In vivo measurement of the attenuation coefficient of the sclera and ciliary muscle

Abstract

We acquired 1325 nm OCT images of the sclera and ciliary muscle of human subjects. The attenuation coefficients of the sclera and ciliary muscle were determined from a curve fit of the average intensity profile of about 100 A-lines in a region of interest after correction for the effect of beam geometry, using a single scattering model. The average scleral attenuation coefficient was 4.13 ± 1.42 mm-1 with an age-related decrease that was near the threshold for statistical significance (p = 0.053). The average ciliary muscle attenuation coefficient was 1.72 ± 0.88 mm-1, but this value may be an underestimation due to contributions from multiple scattering. Overall, the results suggest that inter-individual variations in scleral attenuation contribute to variability in the quality of transscleral OCT images of the ciliary muscle and the outcome of transscleral laser therapies.

Quantification of Scleral Changes During Dynamic Accommodation

“…One of the main limitations that is common across all the studies on scleral changes with accommodation, including ours, is that residual ocular convergence during accommodation might affect the measurements of scleral shape. However, the advantage of our method over prior ones is that it allows to record the dynamic sequences (video #1 and #2) of the sclera during accommodation and perform registration to minimize the effect of convergence or even to retake the measurements if large eye motion artifacts are visually detected in the video sequences (Monterano Mesquita et al, 2021 ).…”

“…A minimum of 10 images for each accommodative state were used. A distortion correction algorithm was applied to the selected images to correct for distortions due to refraction of the OCT beam at the air-sclera boundary (Monterano Mesquita et al, 2021;Ruggeri et al, 2014).…”