Purpose: To examine ocular biometric variables in subjects with Down syndrome.
Methods: In a population-based study we have compared ocular biometric variables in a group of 47 individuals with Down syndrome (20.0+/-3.9 years) with 51 control subjects (21.0+/-4.6 years).
Results: A thinner cornea (0.48+/-0.04 mm vs. 0.55+/-0.03 mm, p<0.001) and higher keratometry values (46.39+/-1.95 D vs. 43.41+/-1.40 D, p<0.001) were found in the Down syndrome group than in the control group. Oblique astigmatism was commonly found in the Down syndrome individuals, showing a strong right-left specificity (right eyes' axes in the 135 degrees -meridian, left eyes' axes in the 45 degrees -meridian). The lens was thinner (3.27+/-0.29 mm vs. 3.49+/-0.20 mm) and the calculated lens power was weaker (17.70+/-2.36 D vs. 19.48+/-1.24 D) in the Down syndrome group than in the control group (p<0.001 in both cases).
Conclusions: Thinning of the corneal stroma may account for the steeper cornea and the high frequency of astigmatism in Down syndrome due to lower corneal rigidity. It may also be of etiological importance to the increased incidence of keratoconus in Down syndrome.