Severe loss of central vision in patients with advanced glaucoma undergoing trabeculectomy.

OBJECTIVE: To evaluate the visual outcomes in patients with advanced visual field (VF) loss undergoing trabeculectomy with mitomycin C.

METHODS: The records of patients with severe preoperative VF defects undergoing trabeculectomy from June 1, 1998, through October 31, 2005, were retrospectively reviewed. Severe loss of central vision was defined as visual acuity (VA) of 20/200 or less in the affected eye, counting fingers or less if preoperative VA was less than 20/200, or more than a 4-line reduction in Snellen VA.

RESULTS: Central vision loss occurred in 7 of 117 patients (eyes) (6%) because of hypotony maculopathy (3 cases), uncontrolled elevated intraocular pressures (2 cases), posterior subcapsular cataract increase (1 case), and inflammatory reaction (1 case). A statistically significant mean VA reduction after surgery from -0.32 to -0.39 (logMAR, P=.01) was found. Differences in VF parameters before and after surgery were not statistically significant. Patients who had severe loss of central vision had statistically significantly higher mean+/-SD preoperative intraocular pressures (27.1+/-8.8 mm Hg vs 19.7+/-8.1 mm Hg; P=.04) and higher rates of surgical complications (43% vs 4%; P=.001) compared with those who did not.

CONCLUSIONS: Severe loss of central vision after a trabeculectomy with mitomycin C occurred in 6% of patients who had glaucoma with marked VF loss. These patients had higher preoperative intraocular pressures and higher rates of surgical complications. Unexplained severe loss of central vision (snuff-out) was rare.