Oral Presentations (OP)

OP-07 Retinal and cortical vascular function across the menstrual cycle

Abstract

Introduction Oestrogen has a protective effect against neurodegenerative conditions, including glaucoma and dementia. Animal models suggest that oestrogen has a vasodilatory effect, which is a possible mechanism for this. However, the full influence of oestrogen on specific cerebrovascular functions is unclear.

Aims This study aims to investigate the influence of hormonal fluctuations across a healthy menstrual cycle on measures of retinal and cortical vascular functioning.

Methods 27 menstruating participants (age mean[SD]=22.94[3.52] years) completed a testing session during the early-follicular, late-follicular, and mid-luteal phase of their menstrual cycle. Bloods were taken to measure circulating hormones.

Retinal vasculature was assessed using a Swept-Source OCT (TOPCON healthcare), including:

  • Choroidal thickness – 6mm2 OCT scan

  • Vessel density, radius, and resistance – 3mm2 OCT Angiography

Cortical data were acquired on a Siemens MAGNETOM Prisma 3T MRI scanner and include:

  • Grey matter Cerebral Blood Flow (CBF) and Arterial Arrival Time (AAT) – MPLD-pCASL scan

  • Global Oxygen Extraction Fraction (OEF) – TRUST sequence

Linear models investigated the amount of variance explained by circulating oestradiol.

Results Oestradiol significantly decreased retinal resistance (χ2(1)=6.1218, P=0.01335), an effect which was greatest in the foveal vessels. Other retinal measures were stable across the menstrual cycle. No association was found with OEF, but oestradiol did significantly increase CBF (χ2(1)=17.801; P=2.452e-5) and AAT (χ2(1)=9.5183; P=0.002034), which was a global effect.

Conclusion Evidence for oestrogen’s vasodilatory influence was demonstrated across a menstrual cycle and in multiple vascular beds. This provides information into how oestrogen influences the cerebrovascular system and highlights possible mechanisms by which oestrogen has a protective effect against neurodegenerative conditions.

Acknowledgements The Wellcome Trust (WT224267)

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