Prognosis of primary ab externo surgery for primary congenital glaucoma

The strategy of pressure reducing surgery in primary congenital glaucoma has changed over the last decade. Ab externo filtering procedures--for example, trabeculectomy or trabeculotomy combined with trabeculectomy, have now been accepted even as primary intervention.

The authors reviewed 61 eyes in 35 consecutive patients with primary congenital glaucoma, who underwent different types of initial ab externo surgery between 1988 and 1996 (median follow up 36 months) to determine the efficacy of different surgical techniques and the influence of various risk factors.

Trabeculotomy was performed in 17 eyes (27.9%), trabeculotomy with trabeculectomy in 15 eyes (24.6%), and trabeculectomy in 29 eyes (47.5%). Regarding age, preoperative intraocular pressure, corneal diameter, ocular axial length, and incidence of corneal haze the subgroups were comparable. Success rates of trabeculotomy, trabeculectomy, and a combined procedure did not significantly differ when assessed by life table analysis. Patient age under 3 months (p = 0.014) and an ocular axial length of 24 mm or more (p = 0.016) proved to be major risk factors for primary ab externo surgery failure. A second operation was necessary in 20 of 61 eyes (32.8%) during follow up.

Prognosis of primary ab externo glaucoma surgery in primary congenital glaucoma seems to be governed more by the individual course and severity of the disease than by modification of surgical techniques.