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H. L. Chandler, K. S. Reuter, L. T. Sinnott, J. J. Nichols; Prevention of UV-Induced Damage to the Anterior Segment Using UV-Absorbing Contact Lenses. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4783.
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To determine if ultraviolet (UV)-absorbing contact lenses prevent UV-induced pathological changes in the cornea, aqueous humor, and crystalline lens (associated with cataract formation).
Twelve rabbits were assigned to one of three treatment groups (n = 4) as follows: 1) senofilcon A contact lenses (Acuvue Oasys, absorbs 99% of UV-B and 90% of UV-A); 2) lotrafilcon A contact lenses (Focus Night and Day, no UV absorption); 3) no contact lens. The contralateral eye was patched without a contact lens. Animals received UV-B (1.667 J/cm2) and UV-A (0.245 J/cm2) exposures daily for 5 days. Post-mortem tissues were examined as follows: in the cornea, expression of matrix-metalloproteinases (MMPs) was evaluated by zymography and apoptosis was evaluated by TUNEL and caspase-3 ELISA; ascorbate in the aqueous humor was evaluated by NMR spectroscopy; in the crystalline lens apoptosis was evaluated by TUNEL and caspase-3 ELISA. Nonparametric tests were used to compare outcomes.
Within the exposed cornea, there was a statistically significant increase in MMP-2 and -9, TUNEL positive cells and caspase-3 activity in the lotrafilcon A group compared to the senofilcon A group (all p = 0.03). A statistically significant decrease in aqueous humor ascorbate was observed in the exposed lotrafilcon A wearing group compared to the exposed senofilcon A wearing group (p = 0.03). Within the exposed crystalline lens, a statistically significant increase in caspase-3 activity was observed in the lotrafilcon A group compared to the senofilcon A group (p = 0.03). An increased number of TUNEL positive cells were noted in both the lotrafilcon A and non-contact lens groups; this was not statistically significant compared to the senofilcon A group. There were no statistically significant differences noted in any of the outcomes examined when the lotrafilcon A wearing group was compared to the non-lens wearing control group.
MMPs can be induced within the cornea by UV exposure and are associated with many pathologic inflammatory cascades. Ascorbate is a scavenger of free radicals in the aqueous humor and can decrease following UV exposure. DNA damage and apoptosis can be induced in both the cornea and lens by UV exposure. We have shown that senofilcon A UV-blocking contact lenses are capable of protecting the cornea, aqueous humor, and crystalline lens from these UV-induced pathological changes processes.
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