Prospective evaluation of early visual loss following glaucoma-filtering surgery in eyes with split fixation.

Purpose: The aim of this study was to evaluate the incidence and etiology of loss of vision in the early postoperative period after glaucoma-filtration surgery in eyes with split fixation.
Methods: This was a prospective, interventional cohort study. Sixty-five eyes of 65 patients with advanced glaucomatous optic nerve damage with split fixation were included. Thirty-four eyes underwent trabeculectomy (group A) and 31 eyes underwent combined cataract and glaucoma surgery (group B). Main outcome measures included the incidence and etiology of visual loss and changes in intraocular pressure, visual acuity, and visual field indices during the first 2 months after surgery.
Results: No significant changes were seen in the mean deviation in group A [mean difference, -0.53±2.23; 95% confidence interval (CI): -1.32, 0.25; P=0.59] and in group B (mean difference, -0.75±2.9; 95% CI: -1.81, 0.31; P=0.16). There was a significant drop in the intraocular pressure from a baseline of 36.87±2.86 to 10.2±3.47 mm Hg (P<0.001) in group A, and from a baseline of 27.74±15.5 to 13.41±5.5 mm Hg in group B (P<0.001). At the end of 2 months, visual loss of 2 lines or more occurred in 2 eyes (3%; 95% CI: 0%, 7%) because of choroidal detachment with increase in lens changes in one eye (group A) and no apparent cause in the other (group B). None of the eyes developed a loss of central vision ("0" dB sensitivity in 4 test points abutting fixation).
Conclusions: Visual loss after surgery in advanced glaucoma is rare and most often because of reversible causes.