Effect of contact lens power on optical coherence tomography of the retinal nerve fiber layer.

PURPOSE

To study the effect of contact lens (CL) power on retinal nerve fiber layer (RNFL) thickness measurements using optical coherence tomography (OCT).

METHODS

Cross-sectional study on 15 healthy subjects. Peripapillary RNFL thickness was measured using time-domain OCT without CL and with CL of different powers (+4 D, +10, -4D, and -10 D), and again without CL. RNFL thickness measurements were compared statistically.

RESULTS

Age of study subjects was 30.5 ± 3.2 (mean ± SD) years. Global RNFL thickness measurements showed good repeatability (average without CL was 107 ± 9.3 μm for the first measurement, and 107.4 ± 7.4 μm for the second [P = 0.8]). There was no significant effect of CL power on global RNFL thickness, although more variability was observed with the -10 D CL. When analyzing individual clock-hour segments, only differences in the 6 o'clock hour segment were statistically significant (between -10 D CL [155.9 ± 22.4 μm] and without CL [143.5 ± 19.3 μm], as well as between -10 D and +4 D CL [138.9 ± 19.9 μm], with P < 0.001). When analyzed for individual quadrants, differences in the inferior quadrant were significant between measurements with -10 D CL and all other CLs.

CONCLUSIONS

Refractive error changes at the corneal plane do not significantly affect RNFL thickness measurements using OCT; caution is warranted in inferior segments, where variations may occur. These results may be applicable to RNFL thickness measurements before and after cataract or refractive surgery.