Off-axis partial coherence interferometry in myopes and emmetropes

Purpose This study describes the axial and peripheral dimensions of myopic and emmetropic eyes in a wide range of retinal locations using a non-contact optical biometer (Zeiss IOLMaster) based upon the principle of partial coherence interferometry. Understanding the optical properties of the peripheral eye may provide insight into myopia development and the possible effects on off-axis visual performance. Methods Fifty-two myopes (spherical equivalent between -2.00 and -9.62 D) and 27 emmetropes (spherical equivalent between -0.50 and +0.50 D) with astigmatism less than 0.75 D, participated in this study. Axial length and peripheral cornea to retina lengths were measured using partial coherence interferometry at the fovea and up to +/- 30 degrees eccentricity along the horizontal and vertical meridian in 10 degrees steps. Relative cornea to retina length was calculated by subtracting the axial length from that obtained at each peripheral location. Results Our results showed significant differences between refractive groups for both horizontal (p < 0.001) and vertical (p < 0.001) meridians, illustrating that the retinal shape profile is significantly different between myopes and emmetropes. Myopic eyes exhibited a greater rate of change in cornea to retina lengths with increasing eccentricity than emmetropic eyes, with the temporal portion of the retina exhibiting the steepest shift. In addition, significant nasal-temporal asymmetry was observed, which was more pronounced in myopic eyes. Conclusions Axial and peripheral cornea to retina dimension measurements, using partial coherence interferometry, suggest that myopic eyes tend toward an ellipsoid shape compared to the spherical emmetropic eyes.