Flicker‐induced retinal vasodilatation is not dependent on complement factor H polymorphism in healthy young subjects

Abstract

PurposeThe complement factor H (CFH) tyrosine 402 histidine (Y402H, rs1061170) variant is known to be significantly associated with age-related macular degeneration (AMD). Whether this genetic variant may impact retinal blood flow regulation is largely unknown. This study investigated whether flicker-induced vasodilation, an indicator for the coupling between neural activity and blood flow, is altered in subjects carrying the rs1061170 risk allele.MethodsOne hundred healthy subjects (aged between 18 and 45 years) were included in this study. Retinal blood flow regulation was tested by assessing retinal vessel calibres in response to stimulation with diffuse flicker light. Retinal vascular flicker responses were determined with a Dynamic Vessel Analyzer (DVA). In addition, genotyping for rs1061170 was performed.ResultsEighteen subjects were homozygous for the risk allele C, 50 were homozygous for the ancestral allele T, and 31 subjects were heterozygous (CT). One subject had to be excluded from data evaluation, as no genetic analysis could be performed due to technical difficulties. Baseline diameters of retinal arteries (p = 0.39) and veins (p = 0.64) were comparable between the three groups. Flicker-induced vasodilation in both retinal arteries (p = 0.38) and retinal veins (p = 0.62) was also comparable between the three studied groups.ConclusionsOur data indicate that homozygous healthy young carriers of the C risk allele at rs1061170 do not show abnormal flicker-induced vasodilation in the retina. This suggests that the high-risk genetic variant of CFH polymorphism does not impact neuro-vascular coupling in healthy subjects.

Factors Determining Flicker-Induced Retinal Vasodilation in Healthy Subjects

“…8,13,[41][42][43][44][45][46][47][48] In other studies, we used the commercially available approach, working at 12.5 Hz. 16,17,23,[49][50][51] Data from these studies were analyzed separately. All study protocols were approved by the Ethics Committee of the Medical University of Vienna and followed iovs.arvojournals.org j ISSN: 1552-5783 the guidelines set forth in the Declaration of Helsinki.…”

Concurrent OCT imaging of stimulus evoked retinal neural activation and hemodynamic responses

“…All of these studies used flickering light stimulation to evoke hemodynamic changes. It is known that flickering light stimulation evoked blood flow response changes in vascular diseased eyes, and thus the measurement of flicker-induced blood flow responses suggests noninvasive detection of functional microvascular alterations [19]. …”

Retinal Vessel Functionality Is Linked With ARMS2 A69S and CFH Y402H Polymorphisms and Choroidal Status in AMD Patients

“…61 , 62 Although there have been several studies conducted in murine models on the role of CFH in retinal development and function, 63 , 64 there is less evidence of the influence of CFH on retinal vessel parameters in humans. Only one study investigated retinal vessel dilation in healthy young carriers of the C risk allele at the Y402H polymorphism and found no abnormal flicker-induced retinal vessel dilation 28 ; however, the study included only 18 homozygous C carriers. We cannot exclude the possibility that the vascular response could alter over the lifespan of these individuals and be poorer when they develop AMD.…”

“…Indeed, dynamic vessel analysis in eyes with drusen and RPD showed diminished retinal arterial dilation in response to flicker light stimulation. 26 However, the literature describing the changes in DVA in the course of AMD is scarce, 27 , 28 and studies have been conducted on relatively small groups of patients, which makes inference impossible.…”