Purchase this article with an account.
Franz Felberer, Julia S. Kroisamer, Peter K. Ahnelt, Christoph K. Hitzenberger, Michael Pircher; Neighbourhood Analysis of the Human Cone Mosaic in AO-SLO Images Recorded In Vivo. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2876.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To investigate the distribution of next neighbors of human cone photoreceptors in images acquired in vivo with an adaptive optics scanning laser ophthalmoscope (AO-SLO).
An AO-SLO instrument operating at 40 fps (imaging area ~300 x 300µm2) with closed loop adaptive optics configuration is used to record images of the human cone mosaic. To increase image quality 40 images are registered to each other and averaged prior to data analysis. Custom software is used to detect each cone. To obtain the number of next neighbors, the distances of each cone to its closest cones are measured. The algorithm regards cones that are within ±30% of the mean distance of the closest seven cones as next neighbors. Finally, the intensity distribution of cones with different numbers of next neighbors is measured.
The number of next neighbor cones could be determined in a healthy volunteer at different locations (1.2° to 7.2° eccentricity from the fovea) on the retina. At 1.2° eccentricity from the fovea 57% of the cones are surrounded by 5 next neighbors (intensity 100.6% of all cone average), 33% have 6 next neighbors (intensity 99.6%) and 10% have 7 next neighbors(intensity 96.7%). This percentage is changed at 7.2 degrees to 40% with 5 next neighbors (intensity 88.2%), 37% with 6 next neighbors (intensity 105.8%) and 23% with 7 neighbors (intensity 111.6%). The distribution of cones with irregular number of next neighbors appears not to be random which corresponds to previously reported observations that have been obtained in vitro.
Fig.1. AO-SLO image of the cone mosaic at 2° eccentricity (left). Number of next neighbors measured for each cone at this eccentricity (right). Green indicates 5 neighbors, red indicates 6 neighbors and blue indicates 7 neighbors.
The number of next neighbors could be determined in AO-SLO images of the human retina. The distribution of cones with irregular number of next neighbors is not random and changes with eccentricity from the fovea.
This PDF is available to Subscribers Only