Straylight in function of wavelength and refraction

Purpose To determine dependencies of straylight on ocular biometry. Methods This prospective study includes 518 eyes of 277 volunteers with healthy eyes of various iris colors and ethnicities who had their retinal straylight tested using the psychophysical Oculus C-Quant device. Ocular axial length and refraction were also measured, respectively using the Zeiss IOL master and the Nidek ARK-700 autorefractometer. Results The measured retinal straylight was validated by comparing our data with the age model described in the literature as log(s) = P1 + log(1+(Age/65)4). Our data was found to agree well, albeit that P1 was slightly higher (0.931 versus 0.87). Subtracting this model from the measured straylight values, a quadratic increase was found in function of axial length L. A similar model was defined for the spherical equivalent refraction SE and retinal image size I. This corresponds to an increasing straylight for increasing degrees of myopia. No correlation with keratometry or corneal astigmatism was found. Conclusion Retinal straylight increases not only with age, but also with axial length. Further study is needed to identify the cause of this dependency.