Jennifer L.Y. Yip

Ethnic differences in primary angle-closure glaucoma.

Purpose of review To summarize recent literature regarding medication adherence with a focus on the complexities inherent in glaucoma management. Recent findings Adherence to medications can be enhanced by undertaking the following strategies: enhanced patient education; improved dosing schedules; increased accessibility to healthcare (including longer hours, evening hours, and shorter wait times), and improved provider–patient relationships (e.g. increased trust). Patients may be less likely to forgo medication use due to cost pressures if the physician trust level is high. Recent studies suggest a role for baseline screening for adherence predictors and focused interventions in addressing modifiable risk factors for poor adherence (such as depression, stress, and lower education). Summary Many factors are associated with the lack of medication adherence in patients. The solution is likely to be multi-dimensional and employ combination strategy (must be individualized for the patient). Educational interventions involving patients, family members, or both can be effective in improving adherence.

Socioeconomic status, systolic blood pressure and intraocular pressure: the Tanjong Pagar Study

Background: Lower socioeconomic status (SES) is associated with higher morbidity and mortality in many countries. Present evidence suggests that glaucoma has similar risk factors to major chronic diseases such as cardiovascular disease. This study investigates the association between SES and intraocular pressure (IOP), an important risk factor for glaucoma. Methods: The Tanjong Pagar Study was a population-based cross-sectional survey of Chinese people aged 40–79 years, who were randomly selected from the Singapore electoral register. Of the 2000 people selected, 1717 were considered eligible and 1090 were examined in clinic and included in the present study. IOP was measured using applanation tonometry. SES was assessed using a standardised questionnaire; education and income were used as the main explanatory variables. The effect of systolic blood pressure (SBP) was also examined. Results: Participants with lower levels of education and income had higher mean IOP (both p<0.01). These associations remained after adjusting for age and central corneal thickness, a strong independent predictor. SBP was strongly associated with both SES and IOP (both p<0.01). Adjusting for SBP attenuated the association between SES and IOP. Conclusion: Participants with lower education and income have a higher mean IOP. This effect may be mediated, in part, by an association of education and income with SBP. This is the first study to suggest that there is a social gradient in the distribution of the only major modifiable risk factor for glaucoma. Increasing similarities exist between the causation models of chronic diseases and that of glaucoma.

Intraocular Pressure and Corneal Biomechanics in an Adult British Population: The EPIC-Norfolk Eye Study

PURPOSE To describe the distribution and determinants of intraocular pressure (IOP) and indices of corneal biomechanics in an adult British population. METHODS Goldmann-equivalent IOP (IOPg), corneal mechanical characteristics (corneal hysteresis, CH; corneal resistance factor, CRF), and IOP adjusted for corneal factors (IOPcc) were measured. Ocular biometric characteristics were also measured in 4184 consecutive individuals aged 48 to 91 years recruited from the European Prospective Investigation into Cancer (EPIC)-Norfolk cohort. Sociodemographic data were recorded with a standardized questionnaire. Blood pressure and anthropometric data were recorded by trained staff according to a standard protocol. RESULTS Mean IOP was similar to that reported in previous United Kingdom population studies (IOPg: 16.0 mm Hg, SD 3.68). These data confirmed systolic blood pressure as the major identifiable correlate of IOP. There was a significant positive association between IOP and axial length of the eye. The IOPg, but not IOPcc, was higher in the women than in the men. No difference in IOP between the different age groups was identified. CRF and CH varied with IOPg, age, sex, and axial length of the eye. CONCLUSIONS The study provided current population-based values for IOP and corneal biomechanical parameters. Mean IOP in this British population was very similar to levels previously reported over 40 years ago. There was no identifiable relationship between IOP and age within this cohort with an older age range, in contrast to previous studies. Systolic blood pressure was identified as the major correlate of IOP.

Systemic Medication and Intraocular Pressure in a British Population The EPIC-Norfolk Eye Study

Objective To determine the association between systemic medication use and intraocular pressure (IOP) in a population of older British men and women. Design Population-based, cross-sectional study. Participants We included 7093 participants from the European Prospective Investigation into Cancer–Norfolk Eye Study. Exclusion criteria were a history of glaucoma therapy (medical, laser, or surgical), IOP asymmetry between eyes of >5 mmHg, and missing data for any covariables. The mean age of participants was 68 years (range, 48–92) and 56% were women. Methods We measured IOP using the Ocular Response Analyzer. Three readings were taken per eye and the best signal value of the Goldmann-correlated IOP value considered. Participants were asked to bring all their medications and related documentation to the health examination, and these were recorded by the research nurse using an electronic case record form. The medication classes examined were angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, α-blockers, β-blockers, calcium channel blockers, diuretics, nitrates, statins, insulin, biguanides, sulfonylureas, aspirin, and other nonsteroidal anti-inflammatory drugs. We examined associations between medication use and IOP using multivariable linear regression models adjusted for age, sex, and body mass index. Models containing diabetic medication were further adjusted for glycosylated hemoglobin levels. Main Outcome Measures Mean IOP of the right and left eyes. Results Use of systemic β-blockers (−0.92 mmHg; 95% CI, −1.19, −0.65; P<0.001) and nitrates (−0.63 mmHg; 95% CI, −1.12, −0.14; P = 0.011) were independently associated with lower IOP. The observed associations between statin or aspirin use with IOP were no longer significant after adjustment for β-blocker use. Conclusions This is the first population-based study to demonstrate and quantify clinically significant differences in IOP among participants using systemic β-blockers or nitrates. Lower IOP observed in participants using statins or aspirin was explained by concurrent systemic β-blocker use. The study findings may have implications for the management of glaucoma patients with comorbidity, and may provide insight into the pathophysiologic processes underlying IOP.

Physical activity and ocular perfusion pressure: the EPIC-Norfolk eye study.

PURPOSE To examine the relationship between physical activity and ocular perfusion pressure (OPP), a consistent risk factor for glaucoma. METHODS The relationship between previous physical activity and current OPP in 5650 participants aged 48 to 90 who attended the first (1993-1997) and third (2006-2010) health check as part of the European Prospective Investigation into Cancer (EPIC)-Norfolk study was examined. Usual combined physical activity at work and leisure was assessed using a validated instrument. Individuals were categorized as inactive, moderately inactive, moderately active, or active. Three IOP measurements were obtained (Ocular Response Analyzer [ORA]; Reichert, Inc., Depew, NY). Mean Goldmann correlated IOP (IOPg) from one eye was used in the analysis. Systolic and diastolic blood pressure (BP) were recorded as the mean of two measurements taken with a sphygmomanometer. Associations between physical activity and low (≤40 mm Hg) mean OPP (2/3 mean arterial pressure - IOP) and low (≤50 mm Hg) diastolic OPP (diastolic BP - IOP) were tested using logistic regression, adjusting for age, sex, body mass index, social class, IOP, and BP. RESULTS Active people had a lower risk of mean OPP ≤ 40 mm Hg and diastolic OPP ≤ 50 mm Hg after adjusting for age, sex, social class, and body mass index (odds ratio, 0.75; 95% confidence interval [CI], 0.60-0.93; P < 0.01) and (odds ratio, 0.73, 95% CI, 0.58-0.93; P = 0.01), respectively. The association between physical activity and perfusion pressure was independent of IOP, but largely mediated through diastolic BP. CONCLUSIONS Lower levels of physical activity were associated with lower OPP. Further research is needed to investigate the potential benefit of increased physical activity as a safe and simple method of modifying glaucoma risk.

Randomised controlled trial of screening and prophylactic treatment to prevent primary angle closure glaucoma

Aims To determine if screening with an ultrasound A-scan and prophylactic treatment of primary angle closure (PAC) with laser peripheral iridotomy (LPI) can reduce the incidence of primary angle closure glaucoma (PACG) in Mongolia. Methods A single-masked randomised controlled trial was initiated in 1999. 4725 volunteer Mongolian participants ≥50 years old from the capital Ulaanbaatar or the rural province of Bayankhongor were recruited, of which 128 were excluded with glaucoma. 4597 were randomly allocated to the control, no-screening arm or screening with ultrasound central anterior chamber depth (cACD), with the cut-off set at <2.53 mm. 685 screen-positive participants were examined and angle closure was identified by gonioscopy in 160, of which 156 were treated with prophylactic LPI. Primary outcome of incident PACG was determined using both structural and functional evidence from objective grading of paired disc photographs from baseline and follow-up, objective grading of follow-up visual fields and clinical examination. Results Six years later, 801 (17.42%) participants were known to have died, and a further 2047 (53.92%) were traced and underwent full ophthalmic examination. In an intention to treat analysis using available data, PACG was diagnosed in 33 participants (1.61%, 95% CI 1.11% to 2.25%), of which 19 were in the screened group and 14 in the non-screened group (OR 1.29, 95% CI 0.65 to 2.60, p=0.47), indicating no difference between groups. Conclusions We were not able to identify a reduction in the 6 year incidence of PACG after screening with cACD <2.53 mm and prophylactic treatment of PAC.

The EPIC-Norfolk Eye Study: rationale, methods and a cross-sectional analysis of visual impairment in a population-based cohort

Objectives To summarise the methods of the European Prospective Investigation of Cancer (EPIC)-Norfolk Eye Study, and to present data on the prevalence of visual impairment and associations with visual impairment in the participants. Design A population-based cross-sectional study nested within an on-going prospective cohort study (EPIC). Setting East England population (the city of Norwich and its surrounding small towns and rural areas). Participants A total of 8623 participants aged 48–92 years attended the Eye Study and underwent assessment of visual acuity, autorefraction, biometry, tonometry, corneal biomechanical measures, scanning laser polarimetry, confocal scanning laser ophthalmoscopy, fundal photography and automated perimetry. Outcome measures Visual impairment was defined according to the WHO classification and the UK driving standard, and was based on presenting visual acuity. Summary measures of other ophthalmic measurements are also presented. Results The prevalence (95% CI) of WHO-defined moderate-to-severe visual impairment and blindness was 0.74% (0.55% to 0.92%). The prevalence (95% CI) of presenting visual acuity worse than the UK driving standard was 5.87% (5.38% to 6.37%). Older age was significantly associated with visual impairment or blindness (p<0.001). Presenting visual acuity worse than UK driving standard was associated with older age (p<0.001), female sex (p=0.005) and lower educational level (p=0.022). Conclusions The prevalence of blindness and visual impairment in this selected population was low. Visual impairment was more likely in older participants, women and those with a lower educational level.

Incidence of Occludable Angles in a High Risk Mongolian Population

Background: Primary angle closure glaucoma (PACG) accounts for nearly 50% of global glaucoma blindness. There are currently no public health strategies to deal with this problem. Screening and prophylactic treatment of primary angle closure suspects (PACS) with laser peripheral iridotomy (LPI) may form a feasible population-level intervention. However, more information about the natural history of PACS is required before such an approach could be considered. Methods: Six hundred and forty-four participants aged 50 years with a central anterior chamber depth (cACD) of <2.53 mm underwent a full slit-lamp examination in 1999. Of these, 160 participants diagnosed as having occludable angles by gonioscopy (ISGEO classification) were excluded from all further analysis, leaving 484 for follow-up. Six years later, 95/484 (19.6%) had died. A total of 201 of 389 participants traced (51.7%) were re-examined. The potential risk factors for the development of an occludable angle were assessed using the chi squared test, t test and the Wilcoxon rank sum test. Results: At follow-up, 41 participants (20.4%, 95% CI: 14.8 to 25.7) were diagnosed as having incident PACS. Narrower angles, identified by grading of limbal chamber depth and gonioscopy at baseline, were strongly associated with incident occludable angles (p = 0.01 and p<0.01, respectively). There was weak evidence of an association with change in cACD (p = 0.05), and no evidence of an association with age, gender, and baseline cACD for the development of occludable angles. Conclusions: Narrower angles as determined by limbal chamber depth grading and gonioscopy at baseline were the main risk factors identified for the development of occludable angles.

Visual acuity, self-reported vision and falls in the EPIC-Norfolk Eye study

Purpose To examine the relationship between visual acuity (VA) and self-reported vision (SRV) in relation to falls in 8317 participants of the European Prospective Investigation into Cancer-Norfolk Eye study. Methods All participants completed a health questionnaire that included a question regarding SRV and questions regarding the number of falls in the past year. Distance VA was measured using a logMAR chart for each eye. Poor SRV was defined as those reporting fair or poor distance vision. The relationship between VA and SRV and self-rated falls was analysed by logistic regression, adjusting for age, sex, physical activity, body mass index, chronic disease, medication use and grip strength. Results Of 8317 participants, 26.7% (95% CI 25.7% to 27.7%) had fallen in the past 12 months. Worse VA and poorer SRV were associated with one or more falls in multivariable analysis (OR for falls=1.31, 95% CI 1.04 to 1.66 and OR=1.32, 95% CI 1.09 to 1.61, respectively). Poorer SRV was significantly associated with falls even after adjusting for VA (OR=1.28, 95% CI 1.05 to 1.57). Conclusions SRV was associated with falls independently of VA and could be used as a simple proxy measure for other aspects of visual function to detect people requiring vision-related falls interventions.

Area deprivation, individual socioeconomic status and low vision in the EPIC-Norfolk Eye Study

Background Poor vision is associated with lower socioeconomic status, but less is known about its relationship to area deprivation. Methods The European Prospective Investigation into Cancer and Nutrition study Norfolk Eye Study was a cross-sectional study of 8563 participants with completed eye examinations. Logarithm of the minimum angle of resolution (logMAR) visual acuity (VA) was measured using standard protocols and low vision (LV) was defined as Snellen equivalent (VA) ≤6/12 in the better eye. Uncorrected refractive error (URE) was defined as improvement of VA by 2 logarithm of the minimum angle of resolution lines with pinhole. The lowest 5% of index of multiple deprivation rank was used to define the most deprived areas. The index of multiple deprivation is a composite measure using routine data from seven domains of deprivation to identify the most disadvantaged areas in England. Logistic regression was used to examine univariable and multivariable associations with LV. Results Ninety-six participants with missing data were excluded, leaving 8467 for analysis (98.9%). The mean age of the study group was 68.7 years (SD=8.1, range=48–92), with 55.1% women. LV was present in 263 participants (3.1%, 95% CI 2.7 to 3.5%). LV was associated with deprivation after adjusting for age, sex, education, social class and cataract surgery (OR=1.7, 95% CI 1.1 to 2.6, p=0.03), but this effect was mitigated by additionally adjusting for URE (OR=1.5, 95% CI 1.0 to 2.4, p=0.09). Conclusions People with LV are more likely to live in the most deprived areas; this association was independent of socioeconomic status and partly mediated by URE. Targeting URE in deprived areas may reduce health inequalities associated with LV.