Changes in vitreous temperature during intravitreal surgery.

PURPOSE: To determine how different intraoperative surgical procedures affect the midvitreous temperature. METHODS: The vitreous temperatures were monitored continuously with an intravitreal thermocouple in 87 eyes of 81 cases undergoing vitrectomy. Thirty-three eyes had diabetic retinopathy (DR), 35 eyes had an epiretinal membrane, and 19 eyes had an idiopathic macular hole. In eyes with DR, the correlation between the number of photocoagulations (PCs) and the change in temperature was analyzed. The temperature was also recorded before and after combined phacoemulsification and aspiration (PEA) and vitrectomy in 10 eyes. RESULTS: The average midvitreal temperature before the vitrectomy was 33.0 ± 1.3°C, 30.7 ± 1.7°C after core vitrectomy, 32.9 ± 1.3°C after membrane peeling, and 29.2 ± 1.4°C after peripheral vitrectomy. The temperature before PC was 29.8 ± 1.3°C, and it increased to 31.5 ± 1.9°C post-PC. The differences in the temperatures between consecutive procedures were significant (P < 0.01, respectively, Wilcoxon signed-rank test). The difference in the temperatures of the same procedures among the different diseases was not significant except after membrane peeling. A significant correlation was detected between the number of PCs and the duration of the PCs, and between the duration of PCs and the change in vitreous temperature after PC (r = 0.719, P = 0.0010, and r = 0.800, P = 0.0002, respectively, Spearman's rank correlation coefficient test). The temperature after PEA decreased significantly by 2.3°C. CONCLUSIONS: Our results showed that vitreous temperatures vary during different vitrectomy procedures.