Quantitative analysis of diabetic macular ischemia using optical coherence tomography

Area of Science:

• Ophthalmology
• Medical Imaging
• Diabetology

Background:

• Diabetic macular ischemia (DMI) is a vision-threatening complication of diabetes.
• Optical coherence tomography (OCT) is crucial for visualizing retinal microvasculature and structural changes.
• Understanding OCT features of DMI is essential for accurate diagnosis and management.

Purpose of the Study:

• To describe the optical coherence tomography (OCT) features of diabetic macular ischemia (DMI).
• To correlate OCT findings in DMI with visual acuity (VA).

Main Methods:

• Collected clinical and OCT imaging data from 100 patients with type 2 diabetes.
• Qualitatively graded DMI severity using Early Treatment Diabetic Retinopathy Study criteria.
• Quantitatively analyzed foveal avascular zone (FAZ) and OCT images with custom software.

Main Results:

• Eyes with DMI showed outer retinal thickening (167.4 ± 18.5 μm) compared to controls (150.4 ± 31.4 μm).
• In eyes without macular edema, DMI was associated with outer retinal thinning (223.1 ± 31.2 μm vs. 244.9 ± 37.2 μm).
• Thinner retinal nerve fiber layer correlated with larger FAZ size (r = -0.231, P = 0.03), especially in eyes without macular edema (r = -0.62, P = 0.001).
• Haller's large vessel layer of the choroid was thicker in eyes with DMI (144.3 ± 51.0 μm vs. 103.5 ± 39.4 μm).
• Thicker retina correlated with worsening VA in DMI (r = 0.52, P = 0.001), but thinner retina correlated with poor VA when macular edema was excluded (r = -0.37, P = 0.004).

Conclusions:

• Diabetic macular ischemia (DMI) is characterized by retinal nerve fiber layer thinning, outer retinal changes, and choroidal Haller's layer thickening.
• These OCT parameters demonstrate a significant correlation with visual acuity.
• OCT findings in DMI can serve as valuable tools for clinical monitoring and future research.