Relationship between formation of a filtering bleb and an intrascleral aqueous drainage route after trabeculectomy: evaluation using ultrasound biomicroscopy

We evaluated the relationship between the development of filtering bleb and the thickness of the aqueous drainage route beneath the scleral flap in patients who had undergone trabeculectomy. The relationship between the postoperative intraocular pressure and the size of the filtering bleb was also studied. We studied 29 eyes of 21 patients who had been followed for at least 1 (mean 9.9) month after the trabeculectomy. Ultrasound biomicroscopy was used to examine the filtering bleb and aqueous drainage route beneath the scleral flap. The thickness of the aqueous drainage route beneath the center of the scleral flap was found to be correlated with the development of a filtering bleb (r = 0.391, p < 0.05). The size of the bleb was correlated with the intraocular pressure (r = -0.560, p < 0.05) which had not been treated with antiglaucoma medication during follow-up. Thus, preservation of the aqueous drainage route beneath the scleral flap probably influenced the development of a filtering bleb following trabeculectomy.