Advanced Diabetic Retinopathy Linked to Choroidal Thickening

New technology could allow doctors new insight into the link between choroidal thickness and diabetic retinopathy (DR).

A team based in South Korea, led by Min Gyu Choi, Department of Ophthalmology, College of Medicine, Chung-Ang University Hospital, analyzed the effects of systemic and ocular profiles on subfoveal choroidal thickness (SFChT) in treatment-naïve eyes with diabetic retinopathy.

In the retrospective, observational, cross-sectional study, the investigators examined 136 total eyes from 136 patients with diabetes and 30 eyes from 30 age-matched healthy controls between September 2016 and April 2018.

Only patients with treatment-naïve eyes without any previous ocular treatment for diabetic retinopathy or diabetic macular edema were included in the study.

The ophthalmologic examination included the measurement of best-corrected visual acuity (BCVA), intraocular pressure (IOP), and refractive error; slit lamp examination; fundus examination and photography; and swept-source optical coherence tomography (SS-OCT).

For the regular systemic workup, the investigators examined body weight, height, body mass index (BMI), blood pressure (BP), complete blood cell count, hemoglobin A1c (HbA1c) level, liver function tests, and kidney function tests and analyzed microalbumin and creatinine levels in urine and the urinary (micro)albumin/creatinine ratio (ACR).

The study included only patients who underwent systemic workups within a span of 4 weeks of the ophthalmologic evaluations.

The investigators excluded patients with prior retinal surgery or panretinal photocoagulation (PRP), intravitreal injection, sub-Tenon's injection, history of ocular trauma or any other eye diseases (such as retinal and choroidal diseases), refractive error greater than ± 3.0 diopter (D), and systemic diseases besides diabetes or hypertension.

Using generalized linear model analyses, the investigators found that the SFChT in treatment-naïve eyes positively associated with the diabetic retinopathy grade and estimated glomerular filtration rate (eGFR) (P = 0.001).

However, the study drug was negatively associated with age (P <0.001) and serum phosphorus levels (P = 0.001). Treatment-naïve eyes with proliferative diabetic retinopathy (PDR; 313.4 ± 9.0 µm) or severe nonproliferative DR (NPDR; 299.7 ± 9.7 µm) had thicker choroid than eyes with mild to moderate NPDR (251.7 ± 11.1 µm) or no DR (231.2 ± 14.5 µm) after adjusting for age, eGFR, and phosphorus levels.

“Choroid is affected by renal function and the grade of DR in patients with diabetes,” the authors wrote. “Advanced retinopathy is associated with choroidal thickening, and the severity of concomitant renal disease is associated with choroidal thinning.”

Diabetic retinopathy is currently the leading of vision loss and blindness in both advanced and developing countries.

The use of enhanced-depth imaging optical coherence tomography allows investigators to view the choroidal thickness in patients with diabetic retinopathy.

Previously, the researchers found SFChT increases as the disease progresses in severity, while several other studies have suggested it decreases in patients with diabetes.

The study, “Effects of Systemic Profiles on Choroidal Thickness in Treatment-Naïve Eyes With Diabetic Retinopathy,” was published online in Investigative Ophthalmology & Visual Science.