Peripheral retinal ischaemia, as evaluated by ultra-widefield fluorescein angiography, is associated with diabetic macular oedema

Abstract

Purpose: To determine the relationship between retinal ischaemia and the presence of macular oedema (DMO) in patients with diabetic retinopathy (DR) using ultra-widefield fluorescein angiography (UWFA) imaging.

Methods: A retrospective review of 122 eyes of 70 treatment-naïve diabetic patients who underwent diagnostic UWFA using the Optos 200Tx imaging system. Two independent, masked graders quantified the area of retinal ischaemia. Based on clinical examination and optical coherence tomography (OCT), each patient was given a binary classification as either having DMO or no DMO. McNemar's test (with Yates' correction as indicated) and a two-sample test of proportions were used to determine the relationship between DMO and ischaemia for binary and proportional data, respectively. Linear and logistic models were constructed using generalised estimating equations to test relationships between independent variables, covariates and outcomes while controlling for inter-eye correlation, age, gender, haemoglobin A1c, mean arterial pressure and dependence on insulin.

Results: Seventy-six eyes (62%) exhibited areas of retinal ischaemia. There was a significant direct correlation between DMO and peripheral retinal ischaemia as seen on UWFA (p<0.001). In addition, patients with retinal ischaemia had 3.75 times increased odds of having DMO compared with those without retinal ischaemia (CI 1.26 to 11.13, p<0.02).

Conclusion: Retinal ischaemia is significantly correlated with DMO in treatment-naïve patients with DR. UWFA is a useful tool for detecting peripheral retinal ischaemia, which may have direct implications in the diagnosis, follow-up and treatment such as targeted peripheral photocoagulation.

Conflict of interest statement

Competing interests: SK serves as a consultation to Optos, PLC. No additional competing interests declared.

Figures

Figure 1

(A): A sample ultra-widefield fluorescein angiogram. Retinal ischaemia is outlined in red. To obtain the proportion of ischaemic to total retina, the pixels enclosed by the outlined area were divided into the total pixels of the image. (B): A close-up view of the superonasal quadrant of (A) showing the difference between ischaemic (I) and non-ischaemic (N) retina. Retinal ischaemia is defined as angiographically visually significant hypofluorescence (capillary dropout) or areas of significant capillary pruning associated with microvascular pathology (microaneurysms, intraretinal microvascular anomalies, perivascular leakage). Note that the ground glass appearance and normal capillary architecture of the non-ischaemic retina differs from the hypofluorescent areas of non-perfusion and ischaemic vasculature highlighted in red. This figure is produced in colour in the online journal—please visit the website to view the colour figure.

Figure 2

An analysis of patients with demonstrable ischaemia on ultra-widefield fluorescein angiogram. Note the strong correlation between the value of haemoglobin A1c and the proportion of retinal ischaemia to total retina (‘ischaemic index’) in this group of patients.

Figure 3

An ultra-widefield fluorescein angiogram with diabetic macular oedema and a peripheral area of ischaemia. Targeted photocoagulation treatment of this area could possibly prove to be another treatment choice if traditional methods were not efficacious.