Visualization of One's Own Cataract

James R. Delp, MD, PC
JAMA. 1983;249(9):1152. doi:10.1001/jama.1983.03330330034028.
Text Size: A A A
Published online


To the Editor.—  A 56-year-old physician, Donald R. Thomas, was able to see the opacities of his cataracts when he illuminated his eye at a distance of 15 to 20 cm from the oculars of a microscope while under high power. Several ophthalmologists did not explain this phenomenon.Its explanation is to be found in a rule of optics that states, "a ray of light that passes through the center of an optical system does not undergo refraction; i.e., the light ray does not change course but emerges in the same direction it entered." A central (axial) ray of illuminating light, as in Dr Thomas' case, qualifies for this effect.In this case, the illumination is essentially an axial ray of light that cannot be refracted (bent) by the optical system of the eye. Thus, any opacity within the pupil of the eye will simply cast its image as a


Sign In to Access Full Content

Don't have Access?

Register and get free email Table of Contents alerts, saved searches, PowerPoint downloads, CME quizzes, and more

Subscribe for full-text access to content from 1998 forward and a host of useful features

Activate your current subscription (AMA members and current subscribers)

Purchase Online Access to this article for 24 hours




Meets CME requirements for:
Browse CME for all U.S. States
Accreditation Information
The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
Note: You must get at least of the answers correct to pass this quiz.
You have not filled in all the answers to complete this quiz
The following questions were not answered:
Sorry, you have unsuccessfully completed this CME quiz with a score of
The following questions were not answered correctly:
Commitment to Change (optional):
Indicate what change(s) you will implement in your practice, if any, based on this CME course.
Your quiz results:
The filled radio buttons indicate your responses. The preferred responses are highlighted
For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
Indicate what changes(s) you will implement in your practice, if any, based on this CME course.
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).


Some tools below are only available to our subscribers or users with an online account.

Sign In to Access Full Content

Related Content

Customize your page view by dragging & repositioning the boxes below.