Corneal thickness variation during eight-incision radial keratotomy.

PURPOSE

To determine the degree of corneal thickness variability that may be encountered during routine radial keratotomy (RK) surgery.

SETTING

Office refractive surgical suite. Laurel Eye Clinic, Brookville, Pennsylvania.

METHODS

This study statistically analyzed variability in corneal thickness measured at the optical zone in 140 consecutive eight-incision RK cases. Pachymetry measurements were assessed at each of the eight circumferential optical zone locations and then evaluated in regard to intra-patient variation by location and inter-patient variation in location thickness patterns. Covariants such as central corneal thickness and differing optical zone size were also analyzed.

RESULTS

Mean corneal thickness (adjusted for optical zone and central thickness) between the three superior locations and the three inferior locations varied by 10 microns. In more than 10% of cases, this adjusted difference was greater than 30 microns. Central corneal thickness and differing optical zone sizes had a significant effect on the results.

CONCLUSION

Corneal thickness measured at the optical zone during eight-incision RK varied significantly by incision location, bringing into question the notion that one blade depth setting is adequate for all incisions.