Total corneal refractive power and shape in Down syndrome

Abstract

Purpose:

To determine the total corneal refractive power in 1–8 mm corneal zones and the 8 mm Q-value in non-keratoconic patients with Down syndrome and normal subjects aged 10–30 years.

Methods:

Right eye data from 203 Down syndrome patients (mean ± standard deviation age: 17.0 ± 4.7 years) and 189 age- and gender-matched normal subjects (17.1 ± 4.5 years) were compared. Main extracted Pentacam indices were total corneal refractive power in steep and flat axes, and mean and difference (corneal astigmatism) total corneal refractive power in 1–8 mm zones.

Results:

Mean total corneal refractive power in 1–8 mm zones was 45.17–45.74 D and 42.91–43.52 D in Down and normal group, respectively (all p < 0.001). The coefficients of variation of total corneal refractive power from the center to the periphery were similar in the two groups (p = 0.855). None of the mean total corneal refractive powers significantly correlated with age, and all of them were significantly higher in females (p < 0.001). Mean total corneal refractive power–based corneal astigmatism in these zones changed from 1.46 to 1.66 D in Down syndrome patients and 1.64 to 1.99 D in normal group. All corneal astigmatism indices were similar between two groups (all p > 0.05). The prevalence of against the rule and oblique astigmatism in all zones were higher in the Down syndrome group (all p < 0.05).

Conclusion:

Adolescent and young non-keratoconic patients with Down syndrome have a more prolate cornea and a homogeneous keratometry distribution. In this population, females have a steeper cornea.