Abstract

We have developed a method and models to quantify photoreceptor loss and physiological change in patients with macular degeneration. We initially considered a metric based on the correlation between acuity and photoreceptor sampling rate in foveal and near parafoveal vision of normal observers¹. Ultimately, however, when comparing results of a task with simulated photoreceptor loss² to those of a conventional acuity vs. eccentricity task³, we realized this metric was untenable. In the case of eccentric viewing, the sampling rate of the receptor array decreases together with mean photoreceptor density and visual acuity. In the case of receptor loss, however, the sampling rate is set by the original near-neighbor relationship of the sampling elements and loss merely introduces broad-band spatial noise. Sampling rate no longer corresponds with mean density. Thus a patient may maintain good visual acuity because his modal foveal sampling rate remains at the original sampling rate, yet because of this, an acuity task is inadequate to quantify photoreceptor loss.

© 1993 Optical Society of America