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Purpose In this study we aimed to develop a non-invasive, in vivo measure of relative s-cone distribution across the human retina. Methods. The target was a 2° disc presented on a CRT display. The disc was flickered at 17.5 Hz, alternating between blue/violet of fixed luminance and yellow of variable luminance The colors differed only in s-cone excitation, the ratio of 1- and m-cone stimulation remaining constant. The subject's task was to find the point of minimum flicker for each trial (and thus equiluminance) by adjusting the luminance of the yellow disc The disc's position relative to a central fixation point was varied at random between trials. Fixation was ensured by monitoring eye-position with an IROG. Results The figure shows the pooled results for five normal subjects (6-9 repeats per subject). is relative luminance (y/b), abscissa is angle on vertical meridian in degrees. Error bars represent ±standard error), (Figure Presented) Conclusions The para-foveal sensation luminance obtained here closely reflects the distribution of s-cones described by Curcio et al (1991: J Comp Neuro 312:610-624). A consistent superior - inferior radial asymmetry with a steeper shoulder on the inferior meridian is present in all our control measurements. Preliminary investigations also suggest that whilst the V-shaped function is broader in older subjects, this technique is a promising tool for investigating pathological changes in s-cone density occurring during the formation of a superior arcuate scotoma in glaucoma.


Journal article


Investigative Ophthalmology and Visual Science

Publication Date