Effects of Refractive Power on Macular Thickness Measurement Using Spectral-Domain Optical Coherence Tomography.

Purpose: To investigate the effects of refractive power on macular thickness measurements by spectral-domain optical coherence tomography (SD-OCT).

Subjects And Methods: For this prospective cohort study, a total of 50 eyes from 50 normal subjects with no systemic or ocular disease and no history of ocular surgery were studied from February 2014 to May 2014. We used soft contact lenses with a wide range of diopters to change the refractive power. The macular thickness of uncorrected eyes without contact lenses was measured by SD-OCT, and we compared the findings with the results of subsequent investigations in which macular thickness was measured in the presence of soft contact lenses of different diopters (-8, -4, 0, +4, and +8). We divided the patients into three groups according to the axial length (AL) and analyzed the effect of induced refraction change. The main outcome measure was macular thickness measured by OCT.

Results: The average age of the subjects was 28.0 ± 3.4 years (mean ± SD), and included 17 eyes with normal AL, 18 eyes with mid-range AL, and 15 eyes with long AL. The central macular thickness was 254.5 ± 17.5 µm for eyes without contact lenses, which was not significantly different from the measurements in the presence of plano contact lenses (254.2 ± 18.1 µm). Even with soft contact lenses of four different diopters (-8, -4, +4, and +8), central macular thickness (254.4 ± 16.2, 253.7 ± 17.3, 257.3 ± 17.9, and 256.9 ± 17.9 µm, respectively) was not significantly different from that of naked eyes in each group.

Conclusion: These results suggest that central macular thickness measured by SD-OCT is unaffected by refractive power.