Anterior chamber dimensions, angles and pupil diameter in patients with Down syndrome: A comparative population-based study

Purpose: To study the anterior chamber (AC) dimensions, angles and pupil diameter (PD) in patients with Down syndrome compared to normal controls. Methods: Prospective study is comparing the AC parameters in patients with Down syndrome aged 10-30 years and age-matched controls. Extracted indices included average anterior chamber depth on the 2-mm ring (ACD-2 mm), 4-mm ring (ACD-4 mm), at the corneal apex from the endothelium (endo-ACD), at the corneal apex from the epithelium (epi-ACD), anterior chamber volume (ACV), mean anterior chamber angle (ACA), and PD measured by Pentacam. Results: Data from 202 patients with Down syndrome (age 17.2 +/- 4.8 years) were compared with 190 normal controls (age 17.2 +/- 4.5 years). In Down and normal groups, mean +/- SD were 2.51 +/- 0.31 and 2.83 +/- 0.34 mm for ACD-2 mm, 1.65 +/- 0.30 and 1.93 +/- 0.31 mm for ACD-4 mm, and 3.03 +/- 0.29 and 3.24 +/- 0.26 mm for endo-ACD, 3.54 +/- 0.29 and 3.80 +/- 0.26 mm for epi-ACD, mean 169.31 +/- 30.38 and 200.17 +/- 33.20 mm(3) for ACV, 40.69 +/- 4.50 and 39.97 +/- 4.12 degrees for ACA, and 2.79 +/- 0.62 and 3.59 +/- 0.80 mm for PD, respectively (all P < 0.001). None of the studied indices significantly correlated with age, except for ACA (P = 0.011). All parameters, except for PD, were significantly higher in males compared to females (all P < 0.001). Temporal ACA was significantly wider in male subjects (44.61 +/- 6.52 vs. 42.24 +/- 6.52 degrees; P < 0.001). Conclusion: The AC in patients with Down syndrome is smaller than normal individuals. AC in females with Down syndrome is smaller than males, and the narrower ACA is attributable to the difference in the temporal angle and not the ACA in other meridians.