Abstract
Purpose: :
To evaluate the effect of refractive power on the measurement of peripapillary retinal nerve fiber layer (RNFL) thickness by Cirrus Fourier-domain optical coherence tomography (OCT).
Methods: :
This prospective study involved 15 eyes of 15 healthy participants. Optical coherence tomography scans to measure peripapillary RNFL thickness were repeated in each eye with different refractive condition by wearing soft contact lens of plano, minus (-2, -4, and -6) and plus diopters (+2, +4, +6 and +8). OCT scan was also performed without wearing soft contact lens to evaluate lens effect alone. Change in RNFL thickness measurements with contact lens of different diopters were analyzed by repeated measure analysis of covariance (RMANOVA). Mean average and quadrant RNFL thicknesses with and without plano contact lens were compared by paired t-test.
Results: :
In average RNFL and quadrant map, RNFL thicknesses significantly increased with scans with soft contact lens of higher plus diopters while decreased with soft contact lens of more minus diopters (RMANOVA, all, p < 0.05). Measurement of peripapillary RNFL thicknesses was not different between scans performed with and without wearing plano contact lens.
Conclusions: :
In Cirrus OCT scan, peripapillary RNFL thickness measurement is affected by refractive power of soft contact lens. It is recommended that special attention should be given when measuring RNFL thickness using OCT in patients with soft contact lens or longitudinal follow up of the patient who previous had surgery that changed refractive power of the patient (i.e. LASIK, cataract surgery, etc).
Keywords: imaging/image analysis: clinical