Changes in Anterior Chamber Depth and Angle Width After Filtration Surgery: A Quantitative Study Using Ultrasound Biomicroscopy

Purpose: To evaluate the anterior chamber configuration by means of ultrasound biomicroscopy in patients with glaucoma and control subjects, and to determine quantitative changes in this configuration after glaucoma filtration surgery (trabeculectomy) and combined cataract and filtration surgery. Methods: The study included 33 eyes of 33 patients with glaucoma (diagnosed with primary open‐angle or exfoliative glaucoma) in which filtration surgery (n = 17) or combined cataract and filtration surgery (n = 16) was performed, and 25 eyes of 25 age‐matched control subjects. Ultrasound biomicroscopy was used to measure anterior chamber depth and the angle width at 500 &mgr;m from the scleral spur in all eyes. The patients with glaucoma were examined 2 days before surgery and 3 and 6 months after surgery. Results: There were no significant differences in anterior chamber depth and angle width between patients with glaucoma before surgery and control subjects. Postoperative values for anterior chamber depth were significantly greater in patients with glaucoma who underwent combined surgery, but no significant changes were observed in those who underwent filtration surgery alone. In contrast, angle width was significantly greater after surgery both in patients who underwent combined surgery and in those who underwent filtration surgery alone. Conclusion: On ultrasound biomicroscopic evaluation, there were no differences in anterior chamber depth and angle width between patients with glaucoma and control subjects. Trabeculectomy alone widens the angle but does not affect the anterior chamber depth; however, combined surgery both deepens the anterior chamber depth and widens the angle.