Abstract
Purpose :
Quantitative measurements of vessel density based on optical coherence tomography angiography (OCTA) to identify the initial vascular changes occurring in the retina of patients with diabetes type 2 and their progression over a two year period.
Methods :
Two-years prospective study of 50 eyes with minimal or mild DR from 50 patients with diabetes type 2 using OCTA. Eyes were examined three times with intervals of one year (v1, v2, v3). At enrollment only eyes graded 10, 20 or 35 ETDRS protocol were included.
Definite changes in vessel density of the superficial retinal capillary plexus (SRP) and deep retinal capillary plexus (DRP), 2SD above or below values of healthy controls, were used to identify vessel closure (≥ 2 SD decrease) and vessel dilatation (≥ 2 SD increase).
Results :
In the 26 eyes with minimal DR (grade 10-20) the SRP showed, at baseline, definite vessel closure (VC) in 8% of the eyes (2/26). During the two year period of follow-up there was a progressive increase in VC, 23% (6/26), at one year (v2), and 42% (11/26), at two years (v3). The DRP at baseline showed definite vessel dilatation (VD) in 39% (10/26) of the eyes without VC presence. During the two year follow-up period the DRP showed a decrease in VD (11.5%) at one year and 15.4% at two years. VC (8%) was detected only at v3.
In the 24 eyes with mild retinopathy (grade 35), the SRP showed, at baseline, definite VC in 33% of the eyes (8/24) and no evidence of VD. During the two-year follow-up period there was a progressive increase in VC, 38% (first year) and 58% (second year) and no evidence of VD (see Table 1).
ETDRS grade changes, during the 2 periods of the study, were limited to one grade worsening in nine eyes in the group 10-20 and two eyes in group 35. One eye improved in group 35.
Conclusions :
In the initial stages of DR in diabetes type 2 there are clear differences in the vascular response of SRP and DRP. The SRP shows only VC which progresses consistently in a period of 2 years. The DRP shows initially VD which decreases progressively with VC developing only in the last visit.
OCTA measurements of vessel density not only contribute to the characterization of the initial changes occurring in the diabetic retina but offer an opportunity to identify better retinopathy progression than ETDRS grade changes.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.