Automated algorithm for segmenting and quantifying calcified drusen in 3D swept source OCT imaging

Abstract

Purpose : Qualitative and quantitative assessment of calcified drusen is clinically important in determining the progression risk of age-related macular degeneration (AMD). The purpose of this study is to develop an automated algorithm for identifying and measuring calcified drusen in swept-source optical coherence tomography (SS-OCT) images.

Methods : The method leverages the higher scattering property of calcified drusen compared with soft drusen. Calcified drusen have a higher optical attenuation coefficient (OAC), which results in a choroidal hypotransmission defect (hypoTD) below the calcified drusen. The algorithm automatically segmented calcified drusen from 3D SS-OCT scans by combining the OAC within drusen and the hypoTDs under drusen. We also propose a correction method for the segmentation of the retina pigment epithelium (RPE) overlying calcified drusen by automatically correcting the RPE by an amount of the OAC peak width along each A-line, leading to more accurate segmentation and quantification of drusen in general, and the calcified drusen in particular (Fig.1.).

Results : A total of 29 eyes with nonexudative AMD and calcified drusen imaged with SS-OCT using the 6 × 6 mm² scanning pattern were used in this study to test the performance of the proposed automated method. We demonstrated that the method achieved good agreement with the human expert graders in identifying the area of calcified drusen (Dice similarity coefficient: 68.27 ± 11.09 %, correlation coefficient of the area measurements: r = 0.9422, mean bias of the area measurements = 0.04781 mm², Fig.2.).

Conclusions : A novel approach has been developed and evaluated for segmenting and measuring calcified drusen utilizing its high optical scattering properties and the distinctive hypoTDs observed in slabs under the calcified drusen.

This abstract was presented at the 2023 ARVO Imaging in the Eye Conference, held in New Orleans, LA, April 21-22, 2023.