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J.C. K. Clarke, D. Minassian, P.T. Khaw, More Flow Surgery Study Group; The More Flow Surgery Study: The Effect of Intraoperative 5FU on IOP Control and Trabeculectomy Bleb Appearance Using the Moorfields Bleb Grading System . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1221.
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Purpose: To determine the influence of intraoperative 5FU on bleb morphology and long term IOP control Methods: The Moorfields Bleb Grading System, ratified by the Moorfields Reading Centre, was used to objectively assess the change in photographic appearance of 368 blebs over a four–year period following trabeculectomy. The grading system divides the superior conjunctiva and bleb into zones. Details of bleb vascularity and morphology were graded. The patients had been enrolled into a prospective placebo controlled clinical trial of intraoperative 5FU (the More Flow Surgery Study). Results: The majority of blebs were classified as either 50% (moderate size) or 75% (large size) of the standard image area. There was a trend for a reduction in mean intraocular pressure with increasing bleb size. For small blebs the mean IOP = 16.6 mmHg (+/– 5.83), moderate blebs 14.3 mmHg (SD+/– 5.97) and large blebs 13.9 mmHg (+/– 7.02) For each documented bleb size the mean IOP in 5FU group was lower than the placebo group with mean IOP for large blebs with 5FU being 13.1 mmHg (+/–6.9) and placebo 14.7 mmHg (+/–7.0) and for moderate sized blebs with 5FU 13.1 mmHg (+/–5.4) and placebo 15.7 mmHg (+/–6.2) Moderate to severe vascularity outside of the central bleb zone increases the risk of future failure in the first 6 weeks post operatively. Hazard ratios for future IOP failure increase with the number of weeks that these vascularity scores are graded from 2.89 (95% CI: 1.60 – 5.19) with 2 weeks exposure, to 3.63 (1.61 – 8.14) with 4 weeks exposure and 6.17 (2.19 – 17.40) with 6 weeks exposure. Intraoperative 5FU as an independent covariate does not influence the vascularity of this peripheral bleb zone, however there is an increase in central bleb thinning with 5FU. At 1 year 14% of blebs were graded as cystic in the 5FU group compared to 5.5% in the placebo group. Conclusions: The use of intraoperative 5FU gives a lower IOP for the same sized bleb compared to placebo and central bleb thinning is commoner. Larger blebs produce lower IOPs but the range is large. Peripheral bleb vascularity is a poor prognostic feature and objective assessment indicates that the risk of future failure increases with prolonged periods of raised vascularity. The simple Moorfields grading system may be useful in helping to predict future bleb characteristics and IOP outcome.
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