Effect of LASIK and contact lens corneal refractive therapy on higher order aberrations and contrast sensitivity...

Corneal and total higher order eye aberrations and their effects on visual function were compared in two groups subjected to different emmetropization techniques-refractive surgery (LASIK) and corneal refractive therapy (CRT).

Twenty eyes of 11 patients and 22 eyes of 13 patients were examined in the CRT and LASIK groups, respectively. Mesopic contrast sensitivity function (CSF) was studied monocularly and binocularly in the two groups of patients undergoing CRT and LASIK who had approximately the same mean refractive error. Corneal asphericity and corneal and total aberrations were calculated, and the differences were analyzed between groups. Visual acuity, corneal and total ocular aberrations, corneal asphericity, and mesopic CSF were determined before and 3 months after treatment.

In both groups, corneal and total higher order aberrations increased after treatment, and the change in some Zernike coefficients was significant. Mesopic CSF diminished after treatment under monocular as well as binocular conditions, with the greatest decline being found in the CRT group under binocular conditions. Corneal asphericity also increased significantly in both groups, which was more accentuated in the CRT group.

Both emmetropization techniques increased higher order ocular aberrations, implying a decline in the mesopic CSF. The increase in aberrations and the consequent deterioration in visual function was more marked in the CRT group.