Refraction and how to refract, including sections on optics, retinoscopy, the fitting of spectacles and eyeglasses, etc. by Thorington James 1858-

Author:Thorington, James, 1858- [from old catalog]
Language: eng
Format: epub
Tags: Eye, Eye
Publisher: Philadelphia, P. Blakiston's son & co.
Published: 1909-03-25T05:00:00+00:00

RETINOSCOPY.

173

Spheric Aberration. —This is of two kinds—-positive and negative. (See Figs. 157 and 158.) In the positive form the peripheral refraction (A, A, that at the edge of the pupil) is stronger than the central (B, B) ; the reverse of this condition, negative aberration, is seen in conic cornea. These two varieties of refraction should not worry the observer, as most of the peripheral aberration is covered up by the iris when mydriasis passes away, and, therefore, is not of any great moment, except in conic cornea.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.