32 Accepted Theory of Accommodation
in the lensless eye having been reported to the Royal So ciety by competent observers, Dr. Young, before bringing forward his theory of accommodation, took the trouble to examine some of them, and considered himself justi fied in concluding that an error of observation had been made. While convinced, however, that in such eyes the "actual focal distance is totally unchangeable," he char acterized his own evidence in support of this view as only "tolerably satisfactory." At a later period Donders made some investigations from which he concluded that "in aphakia1 not the slightest trace of accommodative power remains."2 Holmholtz expressed similar views, and von Graefe, although he observed a "slight resid uum" of accommodative power in lensless eyes, did not consider it sufficient to discredit the theory of Cramer and Helmholtz. It might be due, he said, to the accom modative action of the iris, and possibly also to a length ening of the visual axis through the action of the external muscles.3
For nearly three-quarters of a century the opinions of these masters have echoed through ophthalmological literature. Yet it is to-day a perfectly well-known and undisputed fact that many persons, after the removal of the lens for cataract, are able to see perfectly at different distances without any change in their glasses. Every ophthalmologist of any experience has seen cases of this kind, and many of them have been reported in the litera ture.
In 1872, Professor Forster of Breslau, reported4 a
1 Absence of the lens.
2 On the Anomalies of Accommodation and Refraction of the Eye, p. 320.
3 Archiv. f. Ophth., 1855, vol. ii, part 1, p. 187 et seq. Albrecht von Graefe (1828-1870) was professor of ophthalmology in the University of Berlin, and is ranked with Donders and Arlt as one of the greatest ophthalmologists of the nineteenth century.
* Klin. Montasbl. f. Augenh., Erlangen, 1872, vol. x, p. 39, et seq.