Comparison of Aqueous Humor Nitric Oxide Levels After Different Corneal Collagen Cross-Linking Methods

ABSTRACTPurpose: Nitric oxide production can cause either apoptotic or necrotic cell death through oxidative stress. We aimed to investigate the nitrite oxide metabolites (NOx) and nitrite levels in the aqueous humor of rabbit eyes after different methods of corneal collagen cross-linking (CXL).Materials and methods: Twenty-four eyes of 12 adult New Zealand rabbits were used. They were assigned into four groups, each including six eyes. Group 1 (control) consisted of eyes with no treatment. Group 2 received UV-A power setting at 3 mW/cm2 for 30 minutes of continuous exposure and named as standard CXL group. Group 3 received UV-A power setting at 30 mW/cm2 for 3 minutes of continuous exposure and named as accelerated CXL (A-CXL) group. Group 4 received UV-A power setting at 30 mW/cm2 for 6 minutes of pulsed exposure (1 sec on, 1 sec off) and named as pulse-light accelerated CXL (PLA-CXL). Aqueous humors were aspirated from anterior chamber with a 27G needle after 1 hour UV-A exposure. NOx and nitrite level...