OCT-Derived Quantitative Measurement of Extent of Vascularization (“Zone”) in Retinopathy of Prematurity

Abstract

Purpose

To provide a quantitative approach to the measurement of zone in retinopathy of prematurity (ROP) using ultra-widefield OCT (UWF-OCT).

Design

Diagnostic accuracy study.

Subjects

Infants undergoing ROP screening at Oregon Health Science University between June 2023 and October 2024, whose parents consented for research imaging.

Methods

An investigational UWF-OCT captured scans from the first week of examination in which stage 1 or worse disease was noted on en face imaging in zone I, posterior zone II, or zone II, and image quality was adequate for quantitative analysis. A U-Net automatedly segmented B-scans to isolate the retina and choroid. En face images and retinal depth maps were used to manually identify the position of the optic nerve, fovea, and visualized temporal vascular border. Mean and minimum retinal arclength (RAL) was measured as the geodesic distance from the optic nerve to the vascular border. The area of vascularized retina (AVR) was estimated using the spherical cap formula, mean-RAL, and measured axial length.

Main Outcome Measures

Analysis of variance and generalized estimating equations to compare OCT-derived eye-level measurements with demographics and clinical diagnosis of zone as determined by clinical assessment of en face UWF-OCT images. Area under the receiver operating characteristic curve (AUROC) for RAL compared with zone and all biomarkers at first examination as predictors of future treatment.

Results

Eighty-five eyes from 52 patients met inclusion criteria. Retinal arclength and AVR were both associated with clinical diagnosis of zone and ranged from 7.2 to 17.3 mm and 40.3 to 213.1 mm², respectively (P < 0.001 for both). The mean difference between zone I and zone II of 4.5 mm (95% confidence interval [CI]: 4.0–5.1) for mean-RAL (P < 0.001) and 80.9 mm² (95% CI: 71.6–90.2) for AVR (P < 0.001). Posterior zone II was intermediate for all measurements. All measures of length and area had an AUROC >0.97 for diagnosis of zone I ROP.

Conclusions

We present a framework for objective measurement of zone in ROP using UWF-OCT. This work complements prior work leveraging advances in imaging technology to bring quantitative and objective approaches to the diagnosis and classification of ROP.

Financial Disclosure(s)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.