Objective: To evaluate the long-term effect of trabeculotomy on primary congenital glaucoma.
Methods: This retrospective study included primary congenital glaucoma patients who underwent trabeculotomy as an initial surgery between 1988 and 1999 with follow-up at least one year. Definitions of successful operation were determined as (1) intraocular pressure (IOP) </= 21 mm Hg with clear cornea, (2) no antiglaucoma medication or only local medication of topical antiglaucoma drops, and (3) no adverse progression in cup-disc ratio (C/D) and cornea diameter, or cup-disc ratio (C/D) and cornea diameter reduced compared to pre-operation.
Results: The study included 33 eyes with 72.7% patients who were followed-up for over three years. The mean follow-up time was (54.2 +/- 33.2) months. After trabeculotomy, the average IOP was significantly lowered to (16.1 +/- 6.2) mm Hg from (29.9 +/- 11.7) mm Hg (P < 0.001); and cornea diameter was significantly reduced to (12.9 +/- 1.0) mm from (13.7 +/- 1.4) mm (P = 0.002). Although there was no significant difference in the average C/D after operation (P = 0.148), the change in C/D was significantly different in patients in the success group [(0.7 +/- 0.2) mm, pre-operation, (0.6 +/- 0.3) mm, post-operation, P = 0.007]. Based on the criteria for successful operation, the success rate of trabeculotomy was 97.0%, 93.2, 74.5% at one, three and five years by Kaplan-Meier analysis respectively. For 20 eyes which received only one operation, the success rate was 70.0%. However, in the rest of 13 eyes (39.6%) that had received two or more operations, the success rate was reduced slightly to 69.2%. In patients with successful operations, 41.7% of patients had correct visual acuity >/= 0.4, 29.1% between 0.1 and 0.3, and 29.2% </= 0.1. By linear regression analysis, it was found that C/D > 0.8 (P = 0.013) was risk factor responsible for poor vision. Among 18 eyes that were examined for visual field, glaucomatous visual field loss was found in 14 eyes (77.7%). Early-stage defect was seen in 42.8%, intermediate-stage in 28.6%, and late-stage in 28.6% of eyes. Hyphema was found in 14 eyes (42.4%). However, hyphema in 10 out of 14 eyes (71.4%) was absorbed in just one day. Therefore, hyphema should not be considered as a high risk for surgical failure (P = 0.795).
Conclusions: Trabeculotomy had a high success rate in treatment of primary congenital glaucoma with fewer complications during the follow-up time. Observation from repeated operations also showed satisfactory results. Therefore, the optimal goal in preserving useful visual acuity and visual field is to obtain better control of glaucoma with trabeculotomy and treatment of amblyopia.