Evaluating the effect of subject interface on confocal AOSLO retinal image quality

Abstract

Purpose : Many research-grade AOSLO systems utilize a dental impression to stabilize the head of the individual being imaged. While others use more conventional chin/head rest interfaces like those seen on clinical imaging devices, there are concerns about reduced stabilization afforded by these approaches. Here we assessed retinal image quality when using a chin/head rest compared to when using a dental impression.

Methods : Ten individuals with no known pathology were recruited (ages 21-36 yrs; median age=25 yrs; 1M, 9F). Each individual’s dominant eye was imaged 16 times in a single AOSLO session. Four trials consisting of one video taken at four randomly ordered locations were conducted, and two different subject interfaces (dental impression or chin/head rest) were alternated between trials. The videos were processed into images, and one randomly selected image location for each subject was chosen and co-registered between conditions. A 55 x 55 µm region of interest was then cropped from each image, from which cones were semi-automatically identified to extract quantitative metrics of the cone mosaic. Additionally, these images were evaluated with a signal-to-noise ratio algorithm to determine image quality, and frame motion was extracted from the videos using an automatic reference frame selection algorithm to evaluate eye motion.¹

Results : See Table below for descriptive statistics of the various metrics for both imaging conditions. Total eye motion in distance traveled during video acquisition was not significantly different when using dental impression versus chin/head rest (p=0.56; paired t-test). Additionally, image quality between conditions was not significantly different (p=0.34; paired t-test). Cone nearest neighbor distance and Voronoi area regularity index also did not differ between conditions (p=0.54 and p=0.97, respectively; paired t-test).

Conclusions : The use of a chin/head rest for AOSLO imaging does not significantly increase eye motion, degrade image quality, or impact quantitative metrics of the cone mosaic. Similar comparisons are needed for functional imaging experiments where image stability requirements may be stricter, as well as larger and more diverse patient populations.
1. PMID: 28392976

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Averaged values for total eye motion in distance traveled, image quality, cone nearest neighbor distance and voronoi area regularity index when using a dental impression and chin/head rest.