Characterization of the anterior segment in Trisomy 21-associated cataract using ultrasound biomicroscopy

Backgroundobjectives: To compare the structural anatomy of the anterior segment in pediatric Trisomy 21 (T21) subjects with and without cataracts to age-matched controls. Design: Prospective case-control study. Participants: 40 subjects (57 eyes) age 0-25 years old (9.1 +/- 10.6 years). Methods: This prospective case-control study evaluated anterior segment measurements from ultrasound biomicroscopy (UBM) imaging on 342 images. Results: Among persons with T21 cataract, the iris was significantly thinner than T21 individuals without cataract (0.28 vs 0.32 mm, p = 0.0181). T21/cataract subjects also had significantly thinner lenses than subjects without cataract, regardless of whether they have T21 or are controls (3.1 mm vs 3.5 mm, p = 0.0074). Thinner lens (<3.5 mm) was insignificantly associated with increased odds of cataract (OR = 9.5 [0.872,104], p = 0.065). Thinner iris (<0.32 mm) was associated with increased odds of cataract (OR = 8.4 [1.188, 59.273], p = 0.033). Conclusions: These findings support the hypothesis that subtle quantitative anatomic variants are present in the anterior eye of individuals with T21. Specific anatomic variants are unique to the presence of cataract among subjects with T21.