The effect of acetazolamide on intra-ocular pressure after Trendelenburg positioning - a randomised double-blind crossover trial in volunteers
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Recent evidence suggests Trendelenburg positioning can produce a significant rise in intra-ocular pressure. Peri-operative vision loss in patients undergoing laparoscopic colorectal surgery has been reported with the rise in intra-ocular pressure suggested as a possible factor. Acetazolamide decreases intra-ocular pressure by reducing the formation of aqueous humour, so we aimed to investigate if it could attenuate the intra-ocular pressure rise that can occur in the Trendelenburg position. Nine healthy volunteers were recruited and randomly assigned to a double-blind crossover comparison of placebo or acetazolamide with a minimal 4 days' washout period before the second study day. One and a half hours after taking the medication, volunteers lay head-down at 17 degrees for 4 h. Intraocular pressure measurements were repeated in both eyes every 30 min over a 4-h period. There were two males and seven female volunteers, with a mean (SD) age of 54.3 (18.5) years. The mean (SD) increase in intra-ocular pressure following 4 h in the Trendelenburg position was 3.17 (4.63) mmHg after the placebo, and 0.02 (4.01) mmHg (p = 0.02) after acetazolamide. We have shown than acetazolamide can attenuate the rise that occurs in intra-ocular pressure when in the Trendelenburg position.