Abstract
Purpose :
Diabetic subjects have alterations in the anatomical integrity of the foveal cone mosaic, e.g. disruptions in the foveal cone mosaic that could act as noise in the visual system and lead to a decline in visual performance. We estimated the magnitude of these disruptions in Adaptive Optics Scanning Laser Ophthalmoscope cone maps.
Methods :
We quantified the disruptions to the cone mosaic in 11 diabetic subjects (35-71 yr, 51.0 +/-14.4 yr) who were previously found to have localized dark cone regions. Subjects were consented and tested in a manner approved by the Indiana University Institutional Review Board, which adhered to the Declaration of Helsinki. Confocal images with a 100-micron aperture were collected as a series of 100 frame video sequences. The image sequences were aligned and summed to provide a range of gray scale images that allowed cones to vary from bright to dark. A 3 deg region of interest was analyzed, centered on the region of highest cone density. Two independent graders quantified the extent of the disruptions in the cone mosaic using the following criteria: 1) Continuity of the dark regions, 2) length of at least 3 cones and 3) regions darker than nearby structures. The disruptions could be either gaps between cones or adjacent cones that lacked strong central reflections. We computed the Euclidian distance of each disruption of the cone mosaics.
Results :
Both types of disruptions, gaps between cones and three or more cones in a row lacking reflective centers, were found. Disruptions of the cone mosaic of a size sufficient to create visual noise were typical, with 10 of 11 subjects, having more than 75% of all the disruptions identified by the graders being > 1 min of arc (5 microns/ ≤30 cpd). In 10 of 11 subjects, the presence of at least 5 disruptions of the cone mosaic > than 3 min of arc (15 microns/ ≤10 cpd) and one disruption > than 5 min of arc (25 microns/ ≤6 cpd) were found. These disruptions varied widely in shape and orientation, which negatively impacted the agreement between the graders.
Conclusions :
In the foveal region of diabetic retinas, disruptions of the cone mosaic were typical. Previously, sensitivity to acuity targets was shown to be decreased in a region of an area of dark cones (Tu, 2017). Thus, we anticipate that visual noise produced by these disruptions is of sufficient size to interfere with detection of acuity targets and reading.
This is a 2021 ARVO Annual Meeting abstract.