Identification of androgen, estrogen and progesterone receptor mRNAs in the eye

A role for androgens in regulating circadian behavior and the suprachiasmatic nucleus

The suprachiasmatic nucleus (SCN) of the hypothalamus is the locus of a master circadian clock controlling behavioral and physiological rhythms, including rhythmic secretion of gonadal hormones. Gonadectomy results in marked alteration of circadian behaviors, including lengthened free-running period, decreased precision of daily onset of running, and elimination of early-evening but not late-night activity bouts. Androgen replacement restores these responses. These aspects of rhythmicity are thought to be regulated by the brain clock, although the site of androgen action remains unknown. Anatomically, the rodent SCN is composed of a ventrolateral core and a dorsomedial shell, and the present studies show that androgen receptors (AR) are localized to the ventrolateral core SCN. Using a transgenic mouse bearing dual reporter molecules driven by the AR targeted to both membrane and nucleus, we find that projections of AR-containing cells form a dense plexus in the core, with their fibers appearing to exit the SCN dorsally. In a second transgenic strain, in which the retinorecipient gastrin-releasing peptide cells express a green fluorescent protein reporter, we show that gastrin-releasing peptide cells contain AR. Through immunocytochemistry, we also show that SCN AR cells express FOS after a light pulse. Importantly, gonadectomy reduces the FOS response after a phase-shifting light pulse, whereas androgen replacement restores levels to those in intact animals. Taken together, the results support previous findings of a hypothalamic neuroendocrine feedback loop. As such, the SCN regulates circadian rhythms in gonadal hormone secretion, and in turn, androgens act on their receptors within the SCN to alter circadian function.

Tearful relationships? Sex, hormones, the lacrimal gland, and aqueous-deficient dry eye

Sex and the endocrine system exert a significant influence on the physiology and pathophysiology of the lacrimal gland. The purpose of this article is to briefly review the nature and magnitude of these interactions between sex, hormones and lacrimal tissue, and to address how they may relate to the pathogenesis of aqueous-deficient dry eye. Towards this end, this article has a 3-fold approach: first, to summarize the influence of androgens, estrogens, glucocorticoids, mineralocorticoids, retinoic acid, prolactin, alpha-melanocyte stimulating hormone, adrenocorticotropic hormone, luteinizing hormone, follicle-stimulating hormone, growth hormone, thyroid-stimulating hormone, arginine vasopressin, oxytocin, thyroxine, parathyroid hormone, insulin, glucagon, melatonin, human chorionic gonadotropin and cholecystokinin on the structure and function of the lacrimal gland; second, to discuss the mechanism of action of each hormone on lacrimal tissue; and third, to discuss the clinical relevance of the endocrine-lacrimal gland interrelationship, with a particular focus on each hormone's role (i.e. if relevant) in the development of aqueous-tear deficiency.

Meibomian gland function and the tear lipid layer

The meibomian glands of the lid produce a lipid material whose synthesis is dependent on neuronal, hormonal, and vascular factors. This lipid material is fluid, spreads easily, is a surfactant as well as an aqueous barrier and must remain functional after a blink. To satisfy these requirements, the meibomian lipids have a specific composition. Even after delivery it may be modified by lipases produced by ocular bacteria, and modifications in the lipid components can lead to unique disease states. For example, bacteria may degrade lipids, producing an unstable tear film and irritating free fatty acids; and hormonal imbalances may alter lipid profiles to destabilize the tear film and produce evaporative dry eye.

Membrane-initiated effects of progesterone on calcium dependent signaling and activation of VEGF gene expression in retinal glial cells

Neurosteroids, such as progesterone, influence central nervous system development and function by regulating a broad spectrum of physiological processes. Here, we investigated membrane-initiated actions of progesterone in the retina and identified the membrane-associated progesterone receptor component 1 (PGRMC1). We found PGRMC1 expressed mainly in retinal Muller glia (RMG) and retinal pigment epithelium, and localized uniquely to microsomal and plasma membrane fractions. In RMG, membrane-impermeable progesterone conjugate induced calcium influx and subsequent phosphatidylinositol 3-kinase-mediated phosphorylation of PKC and ERK-1/2. Induction by progesterone also led to PKC-dependent activation of VEGF gene expression and protein synthesis, suggesting a contribution of membrane-initiated hormone effects to VEGF induced neovascularization within retina.

Oestrogen-induced changes in biomechanics in the cornea as a possible reason for keratectasia

AIM

The risk of regression after photorefractive keratectomy (PRK) and the tendency to develop keratectasia after laser-assisted in situ keratomileusis (LASIK) procedure is higher in women than men. Currently, interest is focused on the influence of oestrogen on corneal stability after corneal refractive surgery. The aim of this experimental study was to investigate the change in biomechanical properties of the cornea induced by oestrogen.

METHODS

The influence of oestrogen was investigated in 12 fresh porcine corneas incubated in culture medium with 10 micromol/l beta-oestradiol for 7 days. A group of 12 porcine corneas incubated in culture medium without oestradiol for the same time served as a control group. Strips of cornea were cut and the stress-strain was measured in a biomaterial tester. The Young's modulus was calculated.

RESULTS

During incubation the thickness of the cornea changed in the control group by only 6.4% and in the oestradiol group by 12%. However, the difference in the biomechanical stress values at 10% strain was significantly larger. In the control group the stress value was 120.18+/-28.93 kPa and in the oestradiol group 76.87+/-34.63 kPa (p = 0.002), representing a reduction of the corneal stiffness by 36% due to the oestradiol treatment.

CONCLUSION

Oestrogen is a modulating factor of the biomechanical properties of the cornea that is not explainable only by an increased swelling. The significance of the hormone status of patients and its influence on the biomechanical stability of the cornea, a determining factor after refractive surgery, have been underestimated and may contribute to the development of keratectasia.

Corneal topographic changes in premenopausal and postmenopausal women

BACKGROUND

To asses the effect of menopause on the corneal curvature changes using corneal computerized videokeratography (CVK) in premenopausal and postmenopausal healthy women.

METHODS

Thirty-six postmenopausal women with mean ages of 49.2 (range 39 to 57) were enrolled in this randomized, prospective study, comparing with 26 healthy controls with mean ages of 38.5 +/- 4.9 (range 32 to 49). Subjects were determined to be postmenopausal, by the Gynecology and Obstetrics Department, based on blood Follicular Stimulating Hormone (FSH), Luteinizing Hormone (LH), Estradiol, Progesterone levels and clinical complaints. Complete ophthalmic examination and CVK using Haag-Streit System was performed in both premenopausal and postmenopausal women.

RESULTS

Mean horizontal curvature and vertical curvature of central corneal power in premenopausal women were 43.5 +/- 1.25 Diopter (D), and 44.1 +/- 1.53 D. Mean horizontal curvature and vertical curvature of central corneal power in postmenopausal women were 43.9 +/- 1.4 D, and 44.6 +/- 1.3 D. The mean keratometric astigmatisms of premenopausal and postmenopausal women were 0.81 +/- 0.57 D (4-179 degrees), 0.74 degrees +/- 0.5 D (1-180 degrees) respectively. No significant corneal curvature changes were detected between premenopausal and postmenopausal groups (P > 0.05). On the other hand, we only found negative but significant correlation between horizontal corneal curvature and estrogen level of postmenopausal women (r = -0.346, p = 0.038).

CONCLUSION

Menopause is physiologic process and may also affect corneal topographic changes. In postmenopausal women, corneal steeping was observed minimally compared to premenopausal women. The results suggest that changes in estrogen level of women with menopause are associated with slightly alteration of horizontal curvature of cornea.

Itchy-dry eye associated with polycystic ovary syndrome

PURPOSE

The authors aimed to define the ocular symptomatology of women with polycystic ovaries and hyperandrogenism.

DESIGN

Prospective, observational case series.

METHODS

Of the 62 consecutive patients with an ultrasonographic diagnosis of polycystic ovary (PCO), 16 were identified as having clinical and biochemical signs of hyperandrogenism. All women with a history of ocular symptoms (20/62 total patients [32.3%], 15/16 polycystic ovary syndrome (PCOS) patients [93.7%], and 5/46 PCO patients [10.8%]) underwent a complete eye examination with conjunctival impression cytologic sampling. Clinical measurements of tear function (tear film break-up time [BUT], Schirmer I test) were completed along with analysis of conjunctival goblet cell number, conjunctival immunostaining, and reverse-transcriptase polymerase chain reaction for the mucins MUC1 and MUC5AC. Clinical, histologic, and biochemical data of patients with PCOS were compared statistically with that of patients with PCO and with eight age- and gender-matched healthy controls. Eight of the most severely affected patients received systemic antiandrogen therapy and underwent further ocular evaluation four months after systemic therapy.

RESULTS

Women with PCOS had greater conjunctival hyperemia (P < .001), dryness (P < .001), itching (P < .001), mucous discharge (P < .001), and contact lens intolerance (P < .001) than patients with PCO. Patients with PCOS had a significant reduction of the tear film BUT accompanied by a significant increase in goblet cell number and conjunctival MUC5AC messenger ribonucleic acid expression compared with both PCO patients and healthy subjects.

CONCLUSIONS

Evaluation of the ocular surface should be considered in patients with PCO or PCOS. Women with PCOS were more likely to have itchy-dry eyes, decreased tear film BUT, and increased goblet cell density.

Lipid Deposition on Hydrogel Contact Lenses: How History Can Help Us Today

The tear film is a complex fluid that is precisely maintained and which is essential to the health of the ocular surface. One of the major components of the tear film is lipid, which is produced by the meibomian glands and serves many important functions on the ocular surface. It is estimated that there are more than 45 individual lipids within the tear film, which vary greatly in their structure and properties. The composition of the lipid within the tear film has an enormous influence on the stability of the tear film, with a subsequent impact on the occurrence of dry eye and the ultimate success of contact lens wear. The purpose of this review article is to describe the composition of the tear film lipids and their interaction with contact lens materials, with a particular emphasis on how the chemistry of novel silicone hydrogel materials has resulted in clinicians needing to understand the deposition of lipids onto contact lenses and how they may best manage this complication.

Evidence of a possible impact of the menstrual cycle on the reproducibility of scotopic ERGs in women

The purpose of this study was to investigate the impact of gender and menstrual cycle on the electroretinogram (ERG). Photopic and scotopic ERGs were obtained in 14 females during the luteal and follicular phases of their menstrual cycle and compared to those obtained on two separate (7 days or 14 days apart) sessions from seven age-matched control male subjects. Our results confirm that the amplitude of the photopic ERGs of females is significantly (P < 0.05) larger than males, and this, irrespective of the cycle phase. In comparison, scotopic ERGs revealed significant male-female differences only during the follicular phase. While in males, no significant (P > 0.05) intersession (7 day or 14 day intervals) variability could be demonstrated, significant (P < 0.001) intersession (luteal-follicular) variability was observed in the scotopic ERGs of our female participants, with 8 of the 14 women, demonstrating a marked increase of 20.17 +/- 4.8% in the follicular ERG compared to the luteal. Our data suggests there should be separate normal ERG values for men and women and that the phase of the menstrual cycle should be taken into consideration when interpreting the ERG results from women.

Variations in Central Corneal Thickness During the Menstrual Cycle in Women

PURPOSE

We report changes in the central corneal thickness during various phases of the menstrual cycle.

METHODS

We recruited 16 healthy women of reproductive age and measured the central corneal thickness at 3 points in their menstrual cycle, beginning on days 1 to 3 and again at ovulation and at the end of the cycle (days 27-32). Ovulation was determined with a test that determines the peak of luteinizing hormone in the urine.

RESULTS

We found that the central cornea was thinnest at the beginning of the cycle (mean = 536 microm). Corneal thickness increased at ovulation (mean = 549 microm) and at the end of the cycle (mean = 559 microm). The difference in corneal thickness was statistically significant at ovulation (P = 0.003) and the end of cycle (P = 0.001) compared with values at the beginning of the cycle.

CONCLUSION

The central corneal thickness changes during the menstrual cycle; the cornea is thinnest at the beginning of the cycle and thickest at the end. These changes could be secondary to hormonal influences; estrogen receptors can be found in human corneas, suggesting that estrogen may have a role in corneal physiology.

Ontogenic expression of estrogen receptor-alpha in female rat corneas

PURPOSE

To investigate ontogenic expression of estrogen receptor (ER)-alpha in female rat corneas, as part of basic studies to elucidate the mechanism of estrogenic effects on the corneas.

METHODS

The expression and localization of ERalpha were determined using quantitative reverse transcribed-polymerase chain reaction methodology and immunohistochemistry in the corneas of female rats on day 14 of gestation and postnatal days (PNDs) 0, 21, and 60.

RESULTS

Quantitative analysis of ERalpha mRNA revealed that ERalpha gene expression increased approximately 4 times on PND 21 and about 10 times on PND 60, as compared with expression levels detected on PND 0. Immunohistochemical analysis revealed that expression of ERalpha protein was evident only in nuclei of the corneal epithelial cells from PND 21 onward.

CONCLUSION

Ontogenic expression of ERalpha occurred in female rat corneas.

Androgen Status of the Nonautoimmune Dry Eye Subtypes

PURPOSE

To evaluate androgen levels of patients diagnosed with nonautoimmune dry eye, either with meibomian gland dysfunction (MGD) or without MGD (non-MGD), and normal control subjects. This is a prospective, comparative, case-control study.

METHODS

Sixty-four (32 men and 32 women) subjects were enrolled for each of the three diagnostic groups. All dry eye patients were symptom positive. Nonfasting testosterone (T), sex hormone-binding globulin, serum albumin, dehydroepiandrosterone (DHEA), and DHEA sulphate levels of all study participants were determined using either automated immunoenzymatic assay, or standard radioimmunoassay. Analysis of variance was used to compare androgen levels among the three diagnostic groups in a gender-based design, followed by post-hoc multiple comparisons with the Tukey honestly significant difference test.

RESULTS

Mean T levels in men and women of the three diagnostic groups were not significantly different (p = 0.808, p = 0.156, respectively; ANOVA). Statistical analyses of the three diagnostic groups revealed a significant difference for men and women in bioavailable T levels (p = 0.002, p = 0.014, respectively; ANOVA), DHEA levels (p = 0.009, p = 0.004, respectively; ANOVA), and DHEA sulphate levels (p = 0.001, p = 0.001, respectively; ANOVA), whereas there was no statistically significant difference between non-MGD dry eye patients and controls for any of the measured androgen levels according to the post-hoc tests.

CONCLUSION

This study demonstrates that the androgen pool of nonautoimmune dry eye patients with MGD is significantly depleted compared with that of non-MGD and control cases.

The effects of different hormone replacement therapy regimens on tear function, intraocular pressure and lens opacity

OBJECTIVE

Estrogen may have adverse effects on the ocular surface, intraocular pressure (IOP), lens opacity and tear function. The aim of the present study was to elucidate the effects of different hormone replacement therapy (HRT) protocols on tear function, IOP and lens opacity.

DESIGN AND SETTING

This was a prospective, uncontrolled study carried out at the Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Faculty of Medicine, Uludağ University, Turkey.

PATIENTS AND INTERVENTIONS

Thirty postmenopausal patients who had spontaneous or surgical menopause for at least 1 year and were not taking any medications were assigned to one of three groups. Group 1 comprised 19 patients (n = 38 observations) given conjugated equine estrogen 0.625 mg plus medroxyprogesterone acetate 2.5 mg (Premelle 2.5) daily; Group 2 contained six patients (n = 12 observations) given tibolone 2.5 mg (Livial) daily; and Group 3 comprised five patients (n = 10 observations) treated with estradiol patch, 3.9 mg/12 cm2 (Climara). Tear function, evaluated with Schirmer's test, IOP and lens opacity were determined before treatment and at 6 and 12 months of treatment.

RESULTS

Mean Schirmer's test score in each group and all eyes (n = 60) did not change significantly after 6 months of treatment but decreased significantly at 12 months. The percentage decrease in tear function was greatest in the estrogen-only group (Group 3). Mean IOP did not change significantly in Groups 1 and 2; however, in Group 3, IOP showed a statistically significant decrease from 14.63 +/- 0.84 mmHg before treatment to 12.60 +/- 0.68 mmHg (mean +/- standard error) at the end of treatment. Lens opacity in women of all groups did not change during treatment.

CONCLUSIONS

HRT decreased tear production, the decrease being greater in the estrogen- only group. Woman who are taking or considering HRT should be informed of the potential increased risk of dry eye syndrome with this therapy. In addition, estrogen-only treatment decreased IOP while estrogen plus progesterone and tibolone had no effect. HRT did not affect lens opacity after 12 months of treatment.

Marked sexual dimorphism of lacrimal gland peroxidase in hamster: repression by androgens and estrogens

Peroxidase secreted in tears by the lacrimal glands is a marker of secretory activity of these glands and is believed to have an antimicrobial function. We report for the first time a marked sex difference in lacrimal gland (LG) peroxidase in hamsters ( approximately 3.4-fold higher activity in females), which is due to an unusual repression by physiological levels of androgens in males. LG peroxidase activity was markedly induced in a time-dependent manner after gonadectomy in males and also females ( approximately 8- and 2-fold, respectively) and was strongly repressed by androgen treatment in a dose- and time-dependent manner. Estrogen treatment of gonadectomized hamsters could also repress LG peroxidase but not below female levels. These repressions by androgens and estrogens were significantly prevented upon co-treatment with their respective receptor antagonists. Western blotting showed that differences in LG peroxidase specific activity, in different sex hormonal states and treatments were due to changes in the levels of peroxidase protein in LG. A tear peroxidase with a clear sex difference suggests that it might also have other novel function(s) in hamster tears.

Immunohistochemical analysis of secretoglobin SCGB 2A1 expression in human ocular glands and tissues

Human secretoglobin (SCGB) 2A1 (or lipophilin C, lacryglobin, mammaglobin B) is a small protein of unknown function that forms heterodimers with secretoglobin 1D1 (lipophilin A) in tears. SCGB 2A1 is homologous to mammaglobin (mammaglobin A) and the C3 component of prostatein, the major secretory protein of the rat ventral prostate. Androgen-dependent expression of SCGB 2A1 has been observed in the prostate. Besides identification of SCGB 2A1 in the tear proteome only its mRNA had been detected in the lacrimal gland. Here, we report expression of SCGB 2A1 in all ocular glands and in the keratinized stratified squamous epithelium of the eyelid as well as in the stratified epithelium of the conjunctiva and in the orbicularis oculi muscle. Almost all of these tissues are also known to express the androgen receptor. Therefore, we conclude that presence of the androgen signalling machinery could be the main general determinant of SCGB 2A1 expression. Implications of the presence in tear fluid of an androgen-regulated secretoglobin, which most likely binds hydrophobic ligands, for tear film lipid layer formation and function is discussed.

The color appearance of stimuli detected via short-wavelength-sensitive cones for breast cancer survivors using tamoxifen

This study compared color appearance data for two populations of middle-aged women: (1) women using the selective estrogen receptor modulator tamoxifen as adjuvant therapy following successful treatment for early-stage breast cancer, and (2) healthy amenorrheic (peri- or post-menopausal) control subjects not using any hormonally acting medications. A 3-alternative forced-response paradigm (with "blue", "lavender", or "white" as the allowable responses) was used for assessing the perceived color of 440-nm foveal test stimuli superimposed on a larger 3.6 log td 580-nm background. In contrast to the control subjects, the majority of tamoxifen users described the test stimuli as "white", whether at threshold or slightly suprathreshold. Threshold-sensitivity measurements themselves appeared less effective for distinguishing between subject groups. The results show that a simple color-naming procedure can reveal alterations of foveal short-wavelength-sensitive cone-mediated visual function that are common among tamoxifen users.

Sex hormone receptors in the human eye

Dissimilarities in ocular physiopathology exist between human males and females. These differences can be observed in the lacrimal and other eye-associated glands, the ocular surface, the crystalline lens, and the retinochoroid complexes. Literature on the subject revealed that because of sex steroid hormone (estrogen, progesterone, and androgen) actions, various physiological conditions, such as age, menstrual cycles, pregnancy, and menopause or andropause, where the hormone milieu changes, affect vision. Well-designed scientific studies are lacking on the subject, although such studies hold much potential value. This review analyzes the relatively new area of hormones and vision.

Does Postmenopausal Hormone Replacement Therapy Affect Intraocular Pressure?

PURPOSE

To assess the effects of postmenopausal hormone replacement therapy (HRT) on intraocular pressure (IOP).

PATIENTS AND METHODS

This was a cross-sectional controlled study, including 107 women aged 60 to 80 years receiving HRT and 107 controls who have never received HRT. All subjects underwent IOP assessment and funduscopic photography for cup-to-disc (C/D) ratios, and completed questionnaires regarding personal and family history of glaucoma, hormone replacement therapy, lifetime estrogen and progesterone exposure, and cardiovascular risk factors. Main Outcome Measures included IOP, prevalence of increased IOP, and C/D ratios.

RESULTS

The groups did not differ in mean IOP (15.3 versus 15.3 mm Hg), mean vertical (0.18 versus 0.21) and horizontal (0.17 versus 0.14) C/D ratios, and in prevalence of increased IOP (15% versus 14%), C/D ratio (7% versus 7%), or glaucoma (9% versus 11%). A personal history of ischemic heart disease was the only risk factor associated with increased IOP (O.R. = 4.63, P = 0.003). Lifetime estrogen and progesterone exposure, including pregnancies, deliveries, menstruation years, and the use of oral contraceptives did not significantly affect the risk for increased IOP.

CONCLUSION

Hormone replacement therapy and lifetime estrogen and progesterone exposure do not seem to affect IOP or the risk for increased IOP. A personal history of ischemic heart disease may be associated with a higher risk for this disorder.

Early impact of hormone replacement therapy on vascular hemodynamics detected via ocular colour Doppler analysis

OBJECTIVE

To determine the effects of hormone replacement therapy (HRT) on ocular blood flow.

STUDY DESIGN

In a prospective controlled study, 40 healthy women who presented to the menopause clinic between December 2000 and December 2001 were randomly assigned into the study. The HRT-receiving group was administered estradiol 17-valerate 2 mg the first 11 days, and estradiol 17-valerate 2 mg plus ciproterone acetate 1 mg the next 10 days of the monthly cycle for 6 months. The control group did not receive any HRT for 6 months. The ocular colour Doppler analysis were performed at baseline and after 3 and 6 months. The ocular Doppler analysis was performed in the first half of the cycle in the HRT-receiving group.

RESULTS

Central retinal artery and ophthalmic artery basal Doppler index (peak systolic velocity, end-diastolic velocity, resistive index and pulsatility index) values of the two groups at the beginning of the study did not show any statistically significant difference. Both the right and the left central retinal artery pulsatility index (PI) values of the study group, who received HRT at the end of the third and sixth months, showed a statistically significant decline (paired-samples test, P < 0.05), while the decrease in the resistive indexes was not significant.

CONCLUSION

These results suggest that 6 months of combined hormone replacement therapy with estradiol 17-valerate 2 mg plus ciproterone acetate 1 mg improves ocular vascular Doppler indices which may be a reflection of cerebral vascular status.

Visual sensitivity across the menstrual cycle

This study was designed to evaluate the hypothesis that hormonal change can affect lower level light-adaptation processes, which are likely to be retinally based. Foveal visual sensitivities were measured across several menstrual cycles of four women not using hormonally acting medication and across several menstrual cycles of three women using a triphasic oral contraceptive. One woman, diagnosed with premenstrual syndrome (PMS), was a subject for both groups. Sensitivities were measured for a series of test wavelengths for 580-nm backgrounds of 2.0 and 4.0 log td. Of the six individuals tested, one had clear evidence of visual-adaptation changes occurring in phase with the menstrual cycle. Prior to using the oral contraceptive, this individual (the PMS subject) experienced changes of short-wavelength-sensitive (SWS)-cone-mediated sensitivities of up to about 1.4 log unit on the 4.0 log td background. Her SWS-cone-mediated sensitivities tended to be highest near ovulation and lowest premenstrually. Threshold-versus-illuminance (TVI) curves confirmed that the rate of sensitivity decrease with increasing background illuminance (i.e. the TVI slope) was greater premenstrually. The degree of background-induced desensitization within her middle-wavelength-sensitive (MWS)/long-wavelength-sensitive (LWS) cone pathways also appeared to vary cyclically, but the magnitude of the variation was smaller and the time course appeared to be different. When this subject began oral contraceptive use, the patterns of sensitivity change were all altered. None of the other five subjects experienced changes of SWS-cone-mediated vision that were cyclic and significantly adaptation-state dependent. However, there was evidence for a limited degree of cyclic adaptation change within the MWS/LWS cone pathways of at least one additional subject. We conclude that hormonal change can--for some unknown proportion of women--be linked to alterations of retinal function. However, the alterations are not the same for all visual pathways, and there are pronounced individual differences. The data also demonstrate that individuals' visual adaptation capabilities can vary substantially over periods of weeks.

Molds in floor dust and building-related symptoms among adolescent school children: a problem for boys only?

In this stratified cross-sectional study in eight 'wet' and seven 'dry' schools, 1024 adolescent school children reported potentially building-related symptoms (BRS) in self-administrated questionnaires. From their classrooms dust samples were collected from floors, ventilation ducts, and air; settled dust was collected in cardboard boxes over a period of 5 months. Measurements of temperature, relative humidity and CO2 were performed. BRS were strongly associated with personal factors like recent airway infections, hay fever, asthma and psycho-social work load, but also to molds in floor dust and presence of mechanical ventilation. The association between molds in floor dust and BRS has in stratified analyses shown a strong association among adolescent school boys, and no association among adolescent school girls using multivariable analyses controlling for relevant confounders. In contrast to the menstruating school girls, the symptoms among the small group of not yet menstruating girls were associated with the levels of molds in floor dust. Their symptom prevalences were very similar to those of the boys. This finding makes us suggest a new hypothesis: The higher endogenous estrogen levels of sexually matured adolescent females seems to protect them from the effects of molds in dust, despite their overall higher symptom prevalence.

PRACTICAL IMPLICATIONS

In this cross-sectional epidemiological study of adolescent school children we found independent significant positive associations between building-related symptoms and viable molds in floor dust in boys and non-menstruating girls. In contrast, no such associations were seen among menstruating girls. The identification of these two susceptible groups adds further support the relevance of minimizing sources of dust and mold exposure.

Down regulation of interleukin-1beta-induced nitric oxide production in lacrimal gland acinar cells by sex steroids

PURPOSE

Because the ocular surface is constantly exposed to allergens and irritants, it was reasoned that one cause of dry eye might be damage from inflammatory responses normally regulated by sex steroids. To test this hypothesis, we determined if sex steroids could down regulate nitric oxide (NO) production induced by interleukin-1beta (IL-1beta) in cultured rabbit lacrimal gland acinar cells.

METHODS

Cultured rabbit lacrimal gland acinar cells were exposed to IL-1beta to stimulate NO production. Stimulated cells were treated with different sex steroids and expression of iNOS protein determined by Western blotting and NO production by a nitrate/nitrite colorimetric assay.

RESULTS

It was found that the androgens testosterone, dihydrotestosterone, dehydroepiandrosterone and dehydroepiandrosterone-sulfate and 17beta-estradiol were able to inhibit interleukin-1beta-induced NO production in rabbit lacrimal gland acinar cells at physiological concentrations, while progesterone was not able to inhibit NO production. Sex steroid inhibition of NO production was not due to down regulation of iNOS protein production nor was it due to down regulation of GTP cyclohydrolase I with consequent loss of tetrahydrobiopterin production.

CONCLUSIONS

The results reported here show that androgens and estrogens can down regulate cytokine-mediated responses in cells that are part of the ocular surface protection system and thereby may have an important role in regulating inflammatory responses in the eye. Deficiencies in these steroids, as occurs in postmenopausal women, may lead to damage of the cells responsible for producing the fluids that protect the ocular surface and subsequently to dry eye disease.

Detection of oestrogen receptors (ER) alpha and beta in conjunctiva, lacrimal gland, and tarsal plates

PURPOSE

Lack of Oestrogen and androgen may be of importance in the pathogenesis of keratoconjunctivitis sicca (KCS). The signal of Oestrogens is transmitted via specific Oestrogen receptors (ER). It was the purpose of this study to evaluate the expression of ER alpha and ER beta in tear-producing tissues.

METHODS

Reverse transcriptase-polymerase chain reaction (RT-PCR, ER alpha + beta) and immunohistochemical evaluation (ER alpha only) were performed for ER detection and localization in tissue samples of bulbar conjunctiva (20 samples of 20 patients undergoing cataract surgery), tarsal plates (14 samples of 12 patients undergoing eye lid surgery), and lacrimal glands (20 samples of 13 cornea donors).

RESULTS

Messenger RNA ER alpha was identified via RT-PCR in all tissue samples with variable expression, ER beta predominantly in lacrimal gland tissue. Immunohistochemical staining for ER alpha was negative in most cases, probably due to the thermolability of ERs and very small sample sizes.

CONCLUSIONS

The detection of ER alpha and ER beta mRNA expression supports the concept of a receptor-based effect of Oestrogen in these tissues contributing to KCS. This may encourage therapeutical efforts including topical Oestrogen administration.

Changes in the tear film and ocular surface from dry eye syndrome

Dry eye syndrome (DES) refers to a spectrum of ocular surface diseases with diverse and frequently multiple aetiologies. The common feature of the various manifestations of DES is an abnormal tear film. Tear film abnormalities associated with DES are tear deficiency, owing to insufficient supply or excessive loss, and anomalous tear composition. These categorizations are artificial, as in reality both often coexist. DES disrupts the homeostasis of the tear film with its adjacent structures, and adversely affects its ability to perform essential functions such as supporting the ocular surface epithelium and preventing microbial invasion. In addition, whatever the initial trigger, moderate and severe DES is characterized by ocular surface inflammation, which in turn becomes the cause and consequence of cell damage, creating a self-perpetuating cycle of deterioration. Progress has been made in our understanding of the aetiology and pathogenesis of DES, and these advances have encouraged a proliferation of therapeutic options. This article aims to amalgamate prevailing ideas of DES development, and to assist in that, relevant aspects of the structure, function, and production of the tear film are reviewed. Additionally, a synopsis of therapeutic strategies for DES is presented, detailing treatments currently available, and those in development.

Influence des hormones sur le film lacrymal

Tear film quality depends on fine regulatory mechanisms affected by neuronal and hormonal influences. Indeed, receptors for androgens, estrogens, progesterone and prolactin have been identified in several ocular tissues in the rat, rabbit and in humans. The eye is thus a target organ for sex hormones, particularly the androgens. These hormones regulate the immune system, the morphology and secretory functions of lacrimal glands and the functioning of Meibomian glands. The influence of hormone replacement therapy in menopausal women remains unclear, as some authors support the idea that they improve the quality and the volume of tear film, whereas others have shown that they increase the risk of dry eye. Finally, knowledge of the interactions between the hormones that influence the lacrimal glands is essential for the understanding of the regulation of lacrimal gland function. However, the data presently available strongly suggest that optimal bioavailable androgen levels are essential for normal lacrimal gland function and that prolactin and estrogens also play important roles in providing a hormonal milieu that contributes to normal lacrimal gland function.

Functional aspects of the tear film lipid layer

The lipid layer is an essential component of the tear film, providing a smooth optical surface for the cornea and retarding evaporation from the eye. The meibomian lipids which compose it are well adapted for this purpose. They form a thin, smooth film whose thickness, and probably composition, influences the rate of evaporation. Their melting range ensures sufficient fluidity for delivery to the tear film from the lid margin reservoirs, while the film itself may exhibit a higher viscosity at the cooler temperature of the ocular surface. The factors governing lipid film formation during the blink are not fully understood, but one view is that the polar lipids, interacting with the aqueous sub-phase of the tear film, spread in advance of the non-polar components, which form the bulk of the film. The meibomian lipids stabilise the tear film by lowering its free energy; they carry water into the film during its formation and interact with lipid-binding proteins in the aqueous phase, such as tear lipocalin. The lipocalins, complexed with other tear components, may also contribute to the high, non-Newtonian viscosity of the tear film and its low surface tension, features which are essential for tear film stability. Formation of the lipid film is a complex process. Lipid is delivered to the tear film in the up-phase of the blink, more from the lower than the upper reservoir. The lipid layer comes to a stop well after completion of the blink and remains relatively immobile until it is compressed in the down-phase of the blink that follows. Then, it either retains its structure in a series of subsequent blinks, or is completely re-constituted after mixing with the reservoir lipids. Delivery of meibomian lipid to the marginal reservoirs is mainly the result of continuous secretion, under neural and hormonal control, supplemented by lid action. The reservoirs provide a hydrophobic barrier to tear overspill and to contamination by skin lipids which might destabilise the tear film. They probably also provide the chief route for meibomian lipid excretion.

Uveitis and the menstrual cycle

PURPOSE

To establish whether there is a variation in the incidence of onset of acute anterior uveitis (AAU) in women during the phases of the menstrual cycle.

METHODS

Prospective open study in women attending the Acute Referral Centre with a first or recurrent attack of AAU.

RESULTS

There was a significant increase in the incidence of AAU during the late stages of the menstrual cycle.

CONCLUSIONS

The onset of AAU is partially dependent on the levels of either oestrogen or progesterone, or both. The withdrawal of the proven anti-inflammatory effects of these hormones may provoke the onset of uveitis.

[Dry eye disease as a complex dysregulation of the functional anatomy of the ocular surface. New concepts for understanding dry eye disease]

INTRODUCTION

Dry eye disease is a disorder of the tear film that results in epithelial damage and in a disruption of the normal homeostasis at the ocular surface. It is widespread and causes symptoms ranging from discomfort to blindness.

METHODS

A review of the existing literature was used to compare different past and recent concepts for the understanding of dry eye disease with a focus on aspects of the integrating functional anatomy of the ocular surface.

RESULTS

The understanding of the pathogenesis of dry eye disease has proceeded from the mere recognition of a lack of tears to a consideration of their quality and to the concept of wetting of the ocular surface. However, several other aspects as epithelial differentiation, innervation, hormonal status or immune protection contribute to the intact functional anatomy of the ocular surface. Recently it has been recognized that immunologically regulated mechanisms of inflammation represent a primary or secondary pathogenetic factor for dry eye disease. This is conceivably regulated by the cells of the physiological mucosal immune defence system, the eye-associated lymphoid tissue (EALT). Androgens represent an important trophic factor for the ocular surface and their deficiency predisposes to inflammation.

CONCLUSION

Dry eye disease represents a complex dysregulation of the functional anatomy of the ocular surface that can start from different alterations (e.g. insufficient secretion, defects in wetting or innervation). Immune-based inflammation is able to interconnect and negatively reinforce these different pathomechanisms, resulting in a vicious circle.

The lipid layer of tears: dependent on meibomian gland function

There is growing laboratory and clinical evidence implicating the meibomian glands of the eyelid as playing a critical role in the pathogenesis of various ocular surface disorders such as chronic blepharitis and dry eye. Meibomian glands produce a lipid material whose synthesis is dependent on factors such as stem cells, neurological stimulants and hormones. This lipid material is fluid, spreads easily, is a surfactant as well as an aqueous barrier, and must remain functional after a blink. Before delivery it can be modified by factors such as hormone abnormalities and even after delivery it may be modified by lipases produced by ocular bacteria.

Short wavelength automated perimetry and tamoxifen use

BACKGROUND/AIMS

Oestrogen receptors (ORs) have been reported to be present in the retina, and the selective oestrogen receptor modulator tamoxifen has been reported to affect colour vision. This study aimed, therefore, to determine whether standard doses of tamoxifen affect visual sensitivities mediated via short wavelength sensitive (SWS) cones.

METHODS

Two types of visual fields were measured for middle aged women who were being treated with 20 mg of tamoxifen daily as adjuvant therapy for early stage breast cancer. Visual fields were measured using short wavelength automated perimetry (SWAP) and frequency doubling perimetry (FDP). For SWAP, 24-2 visual fields were analysed. No subjects had tamoxifen retinopathy or other eye disease. For each type of visual field, mean deviations (MDs) were assessed as a function of the duration of tamoxifen use, using a cross sectional design. In addition, the difference between the two types of MDs was computed after standardisation of each type of MD separately, and this difference itself was evaluated as a function of the duration of tamoxifen use. Duration dependent changes for SWAP were further evaluated as a function of eccentricity within the visual field, and the visual field data were compared with foveal data obtained psychophysically.

RESULTS

SWAP sensitivities depended on the duration of tamoxifen use. Subjects who used tamoxifen for about 2 years or less were significantly more likely than subjects who had longer use to have high MDs. The difference between the standardised SWAP and FDP MDs likewise was significantly related to the duration of use, whereas duration of use effects for FDP itself were reduced or absent. Although the duration of use effect observed for SWAP was strongest in the peripheral portion of the visual field, there was evidence of changes in SWS cone mediated vision even at the fovea.

CONCLUSION

Standard dosages of tamoxifen can affect SWAP visual fields. The effects of tamoxifen are not equivalent for SWAP and FDP, indicating that tamoxifen affects some types of visual pathways preferentially or selectively. SWS cone pathways, in particular, are affected. SWAP appears able to reveal effects of tamoxifen occurring years before completion of the standard 5 year regimen of use.

The influence of sex hormones on ocular blood flow in women

PURPOSE

To investigate the influence of sex hormones on ocular haemodynamics, blood flow velocities in the ophthalmic and central retinal arteries and serum levels of sex hormones were measured in pre- and postmenopausal women.

METHODS

Colour Doppler imaging (CDI) was used to determine the flow velocities (peak systolic velocity [PSV] and end-diastolic velocity [EDV]) and the resistive index (RI) in the ophthalmic and central retinal arteries in 22 premenopausal and 32 postmenopausal women, who had never received hormone replacement therapy. Serum levels were measured for oestradiol, free testosterone and follicle-stimulating hormone. The CDI parameters were compared between the two groups and the influence of serum levels of oestradiol and testosterone on blood flow velocities and the resistive indices were analysed.

RESULTS

After correcting for age and mean arterial blood pressure, an analysis of covariance disclosed a significantly lower EDV (p=0.02) and a significantly higher RI (p=0.01) in the central retinal artery of postmenopausal women compared with premenopausal women. Partial correlation analysis, controlling for age, revealed significant correlations between the CDI parameters and serum levels of oestradiol and testosterone. For premenopausal women, PSV (r=0.58, p=0.04) and EDV (r=0.73, p=0.006) in the ophthalmic artery correlated positively with serum oestradiol levels. The RI in the central retinal artery decreased with increasing oestradiol levels in both groups (premenopausal r= -0.40, p=0.04; postmenopausal r= -0.32, p=0.05). Peak systolic velocity in the central retinal artery correlated negatively (r= -0.49, p=0.04), whereas the RI correlated positively (r=0.53, p=0.02) with testosterone levels in the premenopausal group. Postmenopausal women with higher testosterone levels had lower EDV (r= -0.53, p=0.007) in the central retinal artery and higher RI in both vessels (ophthalmic artery r=0.48, p=0.01; central retinal artery r=0.61, p=0.002).

CONCLUSION

Our data provide evidence of a relationship between serum sex hormone levels and blood flow velocities and resistive indices in retrobulbar arteries. Oestradiol appears to have beneficial effects on ocular haemodynamics, whereas testosterone may act as an antagonistic to the effects of oestrogen.

The effect of hormone therapy on the risk for age-related maculopathy in postmenopausal women

OBJECTIVE

To evaluate the effect of postmenopausal hormone therapy (HT) as well as the use of oral contraceptives and lifetime endogenous hormone exposure on the risk for age-related maculopathy (ARM) in postmenopausal women.

DESIGN

This was a cross-sectional, controlled study. A total of 102 women from 60 to 80 years of age who were receiving HT and 100 controls underwent a detailed clinical funduscopic evaluation and stereoscopic fundus photography for the presence and grading of ARM. All participants completed a standardized questionnaire regarding vascular risk factors, HT, and lifetime exogenous and endogenous estrogen and progesterone exposure. Statistical analysis was performed using Student's t test, chi2 test, and a multivariate logistic regression model.

RESULTS

The HT and the non-HT groups did not differ in terms of early (11% v 15%), late (6% v 6%), or wet (2% v 2%) ARM prevalence rates. Women with ARM were significantly older than controls (69 v 66 years; P = 0.001, 95% CI = 0.008 - 0.027) and were more likely to have ischemic heart disease (21% v 9%; OR = 2.86, P = 0.03, 95% CI = 0.020 - 0.360). Lifetime exogenous and endogenous hormone exposures and other cardiovascular risk factors were not significantly different among women with ARM as compared with controls.

CONCLUSION

Postmenopausal HT may not affect the risk for either early or late ARM in women aged 60 to 80 years. The risk for both entities is not necessarily affected by either exogenous or endogenous lifetime hormone exposure. A history of ischemic heart disease may be associated with an increased risk for ARM.

Influence of serum levels of sex hormones on intraocular pressure in menopausal women

PURPOSE

The purpose of this study was to assess the effect that changes in sex hormone levels have on intraocular pressure (IOP) in menopausal women.

SUBJECTS AND METHODS

Thirty menopausal women on hormone replacement therapy and 32 menopausal women who had never received hormone replacement therapy (HRT), matched for age and duration of amenorrhea, participated in this study. Intraocular pressures were measured with Goldmann applanation tonometer. Serum levels were measured for estradiol, free testosterone, and follicle stimulating hormone (FSH). The influence of serum hormone levels on IOP was assessed by correlation analysis.

RESULTS

The mean IOP of postmenopausal women receiving HRT (13.29 +/- 2.28 mm Hg) was not significantly different from that of menopausal women not receiving HRT (13.56 +/- 2.5 mm Hg, P = 0.24). Higher testosterone levels were associated with higher IOPs in women receiving HRT (r = 0.48, P = 0.02) and in those not receiving HRT (r =0.42, P = 0.003). No significant correlations were observed between IOP and serum levels of estradiol and FSH in either group.

CONCLUSION

Our data provide evidence for a relation between serum testosterone levels and IOP in menopause. Higher testosterone seems to have a tendency to increase IOP in menopausal women.

Interactions of testosterone and all-trans retinoic acid in regulation of androgen receptor expression in rat lacrimal gland

All-trans retinoic acid down-regulates androgen receptor (AR) expression in lacrimal gland acinar cells in culture. The goal of this study was to determine if retinoic acid inhibits androgen-stimulated up-regulation of AR protein and AR mRNA expression in lacrimal glands of orchiectomized rats in vivo. Delivery of androgens to orchiectomized rats was accomplished by subcutaneous implantation of a 25 or 50 mg 21-day slow-release testosterone pellet. Rats were treated with retinoic acid by gastric gavage at 20 mg kg(-1) day(-1). After 7 days of treatment lacrimal glands were removed, AR protein expression in frozen sections was determined by immunohistochemistry and total RNA was probed for AR mRNA expression. Serum testosterone was measured by ELISA and serum retinoic acid was detected by HPLC. Orchiectomy decreases serum testosterone to 17 +/- 8 ng dl(-1), compared to 143 +/- 27 ng dl(-1) in normal rats, and reduces the number of lacrimal acinar cell nuclei expressing ARs to less than 30% of normal. Implantation of testosterone pellets restored lacrimal AR expression, but increased serum testosterone to more than 10 times the normal levels. Retinoic acid failed to inhibit AR expression in rats with high serum testosterone. Therefore a dose-response study was conducted in which testosterone was delivered by injection of a single dose of Depotestosterone at 2.5-200 mg kg(-1). Treatment of orchiectomized rats with a dose of testosterone as low as 2.5 mg kg(-1) resulted in serum testosterone levels of 62 +/- 17 ng dl(-1) and significantly increased lacrimal gland AR expression. Delivery of retinoic acid at 20 or 50 mg kg(-1) day(-1) simultaneously with a 2.5 mg kg(-1) testosterone injection prevented restoration of lacrimal gland AR expression and significantly reduced AR mRNA expression. A pharmacologic dose of retinoic acid inhibits AR expression in lacrimal gland acinar cells in vivo, as well as in vitro. This indicates that effects of retinoic acid and testosterone are antagonistic and suggests that retinoic acid may modulate effects of testosterone on the lacrimal gland.

Neurosteroids in the Retina

Steroids may have a powerful role in neuronal degeneration. Recent research has revealed that steroids may influence the onset and progression of some retinal disorders as well as neurodegenerative diseases and, as in brain, they accumulate in the retina via a local synthesis (neurosteroids) and metabolism of blood-circulating steroid hormones. Their crucial role as neurodegenerative and neuroprotective agents has been also upheld in a retinal excitotoxic paradigm. These findings are reviewed especially from the emerging perspective that after an insult local changes in steroidogenic responses and consequent neurosteroid availability might turn out to be offensive or defensive cellular adaptations for the potentiation or prevention of neuronal death.

Expression of estrogen receptor α and 17β-hydroxysteroid dehydrogenase 4 in the ciliary body

PURPOSE

To investigate the expression and distribution of estrogen receptor alpha (ERalpha) and 17beta-hydroxysteroid dehydrogenase 4 (HSD4) in bovine and monkey ciliary body.

METHODS

Immunohistochemical study was employed to investigate the expression of ERalpha and 17beta-HSD4. To detect ERalpha and 17beta-HSD4 transcripts, reverse transcription-polymerase chain reaction (RT-PCR) was used.

RESULTS

In bovine and monkey ciliary body, the staining of the anti-ERalpha antibody was distributed in nonpigmented epithelium, and was not detectable in pigmented epithelium. Vessels in the stroma were also stained. The expression of 17beta-HSD4 was observed in nonpigmented and pigmented epithelium. RT-PCR revealed that the transcripts of ERalpha and 17beta-HSD4 were expressed in monkey ciliary body.

CONCLUSIONS

This study provides evidence for the presence of ERalpha and 17beta- HSD4 in the ciliary body. The presence of ERalpha and 17beta-HSD4 suggests that estrogen may have important functions in the ciliary body.

Sex steroid hormone metabolism takes place in human ocular cells

Steroids are potentially important mediators in the pathophysiology of ocular diseases. In this study, we report on the gene expression in the human eye of a group of enzymes, the 17beta-hydroxysteroid dehydrogenases (17HSDs), involved in the biosynthesis and inactivation of sex steroid hormones. In the eye, the ciliary epithelium, a neuroendocrine secretory epithelium, co-expresses the highest levels of 17HSD2 and 5 mRNAs, and in lesser level 17HSD7 mRNA. The regulation of gene expression of these enzymes was investigated in vitro in cell lines, ODM-C4 and chronic open glaucoma (GCE), used as cell models of the human ciliary epithelium. The estrogen, 17beta-estradiol (10(-7) M) and androgen agonist, R1881 (10(-8) M) elicited in ODM-C4 and GCE cells over a 24 h time course a robust up-regulation of 17HSD7 mRNA expression. 17HSD2 was up-regulated by estradiol in ODM-C4 cells, but not in GCE cells. Under steady-state conditions, ODM-C4 cells exhibited a predominant 17HSD2 oxidative enzymatic activity. In contrast, 17HSD2 activity was low or absent in GCE cells. Our collective data suggest that cultured human ciliary epithelial cells are able to metabolize estrogen, androgen and progesterone, and that 17HSD2 and 7 in these cells are sex steroid hormone-responsive genes and 17HSD7 is responsible to keep on intra/paracrine estrogenic milieu.

Is complete androgen insensitivity syndrome associated with alterations in the meibomian gland and ocular surface?

PURPOSE

This study's purpose was to determine whether complete androgen insensitivity syndrome (CAIS) is associated with alterations in the meibomian gland and ocular surface.

METHODS

Individuals with CAIS, as well as age-matched female and male controls, completed questionnaires which assessed dry eye symptoms and underwent slit lamp evaluations of the tear film, tear meniscus, lids and lid margins and conjunctiva. The quality of meibomian gland secretions was also analyzed.

RESULTS

Our results demonstrate that CAIS is associated with meibomian gland alterations and a significant increase in dry eye signs and symptoms. Clinical assessment revealed that CAIS women, as compared to controls, had a significant increase in telangiectasia, keratinization, lid erythema and orifice metaplasia of the meibomian glands, and a significant decrease in the tear meniscus and quality of meibomian gland secretions. Questionnaire results showed that dry eye symptoms were increased over twofold in CAIS individuals, as compared to controls, including a significant increase in the sensations of dryness, pain and light sensitivity.

CONCLUSION

Our results suggest that androgen insensitivity may promote meibomian gland dysfunction and an increase in the signs and symptoms of dry eye.

Effect of hormone replacement therapy on lacrimal fluid peroxidase activity in woman

OBJECTIVE

Lacrimal fluid peroxidase (POD) is an antioxidant and antimicrobial enzyme involved in the protection of the ocular surface. Our recent findings showed the existence of significant cyclic variations in POD activity that were positively correlated with those of 17beta-estradiol plasma levels throughout the menstrual cycle of fertile women. During the menopause, women lacrimal fluid POD activity significantly (P<0.05) decreased according to the natural oestrogen reduction. Since a possible influence of oestrogen on human POD activity was suggested, aim of the present investigation is to evaluate whether hormone replacement therapy (HRT) might influence this enzyme activity.

METHODS

Lacrimal fluid POD activities of 10 healthy postmenopausal women (mean age: 52.0) and eight healthy postmenopausal women (mean age: 53.0) treated by oral or transdermal routes containing oestrogen or oestrogen plus progestin were determined. Enzyme activity of each tear sample (5 microl) was spectrophotometrically determined by the 5,5'-dithiobis, 2-nitrobenzoic acid thiocyanate (NBS-SCN) assay; total protein content of tears was determined too. 17beta-Estradiol plasma levels were assayed by ELISA test.

RESULTS

HRT significantly (P<0.05) increased tear POD low postmenopausal levels. The significant (P<0.05) rise of 17beta-estradiol plasma levels of treated women was not strictly correlated to the enzyme activity increase in tears.

CONCLUSIONS

The suggested estrogen regulation of lacrimal fluid POD activity could be one possible cause for the female gender predilection in some ocular diseases. HRT is able to increase tear POD activity levels of postmenopausal women, probably contributing to the effective relieve of ocular surface complications occurring during menopause.