Investigators recently learned that the luminal to choroidal area (L/C) ratio decreased in eyes of patients with diabetes, especially in those with severe diabetic retinopathy (DR), compared with normal controls. They note that changes in the L/C ratio and choroidal blood flow deficit may help predict DR development.

This observational cross-sectional study evaluated 104 eyes that were divided into four groups: 

(1) healthy eyes (n=38)

(2) diabetes with no DR eyes (n=22)

(3) non-proliferative DR eyes (n=24)

(4) proliferative DR eyes (n=20)

Initially, panretinal photocoagulation (PRP) had not been employed in any patients. The team used OCT imaging to compare the total choroidal area, stromal area, luminal area and L/C ratio as well as choroidal parameters between PRP-untreated and PRP-treated DR eyes.

After enrollment and initial assessment, 40 of the DR patients underwent PRP treatment; three were lost to follow-up. To investigate the effect of PRP, the choroidal parameters of patients with proliferative and non-proliferative disease—with and without PRP treatment—were also assessed.

The researchers found that the L/C ratios were 0.68±0.06 in controls and 0.63±0.04 in diabetes eyes, with no statistically significant differences in retinal nerve fiber layer thickness, retinal thickness and subfoveal choroidal thickness measurements between the two groups. The vessel densities were significantly different among all patients with some extent of diabetes (groups 2-4), with significant differences in L/C ratios between these three groups. They add that there was no significant difference in any measures between PRP-untreated and PRP-treated DR eyes.

1. Wang H, Tao Y. Choroidal structural changes correlate with severity of diabetic retinopathy in diabetes mellitus. BMC Ophthalmol. August 16, 2019. [Epub ahead of print].