Macular Neural and Microvascular Alterations in Type 2 Diabetes Without Retinopathy: A SS-OCT Study

Abstract

Purpose : This study aimed to identify specific markers indicative of macular neural and microvascular alterations in individuals with Type 2 Diabetes Mellitus (T2DM) lacking clinically observable retinopathy.

Methods :
In this prospective observational study, all eyes underwent swept-source optical coherence tomography angiography (SS-OCTA) using the PLEX Elite 9000. Acquired images were quantitatively analyzed to compare macular neural and microvascular alterations in T2DM patients without retinopathy to age-matched controls. Precise assessments included measuring the thickness of each individual retinal layer and evaluating macular vascular indices within different capillary plexuses.

Results : Forty-nine T2DM patients and 51 age-matched controls were recruited. T2DM patients showed a significant reduction in the mean macular thickness of the ganglion cell-inner plexiform layer (GC-IPL) (82.5 ± 5.5 μm vs. 86.2 ± 5.0 μm, p = 0.001) and macular retinal nerve fiber layer (RNFL) (45.8 ± 3.0 μm vs. 48.1 ± 3.7 μm, p = 0.001). Additionally, macular full retinal thickness was significantly lower in diabetic eyes than controls (324.9 ± 16.3 μm vs. 332.8 ± 13.7 μm, p = 0.009). Vascular measurements revealed subtle changes in macular vascular skeleton density within the total capillary plexuses in T2DM patients (0.132 ± 0.005 vs. 0.135 ± 0.005, p = 0.019).

Conclusions : Metrics derived from SS-OCT, particularly macular RNFL and GC-IPL thicknesses, have proven to be superior indicators for the early detection of diabetic retinal disease in individuals with T2DM lacking clinically observable retinopathy. Further investigations are warranted to comprehensively understand the clinical implications of these findings.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Fig 1. Fig 1 Retinal layer thickness maps (1.0–5.0 mm annulus) for quantitative analysis in a 51-year-old diabetic patient (1st row) and a healthy subject (2nd row). Columns show RNFL (1st), GC-IPL (2nd), inner nuclear layer (3rd), outer retinal layer (4th), and full retina (5th).

 

Fig 2. En face OCTAs, binarized, and skeletonized images depict retinal vasculature in a diabetic patient (upper 3 rows) and a healthy subject (lower 3 rows). Analysis focused on annular regions in the retinal Superficial Vascular Complex (1st column), Intermediate Capillary Plexus (2nd column), Deep Capillary Plexus (3rd column), and Total Capillary Plexus (4th column), delimited by red and green circles (1 and 5 mm).