Does sex matter in glaucoma?

Retinal Ganglion Cells: Global Number, Density and Vulnerability to Glaucomatous Injury in Common Laboratory Mice

How many RBPMS⁺ retinal ganglion cells (RGCs) does a standard C57BL/6 laboratory mouse have on average and is this number substrain- or sex-dependent? Do RGCs of (European) C57BL/6J and -N mice show a different intrinsic vulnerability upon glaucomatous injury? Global RGC numbers and densities of common laboratory mice were previously determined via axon counts, retrograde tracing or BRN3A immunohistochemistry. Here, we report the global RGC number and density by exploiting the freely available tool RGCode to automatically count RGC numbers and densities on entire retinal wholemounts immunostained for the pan-RGC marker RBPMS. The intrinsic vulnerability of RGCs from different substrains to glaucomatous injury was evaluated upon introduction of the microbead occlusion model, followed by RBPMS counts, retrograde tracing and electroretinography five weeks post-injury. We demonstrate that the global RGC number and density varies between substrains, yet is not sex-dependent. C57BL/6J mice have on average 46K ± 2K RBPMS⁺ RGCs per retina, representing a global RGC density of 3268 ± 177 RGCs/mm². C57BL/6N mice, on the other hand, have on average less RBPMS⁺ RGCs (41K ± 3K RGCs) and a lower density (3018 ± 189 RGCs/mm²). The vulnerability of the RGC population of the two C57BL/6 substrains to glaucomatous injury did, however, not differ in any of the interrogated parameters.

Accuracy of perceived glaucoma risk by patients in a clinical setting

Objective

To determine whether patients attending the ophthalmology department underestimate their glaucoma risks.

Method

We conducted a cross-sectional survey with a final study population of 1203 individuals from two medical centers in Taiwan during January 1–June 30, 2019. The “High concern” group was defined as the set of patients who rated themselves as having low risk but who had been rated by physicians as having medium or high risk of developing glaucoma over the next year.

Results

Approximately 12% of the respondents belonged to the “High concern” group. For those with education at the college level or higher, the interaction term was estimated to be 0.294 (95% CI = 0.136–0.634). Marginal effect calculations revealed significant sex-based differences in the effect of knowledge at specific age intervals.

Conclusions

A considerable proportion of patients attending the ophthalmology department underestimate their glaucoma risks. Misjudgment of glaucoma risks can lead to delays in seeking of medical attention. Glaucoma education should be designed according to each patient’s education level and sex, as its effect is not consistent across different education and sex clusters.

Intraocular Pressure Following Prerandomization Glaucoma Medication Washout in the HORIZON and COMPASS Trials

PURPOSE

To assess the effectiveness of topical ocular hypotensive medications in patients with open-angle glaucoma and to identify factors associated with postwashout intraocular pressure (IOP) elevation.

DESIGN

Secondary analysis of prerandomization data from 2 prospective, multicenter, randomized clinical trials.

METHODS

Fourteen hundred subjects (1,400 eyes, 781 from the HORIZON study of the Hydrus micro-stent and 619 from the COMPASS study of the Cypass micro-stent) with primary open-angle glaucoma who were using 0-4 classes of topical IOP-lowering medication underwent Goldmann applanation tonometry before and after a protocol-defined washout period.

RESULTS

The mean (standard deviation) age was 70.7 (8.0) years and 55.6% were female. The change in IOP following washout for patients using 0 (n = 100), 1 (n = 705), 2 (n = 355), 3 (n = 214), or 4 (n = 26) medications was 0.2 (2.8), 5.7 (3.3), 6.9 (3.7), 8.8 (5.0), and 9.5 (4.1) mm Hg, respectively (P < .001, Kruskal-Wallis test). Postwashout IOP change was similar between the HORIZON and COMPASS cohorts. No difference in postwashout IOP change was detected among individual prostaglandin analogues in patients on monotherapy. A generalized linear model identified the following factors to be associated with greater IOP rise upon medication washout: greater number of glaucoma medications, higher unmedicated IOP, thinner central corneal thickness (CCT), lack of prior selective laser trabeculoplasty (SLT), and male sex.

CONCLUSIONS

Cessation of glaucoma medications results in a dose-dependent IOP increase in treated open-angle glaucoma patients. Two independent clinical trial cohorts exhibit similar levels of IOP elevation upon washout, using standardized methodology to estimate real-world medication effectiveness. Thicker CCT and history of SLT may predict reduced response to IOP lowering medications.

Effects of Sex Hormones on Ocular Blood Flow and Intraocular Pressure in Primary Open-angle Glaucoma: A Review

Primary open-angle glaucoma (POAG) is a multifactorial optic neuropathy characterized by progressive retinal ganglion cell death and visual field loss. Some speculate that sex plays a role in the risk of developing POAG and that the physiological differences between men and women may be attributed to the variable effects of sex hormones on intraocular pressure, ocular blood flow, and/or neuroprotection. Estrogen, in the form of premenopausal status, pregnancy, and postmenopausal hormone therapy is associated with an increase in ocular blood flow, decrease in intraocular pressure and neuroprotective properties. The vasodilation caused by estrogen and its effects on aqueous humor outflow may contribute. In contrast, although testosterone may have known effects in the cardiovascular and cerebrovascular systems, there is no consensus as to its effects in ocular health or POAG. With a better understanding of sex hormones in POAG, sex hormone-derived preventative and therapeutic considerations in disease management may provide for improved sex-specific patient care.

Comparison of Outcomes of Glaucoma Screening in Primary Care and Community Settings

Purpose: To compare outcomes of glaucoma screening in primary care and community settings, including the follow-up rates of subjects with positive screening results. Methods: This was a comparative, prospective, non-randomized study. Subjects were recruited by medical students in community-based and primary care settings and screened for glaucoma using the same screening strategy. Results: Two hundred and fifteen total patients were screened, 117 in community settings and 98 in primary care settings. Positive screenings were seen in 34% of patients in the community setting group (n = 40) and 40% of patients in the primary care setting group (n = 39). Of the patients who screened positive, 74% completed their initial follow-up appointment in the primary care setting group compared with 47.5% in the community-based setting group (p = .015). In the primary care setting, 18% were lost to follow up compared with 42.5% in the community-setting (P = .018). African-Americans were more likely to follow-up (P = .025) and less likely to be lost to follow-up (P = .033) in the primary care setting compared with the community-based setting. Conclusion: Patients with a positive glaucoma screening result in a primary care setting are more likely to follow up than those in a community-based setting.

Variation in the Three-Dimensional Histomorphometry of the Normal Human Optic Nerve Head With Age and Race: Lamina Cribrosa and Peripapillary Scleral Thickness and Position

Purpose

This study quantified the thickness and depth of the lamina cribrosa (LC) and peripapillary scleral thickness in high-resolution three-dimensional (3D) fluorescent reconstructions of the optic nerve head (ONH) in eyes from donors of African (AD) and European descent (ED).

Methods

A total of 64 eyes (45 ED, 19 AD) from 51 normal donors were obtained within 6 hours of death and fixed at 10 mm Hg of pressure. The optic nerve head was trephined from the globe and digitally reconstructed at 1.5 × 1.5 × 1.5 μm voxel resolution with an automated episcopic fluorescence technique. The load-bearing ONH connective tissue surfaces were manually delineated in 3D using custom software.

Results

The lamina cribrosa and peripapillary sclera were significantly thinner in AD eyes adjusting for age and sex (LC was 24 ± 11 μm thinner; P = 0.0350; scleral was 56 ± 22 μm thinner; P = 0.0097). The lamina cribrosa was significantly thinner in females (23 ± 11 μm thinner; P = 0.0425). Age was not significantly associated with any morphologic parameter in the ED group. However, increasing age was associated with an increase in scleral thickness (1.3 μm/year, P = 0.0499) and an increase in LC depth (2.3 μm/year, P = 0.0035) in the AD group. The sclera was thickest in the superior and temporal regions while the LC was thinnest superiorly.

Conclusions

Substantial sectorial and racial differences in LC and scleral morphology were observed, as well as increasing LC depth and scleral thickness with age in the AD group. Results suggest greater age-related remodeling of the load-bearing ONH connective tissues in eyes from AD individuals that could explain, in part, the greater predilection to glaucomatous injury seen in aged AD populations.

Gender specific issues in hereditary ocular disorders

This review is intended to summarize the current knowledge from basic science and clinical medical literature cited within PubMed that pertain to gender-related factors and affect those individuals with hereditary ocular disorders. We consider gender-related biological factors that (a) affect disease onset and progression, (b) gender differences for major X-linked ocular disorders, (c) gender-specific conditions, (d) medications that may influence genetic eye disorders, and finally, (e) gender-related issues that influence the management and quality of life of these patients. Several studies have demonstrated the manner in which sex-related hormones in animal models are capable of influencing cell pathway and survival that are likely to affect hereditary eye disorders. There are very few clinical studies that provide compelling evidence for gender differences in human ocular conditions, other than for a number of X-linked disorders. Disease expression for X-linked disorders may be impacted by genetic mechanisms such as lyonization or uniparental disomy. Clinical evidence regarding the impact of gender-related medical conditions and therapies on eye conditions is extremely limited and primarily based on anecdotal evidence. Gender-specific factors may play a major role in the underlying biological pathways that influence the onset, rate of progression, and clinical findings associated with ocular genetic conditions. Clinicians need to be aware of the variable phenotypes observed in female carriers of X-linked disorders of gender specific issues, many of which are inadequately addressed in the current literature. Clinicians need to be sensitive to gender differences in social, cultural, and religious systems and they should also be aware of how their own gender biases may influence how they counsel patients. Finally, it is clear that the lack of effective clinical studies in this area creates an opportunity for future research that will have real benefits for these patients.

Should Men and Women be Managed Differently in Glaucoma?

Introduction

To assess differences in associations of ocular perfusion pressure (OPP) as well as retinal and retrobulbar blood flow between men and women with primary open angle glaucoma (OAG).

Methods

A total of 116 patients with OAG (age 66.9 ± 10.9 years, 70 females) participating in the Indianapolis Glaucoma Progression Study were assessed for OPP, retinal microcirculation, and retrobulbar blood flow. Confocal scanning laser Doppler flowmetry measured peripapillary retinal capillary blood flow. Color Doppler imaging measured peak systolic (PSV) and diastolic blood flow velocities and vascular resistance in the ophthalmic (OA), central retinal (CRA), and nasal and temporal short posterior ciliary arteries (N/T PCA). Bivariate Spearman correlation and multivariate linear regression analyses were performed.

Results

In female patients with OAG, inferior retinal capillary flow was associated with OPP (r = 0.246, P = 0.044). In men, superior and inferior sector retinal blood flow was associated with OPP (r = −0.402, P = 0.006 and r = −0.357, P = 0.016, respectively). There was no statistically significant association between OPP and retrobulbar blood vessel flow velocities in male patients with OAG but there was an association between OA and TPCA PSV and OPP in female patients with OAG (r = 0.290, P = 0.015 and r = 0.357, P = 0.002, respectively). In female patients with OAG, multivariate regression showed no statistically significant effect of any variable on the superior retinal capillary blood flow, with CRA PSV as a sole predictor to the inferior retinal sector (partial rho = 0.302, P = 0.015) and in male patients with OAG, superior sector retinal capillary blood flow was independently associated with intraocular pressure (partial rho = −0.371, P = 0.016) and OPP (partial rho = −0.456, P = 0.002) with a trend of association with OPP in the inferior retina (partial rho = −0.301, P = 0.053).

Conclusions

There was a positive linear association between retinal microcirculation and OPP in females and a negative association in males. Male and female patients with OAG may differ in their vascular autoregulation in response to changes in OPP.

Gender and glaucoma: what we know and what we need to know

PURPOSE OF REVIEW

With growing aging populations and an increase in cases of glaucoma and glaucoma blindness worldwide, aging populations are particularly at higher risk of glaucoma and glaucoma blindness. Awareness of the gender differences might increase attention toward populations at risk.

RECENT FINDINGS

Women not only outlive men, but also outnumber men in glaucoma cases worldwide. Women are at higher risks for angle closure glaucoma, but there is no clear gender predilection for open angle glaucoma. Of interest, there is some evidence suggesting that female sex hormones might be protective of the optic nerve. In addition, it is hypothesized that decreased estrogen exposure is associated with increased risk for open angle glaucoma, yet population-based studies present inconsistent results. Presently, there is insufficient evidence to support hormonal replacement therapy use in glaucoma prevention. In addition, it appears that women carry a larger burden of glaucoma blindness due to longevity and disadvantages in socioeconomic/health beliefs.

SUMMARY

Current evidence suggests that older women are at risk for glaucoma and glaucoma blindness. Further interdisciplinary research involving investigators, specialized in glaucoma, women's health and health disparities, will lead to better understanding of gender health disparities in glaucoma and better targeting populations at risk.

Effect of statin drugs and aspirin on progression in open-angle glaucoma suspects using confocal scanning laser ophthalmoscopy

PURPOSE

To determine the effect of statins and aspirin on the rate of progression of optic nerve parameters in open-angle glaucoma (OAG) suspects, as defined by confocal scanning laser ophthalmoscopy (CSLO).

METHODS

Data of OAG suspects who had undergone at least two CSLO tests at the Beckman Vision Center at UCSF from January 2001 to June 2006 was collected. We conducted a retrospective chart review of 149 eyes from 76 patients considered suspect for glaucoma based on a cup-to-disc ratio >0.5, but with normal intraocular pressures (IOP) and visual fields. Subjects included glaucoma suspects who took statin drugs or aspirin for greater than 23 months. The control group consisted of suspects who never used statins or aspirin. The data were analysed using mixed effects regression.

RESULTS

When comparing controls with the statin group there were significant differences in the progression of multiple CSLO parameters per year, including rim volume (-13.7% controls, +26.7% statin only; P = 0.0156), retinal nerve fibre layer cross-sectional area (-12.2% controls, +24.3% statin only; P = 0.0051), and mean global retinal nerve fibre layer thickness (-10.3% controls, +26.6% statin only; P = 0.0114), with adjustment for age, gender, race, IOP, central corneal thickness, refractive error and multiple systemic comorbidities. No significant differences were found when comparing subjects taking a statin plus aspirin or aspirin alone with the controls.

CONCLUSIONS

Statin drugs may be associated with slowed progression of optic nerve parameters in glaucoma suspects as measured by CSLO.