Hormone Replacement Therapy in Menopausal Women: Effects on the Retinal Arterial Blood Flow and the Optic Nerve Head Topography

Abstract

Abstract: : Purpose: Hormone replacement therapy (HRT) alleviates climacteric symptoms in menopausal women by increasing the estrogen level. There is a large body of evidence that estrogens are vasodilators and neuroprotectors. Since estrogen receptors are present in the retina (Ogutea SB et al, 1999; Munaut C et al, 2001), we investigated whether menopausal women on HRT present differences in their retinal arterial blood flow and optic nerve head (ONH) topography compared to menopausal women who never used HRT. Methods: All menopausal women were recruited from menopause clinics, were healthy and had normal ophthalmic exam. The retinal arterial blood flow was measured using the Canon Laser Blood Flowmeter (Japan). Measures were obtained from one eye in women who never used HRT (n=13) and age–matched women on HRT (n=25). Diameter (D), velocity (Vel) and blood flow (F) measures were obtained on the infero–temporal retinal artery (ITRA) used as an indicator of the overall retinal arterial circulation. The ONH topography was measured using the Heidelberg Retinal Tomograph I (Germany). The ONH topography was measured from one eye in women who never used HRT (n=16) and age–matched women on HRT (n=30) and the standard topographical parameters were derived. Results: Measures of the ITRA showed that D (130.3 ±14.8um vs 116.2 ±12.2um, p=.006) and F (14.3 ±3.7uL/min vs 10.6 ±2.9uL/min, p=.004) were significantly greater in menopausal women on HRT comparatively to women who never used HRT. Moreover, the measures of ONH topography indicated a significant thicker nerve fiber layer (NFL) (0.291 ± 0.06mm vs 0.254 ±0.05mm, p=.03) in menopausal women on HRT comparatively to women who never used HRT. The other standard ONH parameters did not differ significantly between groups. Conclusions: Since the ITRA can be used as an indicator of the overall retinal arterial circulation, these findings indicate that menopausal women on HRT present greater retinal arterial blood flow and thicker NFL than women who never used HRT. These differences could be explained by the vasodilating and neuroprotecting properties of estrogens. Consequently, menopausal women on HRT might be better protected against age–related ocular vascular pathologies such as glaucoma and ARMD.

Keywords: blood supply • neuroprotection • aging