The role of early trabeculectomy in the control of chronic simple glaucoma

Seventy patients of bilateral chronic simple glaucoma with a mean age of 59.7 years, an intra-ocular pressure over 25 mmg Hg, optic disc cupping, and without visual field loss were selected. The eye with higher intra-ocular pressure or the larger optic disc cup was treated by early trabeculectomy while the other eye of the same patient was subjected to medical therapy with topical beta blockers for 3 years (without any surgical treatment). Both the eyes of 70 patients were compared after 3 years. Eyes which had undergone trabeculectomy had a mean intra-ocular pressure of 11.7 mm Hg against 18 mm Hg in the medically treated eyes. Surgically treated eyes had decrease in the mean cup : disc ratio (from 0.54 : 1 to 0.48 : 1) whereas medically treated eyes showed an increase from 0.41:1 to 0.51: 1. Visual field loss occurred in 3/70 operated eyes and in 27/70 medically treated eyes. Twenty-one of 70 treated eyes developed cataract and 12 of these required cataract surgery. Only 18/70 medically treated eyes developed cataracts but none of these required cataract surgery. Early trabeculectomy in cases of chronic simple glaucoma resulted in a large reduction of intra-ocular pressure and consequently reduced the size of optic disc cup and the chances of visual field loss.