Tear fluid and complement activation products in tears after ocular surgery

PURPOSE: Due to technological advancements, surgical invasiveness has been reduced. However, cataract surgery has been implicated in causing postoperative inflammation, including dry eye syndrome. The innate immune system may be involved in postoperative inflammation, and complement activation could potentially play a crucial role in defense against pathogens, homeostasis, and wound healing. To investigate changes in the tear film complement activation products (CAPs) and ocular surface after vitrectomy combined with cataract surgery. METHODS: Forty-three patients (23 women; median age, 69 years) were enrolled in this prospective study and underwent phacoemulsification and vitrectomy. We measured Schirmer's test (ST) and CAPs in the tears at baseline (the day before surgery), 4 days and 1 month after the surgery. Tears were collected in microtubes. The CAPs in the tear fluid were analyzed by cytometric bead array. RESULTS: The median ST (8.5 mm) at baseline increased to 16 mm at 4 days ( P < 0.001) and 10 mm at 1 month (P = 0.44). The C3a levels (1202 pg/ml) at baseline increased to 2753 pg/ml at 4 days (P < 0.001), and 1763 pg/ml at 1 month (P = 0.049). The C4a levels (476 pg/ml) at baseline increased to 880 pg/ml at 4 days (P < 0.001), and 657 pg/ml at 1 month (P = 0.013). The C5a levels (22.6 pg/ml) at baseline increased to 470.9 pg/ml at 4 days (P < 0.001), and 38.3 pg/ml at 1 month (P = 0.0048). The surgical eyes were divided into the short ST group (≦ 10 mm, n = 22) and long ST group (> 10 mm, n = 21) based on the preoperative ST values. At 1 month postoperatively, the C3a levels were 2194 pg/ml in the preoperative short ST group and 1391 pg/ml in the long ST group, with significantly higher C3a concentrations in the short ST group (P < 0.001). CONCLUSIONS: The CAPs levels in tears increased after vitrectomy combined with cataract surgery. A preoperative deficit in tear secretion might induce prolonged complement activation and delayed recovery of ocular surface parameters postoperatively.