Higher order aberrations in children with Down syndrome.

Area of Science:

• Ophthalmology
• Genetics
• Vision Science

Background:

• Down syndrome (DS) is linked to ocular abnormalities and diminished visual function.
• Atypical optical structures, including thinner and steeper corneas and lenses, are reported in DS eyes.
• These optical differences can negatively affect visual acuity.

Purpose of the Study:

• To investigate and compare higher order ocular aberrations (HOAs) in children with DS versus age-matched controls.
• To further understand the impact of ocular structures on visual function in Down syndrome.

Main Methods:

• Shack-Hartmann aberrometry was used to measure HOAs in 44 children with DS and 209 controls (ages 6-16).
• HOAs were analyzed using Zernike polynomials across 3-mm and 5-mm pupils.
• Visual Strehl ratios (VSX) and equivalent defocus values assessed overall optical quality.

Main Results:

• Children with DS exhibited significantly greater total HOAs, third and sixth order aberrations, and coma (P < 0.005).
• Specific Zernike coefficients (Z3(-3), Z3(3), Z0(4)) showed significant differences between groups (P < 0.013).
• DS eyes demonstrated significantly poorer optical quality, as indicated by VSX and equivalent defocus (P < 0.02).

Conclusions:

• Children with DS possess higher HOAs and reduced central optical quality compared to typically developing children.
• While statistically significant, the HOA differences were not considered pathological.
• The observed subtle reduction in optical quality in DS eyes may exacerbate existing visuocortical deficits.