Measuring the foveal avascular zone in diabetes: A study using optical coherence tomography angiography

Diabetes is a global issue that currently affects 425 million people worldwide. One observable microvascular complication of this condition is a change in the foveal avascular zone (FAZ). In this study, we used optical coherence tomography angiography to investigate the effect of diabetes on the FAZ.

A total of 11 participants with diabetes and 11 participants without diabetes took part in this study. Participants in both groups were matched for age (P = 0.217) and sex (P = 0.338), and had no history of ocular disease. Macular optical coherence tomography angiography (OCT-A) scans of participants' right and left eyes were taken. Glycosylated hemoglobin (HbA_1c ) and blood glucose levels were also measured. The FAZ area was manually segmented at the levels of the superficial capillary plexus (FAZ_SCP ) and deep capillary plexus (FAZ_DCP ).

There was a strong relationship between the FAZ area of participants' right and left eyes (P ≤ 0.001) in both diabetes and non-diabetes groups. In the diabetes group, the FAZ_SCP (P = 0.047) and FAZ_DCP (P = 0.011) areas was significantly larger than in the non-diabetes group. Moreover, multiple linear regression analysis predicted a 0.07-mm² increase in the FAZ_SCP and FAZ_DCP areas of individuals with diabetes for every 1% increase in their HbA_1c level.

Our findings show that there is enlargement of the FAZ in individuals with diabetes compared with individuals without diabetes. In the diabetes group, this enlargement appears to be correlated with HbA_1c level. OCT-A imaging could, therefore, be a useful tool to monitor the FAZ and identify potential early microvasculopathy in diabetes.