It never ceases to amaze me about the benefits oestrogen has for women. Here is research showing another health benefit from oestrogen.

Review ARTICLE

Front. Endocrinol., 02 March 2018 | https://doi.org/10.3389/fendo.2018.00066

Gonadal Hormones and Retinal Disorders: A Review

Raffaele Nuzzi¹*, Simona Scalabrin¹, Alice Becco¹ and Giancarlo Panzica^2,3

• ¹Eye Clinic, Department of Surgical Sciences, University of Turin, Turin, Italy
• ²Laboratory of Neuroendocrinology, Department of Neuroscience Rita Levi-Montalcini, University of Torino, Torino, Italy
• ³Neuroscience Institute Cavalieri-Ottolenghi (NICO), Orbassano, Italy

Aim: Gonadal hormones are essential for reproductive function, but can act on neural and other organ systems, and are probably the cause of the large majority of known sex differences in function and disease. The aim of this review is to provide evidence for this hypothesis in relation to eye disorders and to retinopathies in particular.

Methods: Epidemiological studies and research articles were reviewed.

Results: Analysis of the biological basis for a relationship between eye diseases and hormones showed that estrogen, androgen, and progesterone receptors are present throughout the eye and that these steroids are locally produced in ocular tissues. Sex hormones can have a neuroprotective action on the retina and modulate ocular blood flow. There are differences between the male and the female retina; moreover, sex hormones can influence the development (or not) of certain disorders. For example, exposure to endogenous estrogens, depending on age at menarche and menopause and number of pregnancies, and exposure to exogenous estrogens, as in hormone replacement therapy and use of oral contraceptives, appear to protect against age-related macular degeneration (both drusenoid and neurovascular types), whereas exogenous testosterone therapy is a risk factor for central serous chorioretinopathy. Macular hole is more common among women than men, particularly in postmenopausal women probably owing to the sudden drop in estrogen production in later middle age. Progestin therapy appears to ameliorate the course of retinitis pigmentosa. Diabetic retinopathy, a complication of diabetes, may be more common among men than women.

Conclusion: We observed a correlation between many retinopathies and sex, probably as a result of the protective effect some gonadal hormones may exert against the development of certain disorders. This may have ramifications for the use of hormone therapy in the treatment of eye disease and of retinal disorders in particular.

Introduction

There is a growing body of evidence for the importance of gonadal hormone action in the function of the reproductive and other systems (1), including bone (2) and cardiovascular system. Sex hormones (androgenic, estrogenic, and progestinic) are produced by both sexes, though the quantity and mode differ by sex and age. Moreover, they are produced, not only by the gonads, but also by other organs (3, 4), including the central nervous system (CNS) in which estrogens are thought to exert a neuroprotective role (5, 6).

Historically, interactions between gonadal hormones and the eye have received scarce attention; however, recent research into sex-related differences has begun to reveal possible links between estrogens and eye diseases, i.e., glaucoma, age-related macular degeneration (AMD), and cataracts. This has carried over into the evaluation of the implications that postmenopausal hormone replacement therapy (HRT) and anti-estrogenic therapy in breast cancer could have for concomitant eye disorders (7).

Since, research in this area is still at its beginning, the available studies are few and often limited in sample size; this does not allow to reach a univocal and definitive answer about the relationship between sex, sex hormones, and ocular pathologies. The purpose of this review is, therefore, to summarize the results currently present in the literature.