Purpose:
To examine the rates of visual field (VF) change before and following trabeculectomy.
Methods:
The Medical Research Council Moorflow 5-Fluorouracil (5-FU) study was a prospective, double-masked, randomised controlled trial investigating the efficacy of per-operative 5-FU on the outcomes of primary trabeculectomy, which ran at Moorfields Eye Hospital between 1996 and 2002. For this retrospective analysis, patients with a minimum of 4 years pre-operative and 4 years post-operative VF tests (Humphrey Field Analyser full threshold strategy; Carl Zeiss Meditec) were included. Patients who had intraocular pressure (IOP) reduction interventions (e.g. bleb needling, topical antihypotensive therapy) post- filtration surgery were excluded from the analysis. Where relevant, only VFs up to the point of cataract surgery were included. A linear regression analysis of mean deviation (MD) over time was calculated for pre- and post-operative VFs. The regression slopes were compared using a Wilcoxon test, with significance defined as p<0.05.
Results:
Sixty-six eyes of 66 patients (median [interquartile range; IQR] age: 69 [61-75] years) were eligible for the study. Median pre-operative MD was -5.62 [-10.26 to -3.12] dB. Median IOP reduction was -37 [-51 to -28]%. Table 1 summarises the change in MD slope and IOP after trabeculectomy. There was a significant reduction in the rate of MD deterioration after surgery, but this was only weakly associated with percentage reduction in IOP.
Conclusions:
These results suggest that trabeculectomy successfully reduces the rate of global visual field deterioration in patients who do not require further IOP lowering interventions.
Keywords: clinical research methodology • visual fields