Change in retinal nerve fiber layer thickness after laser in situ keratomileusis.

PURPOSE

To determine the effect of laser in situ keratomileusis (LASIK) on retinal nerve fiber layer (RNFL) dropout.

SETTING

Nevyas Eye Associates, Philadelphia, Pennsylvania, USA.

METHODS

This prospective consecutive study comprised 120 eyes. The GDx((R)) nerve fiber analyzer (Laser Diagnostic Technologies, Inc.) was used to measure RNFL thickness, an early indicator of glaucomatous damage, preoperatively and 1 week to 4 months and 6 months postoperatively to determine whether any change in apparent RNFL thickness was due to corneal change or to actual RNFL damage and to determine whether apoptotic cascade caused ongoing RNFL dropout. Humphrey visual fields were done in eyes with an abnormal GDx (increase of 20 in GDx number).

RESULTS

The GDx was normal in 89 eyes, including 6 eyes with tilted discs, an abnormal number, and a normal image and 15 eyes with a nonprogressive increase in the GDx number. Three eyes, normal at the interim, were abnormal at 6 months but had a normal visual field. Eleven eyes had a significant increase in the number at 6 months, including 1 eye that showed a possible glaucomatous visual field defect at 9 months and a normal visual field at 14 months.

CONCLUSIONS

There was no evidence of RNFL thinning or glaucomatous damage. A new baseline GDx should be established post LASIK to correct for corneal change.