Abstract
Purpose :
Type 1 Diabetes Mellitus (T1DM) is a lifelong autoimmune disease that places individuals at risk for complications including diabetic retinopathy (DR). Current T1DM guidelines recommend annual ocular examinations 5 years after onset.
Methods :
We analyzed data from 12 subjects (23-71 yrs, 50% male) (4 T1DM well-controlled (T1C), 4 T1DM uncontrolled (T1U), 4 non-T1DM controls (N)) collected over a period of up to 6 years, with uncontrolled defined as HbA1c>8mmol/mol. Data included age, onset of T1DM, self-reported HbA1c, blood glucose, intraocular pressures (IOP) (Canon TX-20 non-contact tonometer Tokyo, Japan), visual acuity (VA), and blood pressure. Retinal images were taken with a Canon non-mydriatic retinal camera CR-2 Plus AF (Tokyo, Japan). Measurements of the foveal avascular zone (FAZ), foveal vessel density (FD), and vascular density (VD) were calculated from 3mm x 3mm scans with the Optovue AngioVue HD on the RTVue XR Avanti OCTA (Fremont, CA).
Results :
Mean FD values averaged OU were 50.9, 43.3, and 50.8 in the T1C, T1U, and N groups, respectively. FD values differed significantly between T1U and T1C groups (p=0.0008), and not between T1C and N groups (p=0.91). There was also a strong inverse correlation between HbA1c and FD values (Fig 1). ANOVA showed mean FAZ did not differ between the three groups (p=0.98). Two of the T1U developed DR; in both, there was a significant decrease in FD values preceding onset of clinical symptoms in the respective eyes. The first T1U had a FD change from 42.7 to 41.1 manifest as a decrease in VA from 20/60 to 20/100 in addition to edema OD, while the second had a change of 45.06 to 41.73 manifest as hemorrhage into the macula OS.
Conclusions :
There was little difference found in FAZ area, suggesting that FD, which considers vascular branching complexity, may be a more accurate representation of retina health. Early data shows that FD is inversely proportional to HbA1c, and longitudinal trends may provide insight into the clinical manifestation of DR. We suggest optical coherence tomography angiography (OCTA) along with routine measurements at diagnosis, sets a baseline to detect predictive changes to the avascular zone of the macula before apparent clinical symptoms with routine retinal photography. Further investigation is required to determine the role of OCTA measurements in T1DM management.
This is a 2020 ARVO Annual Meeting abstract.