Diagnostic power of local spatial correlations in high-resolution OCT-angiography of young people with Type 1 Diabetes

Abstract

Purpose : To examine the diagnostic power of novel measures obtained from high-resolution macular OCT-angiography (OCTa) in young people with Type 1 Diabetes (T1D) without retinopathy.

Methods : We examined 26 young persons with T1D (16.4 ± 3.19 y, 13 females), and 18 normal subjects (18.2 ± 4.18 y, 9 females) with Heidelberg Spectralis OCTa. We measured 4 of the highest possible resolution OCTa scans, at each quadrant of the macula, with some overlap. We then combined the 4 data sets forming a single high-resolution set that spanned the macula, at 7 retinal layers. This was done in 32 normal eyes and 46 T1D eyes. Each layer was divided into 18 regions that were half the ETDRS grid regions (Figure A, B). For each region we computed 9 measures: the 4 moment-statistics: mean to kurtosis; and 5 Minkowski Functionals (MFs), which combine local spatial correlations up to 3^rd-order. OCTa data was transformed to total deviations (TDs) and pattern deviations (PDs) as in perimetry. We then assessed diagnostic power as area under receiver operator characteristic plots (AUROCs). ROC analysis was done for subjects <17 y (15 T1D, 9 controls), subjects ≥17 y, and all subjects. Retinal photos showed the eyes had no classical retinopathy.

Results : AUROCs were larger in the younger group. For all groups at the worst 3 to 8 regions out of 18 were best, indicating focal changes. The best performing TD measures were the 8-way Perimeter for the Superficial Vascular Plexus (SVP), and the Intermediate and Deep Capillary Plexus (ICP, DCP), with %AUROCs of 78.8 ± 6.21, 79.8 ± 6.18, and 73.0 ± 7.19 (mean ± SE). For the 4-way Euler number the PDs were best for the SVP and Choroid at 82.9 ± 5.86% and 80.3 ± 6.43%. The moment-statistics rarely exceeded 70%. In the older group ICP Perimeter and some ICP moment-statistics were best.

Conclusions : Given the lack of retinopathy diagnostic performance was good. In accounting for local correlations up to 3^rd-order the Minkowski functionals appear to be more informative than global moment-statistics. In particular, the Perimeter and Euler number were more informative than the Mean or Area which are related to standard OCTa density measures. The capillary-rich SVP, ICP and DCP were the most informative layers.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure. A) The ETDRS thickness grid. B) The 18 regions extracted from an OCTa of the SVP.