The Effect of Refractive Power on Retinal Volume Measurement Using Spectral Domain Optical Coherence Tomography

ABSTRACT

PURPOSE: To investigate the change of retinal volume according to anterior segment refractive power using contact lens by spectral domain optical coherence tomography (SD-OCT). METHODS: The retinal volume was measured using a SD-OCT (Heidelberg retinal angiography Spectralis + OCT, Heidelberg Engineering, Heidelberg, Germany) in 60 subjects without any underlying disease. The same examiner performed a 31-section macular volume-scan at 240 µm intervals, re-measured the same area by changing the refractive power of the anterior segment by wearing soft contact lenses of +6.0 diopters and −6.0 diopters. By using the ImageJ software to calculate the cross-sectional area and of the cross-sectional area and the volume was measured. RESULTS: The mean age of the participants was 25.6 ± 1.5 years and the mean axial length was 25.7 ± 1.57 mm. The volume of the posterior pole retina measured without the contact lens was 13.48 ± 0.05 and the mean volume of the retina measured with +6.0 diopter and −6.0 diopter contact lens in the same patient was 13.47 ± 0.07 mm³ and 13.48 ± 0.05 respectively. The mean volume was significantly lower(p = 0.036) in the measurement with the +6.0 diopter lens than in the measurement without the lens, and the mean volume was significantly higher in the measurement with the +6.0 diopter lens (p = 0.042). The change in retinal thickness was increased with longer axial length (r = 0.32, p < 0.05), but the central foveal thickness did not correlate with anterior corneal power (p = 0.463). CONCLUSIONS: The volume of the retina measured using the SD-OCT is affected by the refractive power of the anterior segment and the axial length. Therefore, it is necessary to consider the change of refractive index because it can change the retinal volume measured by SD-OCT.