Perifoveal Microvasculature in Human Eyes with Vascular Comorbidities

Abstract

Purpose: The microvasculature change which precedes the development of clinically manifest ocular disease has not been clarified. This study delineates the morphological characteristics of the perifoveal microvasculature in patients with vascular comorbidities.

Methods: Comparisons were made between 11 human eyes from patients with vascular comorbidities and 17 healthy control eyes. All eyes were absent of clinically evident ocular disease. Microcannulation and targeted perfusion techniques were used to label the retinal microvasculature. Retinae were then flat mounted and the peripapillary region 2mm nasal to the fovea imaged using confocal laser scanning microscopy. Two- and three-dimensional image reconstructions were used to perform quantitative measurements of individual capillary networks within the perifovea. Parameters measured included capillary diameter, capillary loop area, capillary density and capillary surface area. Comparisons were made between normal eyes we previously studied and those from patients with vascular comorbidities.

Results: Capillary diameter was increased in all layers of the retina in patients with vascular comorbidities with the exception of the nerve fibre layer capillary network. Capillary loop area was reduced in all layers of the retina in patients with vascular comorbidities except the deep capillary network of the inner nuclear layer. Capillary density was reduced within the nerve fibre layer of eyes with vascular comorbidities. There was no difference in the relative occupied capillary surface area between healthy and diseased eyes.

Conclusions: Morphometric differences in retinal capillary networks are present between healthy patients and those with vascular comorbidities. Understanding the capillary changes that precede clinical ocular disease may be useful for defining the pathogenesis of retinal vascular disease.

Keywords: 688 retina