Ultrawide field fluorescein angiography (UWF-FA) may be a more precise method for finding microaneurysms than ultrawide field color imaging (UWF-CI) when grading diabetic retinopathy (DR) severity, a study in the British Journal of Ophthalmology reports. The investigation found UWF-FA was able to detect three to five times more microaneurysms than UWF-CI and identify up to 3.5 more fields affecting DR severity.

The retrospective study included patients with type 1 or 2 diabetes mellitus who had UWF-FA and UWF-CI done within a two-week timeframe. The investigators manually counted microaneurysms in individual Early Treatment Diabetic Retinopathy Study (ETDRS) and extended ultrawide field zones. The study determined DR severity based on fields with 20 or more microaneurysms. Severity was defined as: zero fields were classified as mild, one to three fields were deemed moderate and four or more were considered severe.

In 193 patients (288 eyes), 2.4% had no DR, 29.9% had mild non-proliferative DR (NPDR), 32.6% had moderate NPDR, 22.9% were classified as having severe NPDR and 12.2% had proliferative DR.

Overall, UWF-FA microaneurysm counts were 3.5-fold higher than those found in UWF-CI. Specifically, they were 3.2 times higher in ETDRS fields and 5.3 times higher in extended ETDRS fields, in addition to being higher in type 1 diabetes compared with type 2.

In 246 NPRD eyes graded with UWF-CI, UWF-FA found 1.6 times to 3.5 times more fields with 20 or more microaneurysms.

The study found fair agreement between imaging modalities, although differences at all DR severity levels limited direct comparison between the modalities, the researchers noted. However, correcting UWF-FA microaneurysm counts substantially improved DR severity agreement between the modalities, they added.