title: Comparison of Aqueous Humor Nitric Oxide Levels After Different Corneal Collagen Cross-Linking Methods.
abstract: 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).
  
  
  
  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/cm2for 30 minutes of continuous exposure and named as standard CXL group. Group 3 received UV-A power setting at 30 mW/cm2for 3 minutes of continuous exposure and named as accelerated CXL (A-CXL) group. Group 4 received UV-A power setting at 30 mW/cm2for 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. NOxand nitrite levels were measured Results: The nitrite levels in aqueous humor were significantly increased in Group 2 and Group 3 when compared with Group 1 (p = 0.000, p = 0.036, respectively). When treatment modalities were compared with each other, high nitrite level in Group 2 was statistically significant when compared with Group 4 (p = 0.019). NOxlevels were higher in Group 2 when compared with Group 1 (p = 0.006).
  
  
  
  Numerous studies investigated the physiological and pathophysiological roles of NO. NO is considered one of the most important molecule for ocular health. According to NOxlevel in aqueous humor, it seems that PLA-CXL is the safest method due to the similar results with control group.
authors.affiliation: a Department of Ophthalmology , Ataturk Training and Research Hospital , Ankara , Turkey.
authors.forename: Nilay
authors.initials: N
authors.lastname: Yuksel
authors.affiliation: b Department of Medical Biochemistry, Faculty of Medicine , Mugla Sitki Kocman University , Mugla , Turkey.
authors.forename: Ummuhani
authors.initials: U
authors.lastname: Ozel-Turkcu
authors.affiliation: c Department of Ophthalmology, Faculty of Medicine , Gazi University , Ankara , Turkey.
authors.forename: Duygu
authors.initials: D
authors.lastname: Yalinbas
authors.affiliation: d Department of Ophthalmology , National Centre of Ophthalmology named after academician Zarifa Aliyeva , Baku , Azerbaijan.
authors.forename: Sahin
authors.initials: S
authors.lastname: Novruzlu
authors.affiliation: e Department of Medical Biochemistry, Faculty of Medicine , Gazi University , Ankara , Turkey.
authors.forename: Ayse
authors.initials: A
authors.lastname: Bilgihan
authors.affiliation: c Department of Ophthalmology, Faculty of Medicine , Gazi University , Ankara , Turkey.
authors.forename: Kamil
authors.initials: K
authors.lastname: Bilgihan
mesh_terms: D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism*; D003094:Collagen / Q000494:pharmacology*; D003315:Cornea / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D004195:Disease Models, Animal; D007640:Keratoconus / Q000188:drug therapy* / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D018384:Oxidative Stress; D017319:Photosensitizing Agents / Q000494:pharmacology; D011817:Rabbits; D012256:Riboflavin / Q000494:pharmacology*; D014466:Ultraviolet Rays; D014792:Visual Acuity
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D009569:Nitric Oxide; D003094:Collagen; D012256:Riboflavin
keywords: Aqueous humor; corneal collagen cross-linking; nitric oxide