Non-corneal Intraocular Higher Order Aberrations in Eyes With Keratoconus Versus Normal Myopic Eyes.

Purpose: To evaluate and compare non-corneal intraocular higher order aberrations (HOAs) in keratoconic and normal myopic eyes.

Methods: Eighty-eight keratoconic and 106 normal myopic eyes were examined using high-resolution (1) pyramidal ocular wavefront sensor PERAMIS (designed by CSO for SCHWIND eye-tech-solutions GmbH) and (2) anterior segment optical coherence tomography (AS-OCT) MS-39 (CSO). Intraocular HOAs were calculated by subtracting the total corneal aberrations measured by the AS-OCT from the total ocular aberrations measured by the pyramidal aberrometer. Aberrations were reported at an optical zone of 5.5 mm and were referenced to the pupil center.

Results: Every component of absolute intraocular HOAs was larger in keratoconic eyes than in myopic eyes in regard to magnitude and vertical and horizontal components ( < .05). Intraocular HOAs were also more scattered in keratoconic eyes. For trefoil aberrations, the axes of total corneal and intraocular centroid were opposing, almost 60 degrees away in keratoconic eyes. This mirrored the difference in orientation between anterior and posterior corneal trefoil. For each of coma and trefoil, 15.9% of keratoconic and 0% of myopic eyes had intraocular aberrations of 0.50 diopters (D) or greater. A total of 3.4% of keratoconic eyes and 0% of myopic eyes had total intraocular HOAs of 1.00 D or greater (all < .05).

Conclusions: Intraocular HOAs in keratoconus are larger than in normal eyes and can either offset or support their total corneal counterparts. Intraocular HOAs should be computed and taken into consideration when planning customized corrections in eyes with keratoconus. .