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Peak Cone Density Predicted from Outer Segment Length Measured on Optical Coherence Tomography

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posted on 2023-12-26, 09:00 authored by Heather Heitkotter, Mitchell T. Allphin, Ana Untaroiu, Heun Min, Emma Warr, Niamh Wynne, Robert F. Cooper, Joseph Carroll

To compare peak cone density predicted from outer segment length measured on optical coherence tomography with direct measures of peak cone density from adaptive optics scanning light ophthalmoscopy.

Data from 42 healthy participants with direct peak cone density measures and optical coherence tomography line scans available were used in this study. Longitudinal reflectivity profiles were analyzed using two methods of identifying the boundaries of the ellipsoid and interdigitation zones to estimate maximum outer segment length: peak-to-peak and the slope method. These maximum outer segment length values were then used to predict peak cone density using a previously described geometrical model. A comparison between predicted and direct peak cone density measures was then performed.

The mean bias between observers for estimating maximum outer segment length across methods was less than 2 µm. Cone density predicted from the peak-to-peak method against direct cone density measures showed a mean bias of 6,812 cones/mm2 with 50% of participants displaying a 10% difference or less between predicted and direct cone density values. Cone density derived from the slope method showed a mean bias of −17,929 cones/mm2 relative to direct cone density measures, with only 41% of participants demonstrating less than a 10% difference between direct and predicted cone density values.

Predicted foveal cone density derived from peak-to-peak outer segment length measurements using commercial optical coherence tomography show modest agreement with direct measures of peak cone density from adaptive optics scanning light ophthalmoscopy. The methods used here are imperfect predictors of cone density, however, further exploration of this relationship could reveal a clinically relevant marker of cone structure.

Funding

This work was supported in part by the National Center for Advancing Translational Sciences of the National Institutes of Health (NIH) under [Grant UL1TR001436] and the National Eye Institute of the NIH under [Grants F31EY033204 and R01EY017607]. This investigation was conducted in a facility constructed with support from the Research Facilities Improvement Program, [Grant Number C06RR016511], from the National Center for Research Resources, NIH. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. Additional funding was received from the Gene and Ruth Posner Foundation and an individual investigator award (FFB-BR-CL-0720-0784-MCW) from Foundation Fighting Blindness.

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