Ultrasound biomicroscopy of zonular anatomy in clinically unilateral exfoliation syndrome

Purpose: To evaluate the ability of ultrasound biomicroscopy (UBM) to detect abnormalities in the zonular apparatus in unaffected eyes of patients with clinically unilateral exfoliation syndrome (XFS) using a standardized grading system. Methods: The affected and unaffected eyes of 17 patients with clinically unilateral XFS and 17 eyes of 17 control subjects underwent UBM. Radial sections detailing the lens and zonules at 12:00, 1:30, 3:00, 4:30, 6:00, 7:30, 9:00 and 10:30 clock hours were obtained. The images were graded by a masked, experienced UBM observer using a standardized scoring system based on the zonular appearance (0, none; 1 and 2, uneven or disrupted zonules with or without patchy deposits; 3, diffuse granulation, thick zonules or both; 4, total zonular disruption). Affected meridians were compared by the Friedman test, while distributions of unaffected and affected eyes were compared using the Student t-test. Results: In the control group, 15/17 eyes showed normal zonules; the remaining two eyes showed grade 1 changes in some meridians. The mean grade score was 0.33 [standard deviation (SD) 0.84]. Eyes with XFS had a higher score than control eyes, with a mean score of 14.35 (SD 7.14, P < 0.001, Student t-test). In clinically unaffected fellow eyes, the mean score was 10.53 (SD 7.44), and was less than that of XFS eyes (P = 0.008, Student t -test). Twelve XFS eyes (71%) and six unaffected fellow eyes (35%) had grade 3 or 4 in at least one meridian (P = 0.07, Friedman test). Conclusions: Bilateral zonular involvement is present in subjects with clinically unilateral XFS. These zonular changes may be extensive in fellow eyes without clinically evident exfoliation material. UBM assessment of zonular status in fellow eyes prior to cataract extraction may aid in surgical planning.