Total, corneal, and internal ocular optical aberrations in patients with keratoconus

To measure and compare total, corneal, and internal ocular aberrations using combined wavefront analysis and corneal topography in eyes with keratoconus and eyes with normal corneas.

This prospective study comprised eyes of patients with keratoconus and myopic patients seeking refractive surgery. Patients diagnosed with keratoconus and with a classification of "normal" or "keratoconus" on the NIDEK Corneal Navigator corneal disease screening software were selected for inclusion in this study. The normal group comprised eyes with a "normal" classification with 99% similarity. In the normal group, only one eye per patient was randomly selected based on a randomization schedule. Corneal, internal, and total wavefront measurements were provided by the NIDEK OPD-Scan II.

One hundred eyes with keratoconus and 155 normal eyes were enrolled in the study. Statistically significant higher corneal and internal higher order aberrations were observed in the eyes with keratoconus (P<.05). However, an increase in ocular higher order aberrations proportional to corneal higher order aberrations was not observed in the keratoconus group.

A compensatory effect of increased anterior corneal aberrations by internal aberrations in keratoconic eyes was present for some aberrations. The origin of this compensation and the optical mechanism behind it requires further study.