A population-based estimate of cataract prevalence: the Melbourne Visual Impairment Project experience

Sex Hormones and Their Effects on Ocular Disorders and Pathophysiology: Current Aspects and Our Experience

Sex hormones are molecules produced by the gonads and to a small extent by the adrenal gland, which not only determine the primary and secondary sexual characteristics of an individual, differentiating man from woman, but also participate in the functioning of the various systems of the body. The evidence that many eye diseases differ in terms of prevalence between men and women has allowed us, in recent years, to carry out several studies that have investigated the association between sex hormones and the pathophysiology of eye tissues. Specific receptors for sex hormones have been found on the lacrimal and meibomian glands, conjunctiva, cornea, lens, retina, and choroid. This work summarizes the current knowledge on the role that sex hormones play in the pathogenesis of the most common ocular disorders and indicates our clinical experience in these situations. The aim is to stimulate an interdisciplinary approach between endocrinology, neurology, molecular biology, and ophthalmology to improve the management of these diseases and to lay the foundations for new therapeutic strategies.

The effect of hormone therapy on the ocular surface and intraocular pressure for postmenopausal women: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

The aim of the study was to investigate the impact of hormone therapy (HT) on the ocular surface and intraocular pressure in postmenopausal women.

METHODS

This systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses Statement. PubMed, EMBASE, Cochrane Library of Systematic Reviews, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, Chinese Biomedical Literature Database, and China National Knowledge Infrastructure were searched from inception to November 2019 without language restrictions. Only randomized controlled trials that evaluated the impact of HT on the ocular surface and intraocular pressure in postmenopausal women were eligible. The trials had to report at least one of the following outcomes: break-up time, Schirmer test, corneal staining, ocular surface symptom score, and intraocular pressure. Two investigators independently extracted the information, assessed the risk of bias, and evaluated the publication bias. All data were analyzed by Review Manager V.5.3. Sensitivity analysis and subgroup analysis were performed to find the source of heterogeneity and evaluate the different effects among subgroups.

RESULTS

Nine randomized controlled trials (N = 612) were included. The HT group showed significant improvements compared with the control group in break-up time (mean difference [MD] = 2.09, 95% confidence interval [CI] 1.00-3.19, P = 0.0002), Schirmer test without anesthesia (MD = 4.17, 95% CI 1.55-6.80, P = 0.002), Schirmer test with anesthesia (MD = 1.44, 95% CI 0.71-2.18, P = 0.0001), and corneal staining scores (standardized mean difference [SMD] = -0.85, 95% CI -1.39 to -0.30, P = 0.002). Moreover, significant beneficial effects were observed on all four symptoms, including dryness (SMD = -1.21, 95% CI -1.99 to -0.44, P = 0.002), foreign body sensation (SMD = -1.02, 95% CI -1.29 to -0.76, P < 0.00001), ocular fatigue (SMD = -1.74, 95% CI -2.12 to -1.36, P < 0.00001), and burning (SMD = -0.53, 95% CI -0.78 to -0.29, P < 0.0001) after HT. Subgroup analysis revealed that, in terms of break-up time, postmenopausal women younger than 55 years achieved more improvements (MD = 0.88, 95% CI 0.16-1.59, P = 0.02) than women older than 55 years old (MD = 2.60, 95% CI -1.34 to 6.55, P = 0.20), and the estrogen subgroup received more benefits (MD = 3.11, 95% CI 0.93-5.30, P = 0.005) than the estrogen plus progestogen subgroup (MD = 0.42, 95% CI -0.02 to 0.85, P = 0.06). Sensitivity analysis and subgroup analysis suggested that the heterogeneity might derive from the methodological quality, the age of participants, and the intervention of the control group. Intraocular pressure (MD = -1.54, 95% CI -3.39 to 0.32, P = 0.10) was not evidently decreased after HT. No more specific adverse events (relative risk  = 1.66, 95% CI 0.41-6.77, P = 0.48) were found in the HT group.

CONCLUSIONS

Our study revealed that HT could improve ocular surface function in postmenopausal women effectively and safely, especially for those who were younger than 55 years, and estrogen only showed more improvements than estrogen plus progestogen. The effectiveness of HT in treating dry eye in postmenopausal women is, however, still a controversial topic. In addition, we did not find HT led to a significant reduction of intraocular pressure.

Development of topical ophthalmic In Situ gel-forming estradiol delivery system intended for the prevention of age-related cataracts

The goal of this study was to develop and characterize an ion-activated in situ gel-forming estradiol (E2) solution eye drops intended for the prevention of age-related cataracts. Accordingly, in situ gelling eye drops were made using gellan gum as an ion-activated gel-forming polymer, polysorbate-80 as drug solubilizing agent, mannitol as tonicity agent, and combination of potassium sorbate and edetate disodium dihydrate (EDTA) as preservatives. The formulations were tested for the following characteristics: pH, clarity, osmolality, antimicrobial efficacy, rheological behavior, and in vitro drug release. Stability of the formulation was also monitored for 6 months at multiple storage conditions per ICH Q1A (R2) guidelines. The solution eye drops resulted in an in-situ phase change to gel-state when mixed with simulated tear fluid (STF). The gel structure formation was confirmed by viscoelastic measurements. Drug release from the gel followed non-fickian mechanism with 80% of drug released in 8 hr. The formulations were found to be clear, isotonic with suitable pH and viscoelastic behavior and stable at accelerated and long-term storage conditions for 6 months. In vitro results suggest that the developed formulation is suitable for further investigation in animal models to elucidate the ability of estrogen to prevent and delay cataracts.

Evaluation of a novel calpain inhibitor as a treatment for cataract

PURPOSE

The aim of this study is to evaluate the therapeutic potential of a newly synthesized calpain inhibitor, CAT0059, using a naturally occurring in vivo sheep cataract model.

METHODS

The selectivity of CAT0059 was investigated by an in vitro protease assay. The efficacy of CAT0059 in preventing proteolysis of lens cytoskeletal proteins by calpain 2 was investigated using a lens-based cell-free method. The cytotoxicity and stability of CAT0059 in physiological conditions were examined using cultured sheep lenses. Protein binding of CAT0059 by ocular proteins was assessed and quantified by a modified high-performance liquid chromatography assay. CAT0059 was formulated in an eye drop solution and as an eye ointment. These were applied in vivo daily to one eye of the cataract lambs, over a 67- and 97-day trial period, respectively. The progression of cataracts in the treated and untreated eyes was assessed by an independent veterinary ophthalmologist using a slit-lamp microscope.

RESULTS

In vitro assays revealed that CAT0059 was selective for cysteine proteases and also protected lens cytoskeletal proteins from degradation. CAT0059 was stable in physiological conditions and non-toxic to the lens. Only 15% of CAT0059 is bound to proteins in the aqueous humour but >90% bound to lens homogenate. The 67-day CAT0059 eye drop treatment was not effective in slowing the rate of cataract development. However, application of CAT0059 in an eye ointment initially slowed cataract development compared with the untreated eye. This effect was temporary.

CONCLUSIONS

In vitro assays confirmed CAT0059 to be a potent calpain inhibitor. The two in vivo trials addressed the ability of CAT0059 to reach the lens and established its limitations as a therapeutic molecule for cataract treatment.

Diffusion of nanoparticles into the capsule and cortex of a crystalline lens

The purpose of this study is to determine the ability of fluorescent nanoparticles to diffuse into a crystalline lens. Intact porcine lenses from five-month-old pigs, intact human lenses obtained from three donors aged 41, 42 and 45 years, and sections of human lens cortex obtained from four donors aged 11, 19, 32, and 34 years were incubated for 72 h at 7 °C in aqueous solutions of green (566 nm) and red (652 nm) fluorescent water soluble cadmium tellurium (CdTe) nanoparticles. As demonstrated by fluorescent and confocal microscopy, the CdTe nanoparticles diffused into the porcine and human lens capsule and into human cortical lens fibres; however, the nanoparticles did not pass through the intact lens capsule. Nanoparticles can be used as a method for studying intracellular structure and biochemical pathways within the lens capsule and cortical lens fibres to further understand cataractogenesis and may serve as a carrier for chemotherapeutic agents for the potential treatment of primary and secondary cataracts.

Prevalence and risk factors of lens opacities in the elderly in Cuenca, Spain

PURPOSE

To estimate the prevalence of lens opacities in a group of elderly people and evaluate their relation with diverse risk factors.

METHODS

Cross-sectional observational study of the cohort of all persons over the age of 64 years from an urban area and a rural nucleus of the province of Cuenca, Spain. Information on sociodemographic parameters and smoking was compiled using a structured questionnaire. A physical examination was made in which weight, height, and waist circumference were measured, and an ophthalmologic examination was made of visual acuity and lens opacities. Cataracts were classified using the method of the WHO cataract group.

RESULTS

The study included 1155 subjects out of 1435 elderly persons who were invited to participate (response rate 80.5%). The prevalence of cataract in men was 69.2% and in women, 65.5% (p>0.05). The percentage of persons with aphakia/pseudophakia was 17.8% in men and 17.5% in women (p>0.05). In a logistic regression model, age, obesity of more than 35 kg/m2, and low educational level were associated with the presence of cataract or aphakia/pseudophakia.

CONCLUSIONS

The prevalence of cataract in people over 64 years is similar to that of other countries, but the prevalence of subjects with previous surgery for cataracts is the highest reported in the literature. Age, body mass index of more than 35 kg/m2, and low educational level were associated with the probability of having cataracts or undergoing surgery for cataracts.

Comparison of age-specific cataract prevalence in two population-based surveys 6 years apart

Background

In this study, we aimed to compare age-specific cortical, nuclear and posterior subcapsular (PSC) cataract prevalence in two surveys 6 years apart.

Methods

The Blue Mountains Eye Study examined 3654 participants (82.4% of those eligible) in cross-section I (1992–4) and 3509 participants (75.1% of survivors and 85.2% of newly eligible) in cross-section II (1997–2000, 66.5% overlap with cross-section I). Cataract was assessed from lens photographs following the Wisconsin Cataract Grading System. Cortical cataract was defined if cortical opacity comprised ≥ 5% of lens area. Nuclear cataract was defined if nuclear opacity ≥ Wisconsin standard 4. PSC was defined if any present. Any cataract was defined to include persons who had previous cataract surgery. Weighted kappa for inter-grader reliability was 0.82, 0.55 and 0.82 for cortical, nuclear and PSC cataract, respectively. We assessed age-specific prevalence using an interval of 5 years, so that participants within each age group were independent between the two surveys.

Results

Age and gender distributions were similar between the two populations. The age-specific prevalence of cortical (23.8% in 1^st, 23.7% in 2^nd) and PSC cataract (6.3%, 6.0%) was similar. The prevalence of nuclear cataract increased slightly from 18.7% to 23.9%. After age standardization, the similar prevalence of cortical (23.8%, 23.5%) and PSC cataract (6.3%, 5.9%), and the increased prevalence of nuclear cataract (18.7%, 24.2%) remained.

Conclusion

In two surveys of two population-based samples with similar age and gender distributions, we found a relatively stable cortical and PSC cataract prevalence over a 6-year period. The increased prevalence of nuclear cataract deserves further study.

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.

Gender and referral to cataract surgery in Sweden

PURPOSE

To investigate how cataract surgery was initiated and analyse possible gender difference in referral to surgery.

METHODS

Consecutive patients scheduled for first eye cataract surgery at three Swedish community-run eye departments were interviewed concerning how surgery was initiated.

RESULTS

649 patients were interviewed and 63.2% were female. The number of patients referred to surgery by an earlier contact with a health care provider was 271 (41.8%) and the remaining 378 (58.2%) patients had actively requested advice or help because of visual problems caused by cataract and without a prior regular contact. 44.7% of female patients were referred through a health care provider they visited for reasons other than cataract and the corresponding number for male patients was 36.8%. This gender difference is statistically significant at the 5% level.

CONCLUSION

A health care provider that patients visited for other problems than cataract referred female patients to cataract surgery to a significantly higher degree than male patients.

Methodology of the VECAT study: vitamin E intervention in cataract and age-related maculopathy

Cataract is the leading cause of blindness in the world today, while age-related macular degeneration is responsible for the majority of new cases of visual impairment in the Western world. There is a growing body of evidence suggesting a role for antioxidant therapy to prevent the progression of these conditions. A 4-year prospective, randomised, controlled trial of an antioxidant versus placebo in a population of healthy volunteers aged 55-80 years at enrolment is described. This paper outlines the primary aims of the Vitamin E, Cataract and Age-related Macular Degeneration (VECAT) Study, the methodology, and the recruitment rates. Additional data on the toxicity and non-ocular effects of vitamin E will also be collected. Standardised clinical grading of macular and lens features, and comparison of serial macular photographs and digital lens photographs will form the basis for assessment of primary study outcomes. Information collected in this study will assist in the assessment of the potential value of antioxidants in preventing the enormous burden imposed on developed communities by age-related eye disease. In addition, important data on prevalence and progression rates of cataract and macular degeneration will be collected.

Protective effects of estrogen in a rat model of age-related cataracts

Women have a higher incidence of cataracts, and epidemiologic data suggest that the increased risk may be caused by a lack of estrogen in postmenopausal years. We have examined the effects of estrogen on methylnitrosourea (MNU)-induced cataractogenesis in Sprague-Dawley rats. Animals were ovariectomized, injected with MNU, and treated with estradiol or estrone by a continuous-release, subcutaneous Silastic implant, or they received an empty Silastic implant (no hormone). In the no-hormone group, rats developed opaque lenses approximately 6 months after MNU treatment. By 8 months, 74% (14/19) of the no-hormone rats had evident opacity in one or both eyes by simple gross inspection; 58% (22/38) of the eyes in this group were opaque. Estradiol or estrone treatment reduced the incidence of cataractous eyes to 12% or 25%, respectively. Lenses were examined under a dissecting microscope for light transmission. The lenses of the group treated with no hormone had light transmission of 26% +/- 9.2%, whereas lenses from the estradiol-treated animals had light transmission of 72% +/- 5.8%. Histological examination revealed that the anterior cortices of the opaque lenses were disrupted and showed the hallmark signs of age-related cataracts; in addition, some eyes that appeared clear by macroscopic examination showed the early histologic signs of cataractogenesis. It was demonstrated with reverse transcription-PCR that lens cells express both alpha and beta types of estrogen receptor, suggesting that the protective effects of the hormones may be a direct, receptor-mediated phenomenon. Thus, the MNU-treated, ovariectomized rat serves as a model for age-related cataractogenesis, and observation of a clear protective effect of estrogens in this system supports the implications of epidemiologic data.

Prevalence and incidence of age-related cataract in a population sample from Priverno, Italy

PURPOSE

To study the prevalence and incidence of age-related cataract in a random population sample from the town of Priverno in the Lazio Region, Italy.

METHODS

In 1987, 860 people between the ages of 45 and 69 years, already participating in a study on cardiovascular risk factors, underwent an ophthalmological examination. Patients with lens opacities, assessed by a clinical biomicroscopy and a best-corrected VA equal to or worse than 0.2 LogMar (20/30), were defined as age-related cataract cases. Of the 828 patients without age-related cataract at the baseline, 602 were re-examined in 1994. The 7-year Cumulative Incidence was calculated in three ways, as follows: - referring to the baseline sample without age-related cataract; - referring to the follow-up sample without age-related cataract at baseline; and - adjusted for non-response to the follow-up.

RESULTS

In the baseline sample, the prevalence of age-related cataract was 3.7% (2.7%-5.2%, 95% C.I.). Cumulative Incidence referring to the baseline sample was 6.5% (4. 8%-8.2%, 95% C.I.); Cumulative Incidence referring to the follow-up sample was 9.0% (6.7%-11.3%, 95% C.I.). Adjusted Cumulative Incidence of age-related cataract was 7.6% (5.6%-9.5%, 95% C.I.).

CONCLUSIONS

The study suggests that, in the Priverno sample, aging, but not gender, is a very important risk factor for cataract. The authors conclude that more information is needed on incidence of age-related cataract needing surgical rehabilitation and on risk factors causing both progression of lens opacities and visual loss.

Prevalence of cataract in Australia: the Blue Mountains eye study

PURPOSE

The authors determined the age and gender-specific prevalence of nuclear, cortical, and posterior subcapsular cataract (PSC) in a representative sample of older Australians.

METHODS

As part of a population-based study of eye disease in the Blue Mountains, west of Sydney, 3654 people aged 49 to 96 years underwent a detailed eye examination, including lens photography (slit-lamp and retroillumination). The photographs were assessed by masked graders using the Wisconsin Cataract Grading System, with acceptable reproducibility.

RESULTS

Past cataract surgery had been performed in either eye of 6.0% and in both eyes of 2.9% of participants in this study, equally in men and women. Moderate or advanced nuclear opacities were present in 53.3% of women and 49.7% of men. Moderate cortical cataract was present in 25.9% of women and 21.1% of men. Posterior subcapsular cataract was less frequent, found in 6.2% of women and 6.5% of men. After adjusting for age, these gender differences were statistically significant only for cortical cataract. The age-specific prevalence rates found for early and late cataract or for past cataract surgery are very similar to rates reported in the Beaver Dam Eye Study (BDES), Wisconsin, using the same definitions. Comparison of age-specific rates for each cataract type indicated lower rates for nuclear cataract, slightly lower rates for PSC and slightly higher rates for cortical cataract compared with the BDES. However, the rates for nuclear cataract were the only statistically significant differences between the two studies. Previously described susceptibility of the lower nasal lens to cortical cataract was confirmed, supporting a potential role of sunlight exposure in its development.

CONCLUSIONS

The Wisconsin cataract grading system was used in an older Australian population with acceptable reproducibility. The Blue Mountains Eye Study found similar age-specific prevalence rates for most of the types and stages of cataract compared with the BDES.

Estrogen protects lenses against cataract induced by transforming growth factor-beta (TGFbeta)

Cataract, already a major cause of visual impairment and blindness, is likely to become an increasing problem as the world population ages. In a previous study, we showed that transforming growth factor-beta (TGFP) induces rat lenses in culture to develop opacities and other changes that have many features of human subcapsular cataracts. Here we show that estrogen protects against cataract. Lenses from female rats are more resistant to TGFbeta-induced cataract than those from males. Furthermore, lenses from ovariectomized females show increased sensitivity to the damaging effects of TGFbeta and estrogen replacement in vivo, or exposure to estrogen in vitro, restores resistance. Sex-dependent and estrogen-related differences in susceptibility to cataract formation, consistent with a protective role for estrogen, have been noted in some epidemiological studies. The present study in the rat indicates that estrogen provides protection against cataract by countering the damaging effects of TGFbeP. It also adds to an increasing body of evidence that hormone replacement therapy protects postmenopausal women against various diseases.

Contributions to senescence: non-enzymatic glycosylation of proteins

Non-enzymatic glycosylation (NEG) of in vivo proteins is believed to play an important role in the process of senescence. Diabetes mellitus also provides a convenient model to study senescence, as many of its sequalae, e.g. neuropathy, retinopathy, may be found in the post seventy year old normoglycaemic population. Discoveries of the mechanisms by which proteins become irreversibly modified by chronic high levels of glucose and other reducing sugars, has led to an increased understanding of the pathophysiological consequences of senescence. This may eventually enable the development of suitable therapies to improve age-related morbidity.