Ultrasound biomicroscopy measurement of Schlemm's canal in pediatric patients with and without glaucoma

PURPOSE To compare the diameter of Schlemm's canal in children with and without congenital glaucoma as measured in vivo by means of ultrasound biomicroscopy. METHODS In this prospective single-center study of pediatric subjects (<18 years of age) the diameter of Schlemm's canal in nonglaucomatous and glaucomatous eyes was compared. An 80 MHz iUltrasound probe (iScience Interventional Inc, Menlo Park, CA) placed near the limbus was used to identify and measure the canal's diameter with special attention to the anterior segment anatomy (especially in subjects with congenital glaucoma). RESULTS A total of 20 subjects were included; mean age of subjects without glaucoma was 6.6 +/- 6.65 years; of those with glaucoma, 9.4 +/- 11.80 months. The mean canal diameter in nonglaucomatous eyes was 142 +/- 33.2 mu m (range, 90-196 mu m); in glaucomatous eyes, 64.9 +/- 10.90 mu m (P = 0.007). Schlemm's canal could not be identified in 50% of patients with congenital glaucoma. There was a trend toward smaller canal diameter in subjects with no glaucoma <2 years old. Mean canal diameter in nonglaucomatous eyes was 103 8,mu m (range, 90-115 gm) in subjects <2 years of age and 161 20 mu m (range, 110-196,mu m) in subjects >2 years of age (P = 0.0012). CONCLUSIONS In our pediatric study cohort the diameter of Schlemm's canal varied by age and presence of glaucoma.