Pre‐receptoral filters in the eye and their effect on vision

Abstract

SummaryAdvanced Vision and Optometric Tests (www.city.ac.uk/avot) were employed to study changes in macular pigment optical density and visual performance following three months of daily supplementation with carotenoids. The subject investigated was earlier diagnosed with type 2 diabetes, but recovered through diet and exercise, to the point of being free of diabetes.Before supplementation, the tests revealed borderline performance for photopic and mesopic visual acuity (VA), functional contrast sensitivity (FCS) and red / green (RG) colour vision. The subject's thresholds for yellow‐blue (YB) colour vision and rod sensitivity were, however, just above normal, age‐matched limits.Post supplementation, the results revealed increased macular pigment levels in the central retina. In addition, the results also revealed significant improvements in several, other aspects of vision, particularly at lower light levels. VA and FCS improved, but this outcome depended on whether the stimuli were of positive or negative luminance contrast. Rod and cone mediated vision showed significant changes with large improvements in rod sensitivity. Thresholds for detection of RG and particularly YB colours were also significantly lower post‐supplementation.