Cataract progression after trabeculectomy was investigated in a study of 47 eyes with exfoliative glaucoma (ExG) and in 20 eyes with primary open-angle glaucoma (POAG). Cataract progression was assessed from the need for cataract extraction, deterioration of visual acuity by > or = 2 Snellen lines, myopic change in the refraction and increase in the lens opacity value, measured with a Lens Opacity Meter 701. Measurements were made 6 and 12 months after trabeculectomy and at the follow-up visit at 26 +/- 11 months. ExG, age, hypotony (IOP < or = 5 mm Hg) lasting > or = 5 days and early postoperative IOP rise > 30 mm Hg were observed to be risk factors for cataract progression. In pairwise analysis of 14 patients, in which the unoperated eye served as the control, a myopic change of refraction was the most frequent indicator for a change in the structures of anterior segment, possibly indicating cataract progression.