Postmenopausal hormone therapy increases retinal blood flow and protects the retinal nerve fiber layer

To investigate whether postmenopausal hormone therapy (HT) increases retinal and ONH blood flow (BF) and protects ONH topography and the function of retinal ganglion cells in postmenopausal women (PMW). The effect of estradiol (E(2)) treatment on retinal tissue perfusion was also investigated in ovariectomized rats, an animal model for menopause.

Sixty-four healthy PMW were recruited, 29 of whom never used HT ( HT) and 35 of whom had used HT (+HT) continuously since the onset of menopause. Blood flow of the inferotemporal retinal artery (ITRA), peripapillary retina, and ONH rim were measured in one eye. The ONH stereometric parameters and the pattern electroretinogram (PERG) were also measured. In ovariectomized rats, the retinal tissue perfusion was assessed using the BF tracer N-isopropyl-p-[(14)C]-iodoamphetamine ([(14)C]-IMP) in rats treated with either E(2) (n = 7) or placebo (n = 5).

Compared with the HT group, the +HT group presented significantly greater BF of the ITRA (P = 0.006), greater rim volume for the entire ONH region (P = 0.032), and greater rim volume (P = 0.042), height variation contour (P = 0.011), mean thickness (P = 0.033), and cross-sectional area (P = 0.020) of the retinal nerve fiber layer for the inferotemporal region of the ONH when adjusted for age, ocular perfusion pressure, and age at menarche. In ovariectomized rats, E(2) treatment significantly increased retinal perfusion in a range of 22% to 45%.

These findings indicate that estrogens and HT increase retinal blood flow and protect the retinal nerve fiber layer.