The Levels of Cytokines and Nitric Oxide in Rabbit Vitreous Humor after Retinal Laser Photocoagulation

Abstract

OBJECTIVE: To determine the levels of nitric oxide (NO) and cytokines such as interleukin 1-beta (IL-1beta), interleukin 6 (IL-6), interleukin 8 (IL-8), and tumor necrosis factor-alpha (TNF-alpha) on vitreous humor following retinal laser photocoagulation. MATERIALS AND METHODS: The rabbits were divided into 3 groups of 4 animals (8 eyes) each. Twelve pigmented rabbit eyes underwent modified grid pattern photocoagulation with a power of 240 mW (group I); 300 mW (group II); and 360 mW (group III). The eyes received 200 burns using a spot size of 200 micro, and duration of 0.2 s. Vitreous humor samples were collected from each eye preoperatively and at 24 and 72 hours after the laser. RESULTS: When compared to preoperative levels, IL-6 levels were increased in all groups; IL-1beta levels were increased significantly only in group III. IL-8 levels were high in groups II and III only at 72 hours (P <0.05). TNFalpha levels were elevated significantly in group II and III only at 24 hours (P <0.05). NO levels were significantly higher than preoperative values in all groups at all times. CONCLUSION: Our results support that especially IL-6, IL-8, and NO levels increase significantly following laser photocoagulation. This preliminary study suggests that IL-6, IL-8, and NO might be dominant contributing factors in the occurrence of the inflammation postoperatively.