# Retinal Microvascular Resistance Estimated From Waveform Analysis Is Significantly Higher in Diabetic Retinopathy

## TL;DR

This study found that retinal vascular resistance is higher in diabetic retinopathy, suggesting it could help diagnose and track the disease.

## Contribution

The study introduces total capillary resistance (TCR) as a novel diagnostic marker for diabetic retinopathy.

## Key findings

- TCR was significantly higher in DR eyes compared to normal eyes, except in the PDR group.
- TCR showed moderate diagnostic accuracy with an area under the ROC curve of 0.751.
- The optimal TCR cutoff value for DR detection was determined as 0.79 using the Youden index.

## Abstract

Diabetic retinopathy (DR) is a typical complication in patients with diabetes. This study aimed to compare retinal blood flow and vascular resistance between eyes with DR and healthy eyes using laser speckle flowgraphy (LSFG).

In total, 50 normal eyes and 87 DR eyes were examined at Kagawa University Hospital. LSFG was used to measure the mean blur rate (MBR) and total capillary resistance (TCR) of large vessels in the optic papilla. These values were compared across normal eyes and all eyes with DR, moderate nonproliferative diabetic retinopathy (NPDR), severe NPDR, and proliferative diabetic retinopathy (PDR). A TCR receiver operating characteristic (ROC) curve was plotted, and the diagnostic ability of the TCR for DR was determined using the area under the curve. The TCR cutoff value was determined using the Youden index.

No significant difference in MRB was observed between normal eyes and the other groups. TCR was significantly higher in all groups except the PDR group, compared to normal eyes. The TCR area under the ROC curve was 0.751, indicating moderate diagnostic accuracy for DR. Using the Youden index, the TCR cutoff value was 0.79 (sensitivity, 0.740; specificity, 0.701).

Measuring TCR, in addition to MBR, as diagnostic markers provides more detailed pathological information regarding DR.

Comparison of values between groups would be useful in predicting DR onset and stage progression.