Retinal vascular geometry tied to diabetic retinopathy progression
Retinal vascular geometry is significantly associated with progression and incidence of diabetic retinopathy at 1 year, a new prospective cohort study has shown.
“Our study presents novel prospective data on the associations between retinal vessel geometry and DR incidence and progression over 1 year,” said researchers.
The study included 249 Chinese diabetes mellitus patients (mean age 59.9±8.9 years; 74 percent male) referred to the Singapore National Eye Centre for DR screening. Baseline demographic, systemic risk factors, and retinal and vascular information were collected.
Retinal photography was performed to identify DR, defined by the presence of any lesion designated by the Early Treatment Diabetic Retinopathy Study scale. Digital fundus photography was used to measure the retinal vessel network geometry.
Of all the eyes included, 35.7 percent had no DR, 15.3 percent had minimal nonproliferative diabetic retinopathy (NPDR), 14.6 percent had mild NPDR, 23.1 percent had moderate NPDR, 5.1 percent had severe NPDR and 6.1 percent had proliferative DR (PDR). [Invest Ophthalmol Vis Sci 2017;58:BIO200-BIO205]
The 1-year incidence rates of DR and PDR were 21.1 percent (n=19 of 90) and 3.4 percent (n=8 of 235), respectively.
The risk of DR was significantly higher in participants who belonged to the highest quartile of venular fractal dimension (odds ratio [OR], 0.38; 95 percent CI, 0.15 to 0.96; p=0.032) after adjusting for sex, age, smoking status, hypertension and hyperlipidaemia. Univariate analysis showed no association between DR risk and venular fractal dimension.
Incident DR risk was not significantly correlated with any of the other retinal vessel measures.
“[L]arger retinal venular but not arteriolar fractal dimensions were associated with higher DR incidence at 1 year. A larger fractal dimension is believed to represent greater overall complexity of the vascular tree, and the association we found may reflect greater arterio-venous shunting in cases that develop DR,” researchers said.
Univariate analysis showed that higher venular toruosity had a significant association to higher risks of progression of DR (p=0.026) which persisted even after controlling for potential confounders in multivariate analysis (OR, 0.76; 0.59 to 0.97; p=0.005, per SD decrease).
In contrast, lower arterial tortuosity was significantly tied to higher chances of DR regression in both univariate (p=0.024) and multivariate analysis (OR, 1.95; 1.07 to 3.56; p=0.037 per SD decrease).
“Larger retinal venular fractal dimensions are associated with increased likelihood of DR incidence. Higher venular tortuosity is associated with greater likelihood of DR progression, while lower arteriolar tortuosity is associated with greater likelihood of DR regression,” researchers said.
“These geometric measures are likely to represent early changes in the retinal microvasculature, and further study is required to determine if they can contribute to the prediction of DR development in a clinical setting,” they added.