Biomedical subjects

G J Johnson

Publications and source records attributed to G J Johnson.

At least 19 recordsLinked to original sources

PubMed2006

Angle-closure glaucoma in East Asian and European people. Different diseases?

In contrast to the pattern of disease in Europeans, primary angle closure has a higher prevalence and tends to be asymptomatic in East Asians. The higher prevalence is attributed to differences in anterior chamber and angle anatomy. Several studies suggest that central anterior chamber depth is shallower in East Asians than in Europeans, although this is not universally accepted. It is debated whether pupil block is the predominant mechanism of angle closure in Asian people. Meaningful comparison between studies is currently hindered by differences in patient selection, examination technique, and case definition; however, the major scientific deficiency is the paucity of prospective followup data to give an insight into natural history of the disease. This review examines the data on prevalence, risk factors, and mechanism of angle closure. Special consideration is given to limitations of methodology in research to date, with the intention of developing more robust data in future studies.

Anterior Chamber↗

PubMed2005

Routine monitoring of visual outcome of cataract surgery. Part 1: Development of an instrument.

AIM: To develop a system for routine monitoring of visual outcome after cataract surgery. METHODS: Staff from eight eye centres in Asia and Africa defined the data collection form and report formats to be used for monitoring visual outcome after cataract surgery. Several operational research questions were raised and methods developed to address them. The system was field tested for 6 months and the operational studies undertaken. The system was finalised based upon the experience gained. FINDINGS: Two different systems for data collection were developed: a manual paper tally system and a computer system (cataract surgery record forms (CSRF)). Both systems report on operative complications; the proportion with good outcome (can see 6/18) and poor outcome (cannot see 6/60); and causes of poor outcome. Data are collected at discharge and at specified time intervals at follow up. Both systems were well accepted. CONCLUSION: The major problem in field testing was data entry errors in centres using the computerised system. Routine monitoring of cataract outcome should be used by individual surgeons or centres to follow trends in their own results over time, and not to compare surgeons, in an atmosphere of trust and support. Visual acuity at discharge, which can readily be collected on all patients, can be used providing it is appreciated that the final results will be much better. Rapid feedback of results can enhance the consciousness of the eye surgeons to causes of poor outcome. Accuracy in data entry and an efficient flow of record forms are essential.

Adult↗

PubMed2005

Routine monitoring of visual outcome of cataract surgery. Part 2: Results from eight study centres.

AIM: To determine whether monitoring of cataract outcome can be implemented as a routine activity in different hospital settings in Africa and Asia, and to assess the impact of routine monitoring. METHODS: Eight eye centres in Asia and Africa were involved in the study between 1 June and 31 December 2000. Seven centres used a specifically designed cataract surgery record form with computerised data entry and analysis (CCSRF), and one centre used a manual recording form (MCSRF). Data were used to evaluate quality of data entry, follow up after surgery, and to assess trends in the proportion of complications and visual outcome after surgery. FINDINGS: The reporting systems were accepted and used by all centres, and data were recorded for 5198 cataract operations. Overall, 54% of eyes were followed for 8 weeks or more and 41% for 6 months. Follow up rates varied between centres from nil to almost 100%. Visual acuity tended to improve over time. The outcome could be improved at all follow up periods by providing best spectacle correction. At 8 weeks or more follow up, surgical complications or inadequate spectacle correction accounted for 72% of the causes of poor outcome. Three centres showed a significant reduction in complication rates over the course of the 6 month study. Data entry was identified as a problem and the CCSRF software has been modified to include consistency checks to reduce data entry errors. CONCLUSION: A simple system to monitor cataract outcome has been successfully field tested. The results suggest that monitoring can sensitise surgeons to quality control, which can lead to a decrease in complication rates and improved visual outcomes.

Cataract↗

PubMed2004

The environment and the eye.

The use of the 'environment' has become extended to include population changes, the 'domestic' environment, and cultural factors, in addition to physical influences such as global warming and ultraviolet radiation (UVR). The likely effects of each of these classes of agents on the eye and rates of blindness are illustrated by reference mainly to cataract and trachoma--two of the commonest causes of the world blindness.Trachoma infection and its blinding consequences could be eventually eliminated by environmental measures and changes in behaviour. While the threat of increased incidence of blindness from cataract due to ozone depletion and greater solar UVR has receded, global warming may become a factor in the early onset and rapid progression of cataract. Although we continue to need research into the physical and biological causes of cataract, elimination of world blindness will only be achieved when we understand the conceptual and cultural environments which are inhibiting the acceptance of cataract surgery.

Blindness↗

PubMed2004

Defining "occludable" angles in population surveys: drainage angle width, peripheral anterior synechiae, and glaucomatous optic neuropathy in east Asian people.

BACKGROUND: /aim: A current consensus in epidemiological studies of primary angle closure (PAC) is to diagnose the condition only if the posterior (usually pigmented) trabecular meshwork is seen for less than 90 degrees of the angle circumference, termed an "occludable angle." The authors sought to assess the validity of this epidemiological classification by exploring the relation between drainage angle width, peripheral anterior synechiae (PAS) and glaucomatous optic neuropathy (GON). METHODS: 918 Mongolians and 995 Chinese Singaporeans, both groups aged 40 years and older were examined in two population based surveys. Gonioscopic angle width was graded in five categories (0 = closed to 4 = wide open) according the scheme described by Shaffer. Cases with secondary PAS were excluded. RESULTS: The rate of PAS was between 0.3% and 1.7% in people with wide angles (grades 3 and 4). In those with grade 2 angles, PAS were seen in between 8% of eyes. In eyes with grade 1 angles, the rate rose to 17% in Chinese Singaporeans, and 31% in Mongolians. The odds of PAS were higher in people with narrower angles. However, there was a greater absolute number of people with PAS whose drainage angles were classified as "not occludable" than those classified "occludable." CONCLUSIONS: The traditional view that primary angle closure becomes a significant possibility in drainage angles of < or = grade 2 (approximately 20 degrees ) is valid in east Asians. The definition of an "occludable" angle examined here excludes many people with PAS. This probably serves to underemphasise the role of PAC in population surveys of glaucoma prevalence in Asian people.

Adult↗

PubMed2004

A comparison of anterior and posterior chamber lenses after cataract extraction in rural Africa: a within patient randomised trial.

BACKGROUND: Extracapsular cataract extraction (ECCE) with a posterior chamber intraocular lens (PC IOL) is the preferred method of cataract surgery in developed countries. However, intracapsular cataract extraction (ICCE) with an anterior chamber lens (AC IOL) may be appropriate in rural Africa. A randomised controlled trial was carried out to compare these surgical strategies. METHODS: Participants over 50 years requiring bilateral cataract surgery were recruited from outreach clinics in rural north and east Uganda. One eye was randomly allocated to AC IOL or PC IOL, the other eye being allocated to the second strategy. The main outcome measure was WHO distance visual acuity (VA) category after a minimum of 1 year. Secondary outcomes were numbers and causes of complications and refractive corrections. RESULTS: Of the 110 participants recruited, 98 (89%) were assessed at least 1 year after the operation (median follow up 17.5 months). Nine eyes randomised to PC IOL were converted to AC IOL; one eye randomised to AC IOL inadvertently received PC IOL. There was no difference in VA between 95 pairs of eyes for which data for both eyes were available (uncorrected VA, p = 0.26; corrected VA, p = 0.59). 80 (82%, 95% CI 73 to 89) and 82 (84%, 95% CI 75 to 90) eyes randomised to AC IOL and PC IOL respectively had corrected VA of 6/18 or better. 16 (16%, 95% CI 10 to 25) and eight (8%, 95% CI 4 to 15) eyes respectively had secondary procedures or other complications. CONCLUSIONS: Where both strategies are available, ECCE with PC IOL should be first choice because of fewer complications. Where ECCE with PC IOL is not immediately feasible, ICCE with AC IOL is an acceptable interim technique.

Aged↗

PubMed2004

The prevalence of glaucoma in Bangladesh: a population based survey in Dhaka division.

BACKGROUND/AIM: Few studies have reported on the epidemiology and clinical characteristics of glaucoma in south Asia. This project aimed to determine the prevalence of glaucoma of Dhaka, Bangladesh. METHOD: A multistage, stratified, clustered sample was drawn from Dhaka Division, Bangladesh, using systematic sampling to identify individual subjects aged 35 years and older. Examination of all subjects included Snellen visual acuity, slit lamp examination (including gonioscopy and applanation tonometry) and a stereoscopic assessment of the vertical cup:disc ratio (CDR). In selected subjects, a threshold visual field examination was performed. Glaucoma was diagnosed on the basis of statistical abnormality of the vertical CDR combined with an abnormal visual field test, or in subjects with advanced glaucoma who could not complete field testing, a grossly abnormal CDR. If it was not possible to examine the optic discs and the subject was blind, glaucoma was diagnosed on the basis of a raised intraocular pressure. RESULTS: Of 3562 eligible subjects, 2347 were examined (66%). Among people aged 40 years and older, the prevalence of definite glaucoma was 2.1% (95% confidence interval: 1.5 to 2.9; 39 people). The prevalence of definite and probable glaucoma was 3.1% (95% CI: 2.4 to 4.0; 58 people) in subjects of the same age. Primary open angle glaucoma was the most common form of glaucoma, accounting for 75% of the total. Among cases of blindness not attributable to refractive error, 5% were caused by glaucoma. Glaucoma prevalence was higher in men than women, but did not show the typical increase with age. CONCLUSION: Glaucoma prevalence is relatively high in Bangladesh, although it accounts for only a small proportion of blindness in the community. It is estimated that there are approximately 586 000 people 40 years and older with definite or probable glaucoma in Bangladesh.

Adult↗

PubMed2003

Evaluating a new logMAR chart designed to improve visual acuity assessment in population-based surveys.

AIMS: This study aimed to evaluate a new chart designed to improve the collection of visual acuity data in population-based surveys. The Reduced logMAR E chart (RLME) employs three letters per line, 'tumbling E' optotypes, and conforms to accepted contemporary design principles. METHODS: The performance of the chart was assessed within a population-based glaucoma survey in Thailand. Performance indices were test-retest variability (TRV) and agreement with acuity data measured using the ETDRS logMAR chart which acted as the 'gold standard'. RESULTS: The 95% confidence limits for TRV of RLME acuity data were +/-0.15 logMAR. This figure is consistent with published data on the TRV of acuities measured using five-letter-per-line logMAR charts. The mean difference between RLME and ETDRS acuity data was 0.00 logMAR (95% confidence intervals of +/-0.05 logMAR) indicating that RLME acuities agreed well with those of the ETDRS chart. The chart and its method of use was readily accepted by the local ancillary staff who required only minimal training before acuity measurement could be delegated to them. CONCLUSIONS: The study demonstrated that the RLME chart is capable of accurate and repeatable acuity measurements. Certain aspects of the design of the RLME chart may be particularly pertinent to the measurement of vision in population-based surveys.

Aged↗

PubMed2003

The effect of the anorectic agent, d-fenfluramine, and its primary metabolite, d-norfenfluramine, on intact human platelet serotonin uptake and efflux.

Dexfenfluramine, a drug formerly prescribed for treatment of obesity, caused heart valve damage and pulmonary hypertension in some people. The cause of the toxicity has not been defined, but 5-HT has been implicated. The objective of this study was to evaluate the effect of the anorectic agent, d-fenfluramine, and its major metabolite, d-norfenfluramine, on intact human platelet serotonin (5-HT) transport in vitro. The effects of d-fenfluramine and d-norfenfluramine on platelet uptake and efflux of 3H-5-HT were measured in buffer at pH 6.7, to optimize serotonin transporter (SERT) function, and at pH 7.4. Uptake of 3H-5-HT at pH 6.7 and 7.4 was inhibited by both agents at micro m concentrations (IC50, d-fenfluramine approximately 3 microM; d-norfenfluramine approximately 10 microM). However, no efflux of 3H-5-HT from labeled platelets at either pH 6.7 or 7.4 occurred at similar concentrations of d-fenfluramine or d-norfenfluramine. With inhibition of platelet dense granule 3H-5-HT uptake by reserpine, efflux of 3H-5-HT was observed at pH 6, but not at pH 7.4. Fluoxetine, a SERT inhibitor, was a more potent inhibitor of uptake (IC50 0.05 microM) than d-fenfluramine, but the anorectic agent, phentermine, had no effect. Therefore, d-fenfluramine and d-norfenfluramine inhibit human platelet uptake of 5-HT in vitro at tissue concentrations attainable in vivo, but they do not stimulate 5-HT efflux due to dense granule sequestration. Inhibition of platelet 5-HT uptake may play a role in the cardiopulmonary toxicity of d-fenfluramine, but other factors probably contribute, since similar toxicity has not been observed with fluoxetine.

Appetite Depressants↗

PubMed2003

Screening for primary angle closure in Mongolia: a randomised controlled trial to determine whether screening and prophylactic treatment will reduce the incidence of primary angle closure glaucoma in an east Asian population.

AIM: To describe the methods used and initial results of a prospective study designed to determine whether screening and prophylactic treatment will reduce the incidence of primary angle closure glaucoma (PACG) in Mongolia. METHODS: A total of 4725 individuals aged 50 years and above were recruited to the study and randomised to intervention or control groups. All subjects had non-mydriatic optic disc examination. The intervention arm had measurement of anterior chamber depth (ACD) by A-scan ultrasound and intraocular pressure (IOP) with Tonopen. Gonioscopy was performed on test positive cases (ACD <2.53 mm or IOP >or=24 mm Hg either eye). Those with occludable angles were offered laser iridotomy. Primary outcome will be incidence of PACG at 5 year follow up. RESULTS: Glaucoma was diagnosed in 128 (2.7%) subjects. Of the remaining 4597, 2293 were randomised to intervention. Intervention as allocated was received by 2280 (99.4%) individuals. 160 (23.4%) of 685 test positive cases had occludable angles, of which 156 were treated with iridotomy. CONCLUSIONS: This trial is a further step in determining whether screening and prophylactic treatment for primary angle closure in east Asian populations will reduce the incidence of glaucoma.

Aged↗

PubMed2003

Outcomes of cataract surgery in Bangladesh: results from a population based nationwide survey.

AIM: To evaluate the outcome of cataract surgery in the population of Bangladesh. METHODS: Data were collected by the National Blindness and Low Vision Prevalence Survey of Bangladesh, a cross sectional, nationally representative sample (12 782 subjects) of the population aged >or=30 years. An interview recorded socioeconomic data. Each subject was tested for logMAR visual acuity (VA) of each eye, autorefracted, and then underwent optic disc examination. Those with <6/12 VA on presentation in either eye were retested with their refractive correction, dilated, and examined for anterior and posterior segment disease. In aphakic and pseudophakic subjects the date, location and operating conditions (eye camp/hospital), and type of operation(s) were recorded. RESULTS: 11 624 eligible subjects were examined (90.9% response rate) in the survey. 162 subjects, 77 men and 85 women, had undergone cataract surgery in one or both eyes. 199 (88%) eyes had undergone intracapsular cataract extraction (ICCE), and 22 (10%) extracapsular surgery with intraocular lens (ECCE+IOL); surgical technique(s) in four cases were not identified. Presenting VA for the 226 operated eyes were: 68 eyes (30.1%) were 6/12 or better, 31 (13.7%) <6/12 >or=6/18, 63 (27.9%) 6/18 to 6/60, 8 (3.5%) <6/60 >or=3/60, and 56 (24.8%) <3/60. With "best" refractive correction these values were 114 (50.4%), 31 (13.7%), 51 (22.6%), 5 (2.2%), and 25 (11.1%), respectively. Of the 158 eyes with VA of 6/12 or worse on presentation, 44 (28%) were the result of coincident disease (principally age related macular degeneration), 95 (60%) refractive error (44 of these had uncorrected aphakia), and 19 (12%) operative complications. ICCE was more likely to result in a VA of <6/18 (OR: 4.26, p = 0.01) than ECCE+IOL. Likewise, eye camp surgery was more likely to result in a VA of <6/60 (OR: 1.98, p = 0.04). No significant association was found between time since surgery and VA outcome, nor was there a sex difference for postoperative vision. Literate subjects were significantly less likely to have an outcome of <6/18 (OR: 2.38, p <0.01) or <6/60 (OR: 2.87, p <0.01). Following ICCE (199 eyes), 56 (37%) of the 151 eyes with an aphakic spectacle correction achieved 6/12 or better. Females, eye camp surgeries, illiterate subjects, and rural dwellers were less likely to wear their aphakic correction. The ratio of ICCE:ECCE+IOL has reduced in the past 3 years (3.8:1) compared to >or=4 years before the survey (25:1). Hospital based ECCE+IOL surgeries were associated with a better outcome, yet 36% of these eyes were <6/12 postoperatively, after excluding coincident disease. CONCLUSION: This evaluative research study into cataract surgery outcomes in Bangladesh highlights the need for an improvement in quality and increased quantity of surgery with a more balanced distribution of services.

Adult↗

PubMed2003

Prevalence and causes of blindness and visual impairment in Bangladeshi adults: results of the National Blindness and Low Vision Survey of Bangladesh.

AIM: To determine the age, sex, and cause specific prevalences of blindness and visual impairment in adults 30 years of age and older in Bangladesh. METHODS: A nationally representative sample of 12 782 adults 30 years of age and older was selected based on multistage, cluster random sampling with probability proportional to size procedures. The breakdown of the cluster sites was proportional to the rural/urban distribution of the national population. The examination protocol consisted of an interview, visual acuity (VA) testing, autorefraction, and optic disc examination on all subjects. Corrected VA retesting, cataract grading, and a dilated fundal examination were performed on all visually impaired subjects. The definitions of blindness (<3/60) and low vision (<6/12 to >or=3/60) were based on the presenting visual acuity in the better eye. The World Health Organization/Prevention of Blindness proforma and its classification system for identifying the main cause of low vision and blindness for each examined subject was used. RESULTS: In total, 11 624 eligible subjects were examined (90.9% response rate) across the 154 cluster sites. A total of 162 people were bilaterally blind (1.53% age standardised prevalence) while a further 1608 subjects (13.8%) had low vision (<6/12 VA) binocularly. Visual acuity was >6/12 in the "better eye" in the remaining 9854 subjects (84.8%); however, 748 of these people had low vision in the fellow eye. The main causes of low vision were cataract (74.2%), refractive error (18.7%), and macular degeneration (1.9%). Cataract was the predominant cause (79.6%) of bilateral blindness followed by uncorrected aphakia (6.2%) and macular degeneration (3.1%). CONCLUSIONS: There are an estimated 650 000 blind adults (95% CI 552 175 to 740 736) aged 30 and over in Bangladesh, the large majority of whom are suffering from operable cataract. This survey indicates the need for the development and implementation of a national plan for the delivery of effective eye care services, aimed principally at resolving the large cataract backlog and the inordinate burden of refractive error.

Adult↗

PubMed2003

Prevalence of glaucoma in Thailand: a population based survey in Rom Klao District, Bangkok.

AIM: To determine prevalence, demography, mechanism, and visual morbidity of glaucoma in urban Thai people. METHODS: 790 subjects aged 50 years or older from Rom Klao district, Bangkok, Thailand, were enumerated in a population based cross sectional study. Each subject underwent the following investigations: visual acuity, visual field testing, slit lamp examination, applanation tonometry, gonioscopy, and an optic disc examination after mydriasis. Main outcome measures included visual acuity (logMAR), visual fields, intraocular pressure (IOP), gonioscopic characteristics, vertical cup/disc ratio (VCDR), prevalence of types of glaucoma. Glaucoma was diagnosed on the basis of optic disc appearance and visual field defects. In eyes in which the optic disc could not be examined, glaucoma was diagnosed when visual acuity was <3/60 and either IOP >99.5th percentile or there was evidence of previous glaucoma surgery. RESULTS: 701 subjects were examined (response rate 88.7%). In eyes with "normal" suprathreshold visual fields, the mean IOP was 13.3 mm Hg (97.5th percentile = 20 mm Hg). The 97.5th and 99.5th percentiles of VCDR were 0.72 and 0.86 respectively. Of the 701 subjects examined in the clinic, 27 had glaucoma (3.8%, 95% CI: 2.5 to 5.6), 16 had primary open angle glaucoma (POAG, prevalence 2.3%, 95% CI: 1.3 to 3.7), six were primary angle closure glaucoma (PACG, prevalence 0.9%, 95% CI: 0.3 to 1.9), and five were secondary glaucoma (SecG, prevalence 0.7%, 95% CI: 0.2 to 1.7). Among the 43 unilaterally blind subjects, glaucoma was the cause in five subjects (12%). One subject was bilaterally blind due to glaucoma (prevalence 11%, 95% CI: 0.3 to 61.9). 28 people (4%) were glaucoma suspects on the basis of optic disc appearance and six on the basis of visual fields only. 98 subjects (14%) had "occludable angles" in either eye, 22 of whom had primary angle closure (PAC, prevalence 3.1%, 95% CI: 1.9 to 4.7); 14 had peripheral anterior synechiae in either eye and eight had ocular hypertension (OHT). CONCLUSIONS: POAG accounted for 67% of all glaucoma, PACG 21%, and secondary glaucomas 12%. Glaucoma was the second most common cause of severe unilateral visual loss.

Age Distribution↗

PubMed2003

Risk factors for nuclear, cortical and posterior subcapsular cataracts in the Chinese population of Singapore: the Tanjong Pagar Survey.

AIM: To describe risk factors for nuclear, cortical, and posterior subcapsular (PSC) cataracts in Chinese Singaporeans. METHODS: A population based cross sectional study was carried out on ethnic Chinese men and women aged 40-81 years. A stratified, clustered, disproportionate (more weights to older people), random sampling procedure was used to initially select 2000 Chinese names of those aged 40-79 years from the 1996 electoral register in the Tanjong Pagar district in Singapore. Eligible subjects (n = 1717) were invited for a standardised ocular examination and interview at a centralised clinic, following which an abbreviated examination was conducted for non-respondents in their homes. Cataract was graded clinically using to the Lens Opacity Classification System (LOCS) III system. The main outcome measures were adjusted odds ratio for risk factors for specific cataract types (nuclear, cortical and PSC), any cataract and cataract surgery, examined in multiple logistic regression models. RESULTS: Out of the 1232 (71.8%) examined, 1206 (70.2%) provided lens data for this analysis. Increasing age was associated with all cataract types, any cataract, and cataract surgery. There was no significant sex difference in presence of any cataract, specific cataract types or cataract surgery. After controlling for age, sex, and other factors, diabetes was associated with cortical cataract (3.1; 95% CI: 1.6 to 6.1), PSC cataract (2.2; 95% CI 1.2 to 4.1), any cataract (2.0; 95% CI: 0.9 to 4.5), and cataract surgery (2.3; 95% CI: 1.3 to 4.1). Lower body mass index was associated with cortical cataract (1.8; 95% CI: 1.1 to 2.9; lowest versus highest quintile) and any cataract (2.3; 95% CI: 1.3 to 4.0). Current cigarette smoking was associated with nuclear cataract (1.7, 95% CI: 1.0 to 2.9; more than 10 cigarettes per day versus none). A non-professional occupation was associated with nuclear cataract (2.9; 95% CI: 1.5 to 5.8; for production or machine operators and 2.6; 95% CI: 1.2 to 5.5; for labourers or agricultural workers, both versus professionals). Lower education was associated with nuclear cataract (2.3; 95% CI: 1.0 to 5.2, none versus tertiary), while lower household income was associated with PSC cataract (4.7, 95% CI: 1.1 to 20.0; income S$4000). CONCLUSIONS: Age related cataracts are associated with a variety of risk factors among Chinese people in Singapore, similar to those reported in European, Indian, and African derived populations. These data support common aetiological mechanisms for age related cataracts, irrespective of ethnic origin.

Adult↗

PubMed2002

Non-trachomatous corneal opacities in the Gambia--aetiology and visual burden.

AIMS: National blindness surveys conducted in the Gambia in 1986 and 1996 showed an increase in blindness and visual impairment from non-trachomatous opacity. This study aimed to investigate the aetiology of these opacities and to assess the resulting visual burden. METHODS: A population-based, randomised blindness survey was conducted in the Gambia in 1996. Patients with visual impairment or blindness were examined by an ophthalmologist with a slit lamp. Causes of corneal opacity were determined as accurately as possible by clinical history and examination. RESULTS: A total of 154 patients with non trachomatous corneal opacity were examined of whom 39 had bilateral opacities and 115, unilateral. Causes included corneal infection, measles/vitamin A deficiency, harmful traditional practices and trauma (unilateral scarring). Overall, corneal pathology alone was responsible for bilateral visual impairment or blindness in 19 (12%) patients and unilateral visual impairment or blindness in 88 (57%) patients. Those patients with bilateral visual impairment or blindness (mean age 59, SD) were older (P= 0.003) than others (mean age 44, SD = 20). The use of harmful traditional eye practices was associated with bilateral corneal blindness or visual impairment (RR = 2.63, 95% CI 1.11-6.21, P = 0.04). Although none of the corneal scars reported here were attributed to trachoma, in patients over the age of 45, the prevalence of trachomatous conjunctival scarring in this group was 38.8% compared to 19.4% of the whole nationwide sample. DISCUSSION: Strategies for the prevention (including the quest for cheaper anti-microbial drugs and co-operation with traditional healers) and surgical treatment of these corneal opacities are discussed.

Adolescent↗

PubMed2002

Reasons for poor cataract surgery uptake - a qualitative study in rural South Africa.

OBJECTIVES: To understand the reasons for poor cataract surgery uptake in people with blindness or severe visual impairment in rural South Africa. METHODS: A qualitative analysis of detailed, domiciliary interviews with a community-based random sample of elderly Zulus who were blind or severely visually impaired as a result of operable cataract, who had previously been invited for surgery but had failed to attend. RESULTS: Fear of surgery and a fatalistic attitude to the inevitability and irreversibility of blindness in old age were the main reasons for failure to attend for surgery. There was a lower level of disability and perceived need than had been assumed for people with such poor visual acuity. Non-surgical western style health care for systemic illness was common but few patients had sought any form of assistance for their poor vision. Issues of cost and accessibility were relatively unimportant. CONCLUSION: Provision of affordable and accessible cataract surgery for the blind and severely visually impaired members of a community does not guarantee that it will be taken up. Other barriers to surgery may be revealed when practical issues such as cost and accessibility are addressed. Perceptions of visual disability among subjects with cataract may differ from simple objective clinical standards.

Aged↗

PubMed2002

Evaluation of E-optotypes as a screening test and the prevalence and causes of visual loss in a rural population in SW Uganda.

BACKGROUND: Few population-based eye surveys have been conducted in sub-Saharan Africa, limiting the quality of epidemiological information on visual loss from Africa. In the present paper, we describe the prevalence of visual loss in rural Uganda and the screening accuracy of E-optotypes when used by non-medical staff. METHODS: Residents of 15 neighbouring villages were screened for visual loss (<6/18 in either eye) using Snellen's E-optotypes. Individuals who failed were initially referred to an ophthalmic clinical officer (OCO), who retested visual acuity and subsequently referred to an ophthalmologist to determine the cause of visual loss. Subjects from two villages (248 individuals) who passed visual acuity screening were re-examined by the OCO to estimate the accuracy of the screening procedure. RESULTS: Of the 4076 adults (aged 13 years and over, 69.3% of the censused population) who participated, 191 (4.7%) failed the vision screening criteria and 648 (15.9%) had non-vision impairing conditions. The prevalence of visual loss was at least 3.9%: 0.4% had bilateral blindness, 1.6% had bilateral visual impairment, 0.7% had unilateral blindness and 1.2% unilateral visual impairment. Cataract was the leading cause for all categories of visual loss except bilateral blindness, for which suspected glaucoma was most frequent. Refractive errors were the second leading cause of bilateral and unilateral visual impairment. Based on one subject (0.4%) in the validation sample who was found to have low vision, we estimated the sensitivity and specificity of E-optotypes for detecting visual loss to be 93% and 99%, respectively. CONCLUSIONS: Cataract and refractive errors were responsible for most of the visual loss in rural Uganda. Snellen's E-optotypes provide a suitable cost-saving tool for conducting population-based eye surveys in sub-Saharan Africa.

Adolescent↗

PubMed2002

Biometric gonioscopy and the effects of age, race, and sex on the anterior chamber angle.

AIM: To utilise a novel method for making measurements in the anterior chamber in order to compare the anterior chamber angles of people of European, African, and east Asian descent aged 40 years and over. METHODS: A cross sectional study on 15 people of each sex from each decade from the 40s to the 70s, from each of three racial groups-black, white, and Chinese Singaporeans. Biometric gonioscopy (BG) utilises a slit lamp mounted reticule to make measurements from the apparent iris insertion to Schwalbe's line through a Goldmann one mirror goniolens. The main outcome measures were BG measurements of the anterior chamber angle as detailed above. RESULTS: There was no significant difference in angle measurement between black, white, and Chinese races in this study. However, at younger ages people of Chinese race appeared to have deeper angles than white or black people, whereas the angles of older Chinese were significantly narrower (p = 0.004 for the difference in slope of BG by age between Chinese and both black and white people). CONCLUSION: The failure to detect a difference in angle measurements between these groups was surprising, given the much higher prevalence of angle closure among Chinese. It appears that the overall apparent similarity of BG means between Chinese and Western populations may mask very different trends with age. The apparently more rapid decline in angle width measurements with age among Chinese may be due to the higher prevalence of cataract or "creeping angle closure." However, longitudinal inferences from cross sectional data are problematic, and this may represent a cohort phenomenon caused by the increasing prevalence of myopia in the younger Singaporean population.

Adult↗