Abstract
PurposeTo evaluate reliability and repeatability of computer-assisted measurements of cone photoreceptor metrics on Heidelberg Engineering Spectralis™ High Magnification Module (HMM™) Automatic Real-time Tracking (ART™) images.MethodsWe analyzed HMM™ images in three separate study arms. Computer-assisted cone identification software was validated using an open-access adaptive optics (AO) dataset. We compared results of the first arm to data from AO and histology. We evaluated intersession repeatability of our computer-assisted cone analysis in the second arm. We assessed the capability of HMM™ to visualize cones in the presence of pathology in the third arm.ResultsWe included 10 healthy subjects in the first arm of our study, 5 additional healthy participants in the second arm and 5 patients in the third arm. In total, we analyzed 225 regions of interest on HMM™ images. We were able to automatically identify cone photoreceptors and assess corresponding metrics at all eccentricities between 2 and 9° from the fovea. Cone density significantly declined with increasing eccentricity (p = 4.890E-26, Friedman test). With increasing eccentricity, we found a significant increase in intercell distance (p = 2.196E-25, Friedman test) and nearest neighbor distance (p = 1.997E-25, Friedman test). Cone hexagonality ranged between 71 and 85%. We found excellent automated intersession repeatability of cone density counts and spacing measurements. In pathology, we were also able to repeatedly visualize photoreceptors.ConclusionComputer-assisted cone photoreceptor analysis on Spectralis™ HMM™ images is feasible, and most cone metrics show excellent repeatability. HMM™ imaging may be useful for photoreceptor analysis as progression marker in outer retinal disease.
Highlights
In vivo imaging of single photoreceptors of the human retina has been made possible by ocular imaging modalities equipped with adaptive optics (AO) technique [1]
As a proof of principle, we evaluate whether computerassisted cone measurements on High Magnification ModuleTM (HMMTM) images, based on automated and validated cell counts, were reliable and repeatable and could be of sufficient value in future clinical trials
Contrary to AO and histology, cones located near the foveal center could not be resolved by SpectralisTM HMMTM
Summary
In vivo imaging of single photoreceptors of the human retina has been made possible by ocular imaging modalities equipped with adaptive optics (AO) technique [1]. AO is technically challenging and is expensive and not broadly available [4] These limitations make the use of AO in multi-center clinical studies difficult even though, it would be of benefit to approach the loss of individual retinal photoreceptors and accompanying changes of photoreceptor mosaic as biomarkers of early retinal disorder or as treatment response of retinal disease [5]. LaRocca et al were able to visualize single human retinal cones in vivo by a custommade cSLO with a narrower field-of-view (FOV), smaller confocal pinhole, and increased scanning velocity compared to the commercially available cSLO SpectralisTM (Heidelberg Engineering, Heidelberg, Germany) [6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
