Retinal Vessel Pulsatile Characteristics Associated With Vascular Stiffness Can Predict the Rate of Functional Progression in Glaucoma Suspects

Abstract

Purpose Tissue stiffening and alterations in retinal blood flow have both been suggested as causative mechanisms of glaucomatous damage. We tested the hypothesis that retinal blood vessels also stiffen, using laser speckle flowgraphy (LSFG) to characterize vascular resistance. Methods In the longitudinal Portland Progression Project, 231 eyes of 124 subjects received LSFG scans of the optic nerve head (ONH) and automated perimetry every 6 months for six visits. Eyes were classified as either “glaucoma suspect” or “glaucoma” eyes based on the presence of functional loss on the first visit. Vascular resistance was quantified using the mean values of several instrument-defined parameterizations of the pulsatile waveform measured by LSFG, either in major vessels within the ONH (serving the retina) or in capillaries within ONH tissue, and age-adjusted using a separate group of 127 healthy eyes of 63 individuals. Parameters were compared against the severity and rate of change of functional loss using mean deviation (MD) over the six visits, within the two groups. Results Among 118 “glaucoma suspect” eyes (average MD, −0.4 dB; rate, −0.45 dB/y), higher vascular resistance was related to faster functional loss, but not current severity of loss. Parameters measured in major vessels were stronger predictors of rate than parameters measured in tissue. Among 113 “glaucoma” eyes (average MD, −4.3 dB; rate, −0.53 dB/y), higher vascular resistance was related to more severe current loss but not rate of loss. Conclusions Higher retinal vascular resistance and, by likely implication, stiffer retinal vessels were associated with more rapid functional loss in eyes without significant existing loss at baseline.

Is Primary Open-Angle Glaucoma a Vascular Disease? Assessment of the Relationship between Retinal Arteriolar Morphology and Glaucoma Severity Using Adaptive Optics

“…Oxidative DNA damage can affect trabeculae, which induces resistance to aqueous humour outflow and RGCs, driving neurodegenerative changes [29,30]. Disruption of vascular autoregulation in ONH [27,31,32], higher retinal vascular resistance [33], and an imbalance between the vasoconstrictor ET-1 and the vasodilator nitric oxide have been observed in glaucoma [7]. Therefore, the evaluation of blood vessels in eyes with POAG is essential for a better understanding of the multifactorial pathogenesis of glaucoma.…”

Is Primary Open-Angle Glaucoma a Vascular Disease? – Assessment of the Relationship of Retinal Arteriolar Morphology and Glaucoma Severity Using Adaptive Optics

“…Oxidative DNA damage can affect trabeculae, which induces resistance to aqueous outflow and RGCs, driving neurodegenerative changes [29,30]. Disruption of vascular autoregulation in ONH [27,31,32] and higher retinal vascular resistance [33] also seem to play an essential role in the aetiology and progression of glaucoma. In addition, the imbalance between vasoconstrictor ET-1 and vasodilator nitric oxide has been observed in glaucoma, which can lead to endothelial dysfunction, resulting in retinal vascular impairment in glaucoma patients [7].…”