Abstract
Purpose :
Fundus-oriented microperimetry measures visual sensitivity and fixation behavior in retinal coordinates, but utilizes expensive equipment, which provides only monocular measurements. We evaluated a low-cost approach comprising a consumer-grade eye tracker and stereoscopic 3D display that may provide monocular and binocular functional assessment in retinal coordinates.
Methods :
Microperimetry and fixation assessment was performed on a NIDEK microperimeter in 12 eyes with central vision loss (18 to 90 yo). The same subjects completed fixation assessment with a 500Hz eye tracker. Gaze positions of the left and right eyes were recorded while observers fixated a binocular target with their Preferred Retinal Locus (PRL). Fixation stability was calculated from the bivariate contour ellipse area (68%). To provide a retinal landmark, observers reported when a monocular target, independently controlled with active shutter glasses, disappeared into the optic nerve head (ONH) of their left and right eyes. Typical anatomical dimensions were used to compute the locations of the diseased fovea and the PRL relative to the ONH in each eye.
Results :
There was no significant difference between estimates of fixation stability measured with the microperimeter (OD median = 8.28°2; OS median = 7.1°2) and the consumer system (OD median = 59.6°2; OS median = 14.72°2), (OD, ranksum = 30, p = 0.18; OS, ranksum = 35, p = 0.59). There were significant differences between the location of the PRL used under binocular conditions with the consumer system and monocular conditions with the microperimeter. The PRL reported by the microperimeter fell within regions with a manifest scotoma, 50% of the time (6 eyes), but outside a scotoma in the consumer system, suggesting that task instructions may influence behavior.
Conclusions :
Low-cost consumer hardware can provide useful quantitative metrics of binocular visual function in patients with low vision that are not currently possible with a high cost clinical apparatus. We were found comparable fixation stability in the consumer system using a binocular fixation assessment compared to Nidek’s monocular assessments. However, there were significant differences in predicted PRL locations between systems, which may be task specific.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.