Effect of Successful and Partly Successful Filtering Surgery on the Velocity of Glaucomatous Visual Field Progression

Abstract

Purpose 

We sought to determine whether filtering surgery, even when only partially successful, delays or slows visual field (VF) progression.

Methods 

The records of all patients seen in a glaucoma referral practice from 1999 to 2009 were reviewed. Group A comprised eyes with ≥5 VFs before surgery and group B comprised eyes with ≥5 VFs after surgery. Eyes in group B were further divided into those requiring postoperative topical ocular hypotensive therapy (group B-2) and those that did not (group B-1). Automated pointwise linear regression was used to determine global rates (dB/y) of change and progression endpoints. A progression endpoint was determined when 2 or more adjacent test locations in the same hemifield showed a threshold sensitivity decline at a rate of ≥1.0 dB/year with P<0.01.

Results 

A total of 206 treated eyes (206 patients; mean age, 63.8±13.0 y; 11.3±3.1 VFs; 6.4±1.8 y follow-up) were included. Mean global VF progression rates in group A (−0.86±0.8 dB/y) were faster than those in group B (−0.49±0.9 dB/y, P<0.01). Group A also had a greater risk of reaching a progression endpoint compared with group B (odds ratio=2.41, P<0.01). Groups B-1 and B-2 had different follow-up intraocular pressure means (12.7±3.7 vs. 15.5±2.7 mm Hg, respectively; P<0.01) and peaks (19.4±5.2 vs. 21.2±4.2 mm Hg; P=0.08). The velocity of VF progression was similar for groups B-1 and B-2 (−0.40±0.6 vs. −0.58±1.1 dB/y; P=0.22) and there was no significant difference between the 2 groups regarding the risk of reaching a progression endpoint (odds ratio=0.83, P=0.62).

Conclusions 

Filtering surgery reduces the rate of disease progression and this effect persists even if adjunctive glaucoma medical therapy is required.