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The effect of acetazolamide on intra-ocular pressure after Trendelenburg positioning - a randomised double-blind crossover trial in volunteersRecent 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.
Confocal scan laser ophthalmoscope for diagnosing glaucoma: A systematic review and meta-analysisThis systematic review was performed to estimate the diagnostic accuracy of the confocal scanning laser ophthalmoscopy in diagnosing glaucoma. We did a sensitive electronic search to find relevant studies. Two reviewers independently screened relevant articles and extracted required data about study methods and reported results of sensitivity and specificity. A meta-analysis was conducted for pooling data to compare different editions of the Heidelberg Retina Tomograph (HRT) with one of its alternatives, scanning laser polarimetry (GDx) with the criteria of "visual field defect" and "changes of nerve fiber layer" as the reference standard. We identified 37 evaluations from 28 relevant primary studies. In these studies, 9573 eyes (4883 glaucomatous and 4689 non-glaucomatous) were assessed with regards to the reference standard using one of the HRT editions with or without GDx. Diagnostic odds ratios were 9.35 [95% confidence interval (CI): 7.58-11.53] for HRT, 11.84 (95% CI: 9.97-14.06) for HRT II, 11.86 (95% CI: 9.16-15.35) for HRT III, and 21.33 (95% CI, 13.56-33.55) for GDx. Although GDx was more accurate than HRT, all editions of HRT had acceptable performance in diagnosing glaucomatous eyes with an ophthalmologist's clinical examination as the reference standard.;