Intraocular gas dynamics after 20-gauge and 23-gauge vitrectomy with sulfur hexafluoride gas tamponade.

PURPOSE: The purpose of this study was to evaluate the intraocular gas dynamics after 23-gauge transconjunctival sutureless vitrectomy (TSV) as compared with 20-gauge pars plana vitrectomy (PPV). METHODS: A consecutive series of 290 eyes that experienced 20-gauge or 23-gauge vitrectomy with 25% sulfur hexafluoride (SF6) gas tamponade were retrospectively reviewed. Intraocular gas bubble size on postoperative Day 1 and Gas50, the interval to dissipate to a 50% gas fill, were evaluated. RESULTS: The mean intraocular bubble size on postoperative Day 1 was 92.0 ± 8.3% in the 20-gauge PPV cases and 83.8 ± 13.7% in the 23-gauge TSV cases (P < 0.001). The mean Gas50 was 8.6 ± 1.6 days in the 20-gauge PPV cases and 6.6 ± 2.2 days in the 23-gauge TSV cases (P < 0.001). Thorough peripheral vitrectomy and 23-gauge TSV were significantly associated with Gas50 ≤ 4 days (odds ratio, 4.62 and 16.8; P = 0.036 and P = 0.007, respectively). Among thoroughly vitrectomized eyes, 13 eyes treated with 23-gauge PPV with intraoperative suture placement at the sclerotomy sites had gas longevity comparative to those with 20-gauge PPV. CONCLUSION: Eyes treated with 23-gauge TSV tend to have earlier gas disappearance or incomplete gas fill. Intraoperative suture placement would be a solution.

Relationship between diabetic macular edema and peripheral Th1/Th2 balance.

PURPOSE: To determine whether inflammatory reactions are involved in the pathogenesis of diabetic macular edema, we examined the relationship between diabetic macular edema and the ratio of T helper 1 (Th1) to T helper 2 (Th2) cells. METHODS: Thirty-nine diabetic patients with diabetic retinopathy were evaluated at our hospital between February 2004 and February 2005. Blood samples were collected from each patient, and the ratio of CD4+ Th1 to Th2 cells (Th1/Th2) was determined by flow cytometry after fluorescent antibody staining for intracellular cytokines. Logistic regression analysis was used to determine the association of macular edema with age, gender, HbA(1c) level, interval after retinal photocoagulation and Th1/Th2 ratios. Differences in these parameters were also compared between patients with and without macular edema. RESULTS: Logistic regression analysis showed that the Th1/Th2 ratios were significantly associated with macular edema (odds ratio = 0.838; p = 0.02), while other variables were not. The Th1/Th2 ratio was significantly lower in the patients with diabetic macular edema than in those without (p = 0.02; t test). Higher Th1/Th2 ratios tended to be associated with better visual acuity. CONCLUSIONS: Shifts in the balance of Th1/Th2 towards a predominance of Th2 may represent an exacerbating factor for diabetic macular edema, although a causal relationship has still not been definitively determined.