Posters

Assessment of refractive astigmatism and simulated therapeutic refractive surgery strategies in coma-like-aberrations-dominant corneal optics

Poster Details

First Author: W. Zhou NORWAY

Co Author(s):    A. Stojanovic                    

Abstract Details

Purpose:

To raise awareness of the contribution of coma-like higher order aberrations (HOAs) to the amount and orientation of refractive astigmatism in eyes with coma-like-dominant corneal optics and to explore how to account for that contribution in planning therapeutic refractive surgery using topography-guided custom ablation.

Setting:

Synslaser clinic, Tromsoe, Norway

Methods:

Eleven eyes with coma-like-aberrations-dominant corneal optics and with low lenticular astigmatism were selected for astigmatism analysis and for treatment simulations with topography-guided custom ablation. Vector analysis was used to evaluate the contribution of coma-like corneal HOAs to refractive astigmatism. Two different strategies were used for simulated ablations aiming to regularize irregular corneal optics: With both strategies correction of anterior corneal surface irregularities (corneal HOAs) was intended. Correction of total corneal astigmatism and refractive astigmatism was intended as well with strategies 1 and 2, respectively.

Results:

Axis of discrepant astigmatism (refractive astigmatism minus total corneal astigmatism minus lenticular astigmatism) correlated strongly with axis of coma. Vertical coma influenced refractive astigmatism by canceling the effect of the with-the-rule astigmatism and increasing the effect of the against-the-rule astigmatism. After simulated correction of anterior corneal HOAs along with total corneal astigmatism and refractive astigmatism (strategies 1 and 2), only small amount of anterior corneal astigmatism and no total corneal astigmatism remained after strategy 1, while considerable amount of residual anterior corneal astigmatism and total corneal astigmatism remained after strategy 2.

Conclusions:

Coma-like corneal aberrations seem to contribute a considerable astigmatic component to refractive astigmatism in eyes with coma-like-aberrations dominant corneal optics. If topography-guided ablation programmed to correct the corneal HOAs and refractive astigmatism is used, both coma-like corneal aberrations themself and the result of their contribution to the refractive astigmatism will be treated. Disregarding refractive astigmatism and treating total corneal astigmatism along with corneal HOAs is recommended instead.

Financial Disclosure:

NONE