HYDROGEN PEROXIDE, UV RADIATION AND CATARACTS

Title HYDROGEN PEROXIDE, UV RADIATION AND CATARACTS
Author, Co-Author Seymour Zigman
Topic
Year
1994
Day
Tuesday
Program Number
2:20 pm
Room
Marriott Hall 2
Affiliation
Abstract An increase in the hydrogen peroxide level in the aqueous humors of cataract patients suggested that it could be a contributing factor to cataract formation. The ocular tissues are also well-endowed with enzyme catalase. The activity of catalase is reduced in the lens with aging and can also be readily inactivated by exposure of the lens to near-UV radiation. The activity of catalase in the ocular tissues was measured, using an 02 electrode and meter to detect 02 production from H202. Iris, ciliary body, and retina have high catalase activities as compared with lens and cornea. Lenses of rabbits, squirrels, and fish detoxify H202 rapidly. Exposure to near-UV radiation (UV-A at ~ 75 J/cm2) inhibits H202 detoxification. Alpha-tocopherol and deferoxamine protect catalase activity strongly, indicating that toxic free radicals form, such as singlet oxygen and hydroxyl anions. Human eye bank lenses produced 02 rapidly from H202, but intracapsular cataractous lenses did so very slowly. The involvement of H202 in the cataractous process may be due to a diminished capacity of the lens epithelium to detoxify H202, even at normal levels (50 mM). Support: Research to Prevent Blindness, Inc., and National Eye Institute Grant #EY 00459
Affiliation of Co-Authors
Outline