Vision-Threatening Diabetic Macular Ischemia Based on Inferred Progression Pathways in OCT Angiography

Abstract

Purpose

To elucidate the progression pathways of diabetic macular ischemia (DMI) using OCT angiography (OCTA) images and to assess changes in visual acuity (VA) associated with each pathway.

Design

A single-center, prospective case series study.

Participants

One hundred fifty-one eyes from 151 patients with a 3-year follow-up period.

Methods

We obtained 3 × 3 mm swept-source OCTA images and conducted analyses of en face images within a central 2.5 mm diameter circle. Nonperfusion squares (NPSs) were defined as 15 × 15-pixel squares without retinal vessels. Each eye at baseline and after 3 years was embedded into a 2-dimensional uniform manifold approximation and projection space and assigned to 1 of 5 severity grades—Initial, Mild, Superficial, Moderate, and Severe—using the k-nearest neighbors method. We assessed major transitions (involving ≥4 cases) during 3 years. Subsequent probabilistic analyses enabled the construction of a graphical model, wherein directed arrows represented inferred pathways of DMI progression. From this cohort, 103 eyes of 103 patients who did not receive any ocular treatments during the follow-up period were subsequently evaluated for VA changes.

Main Outcome Measures

Inference of DMI progression pathways.

Results

In most cases, NPS counts increased in both the superficial and deep layers. The major transitions between these severity groups at 3 years displayed a unique distribution, and probabilistic analyses suggested a directed graphical model comprising 7 inferred pathways of DMI progression: Initial to Mild, Initial to Superficial, Mild to Superficial, Mild to Moderate, Superficial to Moderate, Superficial to Severe, and Moderate to Severe. Eyes of the Mild and Superficial groups had greater increases in superficial NPS within the central sector than those of the Severe group. Additionally, deep NPS counts within the central sector decreased more in the eyes of the Initial group than in those of the Superficial and Moderate groups. Notably, the eyes of the Superficial and Moderate groups exhibited greater VA deterioration at 3 years compared with those in the Initial group.

Conclusions

A directed graphical model of DMI progression may serve as a useful tool for inferring progression pathways and predicting VA deterioration.

Financial Disclosure(s)

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