Microvascular abnormalities in the bulbar conjunctiva of patients with type 2 diabetes mellitus

To study and quantify microvascular abnormalities objectively in vivo in patients with type 2 diabetes mellitus (T2DM).

The conjunctival microcirculation in 14 patients with T2DM and in age-matched healthy control subjects without diabetes was videotaped and objectively studied by using computer-assisted intravital microscopy (CAIM), a novel and quantitative real-time technology.

Patients with T2DM (N = 14) had significantly (P<0.01) wider conjunctival vessel diameters (71.9 +/- 5.2 mm) than did healthy nondiabetic control subjects (54.0 +/- 4.4 mm). In the study patients, microvascular distribution was significantly (P<0.01) abnormal (36.7 +/- 18.2 versus 45.3 +/- 9.6 cm per unit area, patients versus control subjects), and vessel distribution was uneven on the surface of the bulbar conjunctiva. The arteriole:venule (A:V) ratio in patients with T2DM was extremely variable and differed significantly (P<0.01) from that in the nondiabetic control subjects (A:V approximately 1:2). In addition, a unique sinusoidal (hypertensive) vascular pattern frequently existed in some of the large veins of all study patients with T2DM but in none of the nondiabetic control subjects.

We identified the presence of microvascular changes (abnormalities) in the conjunctival microcirculation of patients with T2DM. Although all these abnormalities did not appear in the same patient at the same time, the sum total of their presence in each patient correlated significantly with disease severity, as noted in the medical records. The severity of microvascular abnormalities, however, did not correlate with the duration of the disease since diagnosis. CAIM may be a useful objective and quantitative technique for assessing microangiopathy in patients with T2DM. The easy noninvasive accessibility of the conjunctival vessels and the ability to identify and locate the same vessels repeatedly for longitudinal evaluations further emphasize the usefulness of this real-time technology.