SS-ASOCT in patients with type 2 diabetes mellitus analyses
A Study was conducted to evaluate iris volume before and after pupil dilation using swept-source anterior segment optical coherence tomography (SS-ASOCT) and investigate the associated factors of iris volume and iris volume change after pupil dilation in patients with type 2 diabetes mellitus (T2DM).

A cross-sectional study was conducted among T2DM registered patients. Anterior chamber volume (ACV), iris volume, anterior chamber depth (ACD), angle opening distance at 500 microm (AOD 500) and pupil diameter were estimated using SS-ASOCT. Venous blood was taken for the measurement of glycosylated haemoglobin A1c (HbAlc). All biometric measurements were performed before and after pharmacologic pupil dilation.

--A total of 117 subjects were included in the analysis. The mean age (±SD) was 64.96 ± 7.75 years, and 62.4% were females.

--After pupil dilation, iris volume decreased in all eyes. Shorter duration of diabetes, longer axial length and smaller pupil diameter were associated with larger iris volume.

--The change in iris volume per millimetre change in pupil diameter was 1.35mm3/mm.

--Smaller baseline iris volume and higher HbA1c level were associated with smaller change in iris volume per millimetre change in pupil diameter, after adjusting for other factors.

SS-ASOCT can ultimately measure Iris volume. Diabetic duration was related to iris volume static anatomy, whereas iris volume dynamic reaction was suggested at the HbA1c level. The macroscopic and microscopic composition of iris in the diabetic population is expected to be affected by diabetic duration and HbA1c level.