Retinal ischemia a risk factor for DME

This retrospective study used ultra-widefield fluorescien angiography (UWFA) imaging to investigate the relationship between peripheral retinal ischemia in patients with diabetic retinopathy (DR) and severity of diabetic macular edema (DME). The results, reported in the May issue of the British Journal of Ophthalmology, indicate that retinal ischemia significantly correlates with DME in treatment-naive patients with DR. The authors also conclude that UWFA is a useful tool for detecting peripheral retinal ischemia, which may have direct implications for diagnosis, follow-up and treatment, such as the use of targeted peripheral photocoagulation.

This is one of the first and largest studies to use UWFA to evaluate retinal ischemia and its relationship to DME. The authors conducted a retrospective review of 70 treatment-naive diabetic patients (122 eyes) who underwent diagnostic UWFA using the Optos 200Tx imaging system, which can assess up to 200 degrees of retina in a single photograph.

Seventy-six eyes (62 percent) exhibited areas of retinal ischemia. There was a significant direct correlation between DME and peripheral retinal ischemia on UWFA (P < 0.001). In addition, patients with retinal ischemia had a 3.75 times increased risk of having DME compared with those without retinal ischemia (CI 1.26 to 11.13, P < 0.02). The authors also found a strong correlation between HbA1C and total surface area of retinal ischemia.

The results lend support to the growing data suggesting that retinal ischemia and release of vasoproliferative growth factors play a role in the pathogenesis of DME, and also suggest that new treatment modalities, such as targeted retinal photocoagulation (TRP), may prove efficacious in treating DME.

In many of the eyes analyzed, DME was present despite minimal posterior diabetic pathology. In some of these eyes, UWFA was able to demonstrate anterior areas of retinal ischemia. The authors say that since the pathogenesis behind the formation of DME is most likely related to peripheral retinal ischemia in these cases, it would be reasonable to consider treating DME by using UWFA and TRP. In combination with macular laser and anti-VEGF therapy, TRP could prove to be important in the growing arsenal of treatment modalities for DME.