• Retina/Vitreous

    This study looked at the location at which vascular caliber is measured and its association with nonperfusion and diabetic retinopathy (DR) severity differences.

    Study design

    This study was a retrospective image review of adults with diabetes mellitus. Investigators evaluated images from 193 patients (285 eyes) using same-day ultrawide field (UWF) fluorescein angiography (FA) and color imaging. Predominantly peripheral lesions (PPL) and DR severity were graded from UWF color images. Nonperfusion was quantified using UWF-FA in defined retinal regions: posterior pole, mid-periphery, and far-periphery. Retinal vessel calibers were measured at an optic disc centered inner and outer zone. The main outcome measures were nonperfusion index in each defined retinal region, and mean arteriole and venule diameter in the inner and outer zones.

    Outcomes

    The study group comprised patients with 24.9% mild nonproliferative DR (NPDR), 22.8% moderate NPDR, 37.5% severe NPDR, and 14.7% proliferative DR (PDR). There were no significant associations between inner zone arteriolar diameter and retinal nonperfusion index, overall or in any retinal region. In the outer zone, eyes with thinnest arteriolar calibers (quartile 1) were associated with a 1.7- to 2.4-fold nonperfusion increase across all retinal regions compared with the remaining eyes. In the outer zone, the percentage of eyes in the thinnest quartile of retinal arteriolar diameter increased with worsening DR severity (mild NPDR: 10% vs PDR: 31%). This association was not observed when measured within the inner zone. All venular caliber associations were not statistically significant when corrected for potentially confounding factors. Thinner outer zone retinal arteriolar caliber (quartile 1) was more common in eyes with PPL compared with eyes without PPL (34% vs 21%; quartile 4). Presence of PPL was associated with thinner outer zone arteriolar caliber (109.7 ± 26.5μm vs 123.0 ± 29.5μm).

    Limitations

    Limitations of this study include the retrospective nature of the study, the use of semiautomated software that automatically selected all possible venules or arterioles, and lack of information about duration and severity of hypertension.

    Clinical significance

    This study provides valuable information about the association of vascular caliber with nonperfusion and DR severity differences based upon the retinal location measurement site. Peripheral arterial narrowing is associated with increasing nonperfusion, worsening DR severity, and presence of PPL. In contrast, inner zone retinal arteriolar caliber is not associated with these findings.