Sunday, December 2, 2007

2.2.4 "Other" cataracts

Besides the more common age-related and diabetic cataracts, there are other unique cataracts.

A major one is toxic cataract from, for example, long-term exposure to systemic or topical steroids. Typically, the opacities are located in the posterior subcapsular region, known as, what else, the posterior subcapsular cataract (PSC). Because PSC is situated right in front of the nodal point of the ocular optical system, in the daytime when the pupils constrict, the patient's vision is worse than that at night.

Then we have radiation cataracts from ocular/orbital exposure to excessive X-ray (both dental and medical), radiation therapy, cosmic rays (in airline pilots and maybe astronauts), infrared ("the glass blower's cataract"), and most important, ultraviolet (UV) from sunlight.

Epidemiological studies have confirmed the correlation between UV exposure and the prevalence of cataracts by investigating populations residing in different climates. More on these studies in the Public Health section (to be posted in the future).

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