Expression of sex steroid hormone receptors in human cornea

Mouse strains and sexual divergence in corneal innervation and nerve regeneration

A variety of mouse strains and sexes are used in studies of corneal wound healing and nerve regeneration. However, there is a gap of knowledge about corneal nerve density and its function in different mouse strains and sexes. In this study, we report a strain divergence of total and substance P (SP) sensory corneal nerves in uninjured mice. The BALB/c mouse showed the highest nerve density, corneal sensitivity, and tear volume followed by CFW and then C57BL/6. No differences were found in total nerves and SP-positive nerves between sexes. After injury damaged the corneal nerves, an important role for mouse strains, biologic sex, and their association to corneal nerve regeneration was identified. All female mice have a faster nerve regeneration rate than males. The molecular mechanism of this sexual divergence involves higher secretion neurotrophic factors in tears, which in turn modulate gene expression in trigeminal ganglion neurons. An important upstream signaling regulator was β-estradiol, and topical treatment with β-estradiol confirmed its function in corneal nerve regeneration. In conclusion, our study shows that the strain and sex of laboratory mice significantly affect the different indicators of corneal innervation and nerve regeneration. Researchers investigating corneal diseases should carefully consider these factors.—Pham, T. L., Kakazu, A., He, J., Bazan, H. E. P. Mouse strains and sexual divergence in corneal innervation and nerve regeneration.

Estrogen- and Progesterone-Induced Variation in Corneal Parameters According to Hormonal Status

OBJECTIVES

To determine the effects of estrogen and progesterone on corneal thickness, curvature, and biomechanics in healthy corneas according to hormonal status.

METHODS

The study included four groups of females: group A (menstruating, not pregnant, not lactating, and not menopausal; n=100), group B (pregnant; n=50), group C (lactating; n=50), and group D (menopausal; n=50). Group A was subdivided according to age, as subgroup A15-25 (age 15-25 years) and subgroup A>25 (age >25 years). Blood estradiol and progesterone levels were measured in each participant. All the participants underwent a full ophthalmologic examination, including corneal thickness and corneal topography measurement, and evaluation of corneal biomechanical properties.

RESULTS

The corneal resistance factor and anterior corneal flat keratometry values were significantly higher in group D (P=0.040 and P=0.026, respectively) than in the other three groups. Posterior corneal steep keratometry values were significantly higher in subgroup A>25 during the preovulatory phase than ovulatory and postovulatory phases (P=0.012). In group B, there was a significant negative correlation between gestational week and intraocular pressure (IOP) (r=-0.322, P=0.024). Corneal volume was significantly higher during the early postpartum period than the late postpartum period in group C (P=0.028). Intraocular pressure, Goldman-correlated IOP, and corneal-compensated IOP differed significantly between the groups (P<0.05).

CONCLUSIONS

Blood levels of estrogen and progesterone were associated with variations in IOP, but estrogen and progesterone did not have a consistent effect on topographic parameters or biomechanical properties in healthy corneas.

Effects of glucocorticoid on the eye development in guinea pigs

Glucocorticoid (GC) has been widely used in clinic. However, the effect of GC on normal and myopic development of eyes is still unknown. In this study, 3-week-old guinea pigs were randomly divided into four groups: No-Lens (control), GC+No-Lens, negative lens-induced myopia (LIM), and GC+LIM. To induce myopia, right eyes were covered with a -10 D lens in GC+LIM and LIM groups. GC+No-Lens and GC+LIM groups received intraperitoneal injections of hydrocortisone (10 mg/kg) once daily for 2 weeks, and then received intragastric hydrocortisone (32.5 mg/kg) every other day for the next 4 weeks, while No-Lens (control) and LIM groups were injected intraperitoneally with saline for 2 weeks, and then given saline by intragastric administertion for the next 4 weeks. Several parameters were assessed: ocular axial length and refractive error, sclera thickness, matrix metalloprotein-2 (MMP-2) and tissue inhibitor metalloprotease-2 (TIMP-2) expressions and localization of the posterior sclera, plasma concentrations of free triiodothyronine (FT3), free thyroxine (FT4), testosterone (T), and oestradiol (E2). Results indicated that: (1) in normal eye development, hydrocortisone could inhibit both the axial elongation and the myopic shift; whereas (2) in LIM eye development, hydrocortisone (a) enhanced the axial elongation, myopic shift and sclera thinning; (b) enhanced the MMP-2 expression and decreased TIMP-2 expression, and (c) elevated the plasma concentration of E2 but decreased the levels of FT3, FT4, and T. In conclusion, glucocorticoid may influence both normal and LIM eye development. The balance of the hormones is fundamental for the eye development.

Female Hormone 17β-Estradiol Downregulated MMP-2 Expression and Upregulated A1PI Expression in Human Corneal Stromal Cells

Collagens are essential for cornea functions. In non-ocular tissues, it has been demonstrated that sex hormones modulate the collagen remodeling. In this study, we investigated whether the primary female hormone 17β-estradiol plays a role in the expressions of matrix metalloproteinases and proteinase inhibitors in cultured human corneal stromal cells. We found that 17β-estradiol treatment significantly reduced the matrix metalloproteinase-2 mRNA in human corneal stromal cells as well as the matrix metalloproteinase-2 proteins, while the matrix metalloproteinase-9 mRNA level was not significantly altered. 17β-estradiol also upregulated the expression of proteinase inhibitor, alpha1-proteinase inhibitor. The expression of transcription factor specificity protein 1 was reduced by 17β-estradiol. Furthermore, 17β-estradiol did not change the viability and apoptosis of the corneal stromal cells. The downregulation of matrix metalloproteinase-2 and upregulation of alpha1-proteinase inhibitor by 17β-estradiol possibly serve as protective factor for the normal tomography in antagonizing the extracellular matrix degeneration in many cornea diseases.

Pregnancy-induced Changes in Corneal Biomechanics and Topography Are Thyroid Hormone Related

PURPOSE

To identify biomechanical and topographic changes of the cornea during pregnancy and the postpartum period and its association to hormonal changes.

DESIGN

Prospective single-center observational cohort study.

METHODS

Participants were 24 pregnant women (48 eyes), monitored throughout pregnancy and after delivery. Biomechanical and topographic corneal properties were measured using the Ocular Response Analyzer (ORA) and a Scheimpflug imaging system (Pentacam HR) each trimester and 1 month after delivery. At the same consultations blood plasma levels of estradiol (E2) and thyroid hormones (TSH, T3t, T4t) were also determined. A factorial MANCOVA was used to detect interactions between hormonal plasma levels and ocular parameters.

RESULTS

Significant differences in corneal biomechanical and topographic parameters were found during pregnancy in relation to T3t (p = .01), T4t (p < .001), T3t/T4t (P = .001), and TSH (p = .001) plasma levels. E2 plasma levels (p = .092) and time period of measurement (p = .975) did not significantly affect corneal parameters. TSH levels significantly affected the maximal keratometry reading (p = .036), the vertical keratometry reading (p = .04), and the index of height asymmetry (p = .014). Those results persist after excluding hypothyroidism patients from the statistical analysis.

CONCLUSIONS

Hormonal changes affecting corneal biomechanics and topography during pregnancy could be thyroid related. Dysthyroidism may directly influence corneal biomechanics and represents a clinically relevant factor that needs further investigation.

Diabetes and pachymetry changes in pregnancy

BACKGROUND

Purpose of this study is to evaluate changes in the central corneal thickness (CCT) in patients during the third trimester and postpartum phases of normal pregnancy, pregestational diabetes mellitus (DM), and gestational diabetes mellitus (GDM).

METHODS

This was a prospective study. Patients that fulfilled the inclusion criteria were recruited from the obstetric clinic. They were grouped into normal pregnancy, pregestational DM, and GDM. Ophthalmic assessment and haematological investigations were done during the third trimester (after 28 weeks of gestation) and in the postpartum phase (6 weeks postpartum).

RESULTS

A total of 192 pregnant patients were recruited for this study. Out of the 192 patients, only 143 of them came back for their follow-up 6 weeks postpartum. A total of 70 (36.5%) normal pregnancy patients, 51 (26.6%) DM patients, and 71 (36.9%) GDM patients were included in this prospective study. Our study showed that the CCT decreased postpartum in all three groups. Patients in all three groups did not have significantly different CCT during the third trimester of pregnancy and postpartum phase. However, patients who had thicker CCT irrespective of the grouping during the third trimester also had a thicker CCT post-delivery (p value <0.001). However, these changes did not appear to affect refractive error and visual acuity.

CONCLUSIONS

Diabetes mellitus during pregnancy did not appear to influence the CCT.

Local synthesis of sex hormones: are there consequences for the ocular surface and dry eye?

Sex hormones are associated with the physiology and pathophysiology of almost all organs in the body, as well as most diseases. Interest in the associations between sex hormones and ocular tissues has increased in recent years. Androgens may have a positive effect on dry eye, whereas the effects of oestrogen on ocular conditions remain unclear. Intracrinology, the local synthesis and metabolism of hormones that is unique to humans, is of relevance to the eye and may help to explain why studies of the relationship between oestrogens and dry eye signs and symptoms are inconclusive. Knowledge of the pathways of hormone formation and metabolism is crucial to understanding the pathogenesis of ocular disease including dry eye. This review examines the mechanisms of steroidal sex hormone biosynthesis and reviews the significance of locally produced sex hormones, with a focus on ocular surface tissues. Much of the current literature is based on animal studies, which may not be transferable to humans due to the absence of intracrine production in animals. A large proportion of the human studies investigate systemic hormone levels rather than local levels. There is subsequently a need for additional studies to provide a better understanding of the local production of sex hormones within the human eye and ocular surface and to clarify the relationships between ocular levels of sex hormones and conditions including dry eye.

Anterior, posterior and biomechanical parameters of cornea during pregnancy in healthy eyes: a cohort study

BACKGROUND

To investigate the effect of pregnancy on anterior, posterior and biomechanical corneal parameters of healthy eyes.

METHOD

In this prospective cohort study, 70 pregnant participants with clinically healthy eyes underwent corneal topographic imaging evaluation by Pentacam and biomechanical assessment by Ocular Response Analyzer (ORA) before pregnancy, at the third trimester of pregnancy (34th week of pregnancy) and 12 months after delivery. The same number of age-matched non-pregnant females was evaluated at the corresponding appointments as the control group.

RESULTS

Assessment of the tomographic, topographic and ORA measurements before pregnancy, at the third trimester of pregnancy and 12 months post partum revealed no statistically significant changes in anterior and posterior corneal flat, steep and mean keratometry, anterior and posterior elevation measurements, central and thinnest corneal thickness, corneal hysteresis, corneal resistance factor and intraocular pressure measurements (p>0.05, repeated measures analysis of variance (ANOVA)). All of the study parameters returned to their baseline levels 1 year after delivery. The ophthalmic parameters of the non-pregnant group remained significantly unchanged during the study period (p>0.05, all comparisons, repeated measures ANOVA). Moreover, no statistically significant differences were found between pregnant and non-pregnant groups in the second (34th week of pregnancy) and third (post partum) appointments (p>0.05, all comparisons, one-way ANOVA).

CONCLUSION

Our findings may suggest a physiological nature for ocular changes during pregnancy that these changes return to baseline values after delivery. The differences between tomographic, topographic and biomechanical corneal parameters before pregnancy, during pregnancy and post partum were not statistically or clinically significant.

TFOS DEWS II Sex, Gender, and Hormones Report

One of the most compelling features of dry eye disease (DED) is that it occurs more frequently in women than men. In fact, the female sex is a significant risk factor for the development of DED. This sex-related difference in DED prevalence is attributed in large part to the effects of sex steroids (e.g. androgens, estrogens), hypothalamic-pituitary hormones, glucocorticoids, insulin, insulin-like growth factor 1 and thyroid hormones, as well as to the sex chromosome complement, sex-specific autosomal factors and epigenetics (e.g. microRNAs). In addition to sex, gender also appears to be a risk factor for DED. "Gender" and "sex" are words that are often used interchangeably, but they have distinct meanings. "Gender" refers to a person's self-representation as a man or woman, whereas "sex" distinguishes males and females based on their biological characteristics. Both gender and sex affect DED risk, presentation of the disease, immune responses, pain, care-seeking behaviors, service utilization, and myriad other facets of eye health. Overall, sex, gender and hormones play a major role in the regulation of ocular surface and adnexal tissues, and in the difference in DED prevalence between women and men. The purpose of this Subcommittee report is to review and critique the nature of this role, as well as to recommend areas for future research to advance our understanding of the interrelationships between sex, gender, hormones and DED.

Dry Eye Management: Targeting the Ocular Surface Microenvironment

Dry eye can damage the ocular surface and result in mild corneal epithelial defect to blinding corneal pannus formation and squamous metaplasia. Significant progress in the treatment of dry eye has been made in the last two decades; progressing from lubricating and hydrating the ocular surface with artificial tear to stimulating tear secretion; anti-inflammation and immune regulation. With the increase in knowledge regarding the pathophysiology of dry eye, we propose in this review the concept of ocular surface microenvironment. Various components of the microenvironment contribute to the homeostasis of ocular surface. Compromise in one or more components can result in homeostasis disruption of ocular surface leading to dry eye disease. Complete evaluation of the microenvironment component changes in dry eye patients will not only lead to appropriate diagnosis, but also guide in timely and effective clinical management. Successful treatment of dry eye should be aimed to restore the homeostasis of the ocular surface microenvironment.

Topographic, tomographic and biomechanical corneal changes during pregnancy in patients with keratoconus: a cohort study

PURPOSE

This study aimed at evaluating the effect of pregnancy on topographic, tomographic and biomechanical parameters of patients with keratoconus (KC) in comparison with non-pregnant patients with KC.

METHOD

In a cohort study, patients with KC, whose disease was stable for at least 2 years, were evaluated before pregnancy, at their third trimester of pregnancy (34th week of pregnancy) and 6 months after pregnancy. As the control group, an equivalent number of age- and severity-matched non-pregnant female patients with KC were evaluated at the corresponding times. All subjects were evaluated with respect to central and thinnest corneal thickness (CCT and TCT), keratometry values, and maximum anterior and posterior elevation measurements (AE and PE) by Pentacam. Furthermore, corneal biomechanical properties including corneal hysteresis (CH) and corneal resistance factor (CRF) were measured using the ocular response analyser.

RESULTS

Twenty-two eyes of 11 patients were equally enrolled in each group. The results revealed that there was a statistically significant difference between the means of all measurements during the course of study (p < 0.001, repeated measures analysis of variance). The values of CCT, TCT, CH, CRF, IOPg and IOPcc were significantly decreased; however, keratometry values, AE, PE and refraction measurements were significantly increased during the study period (p < 0.001). In contrast, no significant differences were observed regarding the study variables in the control group (p > 0.05). According to the Amsler-Krumeich classification, severity of KC increased during the pregnancy and postpregnancy periods (p = 0.038).

CONCLUSION

The obtained results revealed that KC progressed during the pregnancy period and continued to the post-partum period, indicating that pregnancy may be a risk factor for KC progression. Patients with KC, who intend to become pregnant, may consider corneal cross-linking treatment in an attempt to stop KC progression.

Acute corneal hydrops during pregnancy with spontaneous resolution after corneal cross-linking for keratoconus: a case report

BACKGROUND

Keratoconus may progress to acute corneal hydrops even after cross-linking. In some cases, keratoconus progresses during pregnancy. In this report, we present a case of a patient with increased anterior stromal resistance after cross-linking that would favor nonprogression of keratoconus during pregnancy.

CASE PRESENTATION

We report that cross-linking is likely to have had a protective effect in a white pregnant patient with acute corneal hydrops who showed rapid improvement, as documented by corneal topography. Improvement occurred within 8 days, whereas up to 250 days are reported in the literature. No keratoconus progression occurred in the 20-month follow-up period.

CONCLUSIONS

Cross-linking failed to prevent the occurrence of acute corneal hydrops after rupture of Descemet's membrane but most likely helped to accelerate the resolution of the condition. Corneal hardening resulting from cross-linking may have also contributed to stabilizing keratoconus during pregnancy.

Differential Effects of Hormones on Cellular Metabolism in Keratoconus In Vitro

Keratoconus (KC) is a corneal thinning disease with an onset commonly immediately post-puberty and stabilization by 40 to 50 years of age. The role of hormones in regulating corneal tissue structure in homeostatic and pathological conditions is unknown. Our group recently linked altered hormone levels to KC. Our current study sought to investigate and delineate the effects of exogenous hormones, such as androgen, luteotropin, and estrogen, on corneal stroma bioenergetics. We utilized our established 3D in vitro model to characterize the effects of DHEA, prolactin, 17β-estradiol on insulin-growth factor-1 and -2 (IGF-1, -2) signaling and metabolic function in primary corneal fibroblasts from healthy controls (HCFs) and KC patients (HKCs). Our data showed that exogenous DHEA significantly downregulated IGF-1 and its receptor in both HCFs and HKCs with HKCs showing consistently lower basal pentose phosphate flux. Prolactin caused no significant change in IGF-1 levels and an increase in IGF-2 in HKCs correlating with an increase in ATP and NADH levels. 17β-estradiol led to a significant upregulation in pentose phosphate flux and glycolytic intermediates in HCFs. Our results identified hormone-specific responses regulated in HKCs compared to HCFs revealing a novel role for hormones on bioenergetics in KC.

Evaluation of corneal thickness alterations during menstrual cycle in productive age women

PURPOSE

To determine the change in corneal thickness through different phases of menstrual cycle in women who are in their productive age.

MATERIALS AND METHODS

Fifty healthy women with normal past medical history were enrolled in this prospective study. Central corneal thickness was measured with ultrasound pachymeter three times during a menstrual cycle: Beginning of the cycle (days 1-3), ovulation time, and at the end of cycle (days 27-32). We confirmed ovulation time with determining a peak in luteinizing hormone in urine. To avoid the diurnal variation of the corneal thickness which is well recognized, we checked all our subjects at 10 in the morning.

RESULTS

In days 1 to 3 of menstruation, mean corneal thickness was 541.40 ± 11.36 and 540.82 ± 11.70 microns for left and right eyes respectively. At ovulation time the mean thickness changed to 556.50 ± 7.11 and 555.98 ± 7.26 microns for left and right eyes respectively, and at the end of the cycle, the corneal thickness turned in to 536.38 ± 12.83 and 535.48 ± 13.08 microns for left and right eyes respectively. The difference of corneal thickness was statistically significant relating to the different stages of menstrual cycle.

CONCLUSION

The thickest cornea during the menstruation cycle is achieved at the ovulation time and the thinnest at the end of the cycle and this should be taken in to account whilst plan to do a corneal refractive surgery.

The effect of assisted reproductive technology on ocular assessments

PURPOSE

The aim was to study the various ocular assessments in women undergoing assisted reproductive techniques (ART).

METHODS

A total of 117 women with infertility were enrolled for study and the ART protocol was followed. The outcome measures were intraocular pressure (IOP), central corneal thickness, corneal endothelial cell counts, Schirmer I test done at baseline (V0), post-oral contraceptive (V1), post-GnRH agonist induction phase (V2), post-conception (V3), third trimester of pregnancy (V4) and three months post-partum (V5). Schirmer I test (without topical anaesthesia) less than 10 mm in at least one eye was considered a criterion for dry eye.

RESULTS

Out of 117 women enrolled for in vitro fertilisation (IVF), only 48 patients conceived. Sixteen women had abortions and remaining 32 women, who had childbirth were followed until three months post-partum. Baseline mean IOP showed a slight decrement and corneal pachymetry and corneal endothelial cell counts showed slight increment from phases V1 to V4 of ART but statistically they were not significant (p > 0.05). At three months post-partum (V5) mean IOP, corneal pachymetry, corneal endothelial cell counts become closer to baseline in both eyes. The number of patients with at least one eye with dryness (Schirmer I less than 10 mm) significantly increased at the third trimester (p = 0.02) and three months post-partum (p = 0.035), whereas in the rest of the phases, it was comparable to baseline (p > 0.05).

CONCLUSION

The ocular physiological changes (IOP, corneal pachymetry and corneal endothelial cell counts) seen in various phases of ART were non-specific. The ART appears to reduce tear secretions as measured by Schirmer I; however, further research would be required to determine the impact of ART on the tear film and whether ART is associated with symptoms and signs of dry eye.

Endocrine and Metabolic Pathways Linked to Keratoconus: Implications for the Role of Hormones in the Stromal Microenvironment

Hormones play a critical role in regulating tissue function by promoting cell survival, proliferation, and differentiation. Our study explores the influence of endocrine function in regulating metabolism and inflammatory pathways in Keratoconus (KC), which is a corneal thinning disease associated with reduced stromal deposition. KC is known to be a multifactorial disease with an elusive pathogenesis. We utilized a cross-sectional study analyzing clinical features and saliva samples from sixty-four KC patients and fourteen healthy controls. In order to determine if endocrine function varied between healthy controls and KC, we measured hormone levels in saliva and found significantly increased dehydroepiandrosterone sulfate (DHEA-S) and reduced estrone levels in KC patients compared to healthy controls. We measured significant variations in metabolites associated with pro-inflammatory processes, including myoinositol and 1-methyl-histidine, by targeted mass spectrometry. We also measured significantly increased IL-16 and stem cell factor in KC saliva samples compared to healthy controls, with higher expression of these pro-inflammatory proteins correlating with increased KC clinical grade, corneal curvature, and stromal thinning. Our results identify a novel mechanism linking KC and pro-inflammatory markers and suggest that altered hormone levels modulate metabolism, cytokine, and growth factor expression leading to increased severity of the KC condition.

Androgen receptor in human endothelial cells

Androgen receptor (AR) is a ligand-inducible transcription factor, and a member of the steroid-thyroid-retinoid receptor superfamily, that mediates the biological effects of androgens in a wide range of physiological and pathological processes. AR expression was identified in vascular cells nearly 20 years ago, and recent research has shown that AR mediates a variety of actions of androgens in endothelial and vascular smooth muscle cells. In this mini-review, we review evidence indicating the importance of AR in human endothelial cell (HUVEC) homeostatic and pathogenic processes. Although a role for AR in the modulation of HUVEC biology is evident, the molecular mechanisms by which AR regulates HUVEC homeostasis and disease processes are not fully understood. Understanding these mechanisms could provide critical insights into the processes of pathogenesis of diseases ranging from cardiovascular disease to cancer that are major causes of human morbidity and mortality.

Sex-steroid imbalance in females and dry eye

Dry eye (DE) is a multifactorial disorder of the ocular surface unit that results in eye discomfort, visual disturbance and ocular surface damage. It is one of the most common complaints in daily ophthalmic practice. The risk of DE increases with age in both sexes, while its incidence is higher among females. In addition, the condition of menopause in aging women may also contribute to DE onset or worsening as a consequence of an overall hormonal imbalance. Sex hormones play a key role in ocular surface physiology and they impact differently on ocular surface tissues. Reduced estrogen levels were historically thought to be responsible in age-related DE onset but more recent investigations have reconsidered the role of androgens that are present and exert a protective function on the ocular surface. Hormone levels themselves, withdrawal changes in hormone levels, and the changes in hormone-receptor responsiveness are all important factors but it remains to be fully elucidated how estrogen or androgen insufficiency act alone or together in a combined imbalance or interplay to raise the risk of disease. The purpose of this review is to briefly outline current scientific evidence on the influence of androgens and estrogens, on the Lachrymal and Meibomian glands and on ocular surface epithelia including conjunctival goblet cells during reproductive and menopausal periods. The role of sex steroids is also discussed in relation to the pathogenesis of different forms of DE and Sjogren's syndrome (SS). The impact of systemic hormone therapy (HT) in DE post-menopausal women still appears as a controversial issue, despite the many clinical studies. Finally, the outcomes of topical applications of steroid-based products are summarized, underlying the need for potential (tear) biomarker(s) in the rationale of DE-targeted therapy.

Cornea in PCOS patients as a possible target of IGF-1 action and insulin resistance

OBJECTIVES

Previous studies suggest that serum IGF-1 is higher in women with polycystic ovary syndrome (PCOS). The ophthalmologic effects of IGF-1 excess have not yet been investigated in women with PCOS. The aim of the current study is to compare the corneal thickness of patients with PCOS and those of healthy subjects.

METHODS

Forty three patients with PCOS and 30 age-matched and gender-matched healthy individuals were enrolled in this cross-sectional study. Central corneal thickness (CCT) was measured in patients with PCOS and in healthy individuals with an ultrasound pachymeter. IGF-1 values were also determined in the study group.

RESULTS

Women with PCOS had significantly higher levels of IGF-1 and homeostasis model assessment (HOMA-IR) levels than the control group. Right and left CCT measurements were higher in the PCOS group than in the control group. A positive correlation between IGF-1 and right and left CCT was identified in both groups. In multiple linear stepwise regression analyses, IGF-1 independently and positively associated with HOMA-IR in women with PCOS. A correlation between total testosterone and CCT was identified in the whole group. In multiple stepwise regression analyses, total testosterone independently and positively associated with left central corneal thickness in the whole group.

CONCLUSIONS

These findings indicate that PCOS has target organ effects on the eye. Consequently, it can change central corneal thickness. Higher IGF-1 levels seem to be the main causes of increased corneal thickness. Insulin resistance in PCOS is one of the underlying causes and promotes increase in IGF-1. We suggest a careful and detailed corneal evaluation in PCOS patients to prevent the potential risk of increased CCT, in addition to the already-known complications.

Refractive surgery in systemic and autoimmune disease

Patients with underlying systemic disease represent challenging treatment dilemma to the refractive surgeon. The refractive error in this patient population is accompanied by a systemic disease that may have an ocular or even a corneal component. The literature is rather sparse about the use of laser refractive surgery (LRS) and such procedure is not approved by the United States Food and Drug Administration (FDA) in this patient population. Patients with collagen vascular disease, diabetes mellitus (DM), allergic and atopic disease, or human immunodeficiency virus (HIV) are never ideal for LRS. Patients with uncontrolled systemic disease or ocular involvement of the disease should not undergo LRS. However, a patient with well-controlled and mild disease, no ocular involvement, and not on multidrug regimen may be a suitable candidate if they meet stringent criteria. There is a need for a large, multicenter, controlled trial to address the safety and efficacy of LRS in patients with systemic disease before such technology can be widely adopted by the refractive surgery community.

Sex hormones and the dry eye

The greater prevalence of dry eye in women compared to men suggests that sex hormones may have a role in this condition. This review aims to present evidence for how sex hormones may affect the ocular structures involved in the production, regulation and maintenance of the normal tear film. It is hypothesised that hormone changes alter the homeostasis of the ocular surface and contribute to dry eye. Androgens impact on the structure and function of the meibomian and lacrimal glands and therefore androgen deficiency is, at least in part, associated with the aetiology of dry eye. In contrast, reports of the effects of oestrogen and progesterone on these ocular structures and on the conjunctiva are contradictory and the mechanisms of action of these female-specific sex hormones in the eye are not well understood. The uncertainty of the effects of oestrogen and progesterone on dry eye symptoms is reflected in the controversial relationship between hormone replacement therapy and the signs and symptoms of dry eye. Current understanding of sex hormone influences on the immune system suggests that oestrogen may modulate a cascade of inflammatory events, which underlie dry eye.

Corneal biomechanical parameters during pregnancy

PURPOSE

To evaluate the variation in biomechanical properties and central corneal thickness (CCT) for each trimester during pregnancy and to compare the values with those in nonpregnant women.

METHODS

We prospectively studied the eyes of 32 pregnant and 34 age-matched non-pregnant women. The parameters included corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOP), and corneal-compensated IOP measured by the Ocular Response Analyzer (ORA). The CCT was also measured with an ultrasonic pachymeter attached to the ORA.

RESULTS

The mean age was 27.0 ± 3.8 years in the study group and 28.0 ± 4.1 years in the control group. The mean CH measurement was 10.6 ± 1.4 mmHg in the study group and 10.1 ± 1.3 mmHg in the control group. The mean CRF value was 9.6 ± 1.7 mmHg in the study group and 10.0 ± 1.4 mmHg in the control group. The mean CCT value was 541.1 ± 22.4 µm in the study group and 536.5 ± 27.1 µm in the control group. No statistically significant differences were found regarding CH, CRF, or CCT values between the 2 groups (independent t test, p = 0.160, p = 0.355, p = 0.450, respectively).

CONCLUSIONS

Hormonal changes during pregnancy may not affect corneal biomechanics. This may be due to the balanced effect of the various hormones on the cornea during pregnancy.

Effects of ovarian hormones on internal circadian organization in rats

The circadian clock in the suprachiasmatic nucleus (SCN) of the hypothalamus is the central pacemaker driving rhythms in endocrine physiology. Gonadal steroid hormones affect behavioral rhythms and clock gene expression. However, the impact of fluctuating ovarian steroid levels during the estrous cycle on internal circadian organization remains to be determined. Further, it is not known if steroid hormone depletion, as in menopause, affects the timing system. To determine the influence of estrous cycle stage and steroid depletion on circadian organization, we measured clock gene expression in the SCN and peripheral tissues from cycling and ovariectomized (OVX) period1-luciferase (per1-luc) transgenic rats. The estrous cycle had modest effects on mean phase and phase distribution of per1-luc expression in the SCN. Surprisingly, peak per1-luc expression in the SCN was widely distributed mainly at night, regardless of cycle stage, an effect eliminated by OVX. Treatment of SCN tissue explants with ovarian steroids did not significantly affect per1-luc expression, suggesting that brain regions outside the SCN mediate the phasic effects of steroids. Our data demonstrate that estrous cycle stage has tissue-dependent effects on the phase of per1-luc expression, phase synchrony among oscillators, and the phase relationship between some peripheral clocks and the light-dark cycle. They also reveal that steroid hormone depletion following OVX alters the timing system, suggesting that the decline in hormone levels, common during the transition to menopause, may be associated with irregular internal circadian organization. This effect on the timing system could contribute to the behavioral and physiological changes associated with this transition.

Excess androgen during puberty disrupts circadian organization in female rats

Circadian clocks have been described in each tissue of the hypothalamo-pituitary-ovarian axis. Although a role for the clock in the timing of ovulation is indicated, the impact of diseases that disrupt fertility on clock function or the clocks' role in the etiology of these pathologies has yet to be fully appreciated. Polycystic ovary syndrome (PCOS) is a particularly devastating endocrinopathy, affecting approximately 10% of women at childbearing age. Common features of PCOS are a polycystic ovary, amenorrhea, and excess serum androgen. Approximately 40% of these women have metabolic syndrome, including hyperinsulinemia, dyslipidemia, and hyperleptinemia. It has been suggested that excess androgen is a critical factor in the etiology of PCOS. We have examined the effects of androgen excess during puberty on the phase of circadian clocks in tissues of the metabolic and hypothalamo-pituitary-ovarian axes. Female period1-luciferase (per1-luc) rats were exposed to androgen (5α-dihydrotestosterone [DHT]) or placebo for 4-6 weeks (short term) or 9-15 weeks (long term). As expected, DHT-treated animals gained more weight than controls and had disrupted estrous cycles. At the end of treatment, tissues, including the liver, lung, kidney, white adipose, cornea, pituitary, oviduct, and ovarian follicles, were cultured, and per1-luc expression in each was recorded. Analysis of per1-luc expression revealed that DHT exposure increased phase distribution of multiple oscillators, including ovarian follicles, liver, and adipose, and altered phase synchrony between animals. These data suggest that excess androgen during puberty, a common feature of PCOS, negatively affects internal circadian organization in both the reproductive and metabolic axes.

Classification of secondary corneal amyloidosis and involvement of lactoferrin

PURPOSE

To classify secondary corneal amyloidosis (SCA) by its clinical appearance, to analyze the demographics of the patients, and to determine the involvement of lactoferrin.

DESIGN

Retrospective, observational, noncomparative, multicenter study.

PARTICIPANTS

Twenty-nine eyes of 29 patients diagnosed with SCA by corneal specialists at 9 ophthalmologic institutions in Japan were studied.

METHODS

The clinical appearance of SCA was determined by slit-lamp biomicroscopy and was classified into 3 types. The demographics of the patients, for example, age, gender, and the duration of the basic disease (trichiasis, keratoconus, and unknown), were determined for each clinical type. Surgically excised tissues were stained with Congo red and antilactoferrin antibody. The postoperative prognosis also was determined.

MAIN OUTCOME MEASURES

Clinical appearance of the 3 types of SCA, along with the gender, age, and duration of the basic diseases were determined.

RESULTS

Classification of SCA into 3 types based on clinical appearance found 21 cases with gelatinous drop-like dystrophy (GDLD)-like appearance (GDLD type), 3 cases with lattice corneal dystrophy (LCD)-like appearance (LCD type), and 5 cases with the combined type. Patients with the GDLD type were younger (average age: 40.9 years for the GDLD type, 74.3 years for the LCD type, and 46.8 years for the combined type), predominantly women (85.7% for the GDLD type, 33.3% for the LCD type, and 60% for the combined type), and had the basic disease over a longer time (average duration: 22.1 years for the GDLD type, 14.0 for the LCD type, and 11.4 for the combined type). The distribution of the basic diseases (trichiasis vs. keratoconus vs. unknown) was not significantly different for each type. Surgical treatments, for example, phototherapeutic keratectomy, lamellar keratoplasty, and simple keratectomy, resulted in a good resolution in all surgically treated cases. One subject dropped out of the study. Spontaneous resolution was seen in one subject after epilation of the cilia. Amorphous materials in the excised tissues showed positive staining results by Congo red and by antilactoferrin antibody.

CONCLUSIONS

Secondary corneal amyloidosis can be classified into 3 clinical types based on its clinical appearance. Larger numbers of females and lactoferrin expression were seen in all 3 types.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Pregnancy-induced Progression of Keratoconus in a 37-Year-Old Patient

Purpose

To report a case of keratoconus that progressed during pregnancy without any accompanying disease.

Methods

A case report.

Results

A patient with keratoconus that worsened during pregnancy demonstrates that pregnancy can be a previously unrecognized risk factor for progression of keratoconus.

Conclusion

To our knowledge, this is the first case reported in Brazil and the third paper in the world showing pregnancyinduced keratoconus progression in a patient with no accompanying disease.

How to cite this article

Glicéria J, Valbon BF, Santos RT, Ambrósio R Jr. Pregnancy-induced Progression of Keratoconus in a 37-Year-Old Patient. Int J Kerat Ect Cor Dis 2013;2(2):84-88.

Selenium compound protects corneal epithelium against oxidative stress

The ocular surface is strongly affected by oxidative stress, and anti-oxidative systems are maintained in corneal epithelial cells and tear fluid. Dry eye is recognized as an oxidative stress-induced disease. Selenium compound eye drops are expected to be a candidate for the treatment of dry eye. We estimated the efficacy of several selenium compounds in the treatment of dry eye using a dry eye rat model. All of the studied selenium compounds were uptaken into corneal epithelial cells in vitro. However, when the selenium compounds were administered as eye drops in the dry eye rat model, most of the selenium compounds did not show effectiveness except for Se-lactoferrin. Se-lactoferrin is a lactoferrin that we prepared that binds selenium instead of iron. Se-lactoferrin eye drops suppressed the up-regulated expression of heme oxygenase-1, cyclooxygenase-2, matrix metallopeptidase-9, and interleukin-6 and also suppressed 8-OHdG production in the cornea induced by surgical removal of the lacrimal glands. Compared with Se-lactoferrin, apolactoferrin eye drops weakly improved dry eye in high dose. The effect of Se-lactoferrin eye drops on dry eye is possibly due to the effect of selenium and also the effect of apolactoferrin. Se-lactoferrin is a candidate for the treatment of dry eye via regulation of oxidative stress in the corneal epithelium.

Estrogen negatively regulates epithelial wound healing and protective lipid mediator circuits in the cornea

Estrogen receptors (ERs) are expressed in leukocytes and in every ocular tissue. However, sex-specific differences and the role of estradiol in ocular inflammatory-reparative responses are not well understood. We found that female mice exhibited delayed corneal epithelial wound closure and attenuated polymorphonuclear (PMN) leukocyte responses, a phenotype recapitulated by estradiol treatment both in vivo (topically in male mice) and in vitro (corneal epithelial cell wound healing). The cornea expresses 15-lipoxygenase (15-LOX) and receptors for lipoxin A(4) (LXA(4)), which have been implicated in an intrinsic lipid circuit that regulates corneal inflammation and wound healing. Delayed epithelial wound healing correlated with lower expression of 15-LOX in the regenerated epithelium of female mice. Estradiol in vitro and in vivo down-regulated epithelial 15-LOX expression and LXA(4) formation, while estradiol abrogation of epithelial wound healing was completely reversed by treatment with LXA(4). More important, ERβ and ERα selectively regulated epithelial wound healing, PMN cell recruitment, and activity of the intrinsic 15-LOX/LXA(4) circuit. Our results demonstrate for the first time a sex-specific difference in the corneal reparative response, which is mediated by ERβ and ERα selective regulation of the epithelial and PMN 15-LOX/LXA(4) circuit. These findings may provide novel insights into the etiology of sex-specific ocular inflammatory diseases.

Breast cancer medications and vision: effects of treatments for early-stage disease

This review concerns the effects on vision and the eye of medications prescribed at three phases of treatment for women with early-stage breast cancer (BC): (1) adjuvant cytotoxic chemotherapy, (2) adjuvant endocrine therapy, and (3) symptomatic relief. The most common side effects of cytotoxic chemotherapy are epiphora and ocular surface irritation, which can be caused by any of several different regimens. Most notably, the taxane docetaxel can lead to epiphora by inducing canalicular stenosis. The selective-estrogen-receptor-modulator (SERM) tamoxifen, long the gold-standard adjuvant-endocrine-therapy for women with hormone-receptor-positive BC, increases the risk of posterior subcapsular cataract. Tamoxifen also affects the optic nerve head more often than previously thought, apparently by causing subclinical swelling within the first 2 years of use for women older than ∼50 years. Tamoxifen retinopathy is rare, but it can cause foveal cystoid spaces that are revealed with spectral-domain optical coherence tomography (OCT) and that may increase the risk for macular holes. Tamoxifen often alters the perceived color of flashed lights detected via short-wavelength-sensitive (SWS) cone response isolated psychophysically; these altered perceptions may reflect a neural-response sluggishness that becomes evident at ∼2 years of use. The aromatase inhibitor (AI) anastrozole affects perception similarly, but in an age-dependent manner suggesting that the change of estrogen activity towards lower levels is more important than the low estrogen activity itself. Based on analysis of OCT retinal thickness data, it is likely that anastrozole increases the tractional force between the vitreous and retina. Consequently, AI users, myopic AI users particularly, might be at increased risk for traction-related vision loss. Because bisphosphonates are sometimes prescribed to redress AI-induced bone loss, clinicians should be aware of their potential to cause scleritis and uveitis occasionally. We conclude by suggesting some avenues for future research into the visual and ocular effects of AIs, particularly as relates to assessment of cognitive function.

Baseline factors related to endothelial cell loss following penetrating keratoplasty

OBJECTIVE

To identify baseline (donor, recipient, and operative) factors that affect endothelial cell loss following penetrating keratoplasty for a moderate-risk condition (principally Fuchs dystrophy or pseudophakic or aphakic corneal edema).

METHODS

In a subset (n = 567) of Cornea Donor Study participants, preoperative and postoperative endothelial cell densities (ECDs) were determined by a central reading center. Multivariate regression analyses were performed to examine which baseline factors correlated with ECD over time.

RESULTS

Larger grafts (P < .001), younger donor age (P < .001), and female donor (P = .004) were significantly associated with higher ECD during follow-up. Median endothelial cell loss at 5 years was 68% for grafts larger than 8.0 to 9.0 mm in diameter, 75% for grafts 7.0 mm to smaller than 8.0 mm in diameter, and 74% for grafts 8.0 mm in diameter. Grafts from female donors experienced a 67% cell loss compared with a 72% cell loss among grafts from male donors. Method of tissue retrieval, donor cause of death, history of diabetes, and time from death to preservation or to surgery were not significantly associated with changes in ECD over time.

CONCLUSIONS

Following penetrating keratoplasty for endothelial dysfunction conditions, larger donor graft size, younger donor age, and female donor were associated with higher ECD over 5 years. These data warrant exploring the possibility that similar associations may exist following endothelial keratoplasty.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00006411.

[Central corneal thickness in a healthy Spanish population]

OBJECTIVE

To study the central corneal thickness of a Spanish population group and determine the influence of age, gender, axial length and refractive error on central corneal thickness (CCT) values.

METHODS

An observational, cross-sectional, double masked study was conducted on 357 eyes of consecutive Caucasian patients without ophthalmic disease. They were distributed according to age, and high refractive defects were excluded. Ultrasonic pachymetry and a complete eye examination were performed on all patients. The relationship between the central corneal thickness values and variables of age, refractive error, axial length and gender was assessed.

RESULTS

The mean central corneal thickness was 548.21 μm with a standard deviation (SD) of 30.7 μm (range 464 to 633 μm). The normal central corneal thickness value of the population studied was 486.81 to 609.61 μm (95% confidence interval). No statistical association was found between central corneal thickness values and variables of age, refractive error, axial length and gender.

CONCLUSIONS

Central corneal thickness varies according to race. We have analysed, for the first time, normal central corneal thickness values of a healthy Spanish population.

Estrogen receptor beta gene polymorphism and intraocular pressure elevation in female patients with primary open-angle glaucoma

PURPOSE

To assess whether the genetic polymorphisms of estrogen receptor beta (ESR2) are associated with primary open-angle glaucoma (POAG).

DESIGN

Case-control study.

METHODS

Four hundred and twenty-five Japanese patients with POAG, including normal-tension glaucoma (NTG, n = 213) and high-tension glaucoma (HTG, n = 212), and 191 control subjects without glaucoma were analyzed for polymorphisms of rs1256031 and rs4986938 in the ESR2 gene. The genotypic and allelic frequencies were compared between NTG or HTG patients and control subjects. The phenotypic features of patients with POAG were compared between each genotype.

RESULTS

There were significant differences in the genotype frequencies of rs1256031 and rs4986938 between the HTG patients and control subjects in women (P = .033 and P = .043 respectively). The frequencies of the C allele of rs1256031 and G allele of rs4986938 were significantly higher in patients with HTG in comparison to the control subjects in women (rs1256031: 53.6% vs 43.4%, P = .044; rs4986938: 89.2% vs 80.6%, P = .027). The maximum intraocular pressures in female POAG patients with the CC or TC genotypes of rs1256031 were significantly higher than that in female POAG patients with the TT genotype (P = .039, analysis of variance, P = .018 and P = .026 respectively).

CONCLUSION

The ESR2 gene polymorphism is therefore considered to be associated with an intraocular pressure elevation in female patients with POAG.

Human lipocalin-1 association with 3H-testosterone and 3H-estradiol

PURPOSE

Topical androgens and estrogens have been studied for use in treating ocular conditions such as dry eye. The aim of this study was to identify proteins from normal human tears that associated with exogenously added sex steroid hormones. One of the major proteins in ocular tears is lipocalin-1. It binds a variety of lipids and other hydrophobic molecules and is proposed to function as a carrier protein or a lipid scavenger.

METHODS

Normal human tears were incubated with (3)H-testosterone or (3)H-estradiol. Labeled tear proteins were separated on a Q Sepharose Fast Flow (QFF) Hi Trap strong anion exchange column with a step gradient of NaCl. (3)H-testosterone or (3)H-estradiol was measured in aliquots of eluted fractions using scintillation counts, and the remainder of each sample was gel electrophoresed and silver stained. In separate experiments, (3)H-steroid-labeled tear proteins were electrophoresed in 15% polyacrylamide gels and excised from the gels. Tritium content of the proteins was measured in a scintillation counter. Immunoblots with antibodies to lipocalin-1 verified the migration of lipocalin-1 in the gels.

RESULTS

(3)H-steroid labeled tear proteins were found in the 0.15 M NaCl fractions of QFF strong anion exchange columns. 18 kD lipocalin-1 (among other tear proteins) eluted in the 0.15 M NaCl fraction. Excision of labeled tear proteins from 15% polyacrylamide gels indicated that radioactive label was associated with an 18 kD protein. Immunoblots verified that lipocalin-1 migrated as an 18 kD protein.

CONCLUSIONS

The sex steroid hormones testosterone and estradiol associated with 18 kD lipocalin-1 in human tears.

Influence of bilateral medial collateral ligament injury on mRNA expression in distal corneal tissues of control and ovariohysterectomized rabbits

PURPOSE

Corneal tissues are reported to be impacted by physiological changes (eg, menopause), systemic autoimmune diseases, and osteoarthritic-like conditions. In this study, changes in specific mRNA levels in the cornea after a ligament injury in normal and rabbits subjected to surgical menopause were examined.

METHODS

Skeletally mature female rabbits were either sham-operated (control) or were subjected to surgical menopause (OVX). Eight weeks post-OVX, subsets of control and OVX animals were subjected to bilateral injuries to their medial collateral ligaments (MCL) of the knee, and 6 and 14 weeks postinjury, corneal tissues were harvested. Using reverse transcriptase-polymerase chain reaction, mRNA levels for several relevant molecules, including matrix molecules, growth factors, cytokines, proteinases, and hormone receptors, were assessed.

RESULTS

mRNA levels for estrogen receptor, decorin, collagens, several growth factors, and inflammatory cytokines decreased in central corneal tissue 6 weeks after distal MCL injury in control animals. The central corneal tissues of animals subjected to OVX alone also exhibited decreases in mRNA levels for a similar set of molecules. When OVX animals were further subjected to MCL injury, the mRNA levels for many of these molecules did not vary from those in the uninjured OVX group. Interestingly, mRNA levels for most molecules were still altered 14 weeks post-MCL injury in the control and OVX animals, a time when the MCL has healed.

CONCLUSIONS

Corneal tissues respond to changes resulting from OVX and/or injury. OVX combined with a ligament injury does not appear to have an additive impact on corneal mRNA levels for most of the molecules assessed.

Corneal Epithelial Cultures Generated from Organ-Cultured Limbal Tissue: Factors Influencing Epithelial Cell Growth

PURPOSE

To explore the in vitro proliferative potential of human limbal epithelial cells after 31 degrees C organ-culture storage and to investigate putative factors influencing it.

METHODS

185 cultures of limbal explants were carried-out either from full-thickness explants (n = 102) or from enzymatically dissociated cells (n = 83) seeded on a feeder layer of human keratocytes. Epithelial outgrowth was assessed by phase contrast microscopy using a computerized image analysis software. Cell phenotype was evaluated by transmission electron microscopy and immunocytology. Univariate and multivariate analysis were performed to determine factors influencing epithelial growth in culture.

RESULTS

An epithelial outgrowth of 100 square mm or more was observed in 52% of cultures, (average growth area: 440 +/- 256 mm at three weeks). Corneal epithelial phenotype was confirmed by transmission electron microscopy, and cytokeratin pattern. Cytokeratine 19, deltaNp63, nestin and vimentin positive staining revealed undifferentiated epithelial cells in both explant and cell suspension cultures at three weeks. Short death to cornea retrieval time (p < 0.03) and female donors (p < 0.01) were associated with higher cell growth. Enzymatic treatment of explants by trypsin, but not dispase, decreased cell proliferation at two (p < 0.03) and three weeks (p < 0.04). Donor age, duration of corneal storage, and source of the explant did not influence the cell growth.

CONCLUSION

Organ-culture conditions can preserve limbal cell mitotic potential if limbal tissue is excised early after circulatory arrest. Human keratocytes can be used as a feeder layer allowing epithelial cells to maintain poorly differentiated phenotype in culture. Further investigations are needed to explain the influence of the donor sex on epithelial cell growth in culture.

Experimental use of estriol for visualizing the vitreous body in the anterior chamber after posterior capsule rupture in animal models

PURPOSE

To compare the efficacy and safety of estriol and triamcinolone acetonide suspensions in visualizing the prolapsed vitreous body in the anterior chamber after posterior capsule rupture in animal models.

SETTING

Tsukuba University Institute of Clinical Medicine, Ibaraki, Japan.

METHODS

To evaluate efficacy, triamcinolone acetonide or estriol suspension was injected into the anterior chambers of porcine eyes after intentional posterior capsule rupture. To evaluate safety, triamcinolone acetonide 5.0 mg or estriol in 0.1 mL suspension was injected into the anterior chamber of New Zealand white rabbits. Slitlamp examinations, intraocular pressure (IOP), corneal endothelial cell density (ECD) measurements, and histologic examinations were performed up to 28 days after the injection.

RESULTS

Triamcinolone acetonide and estriol were equally effective in allowing visualization of the prolapsed vitreous body in the anterior chamber. The granules of triamcinolone acetonide or estriol disappeared 1 day after the injection and did not affect the IOP or corneal ECD. No statistically significant histological changes were observed in the eyes 28 days after the injection of triamcinolone acetonide or estriol.

CONCLUSIONS

Estriol was effective for the visualization of the prolapsed vitreous body in the anterior chamber after posterior capsule rupture. In experimental models, no significant side effects were observed after the injection of estriol in the anterior chamber. Results suggest that estriol is an alternative reagent for visualizing the vitreous body, especially in steroid responders, because it has no glucocorticoid or mineralocorticoid activity.

Physiological changes associated with the menstrual cycle: a review

The cyclic hormonal changes that regulate the menstrual cycle are a significant biological influence on the female body, one with both physical and emotional ramifications. Menstruation is governed by tightly orchestrated changes in the levels of ovarian estrogen and progesterone, which produce varying responses in diverse tissues and organs. The skin, the largest organ in the body, is replete with estrogen receptors (in both dermis and epidermis) and to a lesser extent, progesterone receptors. Cyclically fluctuating levels of estrogen and progesterone influence numerous characteristics of the epidermis, including skin surface lipid secretion and sebum production, skin thickness, fat deposition, skin hydration, and barrier function. Dermal collagen content, which contributes to skin elasticity and resistance to wrinkling, is also influenced. Interestingly, estrogen levels also influence skin pigmentation and UV susceptibility, as well as resident microflora. In addition, changing hormone levels across the menstrual cycle produce measurable variations in immune function and disease susceptibility. An understanding of the profound influence that fluctuating estrogen and progesterone levels have on the biological responses of the premenopausal adult woman is critical to optimizing the efficacy of medical therapies in this population.