Ocular risk markers good predictors for vision-threatening complications in T2DM: Study

Diabetic retinopathy (DR) is a common complication of diabetes and may lead to blindness through vision-threatening complications, such as diabetic macular oedema and proliferative DR (PDR). Several studies have established that certain systemic factors have associations with incidence and progression of DR, namely, glycemic control, arterial hypertension, high cholesterol and hyperlipidemia obesity, inflammatory markers, sleep-disordered breathing, and exercise (1,2). In addition to systemic factors, there are ocular factors that should be considered, since they may identify the eyes at risk (2).

The researchers here report a 5-year prospective longitudinal observational cohort study that investigates the risk of both systemic and ocular factors that may play a role in the development of diabetic macular oedema and PDR, the vision-threatening complications of DR.

This observational cohort study included eyes/patients with mild nonproliferative PDR, Early Treatment Diabetic Retinopathy Study (ETDRS) classification grades 20 and 35 (3), who were followed for a period of 5 years or until the time of development of centre-involved macular oedema (CIME), clinically significant macular oedema (CSME), or PDR. A total of 212 patients were included: men and women with diagnosed adult-onset type 2 diabetes, aged 42–82 years, with a maximum baseline HbA1c value of 10% (86 mmol/mol). Exclusion criteria included any laser treatment or intravitreal injections or any other comorbidity that could affect the retina. Also excluded were subjects with uncontrolled systemic hypertension >210 mmHg and a history of ischemic heart disease.

A complete eye examination, which included best-corrected visual acuity, slit-lamp examination, intraocular pressure measurement, digital seven-field colour fundus photography, and optical coherence tomography, was performed annually. Additionally, 45°/50° field-2 images were obtained for microaneurysm turnover (MAT) analyses using RetmarkerDR. Of the 212 eyes included in the study, 172 individuals with type 2 diabetes, one eye per person, completed the study. Fourteen eyes developed CSME (8%) and 10 developed CIME (6%), whereas 4 eyes developed PDR (2%), with 1 of these eyes showing both CSME and PDR (3).

The results of the study are:

• Development of macular oedema, either CSME or CIME, and PDR is associated with ocular risk markers such as baseline MAT, CRT, and GCL+IPL thickness metrics.
• They can help better predict the development of complications than systemic markers of metabolic control.
• Eyes with mild retinopathy in individuals with type 2 diabetes with MAT <6 and with HbA1c measurements <8% (64 mmol/mol) showed a very low likelihood of developing CSME or PDR (3 of 88 [3%]) in a period of 5 years.
• On the other hand, an eye with mild retinopathy in a patient with type 2 diabetes, with MAT ≥6, and with HbA1c ≥8% (64 mmol/mol), showed high likelihood of developing CSME and PDR (9 of 25 [36%]).

Thus, the researchers concluded that ocular risk markers are more informative than systemic risk markers for prediction in eyes of patients with well-controlled diabetes with mild retinopathy which ones are at risk for developing vision-threatening complications.

Reference:

Ocular and Systemic Risk Markers for Development of Macular Edema and Proliferative Retinopathy in Type 2 Diabetes: A 5-Year Longitudinal Study by António C.-V. Martinho et al published in the Diabetes Care.

https://doi.org/10.2337/dc20-1125