The Influence of IOP on Structural and Functional Changes Following Trabeculectomy- Results From the MoreFlow Study

Abstract

 

Purpose:

 

To assess the effect of intraocular pressure (IOP) reduction on progression of optic disc (OD) & visual field (VF) changes in glaucoma patients following trabeculectomy.

 

Methods:

 

The MoreFlow study was an 80 month prospective study of per-operative 5-FU vs placebo. Pre-operatively, patients had OD imaging with the Heidelberg Retina Tomograph (HRT; Heidelberg Engineering GmbH) & full-threshold 24-2 VF (Carl Zeiss Meditec). Post-operatively, OD imaging was performed annually & VF testing at 4-monthly intervals. This analysis only includes patients with a minimum of 3 years post-op OD & VF data. OD images were analysed using linear regression of sectoral rim area (RA) over time & change defined as a significant slope >1% of baseline RA/year in any sector. VF were analysed with PROGRESSOR software using the 3-omitting analysis technique. OD & VF data were analysed by separate masked observers & patients classified as progressors or not. Average VF mean deviation (MD) was used to establish levels of pre-existing disease. Percentage change between pre-op IOP & mean post-op IOP (defined as mean IOP from 3 months post-op to final visit) was calculated.Progression determined by OD and VF measures was compared & the level of IOP change in each group assessed using an ANOVA (Tukey post-hoc test) significance set at the p<0.05 level.

 

Results:

 

Of 258 eyes analysed, 22 progressed by OD alone, 49 by VF alone and 16 by both VF & OD. Degree of pre-existing disease & mean post-op IOP in each group was not significantly different. Percentage IOP reduction was significantly greater in eyes that showed no progression compared with those showing progression by both VF & OD (Table 1).Table 1: IOP & pre-existing disease characteristics in the 4 groups (*significantly different from ‘VF & OD’, SD = standard deviation)  

 

Conclusions:

 

The analysis suggests that the degree of IOP reduction following trabeculectomy has an important role in the progression of glaucoma as detected by both functional & structural methods.

 

Clinical Trial:

 

Medical Research Council

 

Keywords: optic disc • visual fields • clinical (human) or epidemiologic studies: outcomes/complications