Evaluation of Post–Myopic LASIK Regression for Cornea Ectasia and Increase of Globe Length With Optical Interference Biometry in 500 Consecutive Eyes

Abstract

Abstract: : Purpose: To evaluate the occurrence of post–LASIK cornea ectasia with optical interference biometry in 500 routine, consecutive eyes treated for myopia and myopic astigmatism. Methods: We evaluated 500 consecutive LASIK cases for axial length change using optical interference laser immediately before LASIK and 6 months after surgery. Other parameters studied were peri–operative: refractive error, topography, Orbscan, ultrasonic cornea pachymetry, flap thickness, UCVA, and BSCVA as well as aberrometry and contrast sensitivity. Results: Preoperative myopia ranged from –0.75 to –12.0 spherical equivalent (–4.55). Astigmatism ranged from 0 to –4.50 (–1.25). Axial length changed from 25.92 mm pre–op to 25.79 mm, a mean difference of 0.1375 mm which was statistically significant (Chi square) (p<0.05). The change correlated with the amount of myopic spherical equivalent corrected. There was a well documented increase in the axial length of 150 (15 to 350) microns in 32 cases. This sub–group had a mean pre–op spherical equivalent of –7.50 and pre–op pachymetry 535 microns. 29 of these eyes received enhancement with stable refraction for 4–9 months (5.2). Conclusions: In this group of consecutive myopic LASIK cases we were able to correlate post–operative myopic regression to "forward" cornea movement and not ectasia, with an objective measurement of total axial length. As expected, this sequelae appears to correlate with amount of myopia corrected, pre–op corneal pachymetry and patient age. Within our treatment protocol it did not appear to be an uncontrolled complication.

Keywords: refractive surgery: LASIK • laser • anterior segment