3 11 11 10 36 37.5 55 57.3 Diirr Real-Gymn. [9-19] 271 81 30.4 2 12.5 9 18. 8 16. 15 38.5 23 33.9 22 50. 22.2 Homatr’p 10-14 808 1610 26 1 58 51 3.4 4 1. 11 3. 10 3 10 3.9 16 6. 1522 94.1 Reich Girls’ Inst. 173 40 23.1 57 33. 1 17. 53. 63 36.4 Reich Mil. Gymn. 252 61 24.2 49 19.4 6.7 60. 129 51.2 +!•- -l.D. >1 D. >1. D. Becker S-18 250 500 348 69 6 61 12.2 75 15. +1- -l.D. >1. D. >1- D. Beselin 8-18 607 412 67.9 58 9.5 105 17.3 Hoffmann... Lvceum, 9-20 517 246 47.4 190 36.6 22 18.2 17 20.2 38 38.8 36 35.9 40 65. 35 67.3 ? 81 15.6 Schleich Upper Gymn. 14-18 60 120 16 13.3 86 71.6 14 11.6 23 gation it is hardly more than incidental. We will group these institutions, then, by the side of the so-called “higher schools,” which aim at liberal education ; only premising that we are dealing now with pupils between the fourth and the twelfth school year, or between about the ninth and the eighteenth years of life^-— Combining the foregoing figures, we find as the result of examinations as to myopia in 50 gymnasiums and lyceums, 14 realschule, 7 seminaries, and about 50 other schools :— In 55,342 examinations (individuals or eyes) 14,907 = 26.94 p. c. myopic. Studying, now, those in which all conditions of refraction were sought, we obtain :— In 42,763 exam. Em. 15,996 = 37.40p. c., M. 11,757 = 27.49 p. c., H. 13,145 = 30.74 p. c., the H. probably here, as before, fairly representing the manifest hyper- metropia, and the other figures the apparent myopia and apparent emme- tropia, respectively. In the studies where the H. t. was sought, we find:— In 9965 examinations Em. 2159 = 21.66 p. c., M. 2149 = 21.56 p. c., H. 5587 = 56. p.c., Here Just’s results are again excluded, as well as those of Weber, of Becker, and of Beselin, where the figures given are confessedly incomplete and not available for our purpose ; while Erismann’s 1825 = 43 per cent. II. m., Pfliiger’s 404 = 40 per cent. H. m., Emmert’s 2712 =76.1 per cent. H. m., and Kotelmann’s 273 = 48.8 per cent. H. m. are, of course, omitted. Studies of the relations of normal vision, apparent Em. and Em., of appa- rent M. and M., and of II. absolute, H. manifest and H. total, give re- sults closely similar to those already set forth, and need not be here repeated in detail. The data as to students of more advanced grade are limited, but doubt- less worth summarizing:— Age. Persons . Eyes Em. M. H. m. Cohn, Univ. of Breslau, 17-27 410 134 =32.7 p. c 244 =59.5 p. c. 15 =37. p. c Cohn, Medical students. 108 216 81 37.5 “ 116 54. “ 19 8.8 ‘‘ Gartner, Theol. “ Tubingen, +19 713 1426 324 22.9 “ 1096 76.9 “ 2 0.2 “ Derby, H., Graduates, Amherst, 19-28 254 87 34.3 “ 120 47.2 “ 47 1S.5 “ Collard, Univ. of Utrecht, 17-38 410 820 389 47.4 “ 286 35. “ 158 19.2 “ Van Anrooy, Univ. of Leyden, 17-38 470 939 527 66.23 “ 291 31. “ 114 12.15 “ Randall, Sled, students, Phila. 19-31 71 142 51 54 10.5 “ 37 26. “ 17-38 2436 4207 1593= =37.86 p.c. 2207= =52.46 p.c. 392 =9.31 p. c In the first examination of this series H. abs. alone was noted; in the others the II. manifest was sought, but only in that of the writer, which ends the list, does the attempt seem to have been made to find the H. total by the ophthalmoscope or other means. In this last case the results were:— 71 Persons. 142 Eyes. Em. 30 = 21.1 p. c. M. 17 = 12.4 p. c. H. 93 = 65.5 p. c. And for all— 90 Persons. 180 Eyes. Em. 32 “ 18.8 p. c. M. 17 = 9.44 p. c. H. 131 - 72.77 p. c., figures in marked contrast to those above. 24 Looking backward over the long array of investigations which have been here grouped together, a few words of general comment seem per- missible before passing to our conclusions. It is very evident that the majority of the studies cited can make no claim to being the unimpeach- able foundation for our investigation of the refraction of the human eye; indeed few have been undertaken with the solution of any such question in view. The details of the methods employed in each examination would make clearer, perhaps, than is now the case, the true status and value of each ; but lack of space excludes them, and the writer is unwill- ingly forced to group the studies and marshal their results as his study of the original data indicates is correct, and to set them forth apparently solely upon his own authority. Careful study of the original records will show, however, that the records have been in no instance classified, recast, or emended, arbitrarily; and if any judgment has been passed not fully upheld by the data furnished by each investigator, it has only been in holding as competent some of the investigations which are not a priori clearly self-condemned. In view of the great preponderance of the hyper- metropic refraction in all investigations where its presence has been sought with a care in any degree adequate, it must be as evident to others as it is to the writer, that many of the studies giving low percentages in this matter cannot be correct. Such a conclusion, however, would by many be deemed a result of reasoning a posteriori, and has not been here drawn. For the figures given, unimpeachable accuracy cannot be claimed, especially when the sources from which they are derived are rarely free from palpable errors ; and confusion and error are too easy of entrance to have been entirely excluded in the writer’s own work. All that repeated careful revision and verification can do has been sedulously employed to secure correctness, and where possible the data have been submitted for verification to the investigators themselves, to many of whom the writer’s thanks are therefore due. It is then evident, that for the solution of the broader questions of the prevailing condition of refraction and other similar generalizations, few of the investigations thus far made are fully available; and it is to be hoped that future students of the subject will recognize these shortcomings and furnish us with fuller, broader, and more accurate data. The oppor- tunities to employ mydriatics in extensive studies will continue to be very rare ; it is therefore incumbent upon those who shall have such chances, if they would contribute fully to the elucidation of this important subject, to furnish at the same time data as complete as possible as to the vision without and with glasses, the accommodation and the apparent re- fraction, before the mydriatic, as well as the intraocular condition and the functional comfort of the eyes; and to furnish proof, where possible, that the mydriatic had been pushed to full paralysis of accommodation. Thus only can the strict requirements of the subject be met. For those 25 who are debarred from the use of mydriatics, combination of all other methods of study is necessary, if they desire to render as slight as possible the doubt which must always attach to determinations of the refraction made in eyes with unparalyzed accommodation. The following conclusions seem fully upheld by the results of the investi- gations thus far made:— 1. Myopia is almost unknown in infancy and very infrequent before the beginning of school-life. In the earlier school-years its percentage is still low and it is only in the advanced classes, especially of the German schools, that it ever attains to a preponderance. It has been found in not more than 39 = 2.54 per cent, of 1534 eyes of infants, in not more than 28 = 7.86 per cent, of 356 eyes of children under the school-age, and in only 1582 = 6.79 per cent, of 23,315 eyes of children examined during the first three school-years—figures which more accurate methods might have made lower. Among 3052 eyes of young men, upon whom the school influence had not been excessive, it was found in 347 = 11.4 per cent—a percentage which probably oversteps the maximum which it is likely to attain outside of the schools. 2. Hypermetropia is the enormously preponderating condition in infancy and early childhood, and the first years of school life witness little reduc- tion in its proportion. Outside of the schools it remains by far the most frequent refraction throughout life, and in the schools it is decreased by the change of eyes to the myopic refraction in a degree apparently vary- ing according to the circumstances calling into existence that defect. It was found in 1400 = 91.26 per cent, of the 1534 eyes of infants exam- ined, in 291 = 81.75 per cent, of the 356 eyes of young children, and in 2564 = 76. per cent, of the 3358 eyes of children in the elementary school years, among whom it was sought with adequate care. So also in the higher schools, it constituted at least 56 per cent, of the whole number of eyes studied by competent methods, being found in 5587 of the 9965 examined. 3. Astigmatism has been rarely sought with care, and the data with regard to its frequency are not sufficiently wide to justify definite conclu- sions. The findings of the studies where it has been well looked for, concur with the clinical work in indicating a measurable degree of astig- matism (0.5 D. or more) in the majority of ametropic eyes. 4. Emmetropia in a mathematically strict sense has probably no exis- tence. Approximate emmetropia (Am. is infrequent in all ages, probably at no epoch exceeding 10 per cent. Its apparent proportion is swollen by the array of eyes “ not proven” ametropic, and we have but few studies where the accommodation has bden with certainty set aside and its existence fairly well shown. Cohn among 299 atropinized eyes proved in no single instance its presence. Under homatropine Hansen found it in but 26 of 1610 eyes, and Diirr in 30 of 414 eyes: it consti- 26 tuted at most GO = 2.6 per cent, of these 2323 eyes. Among the infants and young children 135 = 7.36 per cent, of the 1834 examined under atropine may have been emmetropic ; and Roosa’s brief study indicates that it is probably as rare in adult life, even when perfect function appa- rently proves its presence. 5. The question of what is the normal refraction of the human eye is still an open one, and further material on the subject and closer study of the data in hand will be necessary before drawing conclusions as to it. Much light will be thrown upon the question by studies like Risley’s of the relations of normal vision, intraocular health, and functional comfort, to the refraction. For the present the conclusion of this author, whose work stands almost alone, may be accepted. “ The emmetropic is the model or standard eye—since emmetropia is shown not only to remain nearly constant in percentage throughout the school life, but that it is also the condition of health, and withal enjoys the highest acuity of vision and the greatest freedom from pain.”1 Yet hypermetropia is the prevail- ing—almost the exclusive—condition of the refraction among most animals, among children, among uncivilized peoples, and among all eyes uninjured by the educational process. 1806 Chestnut St. Bibliography. 1. James Ware. Observations relative to the near and distant sight of different per- sons. Philosoph. Trans. Royal Society, London, 1813, i. p. 31. 2. Szokalski. Ueber die hygienische und therapeutische Anwendung des Schutz- brillen Vierteljahrschrift f. d. prakt. Heilkunde, Frag. 1848, p. 139. 3. J. II. Schurmayer. Handbuch der medicinischen Policei, 2d ed. Erlangen, 1856. 4. 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Die Augen der Uhrmacher, Goldarbeiter, Juweliere und Lithographen, Centblt. f. pr. Augenh., Apr. 1877. 48. H. Dor. Etude sur l’Hygiene Oculaire au de Lyon, Paris, 1878. Reprint, Lyon Medical. 28 49. A. Ott. Myopie und Schule, Corrbl. f. schweiz. Aerzte, Nos. 15 and 16,1878. 50. Seggel. Die Zunahme der Kurzsichtigkeit an den hoheren Unterrichtsanstalten, Munich, 1878. 51. M. Reich. Einiges fiber die Augen der Armenier und Georgier in den Scliulen von Tiflis, Arch. f. Ophth., xxiv. 3,p. 231,1878. 52. Burchardt. Ueber die Verhfitung der Kurzsichtigkeit, Deutsch. Med. Wochensch. No. 1, 1878, p. 6. 53. D. B. St. JohnRoosa. An examination under Atropine of the refractive state of eyes with normal vision, etc., Trans. Am. Ophth. Soc., ii. 4, p. 462,1878. 54. . Kurzsichtigkeit unter den Schiilern in Hessen, Deutsche Z. f. Prakt. Medicin, No. 13,1878, Nagel’s Jahresbrt., ix. p. 418. 55. Haenel. Kurzsichtigkeit in Dresdener Schulern, Festschrift, Dresden, 1878. 56. Hasket Derby. Influence on the Refraction of Four Years of College Life, Trans. Am. Ophth. Soc., 1879. 57. Horstmann. Ueber Refractions-Verhaltnisse von Kindern. Kl. Monatsbl. f. Augenh. Supl. 1879. 58. Eugen Netoliczka. Untersuchungen fiber Farbenblindheit und Kurzsichtigkeit, Graz, 1879. Abstract, xxviii. Jahresb. d. Steierm. Landes-Oberrealschule. 59. O. Just. Beitrage zur Statistik der Myopie und des Farbensinns, Arch. f. Augenh., viii. p. 191, 1879. 60. Nicati. La Myopie dans les Ecoles de Marseille, Gaz. Hebdomadaire, p. 695,1879. 61. Kotelmann. Die Augen von 9 Lapplandern, etc., Berl. Klin. Wochensch., No. 47, 1879. 62. Kotelmann. Die Augen der Gymnasiasten und Realschuler in Wandsbeck, Program d. Gymn. 1879. 63. Priestley Smith. Shortsight in Relation to Education, Birmingham, 1880. 64. Ed. T. Ely. Ophthalmoscopic Observations upon the Refraction of the Eyes of newly-born Children, Archives of Ophthal., ix. p. 29,1880. 65. Horstmann. Examination of the Eyes of newly-born Children, Centralblatt f. p. Augenh. Oct. 1889, p. 327. 66. Wm. S. Dennett. Report of Examination of Eyes of the Pupils in Schools of Hyde Park, Hyde Park, Mass., 1880. 67. ) B. Beheim Schwarzbach. Ueber Yorkommen und Behandlung von Augenkrank- 68. > heiten, in ausserefiropaischen Landern, Inaug. Diss. Wurzburg, 1880. 69. E. Emmert. Auge und Schadel, Berlin, 1880. 70. B. Florschfitz. Die Kurzsichtigkeit in den Coburger Schulen, Coburg, 1880. 71. Herzenstein. Die Untersuchung der Augen bei Schulern des Militar-gymnasiums zu Orel. Mil. Sanitat Jaunr. No. 11. Centralbl. f. p. Augenh. 72. Schillbach. Examination of the Eyes of Pupils in Gymnasium of Jena, Jahresbrt. d. Gymn. Jena, 1879 and 1880. 73. E. Netoliczka. Untersuchungen fiber Farbenblindheit und Kurzsichtigkeit, ii. Graz, 1880. 74. L. Konigstein. Untersuchungen an den Augen neugeborener Kinder, Med. Jahr- buch, i. p. 1, Vienna, 1881. 75. H. Cohn. Die Augen der Medicin-studirenden, Med. Jahrbuch. i. p. 21, Vienna, 1881. 76. A. v. Reuss. Augen-Untersuchungen an zwei Wiener Volksschulen, Wiener Med. Presse, Nos. 7 and 8,1881. 77. M. Weber. Beitrag zur ophthalmologischen Schulhygiene, Inaug. Diss., Berlin, 1881. 78. S. D. Risley. Weak Eyes in Public Schools of Philadelphia, Trans. Penna. State Med. Soc., p. 789,1881. 79. Badal. Examen des Yeux des deux cents Sourdes-Muettes de l’Institution Na- tional de Bordeux, Annales des Maladies de l’Oreille, du Larynx, etc., vii. 4, p. 198, 1881. 80. Q. C. Collard. De Oogen der Studenten aan te Rijks-Universiteit te Utrecht, Inaug. Diss., Utrecht, 1881. 81. Aug. Westphal. Untersuchung der Augen der Gymnasiasten, Jahresbrt. d. Gym- nasium zu Schleiz, p. 26, Schleiz, 1881. 82. Eug. Netoliczka. Untersuchungen fiber Kurzsichtigkeit an den Grazer Mittel- schulen, xxx. Jahresbrt. d. Steierm. Landes Oberrealschule. 29 83. Reich. Die Augen der Zoglinge des Tiflis’schen Militar-gymnasiums, Kaukas. med. Gesel. Centralbl. f. p. Augenh. p. 536, 1881. 84. Fox, L. Webster. Examination of Indians at the Government School in Carlisle, Pa., Phila. Med. Times, xii. 372, p. 346, 1882. 85. 0. Paulsen. Ueber die Enstehung des Staphyloma posticum chorioideae, Arch. f. Ophth., p. 225, 1882. 86. Lyder Borthen. Refractions-und Farbenblindheits-Untersuchungen von Schulkin- dern, etc., Kl. Monatshl. xx. p. 406, 1882. 87. P. Schubert. Ueber den Einfluss der Schiefschrift auf die Augen der Kindern Aerztl. Intelligenzbl., No. 21, 1882. Private Communication. 88. P. F. Roberts. Examen de la Vision practicado en las Eculas publices de la Cuidad de Buenos Aires, Buenos Ayres, 1882. Cohn, Hygiene des Auges in den Schulen. 89. F. Erismann. Hygiene der Schule, Handb. d. Hygiene, etc., von Pettenkofer und Ziemssen, p. 2,1882. Centbl. f. pr. Augenh. 90. Mittendorf. Einfluss der Civilization auf das menschliche Auge, etc., Verhand. d. Deutschen Gesellig-Wissenschaftlichen Vereins von New York, v. p. 30, 1882. 91. E. Nordenson. Recherches ophthalmometriques sur l’astigmatisme de la Cornee chez des fooliers de 7 it 20 aus, Extract, Annales d’Oculistique, livraison Mars- Avril, 1883, Ghent, 1883. 92. Wm. Manz. Ueber die Augen der Freiburger Schuljugend, Freiburg, 1883. 93. Berlin & Rembold. Untersuchungen iiber den Einfluss des Schreibens auf Auge und Korperhaltuug des Schulkindes, second edition, Stuttgart, 1883. 94. Gaertner. Quoted by Berlin and Rembold, p. 46. 95. Hasket Derby. Influence on the Refraction of Four Years of College Life, Trans. Am. Ophth. Soc., iii. p. 456, 1883. 96. Dobrowolsky. The Eyes of the Pupils of the Ural High-school, Wratch No. 6, Nagel’s Jahresbrt., xiv. p. 189. 97. Diirr. Die Refraktion von 414 Schiilern nach Anwendungvon Homatropin, Arch. f. Ophth., xxix. 1, p. 103. 98. Diirr. Ueber die Kurzsichtigkeit in den hoheren Schulen Hannovers, Verhandl. u. Mittheil. d. Vereins. f. off. Gesundheit, Hanover. 99. Wm. Hansen. Welche Refraction ist in 10 bis 15 Lebensjahre die vorherrschende ? Kl. Monatsbl., xxi. 5, p. 196, May, 1883. 100. Reich. Nearsight in the Transcaucasian Girls’ Institute, etc., Med. Sbornik. d. Kauk. Med. Ges. No. 34, Centralbl. f. Augenh., p. 483, 1883. 101. Motais. Hygiene de la vue chez les Typographes, Paris, 1883. 102. Schtschepotjeff. The Eyes of the Normal pupils of Astrachan, Tagh. d. Kasan. arz. Vereins 13, Nagel, xvi. p. 579. 103. Schadow. Die Augen der Schulkinder Borkums, Kl. Monatsbl., xxi. p. 150, Apr. 1883. 104. Hadlow. Shortsight amongst Boys of the Greenwich Hospital School, Brit. Med. Jour., May 5,1883. 105. M. Tscherning. Studien iiber die Aetiologie der Myopie, Arch. f. Ophth., xxix. i. p. 201. 106. v. Reuss. Untersuchungen der Augen von Eisenbahn-Bediensteten auf Farbensinn & Refraction, Arch. f. Ophth., xxix. 2, p. 229. 107. Schleich. Die Augen 150 neugeborener Kinder ophthalmoskopisch untersucht. Mittheil. aus d. Ophth. Klinik zu Tubingen, ii. 1, p. 44,1884. 108. H. Schaefer. Die Augen der Zoglinge de Taubstummenanstalt in Gerlachsheim (Grossh. Baden), Centralb. f. Augenh., Mai, 1884. 109. Seggel. Ueber normale Sehscharfe und die Beziehung der Sehscharfe zu Refraction, Arch. f. Ophth., xxx. 2, p. 69, 1884. 110. Gustav Ulrich. Refraction und Papilla optica der Augen der Neugeborenen. Inaug. Diss. Konigsberg, i. P. 1884. 111. J. Bjerrum. Trans. Internat. Med. Congress, Copenhagen, 1884. Quoted by Horstmann (vide 115). 112. Otto Beselin. Ueber Refraction und Grundlinie der Augen, etc., Arch. f. Augenh. xix. 4, p. 113. L. Kotelmann. Die Augen von 22 Kalmiicken, Zeitsch f. Ethnologie, xvi. 2, p. 77, 1884. 114. Seggel. Trans. Inter. Med. Congress, Copenhagen, 1884. Annales d’Oculistique. 30 115. Horstmann. Die Refractions-Verhaltnisse des mensehlichen Auges bis zum sechsten Lebensjahre, Ber. u. d. xvi., Versammlung d. Ophth. Gesel., Heidel- berg, 1884. 116. L. Webster Fox. Examination of the Eyes of Indian Girls from the Carlisle School. Private Communication. 117. H. Van Anrooy. De Oogen der Studenten aan te Rijks-Universiteit te Leiden, Inaug. Diss., Leyden, 1884. 118. M. Del Carlo & A. Pardini. Inchiesta Ottometrica nelle Seuole dell’ Italia. Bollettino d’Oculistica, vi. 8 Apr. 1884. 119. M. Scellingo. Inchiesta Ottometrica nelle Seuole dell’ Italia, Bollettino d’Ocu- listica, vi. 9 and 11. 120. G. Masini. Idem. Bollettino d’Oculistica, vi. 10 bis. 121. G. Moyne. Idem. “ “ vi. 12 and 13 bis. 122. P. Brignone. Idem. “ “ vii. 2 and 3, 1884. 123. A. Hoffmann. Ueber Beziehungen der Refraction zu den Muskelverhaltnissen des Auges. Inaug. Diss. Strassburg, 1884. 124. Schleich. Die Augen im Obergvmnasium zu Tubingen. Private Communication. 125. Randall. A Study of the Eyes of Medical Students. Trans. Penna. State Med. Soc. 1885.1 1 The studies of Giraud-Teulon (Paris,Gaz. Hbd., p. 514,1870), of Lopatin (Oljinski), of L. Zwingmann and of Buschbeck (Plauen, Yierteljrs. f. gericht. Med. u. of. Sanitatsw. Jan. 1881), have been thus far inaccessible. //?/ J/? /AA JfidhsT /,{&) ZsOYl4 hsL£U>k. 'is AHW-f i*-j 't-'t-i £■ 0$C fjj- £/ £YY y{riLfiA'~h CJL ft'O fot (ti'iuij /il '1st jrv U,U ~f~~ -ff- /a . y kYlflJYt'hjLy- ftsQ £144,1,■ &-'lAY) fJ^A 'itt C-Jl Und&v jC/Yj cti d M'/' /V AV/, AYC- 7r / / / / / / / • Ct f YCsuitsij £jh $U. y'CC'C Yidj As— lYSt^xYtrlL-j favA4*y SYy£ CL CC, * //^JY'Y^ ~vf~ h i+czA h4st?>-e o~*y{ z< /ify?it "■ :--i£t~ /Yi.£,-£,Usu3 ts/~ /v^~~£T ut' £ i i, £,4'l //u,4 £?.-v ijLd^fc,C~14 £WsC#f &H, £,£ {7x) £] j p iAS'lsW. 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