Risk factors for early angle-closure disease in a Burmese population: the Meiktila Eye Study.

PURPOSE: To determine risk factors for early angle-closure disease (AD) in a Burmese population. METHODS: A cross-sectional, population-based survey of the inhabitants, 40 years of age and over, from villages in the Meiktila District was performed; 2481 eligible participants were identified, 2076 participated in the study, and 2050 could be categorized as having early AD (defined by the presence of so-called occludable angles (<90 degrees of posterior trabecular meshwork visible on gonioscopy), but without glaucomatous optic neuropathy). The ophthalmic examination included Snellen visual acuity, slit-lamp examination, tonometry, gonioscopy, biometry, and dilated stereoscopic fundus examination. RESULTS: The mean axial length (AL) and anterior chamber depth (ACD) in those with occludable angles were 21.9 and 2.60 mm, respectively; in those with non-occludable angles, the corresponding lengths were 22.74 and 2.84 mm, respectively (P<0.001 for both comparisons). In the univariate analyses, age, female gender, nuclear and cortical cataract, steeper corneal curvature, more anterior lens position, and myopia were also significantly associated with occludability. In the multivariate analysis, age, AL, ACD, and nuclear cataract were significantly associated with occludability. CONCLUSION: In this Burmese population, those with occludable angles had significantly shorter ALs, ACDs, and thicker lenses than those without occludable angles. In multivariate analysis, increasing age, decreasing AL, decreasing ACD, and nuclear cataract were significant predictors of early AD. The presence of nuclear cataract per se should raise clinical suspicion of the possibility of AD in this population.

Ocular biometry and determinants of refractive error in rural Myanmar: the Meiktila Eye Study.

OBJECTIVE: To describe the ocular biometry and determinants of refractive error in an adult population in Myanmar. METHODS: A cross-sectional, population-based survey of the inhabitants 40 years of age and over from villages in the Meiktila District was performed; 2481 eligible participants were identified, and 2076 participated in the study. Biometric components including axial length (AL), anterior chamber depth (ACD), vitreous chamber depth (VCD), lens thickness (LT) and corneal curvature (CC) were measured. Lens opalescence was measured using the Lens Opacity Grading System III. Non-cycloplegic refraction was measured with an autorefractor. RESULTS: Complete biometric, refractive and lenticular data were available on 1498 participants. Men had longer ALs, ACDs, VCDs and steeper CCs than women. There was an increase in LT, nuclear opalescence (NO) and myopic shift with increasing age, with no significant change in AL with age. In the 40-59 year age group, VCD was a significant predictor of refractive error, but LT (p<0.001) and NO (p<0.001) were stronger predictors. In the 60+ age group, NO (p<0.001) was also the dominant predictor of refractive error. CONCLUSION: This Burmese population, particularly women, has a relatively short AL and ACD. NO is the strongest predictor of refractive error across all age groups in this population.

Cataract in rural Myanmar: prevalence and risk factors from the Meiktila Eye Study.

AIMS: To determine the prevalence of and risk factors for cataracts in a rural region of central Myanmar. METHODS: A cross-sectional, population-based survey of inhabitants >or=40 years of age from villages of central Myanmar; 2076 participated, and 2044 (82.3%) had an examinable lens in at least one eye. Data recording included smoking history, occupation, education level, betel-nut chewing, height and weight, and dilated lens assessment using Lens Opacities Classification System III grading: nuclear (>or=4), cortical (>or=2) and posterior subcapsular (>or=2) cataracts. Aphakic and pseudophakic eyes were included as operated cataracts for statistical analysis. RESULTS: The prevalence of any cataract including operated eyes was 40.39% (95% CI 37.30 to 43.48%): 27.35% nuclear, 20.91% cortical and 11.34% posterior subcapsular cataracts. No significant association was found between cataract and betel-nut use, gender, smoking or outdoor occupation. The likelihood of all cataract types increased with age (multivariate analysis including operated eyes: OR 1.154, CI 1.13 to 1.18, p<0.001). Low level of education and low body mass index were associated with nuclear cataracts. Large village size was associated with increased risk for nuclear cataract (OR 3.23, CI 1.989 to 5.250, p<0.001) and decreased risk for cortical cataract (OR 0.20, CI 0.08 to 0.47, p<0.001). CONCLUSIONS: The prevalence of cataract in rural Myanmar is similar to that in other developing Asian regions. Cataracts are strongly associated with increasing age, and are more common in those with lower education and lower body mass index.

Pseudoexfoliation in a rural Burmese population: the Meiktila Eye Study.

AIMS: The aim of this study was to report on the prevalence and correlates of pseudoexfoliation syndrome (PXF) in a rural Burmese population. METHODS: The study was a cross-sectional, population-based survey of the inhabitants > or =40 years in the Meiktila District. Ophthalmic examination included Snellen visual acuity, slit lamp examination, tonometry, gonioscopy, dilated fundus examination and frequency doubling perimetry. RESULTS: In a population of 2076 subjects (4016 eyes) the prevalence of PXF was 3.4% (95% CI 2.14 to 4.67%; 78 eyes). Twelve eyes with PXF were blind. In the univariate analysis, PXF was associated with: increasing age, blindness (odds ratio (OR) 4, 95% CI 1.84 to 8.68; p<0.0004), increasing intraocular pressure (IOP) (OR 1.08, 95% CI 1.04 to 1.11; p<0.00001), nuclear cataract (OR 6.92, 95% CI 2.89 to 16.59; p<0.00001), cortical cataract (OR 4.78, 95% CI 2.37 to 9.65; p<0.00001) and the presence of an occludable angle (OR 3.05, 95% CI 1.52 to 6.13; p<0.002). In the multivariate analysis, only increasing age and IOP remained significantly associated with PXF. CONCLUSIONS: The prevalence of PXF in the Burmese population is greater than previously reported in other East Asian populations. Increasing age and IOP are the strongest predictors of PXF, and it is associated with cataract, occludable angles and blindness.

Anisometropia in an adult population in rural myanmar: the Meiktila Eye Study.

PURPOSE: To determine the prevalence and risk factors for anisometropia in a rural adult population in central Myanmar. METHODS: A population-based ophthalmic survey was conducted in rural villages in central Myanmar. Ansiometropia was assessed in subjects with phakic eyes. The severity of anisometropia was defined as the absolute difference of the spherical equivalent between the two eyes. RESULTS: Prevalence of anisometropia (> or =1.0 D) in all participants was 35.3% (95% CI 32.7-37.9%); severe anisometropia (> or =2.0 D) was present in 18.9 % (95% CI 16.8-21.0%). There was no significant gender difference in anisometropia prevalence or severity. Prevalence and severity of anisometropia were significantly associated with age. Multiple logistic regression analysis revealed that cataract, myopia, but not age, were associated with anisometropia. The between-eye differences in axial length (r = 0.15, p < 0.001) and corneal curvature (r = 0.19, p < 0.001) were significantly correlated with the severity of anisometropia. CONCLUSIONS: Prevalence of anisometropia is relatively high in this rural adult population in Myanmar. Myopia and cataract, but not increasing age, are the potential risk factors of anisometropia in this population.

Prevalence of refractive error in rural Myanmar: the Meiktila Eye Study.

OBJECTIVE: To determine the prevalence of refractive error and associated risk factors in the Meiktila District of central rural Myanmar. DESIGN: Population-based cross-sectional study. PARTICIPANTS: Randomized stratified cluster sampling of the inhabitants 40 years or older from villages in Meiktila was performed; 2481 eligible participants were identified, 2076 participated in the study, and adequate refractive data were obtained on 1863 individuals (75.1%). METHODS: Demographic data including age, gender, and education level were obtained from all participants. The ophthalmic examination included autorefraction, nuclear opalescence (NO) grading at the slit lamp, and applanation tonometry. MAIN OUTCOME MEASURES: Refractive errors were classified by type of ametropia and their prevalence was determined. Univariate and multivariate analyses were performed and odds ratios were calculated for the predictors of refractive error within the statistical models. RESULTS: Mean refractive error measured -1.3 diopters (D) (standard deviation [SD], 2.9) and mean cylindrical error measured 1.1 D (SD, 1.5). Myopia of >-1.0 and >-6.0 D occurred in 42.7% (95% confidence interval [CI], 40.4%-44.9%) and 6.5% (95% CI, 5.4%-7.6%) of subjects, respectively. Myopic refractive error was associated significantly with a higher degree of NO (P<0.001) and age. Hypermetropia of >+1.0 D occurred in 15% (95% CI, 5.4%-7.6%) of the population and was associated with higher education levels (P<0.001). Astigmatism worse than 1.0 D occurred in 30.6% (95% CI, 28.5%-32.7%) of the population and was associated with age (P<0.001) and NO (P<0.001). CONCLUSION: Myopia was more prevalent in older subjects and in those with increased NO. The prevalence rates of myopia in the > or =40 age group are higher than those found in other Asian regions and are likely to contribute to visual impairment.

The prevalence, severity and risk factors for pterygium in central Myanmar: the Meiktila Eye Study.

AIMS: To determine the prevalence, severity and risk factors associated with pterygium in adults in central Myanmar. METHODS: Population-based, cross-sectional survey of the people 40 years and over residing in rural Myanmar. Pterygium was graded for severity (T1 to T3) by visibility of episcleral vessels, and the apical extent was recorded. An autorefractor was used to measure refractive error. RESULTS: There were 2481 subjects identified, and 2076 (83.7%) participated. The prevalence of pterygium in either eye was 19.6% (95% confidence interval (CI) 16.9 to 22.2) and of bilateral pterygium 8.0% (95% CI 7.7 to 8.3). Outdoor occupation was an independent predictor of pterygium (p<0.01). The mean apical extent from the limbus was 2.2 mm (95% CI 2.05 to 2.35). Higher-grade pterygia did not have a significantly greater apical extent (p = 0.35). The presence of pterygium was associated with astigmatism, (p = 0.01), and the amount of astigmatism increased as both the severity (p<0.01) and apical extent increased (p<0.01). Two people of the 84 people blinded in both eyes were bilaterally blind from pterygium (1.7%; 95% CI 0.2 to 6.1), and pterygium accounted for 2.2% (95% CI 0.7 to 5.0) of blindness in at least one eye. No participant had low vision in both eyes due to pterygium, but pterygium led to 0.8% (95% CI 0.3 to 1.6) of low vision in at least one eye. Pterygium was therefore associated with 0.4% (95% CI 0.04 to 1.3) of binocular visual impairment and 1.0% (95% CI 0.6 to 1.8) of visual impairment in a least one eye. CONCLUSIONS: There is a high prevalence of pterygium in central Myanmar, and the risk of developing this condition increases with outdoor occupation. Pterygium in this population is associated with considerable visual morbidity, including blindness.

Gonioscopy findings and prevalence of occludable angles in a Burmese population: the Meiktila Eye Study.

AIM: To determine the prevalence of preglaucomatous angle-closure disease in central Myanmar. METHODS: A population-based survey of inhabitants >or=40 years in the Meiktila District was carried out; 2481 subjects were identified, 2076 participated and 2060 underwent gonioscopy of at least one eye. Eyes with angles traditionally described as "occludable" were recorded as primary angle-closure suspects (PACS); eyes with PACS and peripheral anterior synechiae (PAS), or an increased intraocular pressure but without primary angle-closure glaucoma, were recorded as primary angle closure (PAC). RESULTS: The prevalence of PACS in at least one eye was 5.7% (95% CI 4.72 to 6.62); prevalence increased with age and was more common in women (p<0.001). The prevalence of PAC in at least one eye was 1.50% (95% CI 1.47 to 1.53). All participants with PAS had at least 90 degrees of closure (range 90-360 degrees). CONCLUSION: The prevalence of preglaucomatous angle-closure disease (PACS and PAC) in this population was 5.7% and 1.5%, respectively. PACS was more common in women, and its prevalence increased with age.

Prevalence of glaucoma in rural Myanmar: the Meiktila Eye Study.

AIM: To determine the prevalence of glaucoma in the Meiktila district of central, rural Myanmar. METHODS: A cross-sectional, population-based survey of inhabitants > or =40 years of age from villages in Meiktila district, Myanmar, was performed; 2481 eligible participants were identified and 2076 participated in the study. The ophthalmic examination included Snellen visual acuity, slit-lamp examination, tonometry, gonioscopy, dilated stereoscopic fundus examination and full-threshold perimetry. Glaucoma was classified into clinical subtypes and categorised into three levels according to diagnostic evidence. RESULTS: Glaucoma was diagnosed in 1997 (80.5%) participants. The prevalence of glaucoma of any category in at least one eye was 4.9% (95% CI 4.1 to 5.7; n = 101). The overall prevalence of primary angle-closure glaucoma (PACG) was 2.5% (95% CI 1.5 to 3.5) and of primary open-angle glaucoma (POAG) was 2.0% (95% CI 0.9 to 3.1). PACG accounted for 84% of all blindness due to glaucoma, with the majority due to acute angle-closure glaucoma (AACG). CONCLUSION: The prevalence of glaucoma in the population aged > or =40 years in rural, central Myanmar was 4.9%. The ratio of PACG to POAG was approximately 1.25:1. PACG has a high visual morbidity and AACG is visually devastating in this community. Screening programmes should be directed at PACG, and further study of the underlying mechanisms of PACG is needed in this population.

Prevalence and causes of visual impairment in rural myanmar: the Meiktila Eye Study.

OBJECTIVE: To determine the prevalence and causes of visual impairment in the Meiktila district of central, rural Myanmar. DESIGN: Population-based cross-sectional study. PARTICIPANTS: Random, stratified, cluster sampling of the inhabitants 40 years of age and older from villages in the Meiktila district was performed; 2481 eligible participants were identified and 2076 participated in the study. METHODS: The ophthalmic examination included presenting and pinhole Snellen visual acuity with an illiterate E chart, slit-lamp examination of the anterior segment, and dilated stereoscopic fundus examination. The principal cause of visual impairment was recorded. MAIN OUTCOME MEASURES: Visual impairment and blindness were defined by both presenting and corrected visual acuity according to World Health Organization criteria: better eye < 6/18 and < 3/60, respectively. RESULTS: Comprehensive examinations, including Snellen visual acuity, were performed on 2073 participants (83.6%) The prevalence estimate of presenting visual impairment was 40.4% (95% confidence interval [CI], 36.1-44.7) and of presenting blindness was 8.1% (95% CI, 6.5-9.9). After pinhole correction, the corresponding prevalences were 26.8% (95% CI, 23.5-30.1) and 5.3% (95% CI, 4.0-6.6). Cataract, uncorrected refractive error, and glaucoma were the most common causes of visual impairment. CONCLUSIONS: Visual impairment and blindness remain major public health problems in rural Myanmar. Specific programs directed toward reducing the cataract burden need to be implemented.

Retinal detachment neuropathology and potential strategies for neuroprotection.

Understanding the neuropathology of retinal detachment from postmortem and animal models allows identification of cellular targets, receptors and mediators for pharmacological manipulation. In this review, concepts of retinal detachment and neuropathology are examined at cellular and structural anatomical levels using postmortem and animal model data. Possible neuroprotective strategies are reviewed in the setting of the new environment created by successful retinal reattachment surgery.

Sedation for vitreoretinal surgery: a comparison of anaesthetist-administered midazolam and patient-controlled sedation with propofol.

Local anaesthesia is increasingly being used for vitreoretinal surgery, but the optimal technique for sedation remains unclear. Anaesthetist-administered midazolam, which is often used, was compared in this study to patient-controlled sedation with propofol in 43 patients undergoing 50 vitreoretinal procedures. A variety of patient, anaesthetist and surgical endpoints were measured. There were no significant outcome differences between the two agents except that midazolam produced more amnesia for the local anaesthetic eye block. However, several outcomes and the observations in patients who experienced both agents showed a trend in favour of propofol for intraoperative sedation. We conclude that both approaches are safe and that patient-controlled sedation with propofol is at least as satisfactory as anaesthetist-administered midazolam.

Prevalence of blindness and visual impairment in an elderly urban population.

BACKGROUND: Accurate data on the prevalence of blindness in urban populations is not readily available. The Australian Longitudinal Study of Ageing is a prospective multidimensional study examining a broad range of age-related health issues, including visual function. METHODS: A population-based sample of 1466 persons, 70 years of age and over, from the Adelaide metropolitan area underwent visual acuity measurement. RESULTS: Approximately 1% were legally blind by Australian definitions. CONCLUSIONS: This percentage is low by world standards, however projections indicate that the absolute number of blind elderly people is rapidly increasing. Data such as this are crucial for the planning of adequate ophthalmic care.

Prevalence and causes of blindness in the South Australian population aged 50 and over.

PURPOSE: To conduct a population based study examining the prevalence and causes of blindness and visual impairment in the South Australian population aged 50 and over. METHODS: A random stratified cluster sample of 2115 persons was recruited from geographically exhaustive local government areas within South Australia. All participants underwent distance visual acuity measurements. In those participants with corrected visual acuity < 6/18 in the better eye a cause was determined. RESULTS: Cataract and macular degeneration were the most common causes of monocular and binocular blindness. The prevalence of monocular and binocular blindness in South Australia in the population aged 50 and over is calculated to be approximately 3.7% and 1.3%, respectively. These rates increase significantly in the elderly (70 years of age and over) subgroups. CONCLUSIONS: Degenerative conditions are the principal causes of visual impairment in South Australia. The number of visually impaired persons in South Australia is likely to increase over the coming decades. Accurate data are essential in order to optimise the use of limited resources.

Interrater agreement in oculo-kinetic perimetry--a screening test for glaucoma.

In a study at the Flinders Medical Centre, South Australia, 24 glaucomatous eyes with known field defects were tested by three examiners of different backgrounds using oculo-kinetic perimetry, a screening test for glaucoma. The interrater agreement was excellent; only in one case did results differ. Seventeen eyes had a defective result, but in six cases the test was normal. Both patients and untrained staff find this test easy to do, but the apparent high false-negative rate is cause for concern and needs further evaluation. Oculo-kinetic perimetry may well be better used as a complementary test by those opticians doing tonometry and by general practitioners who currently rarely screen for glaucoma.

Epidemiology of blindness and visual impairment in the kingdom of Tonga.

Data on the prevalence and causes of blindness and visual impairment in Polynesians are not readily available nor are they population based. This survey was designed to obtain an accurate estimate of blindness and its causes in Tonga. A sample of 4056 persons, aged 20 years and over, was selected by stratified cluster sampling. Participants received a screening, visual acuity examination, and, if visually impaired, were referred for detailed ophthalmic examination to determine the cause. The prevalence of bilateral blindness in the study population was 0.47% and all affected were aged over 50 years. It is estimated that the national prevalence of bilateral blindness, adjusted for the sample weight applied in the selection procedure, is 0.56% (95% confidence interval 0-1.13). Monocular blindness was three times more frequent. Cataract was responsible for 68.4% of bilateral and 30.3% of monocular blindness. Risk factors for life time experience of cataract included age and diabetes (self-reported). Neither smoking nor the presence of pterygium were independently associated with cataract. Increasing years of education were protective against cataract for women, but not men. Corneal opacity from infection or trauma, and diabetes were responsible for most of the remaining visual impairment. While these results do not represent a significant public health problem by world standards they do provide a basis for planning blindness prevention programmes in the region.

Technology assessment applied: a comparison of ophthalmic diagnostic techniques to detect diabetic retinopathy among Aboriginal people in central Australia.

Diabetes mellitus is one of the non-communicable diseases that has accompanied Aboriginal exposure to Western life style. The prevalence of diabetes mellitus is higher in the Aboriginal population than in non-Aboriginal Australians (Holding, 1985) and many Aboriginals who have diabetes mellitus develop diabetic retinopathy. Early detection facilitates treatment and prevention of blindness, a sequela of diabetic retinopathy. This paper describes the use of technology assessment as a framework for comparing two diagnostic technologies, fundal camera and ophthalmoscope, for use with Aboriginal people in central Australia.

The prevalence of trachoma in preschool and school children in Olimpia, Guaraci and Cajobi, Sao Paulo, Brazil.

A school-based prevalence survey of trachoma was conducted in three rural municipalities in the state of Sao Paulo, Brazil, in 1989. A total of 950 children aged 4-11 years were examined. The prevalence of inflammatory trachoma was found to be 6.3%, peaking at 24.1% in the 4 year-old age group. The prevalence of trachomatous scarring was 2.7% and was more prevalent in older children. Risk factors included household sleeping arrangements and nasal discharge.

PIP: In December 1989, researchers gathered data on 950 4-11 year old children attending preschool or primary schools in the rural municipalities of Olimpia, Guaraci, and Cajobi in northwestern Sao Paulo State, Brazil to measure prevalence of active trachoma and to identify its risk factors. Overall prevalence of trachoma was 8.6%. Physicians treated all trachoma cases with topical 1% tetracycline twice daily for 6 weeks and examined them later at a local health care center. Prevalence of inflammatory trachoma stood at 6.3%. This was similar to its prevalence in an Olimpia's neighboring town called Bebedouro. Prevalence of trachomatous scarring was 2.7%. Thus the northwestern part of Sao Paulo state was an important focus of endemic trachoma infection. Inflammatory trachoma was highest among the 4 year olds (24.1%) and fell to 0 by age 11. On the other hand, trachomatous scarring was relatively rare in 4-5 year olds then increased to 7% in 10-11 year old children. In fact, the mean age for inflammatory trachoma was 6.6 years and for trachomatous scarring 8.5 years. Perhaps the recently implemented trachoma control activities in Olimpia explained the lowest prevalence of inflammatory trachoma (5.4%). Guaraci experienced the highest prevalence rate (9.6%), but did not have any cases of trachomatous scarring. Children who slept with others were significantly more likely to have inflammatory trachoma than were those who slept alone (p.005). Sleeping pattern was the only personal hygiene variable significantly associated with inflammatory trachoma. Not even face washing was significantly associated with it. The only clinical symptom significantly associated with inflammatory trachoma was nasal discharge (p.001). A considerable community-based epidemiological survey would qualify these results.

Epidemiology of blindness and visual impairment in Vanuatu.

A population-based survey of blindness was conducted in Vanuatu. Data were gathered on a sample of 3520 of the approximately 150,000 inhabitants of Vanuatu aged at least 6 years, in order to estimate the prevalence and causes of blindness among the whole population. An overall prevalence of blindness of 4.0 per 1000 was found, 85% of which was due to cataract, an avoidable cause of this disability.