The effects of female sex hormones on the human cornea across a woman's life cycle

Corneal thickness, contrast sensitivity and binocular vision in menopausal and non-menopausal women

OBJECTIVE

This study aimed to investigate the effects of menopause on ocular health and visual function.

METHOD

Sixty-two women (31 premenopausal and 31 postmenopausal) who visited Rasht Health Center were selected and matched based on their ages and compared in terms of their hormonal status, central corneal thickness (CCT), contrast sensitivity (CS), binocular vision variables and refractive error.

RESULTS

CCT and corneal curvature were significantly thinner in postmenopausal women. However, menopause had no significant impact on CS, binocular vision or refractive error.

CONCLUSION

Age-related hormonal abnormalities play a significant role in corneal thinning, highlighting the intricate relationship between systemic hormonal changes and ocular health. In contrast, binocular vision functions remain unaffected by menopause.

Comparative Insights into the Role of Sex Hormones in Glaucoma Among Women and Men

Baseline differences in sex hormone levels between males and females influence tissues including the brain and eye. To investigate the effects of estrogens and androgens on ocular physiology and glaucoma, we review the current literature on the influence of primary sex hormones on ocular function, glaucoma incidence and related parameters like intraocular pressure (IOP) at physiologic levels and related to hormone therapies in men and women. These articles reveal activity of estrogen, testosterone, and progesterone within ocular tissues including the retinal pigment epithelium and ciliary epithelium where they likely influence glaucoma pathophysiology through effects on ocular blood flow and aqueous outflow. A growing body of evidence demonstrates a protective role of estrogen in glaucoma. With fluctuations across a woman's lifetime through menstrual phases, pregnancy, and menopause, the general association seen is a lower risk of glaucoma and lower IOP with higher estrogen. Exogenous hormones in the form of oral contraceptive pills and hormone replacement therapy also appear to affect glaucoma risk, although published findings are inconsistent. Few studies have reported a positive association between IOP and serum testosterone, and men treated with androgen deprivation therapy have shown a reduced risk of glaucoma while masculinizing hormone therapies at supra-physiologic testosterone levels have significantly increased IOP. Sex hormone perturbations affect components of glaucoma pathogenesis including IOP and ocular blood flow and overlap with known risk factors like age and sex. Standardized studies are needed to further elucidate the roles of estrogen and testosterone in glaucoma risk and progression.

Physiological and pathological changes to the eye and vision during and after pregnancy

Pregnancy introduces a multitude of changes in the body, including hormonal fluctuations and metabolic changes, which can lead to atypical ocular signs and symptoms. Ocular manifestations range from fluctuations in vision, to microstructural changes in the retina and choroid, to dry eye disease. This narrative review highlights the range of pregnancy-related effects on the eye and vision that are likely to present in the context of routine eyecare. Specifically, physiological ocular changes and pathological ocular changes that manifest for the first time, or are exacerbated, in uncomplicated pregnancy are discussed. The literature has evolved from simply noting differences in the eye between pregnant and non-pregnant groups, to refining knowledge of the proposed underlying pathophysiology with the advent of newer technologies in eyecare. A particular focus of this review is navigating when pregnancy changes in the eye occur or peak during the gestational period, and whether the changes are short-lived or might extend past pregnancy. While many pregnancy-associated changes are temporary and resolve post-partum, it is also recognised that some changes persist after pregnancy, with a notable absence of literature on ocular changes with loss or termination of pregnancy. Currently or previously pregnant women (or those planning to become pregnant), and other health professionals, should be educated about the importance of seeking eyecare before, during and after pregnancy.

Alterations in corneal sensitivity according to age and gender in healthy population in Turkey

CLINICAL RELEVANCE

Knowing the changes in corneal sensitivity according to age and gender is important for the correct evaluation of pathologies.

BACKGROUND

The aim of this work was to analyse variability of corneal sensitivity according to age and gender in the healthy population in Turkey.

METHODS

Healthy volunteers between the ages of 20 and 84, who applied to outpatient clinic due to routine examination, were included. Exclusion criteria were any ocular diseases other than refractive error, any systemic disease, contact lens use, chronic ocular and systemic drug use, and previous ocular surgery. Central and 4 quadrants (superior, inferior, nasal, temporal) corneal sensitivity measurements were performed with a Cochet-Bonnet esthesiometer (Luneau Ophthalmology, France). The patients were divided into 5 groups according to their ages (Group 1:20-29, Group 2:30-39, Group 3:40-49, Group 4:50-59, Group 5 ≥ 60). The data were evaluated in terms of groups and gender.

RESULTS

The right eyes of 324 volunteers were included. The mean age was 44.31 ± 15.65 (20-84) and the female/male ratio was 165/159. The mean central, superior, inferior, nasal, and temporal sensitivities were 50.15 ± 9.7,48.62 ± 10.3,48.59 ± 10.3,47.73 ± 10.2,47.71 ± 10.3 mm, respectively. Sensitivities in all quadrants decreased significantly depending on age (p = 0.001 for all, central, superior, inferior, nasal and temporal correlation coefficients,r = -0.783, -0.791, -0.789, -0.760, -0.775, respectively). The decrease accelerated in Group 4 and 5. Gender-related changes were detected as significant in central and temporal quadrants (p = 0.038, p = 0.019). When sensitivity according to gender was evaluated within each decade, significant difference was detected in Group 2 and 4 (p < 0.05).

CONCLUSION

Corneal sensitivity decreases with age, most significantly in 5th and 6th decades. Sensitivity differs between genders in central and temporal quadrants. Geographic location, gender, and ethnicity may affect sensitivity values. The present study defines normal values in aTurkish population and may guide the evaluation of pathologies that impair corneal sensitivity.

Association of Di(2-ethylhexyl) Phthalate Exposure with Reproductive Hormones in the General Population and the Susceptible Population: A Systematic Review and Meta-Analysis

Di(2-ethylhexyl) phthalate (DEHP), an environmental endocrine disruptor, has hormone-like activity and endocrine-disrupting effects. However, the types of reproductive hormones associated with DEHP vary across the studies. Thus, we conducted a systematic review and meta-analysis to pool existing epidemiological evidence. We searched three databases up to January 31, 2024, for eligible original studies to ultimately include 37 studies from eight countries with a total of 28 911 participants. DEHP exposure was evaluated with urinary metabolites. Since the main types, production sites, blood concentrations, and functions of reproductive hormones differ between men and women, we reported the combined effect values by gender. Subgroup analyses were conducted by age, subfertility status, and the national sociodemographic index (SDI) level. Furthermore, the effect of maternal exposure during pregnancy on children's reproductive hormone levels was analyzed separately. Overall, in general, in men, DEHP was positively correlated with sex hormone binding-globulin (SHBG) and adversely correlated with total testosterone (TT), free androgen index (FAI), and follicle-stimulating hormone (FSH). Results indicated that among men of reproductive age, DEHP exposure was associated with more significant hormonal suppression in infertile men compared with fertile men. Notably, age subgroup analysis among women revealed that postmenopausal women were more vulnerable to DEHP, which was related to lower TT and estradiol (E2). However, this study did not observe a significant association between prenatal DEHP metabolites and reproductive hormone levels in children. Our research identifies the most susceptible hormones (androgen suppression) after DEHP exposure and suggests that infertile men and postmenopausal women are in great need of more attention as sensitive populations.

Keratoconus

Keratoconus is a progressive eye disorder primarily affecting individuals in adolescence and early adulthood. The ectatic changes in the cornea cause thinning and cone-like steepening leading to irregular astigmatism and reduced vision. Keratoconus is a complex disorder with a multifaceted aetiology and pathogenesis, including genetic, environmental, biomechanical and cellular factors. Environmental factors, such as eye rubbing, UV light exposure and contact lens wearing, are associated with disease progression. On the cellular level, a complex interplay of hormonal changes, alterations in enzymatic activity that modify extracellular membrane stiffness, and changes in biochemical and biomechanical signalling pathways disrupt collagen cross-linking within the stroma, contributing to structural integrity loss and distortion of normal corneal anatomy. Clinically, keratoconus is diagnosed through clinical examination and corneal imaging. Advanced imaging platforms have improved the detection of keratoconus, facilitating early diagnosis and monitoring of disease progression. Treatment strategies for keratoconus are tailored to disease severity and progression. In early stages, vision correction with glasses or soft contact lenses may suffice. As the condition advances, rigid gas-permeable contact lenses or scleral lenses are prescribed. Corneal cross-linking has emerged as a pivotal treatment aimed at halting the progression of corneal ectasia. In patients with keratoconus with scarring or contact lens intolerance, surgical interventions are performed.

The Corneal Epithelial Thickness Profile in a Healthy Saudi Population

INTRODUCTION

Epithelial mapping appears to be a valuable technique for a corneal and refractive surgeon, useful for distinguishing corneas with the true presence of corneal ectasia from those that are suspicious. Interpreting the epithelial thickness map data requires an understanding of corneal epithelial thickness (CET) normal values and variable patterns. Unlike corneal thickness, epithelial thickness assessment with anterior segment optical coherence tomography (AS-OCT) seems to be influenced by gender and age. The study aimed to investigate the detailed mapping of CET characteristics in normal eyes from the Saudi population and to assess its variation with age and sex using anterior segment 7-mm-wide OCT (AS-OCT) scans.

METHODS

Regional epithelial thickness was assessed using an anterior radial scanning protocol with REVO NX (Optopol Technology S.A, Zawiercie, Poland) in 596 eyes of 298 individuals aged 10 to 98. CET maps in a 7 mm diameter were automatically generated by the built-in software, displaying thickness in 17 sectors divided into three zones, i) a central zone within the 0-2 mm diameter, ii) ring 1 zone, a paracentral (P-CET) zone from 2 to 5-mm, and iii) ring 2 zone, a midperipheral zone (MP-CET) from 5 to 7 mm. Ring 1 and 2 zones were further divided into eight sectors each, including superior (S), inferior (I), nasal (N), temporal (T), superonasal (SN), inferonasal (IN), superotemporal (ST), and inferotemporal (IT). An analysis was done on correlations between age and gender and the CET across different zones.

RESULTS

Males and older adults had a substantially thicker CET than females and younger participants, with the C-CET measuring 59.2±4.5µm. In three zones, no interocular asymmetry was seen. Superiorly, CET is significantly thinner than inferiorly (p<0.05), with temporal zones being thinner than nasal zones (p<0.05). The C-CET increases with age in the seven groups of both genders, but its dependence on age is weaker in paracentral sectors; C-CET was 3.5% thicker in males. Paracentral nasal and inferior zones showed 2.2-3.6% thicker CET while the superior and temporal paracentral zones showed 3-5% thicker CET among males compared to females.

CONCLUSION

From 17 CET zones of central 7 mm cornea the C-CET was affected by gender and age. The CET distribution in these healthy Saudis' eyes was non-uniform with the CET being thinner in the superior cornea. This finding could aid in predicting corneal diseases and planning refractive procedures.

Presbyopia, Dry Eye, and Retinal Thickness in the Middle-Aged Population: Focusing on Sex Differences

Purpose

Risk factors for presbyopia have not been fully determined although previous studies suggested presbyopia was associate with age, dry eye, and retinal ganglion cell complex thickness (GCC). We accessed these signs and common ocular symptoms in the middle-aged population focusing on sex differences when women have drastic hormonal change.

Methods

This cohort study consecutively enrolled 2743 patients aged 36-45 years (n=1000), 46-55 years (n=1000), and 56-65 years (n=743). All underwent ocular surface tests and had near add power and GCC measured. Common ocular symptoms were asked using questionnaire.

Results

Among female participants, visual symptoms (eye strain and photophobia) were more prevalent in the age group 46-55, whereas non-visual symptoms (dryness, irritation, and pain) were not. We identified symptomatic presbyopia (near add power ≥ 1.5D) in 14.4%, 73.8%, and 97.8%, positive corneal staining in 29.1%, 23.8%, and 23.9%, and a mean GCC of 98.2 μm, 105.3 μm, and 89.6 μm in the age groups 36-45, 46-55, and 56-65, respectively. Mean tear break-up time were 3.3, 3.5, and 3.3 seconds, respectively. Results indicated a large progression of presbyopia (P<0.01) from the period of 36-45 years onward and significantly increased GCC (P<0.01) in women of age group 46-55. No notable tendency was observed in symptoms and GCC for male participants.

Conclusion

Visual symptoms in women were worse between 46 and 55 years than before or after these ages. The increase of symptomatic presbyopia and GCC may be contributing to visual symptoms in addition to menopausal transition symptoms in this age group.

The relationship between sex hormone levels and ocular surface parameters in girls with idiopathic central precocious puberty

Purpose

The study aimed to investigate the correlation between the change of sex hormone levels and ocular surface parameters in girls with idiopathic central precocious puberty(ICPP).

Methods

Eighteen girls with ICPP and 18 age-matched normal girls participated in this study, all of the participants had undergone physical measurements, laboratory tests, imaging examination and ocular surface assessments.

Results

The Objective Scatter Index (OSI) in the ICPP group was significantly higher than in the control group (P = 0.031), girls with ICPP showed slightly lower MNITBUT compared to the normal control group, although this difference was not statistically significant. Bivariate analysis revealed a positive association between estradiol and OSI (r=0.383, P=0.021), Additionally, in the study population, both Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH) were negatively correlated with Mean noninvasive tear breakup time (MNITBUT) (r=-0.359, P=0.031)(r=-0.357, P=0.032).

Conclusion

In comparison with the normal control group, alterations in the OSI were observed in girls with ICPP. This alteration may be associated with an elevation in estrogen levels. Although there was a slight non-significant decrease in NITBUT in ICPP girls, the negative correlation between LH and FSH with MNITBUT suggests new perspective for further investigation.

The Appropriateness of Medical Devices Is Strongly Influenced by Sex and Gender

Until now, research has been performed mainly in men, with a low recruitment of women; consequentially, biological, physiological, and physio-pathological mechanisms are less understood in women. Obviously, without data obtained on women, it is impossible to apply the results of research appropriately to women. This issue also applies to medical devices (MDs), and numerous problems linked to scarce pre-market research and clinical trials on MDs were evidenced after their introduction to the market. Globally, some MDs are less efficient in women than in men and sometimes MDs are less safe for women than men, although recently there has been a small but significant decrease in the sex and gender gap. As an example, cardiac resynchronization defibrillators seem to produce more beneficial effects in women than in men. It is also important to remember that MDs can impact the health of healthcare providers and this could occur in a sex- and gender-dependent manner. Recently, MDs' complexity is rising, and to ensure their appropriate use they must have a sex-gender-sensitive approach. Unfortunately, the majority of physicians, healthcare providers, and developers of MDs still believe that the human population is only constituted by men. Therefore, to overcome the gender gap, a real collaboration between the inventors of MDs, health researchers, and health providers should be established to test MDs in female and male tissues, animals, and women.

Novel Correlation between TGF-β1/-β3 and Hormone Receptors in the Human Corneal Stroma

This study investigated the interplay between transforming growth factor beta (TGF-β1/T1 and TGF-β3/T3), and sex hormone receptors using our 3D in vitro cornea stroma model. Primary human corneal fibroblasts (HCFs) from healthy donors were plated in transwells at 106 cells/well and cultured for four weeks. HCFs were supplemented with stable vitamin C (VitC) and stimulated with T1 or T3. 3D construct proteins were analyzed for the androgen receptor (AR), progesterone receptor (PR), estrogen receptor alpha (ERα) and beta (ERβ), luteinizing hormone receptor (LHR), follicle-stimulating hormone receptor (FSHR), gonadotropin-releasing hormone receptor (GnRHR), KiSS1-derived peptide receptor (KiSS1R/GPR54), and follicle-stimulating hormone subunit beta (FSH-B). In female constructs, T1 significantly upregulated AR, PR, ERα, FSHR, GnRHR, and KiSS1R. In male constructs, T1 significantly downregulated FSHR and FSH-B and significantly upregulated ERα, ERβ, and GnRHR. T3 caused significant upregulation in expressions PR, ERα, ERβ, LHR, FSHR, and GNRHR in female constructs, and significant downregulation of AR, ERα, and FSHR in male constructs. Semi-quantitative Western blot findings present the interplay between sex hormone receptors and TGF-β isoforms in the corneal stroma, which is influenced by sex as a biological variable (SABV). Additional studies are warranted to fully delineate their interactions and signaling mechanisms.