Assessment of nerve fiber layer thickness before and after laser in situ keratomileusis using scanning laser polarimetry with variable corneal compensation.

PURPOSE

To determine the effect of laser in situ keratomileusis (LASIK) on retinal nerve fiber layer (RNFL) thickness measurements obtained by scanning laser polarimetry with variable corneal compensation (SLP-VCC).

SETTING

Gimbel Eye Centre, Calgary, Alberta.

METHODS

Retinal nerve fiber layer thickness measurements were performed in both eyes of 25 consecutive healthy patients the day of LASIK surgery and 1 month after by trained examiners using the GDx-VCC nerve fiber analyzer. Thickness measurements and all other parameters provided by the software of the machine before and after LASIK were analyzed using the paired Student t test.

RESULTS

Mean age of the patients was 39 years +/- 9.6 (SD) (range 24 to 57 years). The mean preoperative spherical equivalent was -4.15 +/- 1.76 diopters (D) (range -1.0 to -7.50 D) and the mean postoperative spherical equivalent, 0.12 +/- 0.39 D (range -0.75 to +1.00 D). Mean ablation depth was 62 +/- 23 mum. No statistically significant difference was found in SLP parameters after LASIK (P<.05). No clinically significant difference in RNFL thickness measurements was noted in any eye.

CONCLUSION

These data suggest that SLP-VCC mean thickness measurements are not influenced by LASIK-induced alterations in corneal architecture. Measurements obtained with SLP-VCC before surgery may be used for future comparisons.