To analyse the effect of congenital unilateral ptosis on the ocular higher order aberrations (HOA) and to compare these eyes with normal fellow eyes this study has been performed. In this observational comparative case series, 16 eyes of 16 patients less than 15 years old with congenital unilateral upper eyelid ptosis were included. Corrected distance visual acuity (CDVA), corneal topography, ocular HOA’s with Zywave workstation was recorded. The amount of ptosis was measured from marginal reflex distance (MRD1). The ocular HOA’s were compared between the ptosis and the normal fellow eyes after making necessary corrections to avoid errors due to enantiomeric midline symmetry. The mean age was 12.5±2.7years (range7-15years). The mean MRD1 was -0.9±1.8mm in the ptosis eyes. There was significant difference noted in the mean 6mm Zernicke coefficients Z3−3 (p=0.002), Z4−2 (p=0.034), Z42 (p=0.008), Z5−5 (p=0.044), Z51 (p=0.039), Z53 (p=0.036), Z55 (p=0.044) between the ptosis and the fellow eyes. The mean Z3−3 was -0.17±0.15 and 0.07±0.12 in the ptosis and the normal eyes respectively. There was a significant difference (p=0.023) in total RMS (root mean square) between the ptosis and the normal eyes. Total coma aberration correlated with CDVA (p=0.004) and MRD (p=0.030) in the ptosis eyes. There was no correlation (p=0.815) between the age (duration of ptosis) and total RMS. In conclusion, Eyes with congenital ptosis differed from their normal fellow eyes in the higher order aberrations. None of the HOA’s which differed between the two groups affected the visual acuity in the ptosis eyes
