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.

Randall, Burton Alexander, 1858-1932.

Date:: [1885]

Credit: 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. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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$reason for tlie labor necessary to educe tliem. 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 It 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 mucii 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$