Manifest lesions of diabetic retinopathy are most common in the nasal fields and posterior pole, suggesting that combined examinations of the posterior pole and nasal mid-peripheral retina would aid physicians in detecting retinal lesions. This is according to research published in the British Journal of Ophthalmology.
Researchers conducted a hospital-based retrospective study (ClinicalTrials.gov identifier NCT03528720) of 324 Chinese patients with diabetic retinopathy to examine the distribution of manifest lesions in diabetic retinopathy by both fundus fluorescein angiography and color fundus photography. Fundus fluorescein angiography images and color fundus photography images taken between January 2014 and December 2016 were included in the study.
The study population included a total of 566 eyes (patient mean age, 57.2±10.9 years; 57.4% men). Mild nonproliferative diabetic retinopathy was seen in 65 patients, moderate disease in 99, and severe 194. An additional 208 eyes had proliferative diabetic retinopathy.
Microaneurysm distribution across the 9 fields showed a statistically significant difference (F=6.39; P <.001), with the highest frequency in the posterior pole (67.7%), followed by the inferior nasal and nasal fields (59.4% and 55.4%, respectively); difference among the 3 fields were not statistically significant.
Investigators did note statistically significant difference for microaneurysm and hemorrhages/exudates (He/Ex) frequencies across the 9 fields (F=14.5; P <.01 and F=19.54; P <.001), with microaneurysms more prevalent in the posterior pole, nasal superior, inferior nasal, and inferior retina; He/Ex were most frequently found in the posterior pole but were “significantly lower in other fields.”
In patients with severe nonproliferative diabetic retinopathy, intraretinal microvascular abnormalities (IRMA), venous beading, and capillary nonperfusion areas (NPA) were all important clinical signs clearly shown on fundus fluorescein angiography images. IRMA and NPA frequencies were significantly different (F=34.68 and F=18.77; P <.001 for both) among the 9 fields, with the highest IRMA frequency found in the inferior nasal mid-peripheral retina (60.3%).
In proliferative diabetic retinopathy, optic disc or retina neovascularization were analyzed, and a statistically significant difference in neovascularization frequency in the 9 fields was found (F=42.81; P <.001); the highest neovascularization frequency was in the inferior nasal field (76%), a statistically significant difference compared with the posterior pole (including neovascularization of the disc, 63.5%).
Study limitations include those inherent to a hospital-based retrospective study and associated potential selection bias, potential subjectivity in reading images and counting clinical signs, and the difficulties associated with observing peripheral retinopathy in 9-field, 55-degree images due to machine and technique limitations.
“Future prospective trials will be performed to determine whether the mid-peripheral changes in particular fields are associated with the risk of [diabetic retinopathy] progression,” the researchers concluded.
Li X, Xie J, Zhang L, et al. Differential distribution of manifest lesions in diabetic retinopathy by fundus fluorescein angiography and fundus photography. BMC Ophthalmol. 2020;20(1):471.