The Detection of Glaucoma Using Pupillography

Glaucoma is often asymmetric in nature, and an afferent pupillary defect (APD) is frequently present in persons with glaucoma. The investigators propose to conduct a clinic-based prospective study to assess the accuracy of using a binocular pupillographic device (RAPiD, Konan Medical, USA) to detect people with glaucoma. This device is designed to record and analyze pupil responses at multiple, controlled stimulus intensities, while using varied patterns and color stimuli. The asymmetric nature of glaucoma suggests that a high proportion of persons with glaucoma will have an APD (although many may be subtle and would be missed with less refined testing methods). When glaucoma patients have severe nerve damage or when field loss is bilateral and symmetric, an APD may not be present or may be too small to detect. Noting this limitation, the investigators will compare pupillary responses to stimuli at different locations (for example the superior compared to the inferior hemifield) to determine whether the investigators can detect asymmetric glaucoma damage within the same eye. In addition, it is likely that the pupil response in glaucoma will be diminished when compared to normal, which will also help with detection. Aim1: To examine the amplitude, latency and velocity of the pupil light reflex by optimizing its measurement to stimuli of various intensities and colors, and to characterize the variability of this response in normal subjects. Aim2: To quantify the amount of structural loss (retinal nerve fiber layer thickness and optic nerve head parameters) and functional loss (visual field mean deviation) necessary for an APD (as detected by RAPiD) to manifest. Aim3a: To develop an algorithm that best discriminates those with and without glaucoma by individual or combined use of 1) detecting an APD between the two eyes, 2) comparing pupil responses in different parts of the visual field within the same eye, and 3) comparing responses of diseased eyes to responses of "normal" eyes. Aim 3b: To assess the validity of this algorithm in glaucoma detection and to assess the reproducibility of the pupil response measurements at a follow-up visit within 7 months.