JAMA Ophthalmology, July 2018
Dupas et al. used optical coherence tomography angiography (OCT-A) to examine the relationship between visual acuity (VA) and macular vessel density in patients with diabetic retinopathy (DR) and poorly controlled type 1 diabetes. They found that decreased VA in patients with severe DR may coincide with greater loss of vessel density in the deep capillary plexus.
This study included a retrospective cohort of 22 patients (22 eyes) with type 1 diabetes who did not have macular edema (mean age, 30 years). All patients had bilateral DR that progressed rapidly and required panretinal photocoagulation (PRP), and all were required to have undergone imaging with OCT-A at least once in the 12 months following PRP. The control group consisted of 12 eyes from age-matched healthy participants with normal vision.
Eyes were classified into 2 groups based on their VA (normal and decreased). Primary outcome measures were VA and the mean vessel density in the deep capillary complex and the 3 retinal capillary plexuses (superficial, intermediate, and deep).
The mean hemoglobin A1c level for the 22 patients with DR was 8.9%. Thirteen eyes with DR had normal VA, and 9 had decreased VA. In all 4 regions examined, mean vessel density was lower for DR eyes with normal VA than for control eyes (deep capillary complex, 44.3% vs. 50.6%; superficial vascular plexus, 44.1% vs. 49.1%; intermediate capillary plexus, 43.8% vs. 49.3%; and deep capillary plexus, 24.5% vs. 30.5%).
Among the DR group, mean vessel density was lower in the eyes with decreased VA. The loss was more pronounced in the deep capillary complex (34.6% vs. 44.3% for DR with normal VA), especially in the deep capillary plexus (15.2% vs. 24.5%), as opposed to the superficial vascular plexus (39.6% vs. 44.1%).
Despite the small sample size, the results suggest that in severe DR without macular edema, decreased VA has strong association with low vessel density in the deep capillary complex. (Also see related commentary by Chui Ming Gemmy Cheung, FRCOphth, and Tien Yin Wong, MBBS, PhD, FRCS, in the same issue.)
The original article can be found here.