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G J Johnson

Publications and source records attributed to G J Johnson.

At least 37 records · Page 2Linked to original sources
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↗
PubMed2002

Aetiology of suppurative corneal ulcers in Ghana and south India, and epidemiology of fungal keratitis.

BACKGROUND: A multicentre study was carried out in Ghana and southern India to determine the aetiology of suppurative keratitis in two regions located at similar tropical latitudes. Studies of fungal keratitis from the literature were reviewed. METHODS: Patients presenting at rural and urban eye units with suspected microbial keratitis were recruited to the study. Corneal ulceration was defined as loss of corneal epithelium with clinical evidence of infection with or without hypopyon. Microscopy and culture were performed on all corneal specimens obtained. RESULTS: 1090 patients were recruited with suspected microbial keratitis between June 1999 and May 2001. Overall the principal causative micro-organisms in both regions were filamentous fungi (42%): Fusarium species and Aspergillus species were the commonest fungal isolates. Pseudomonas species were most frequently isolated from cases of bacterial keratitis in Ghana but in India the commonest bacterial isolates were streptococci. CONCLUSION: Infections of the cornea due to filamentous fungi are a frequent cause of corneal damage in developing countries in the tropics and are difficult to treat. Microscopy is an essential tool in the diagnosis of these infections. A knowledge of the "local" aetiology within a region is of value in the management of suppurative keratitis in the event that microscopy cannot be performed.

Aspergillosis↗
PubMed2002

Longitudinal study of trachomatous trichiasis in the Gambia.

AIM: Investigation of the natural history of trachomatous trichiasis in the Gambia and of the outcome of self epilation and surgery for the condition. METHODS: A 1 year longitudinal study of 190 subjects with trichiasis was performed. Major trichiasis cases (five lashes or more) were referred for surgery and minor trichiasis cases were advised to epilate. Outcome measures included progression of trichiasis and corneal scarring; attendance for and results of surgery. RESULTS: 34 of 148 (23%, 95% CI 16 to 31) subjects with major trichiasis attended for surgery over the year. Progression from minor to major trichiasis occurred in 18 of 55 subjects (33%, 95% CI 21 to 47). Progression of corneal scarring occurred in 60 of 167 patients (36%, 95% CI 29 to 44). Clinically active trachoma and conjunctival bacterial isolation predicted progression of corneal opacity. Surgery was successful in 39 of 54 (72%) eyes. CONCLUSIONS: Despite the overall decline in trachoma in the Gambia, patients with both minor and major trichiasis remain at risk of developing corneal opacity. Active trachomatous inflammation and additional infection with bacteria may accelerate this process. Antibiotic treatment for trichiasis patients (in addition to surgery) should be investigated. Surgery for minor trichiasis may be indicated. Regular audit of surgical results is necessary with retraining where needed.

Adolescent↗
PubMed2002

Education, socioeconomic status, and ocular dimensions in Chinese adults: the Tanjong Pagar Survey.

AIM: To relate indices of education, occupation, and socioeconomic status to ocular dimensions and refraction in an adult population. METHODS: A population based, cross sectional survey of adult Chinese aged 40-81 years residing in the Tanjong Pagar district in Singapore. Ocular dimensions, including axial length, anterior chamber depth, lens thickness, and vitreous chamber depth, were measured using an A-mode ultrasound device. Corneal radius of curvature and refraction were determined with an autorefractor, with refraction further refined subjectively, and lens nuclear opacity was graded clinically using the modified Lens Opacity Classification System III score. Data on education, occupation, income, and housing type were obtained from a standardised interview. RESULTS: Biometric data were available on 951 phakic subjects. After controlling for age, sex, occupation, income and housing type, higher education was associated with longer axial lengths (0.60 mm; 95% confidence interval (CI): 0.34, 0.85, for every 10 years of education), longer vitreous chambers (0.53 mm; 95% CI: 0.30, 0.77), and more myopic refractions (-1.50 dioptres, 95% CI: -2.08, -0.92). Adjustment for axial length attenuated the refractive association of education (-0.68 dioptre, 95% CI: -1.14, -0.21). Similarly, near work related occupations (managers, professionals, and office workers) and higher income were independently associated with longer axial lengths, longer vitreous chambers, and more myopic refractions, and adjustment for axial length attenuated the refractive associations. CONCLUSIONS: Adults with greater education, near work related occupations, and higher income are more likely to have longer axial lengths and vitreous chambers, and more myopic refractions. The refractive associations of education, occupation, and income are largely explained by variations in axial length.

Adult↗
PubMed2001

The prevalence and risk factors for pterygium in an adult Chinese population in Singapore: the Tanjong Pagar survey.

PURPOSE: To determine the prevalence and risk factors for pterygium in the Chinese population of Singapore. METHODS: A population-based survey was conducted in Singapore, an island located 1 degree north of the equator with a stable tropical climate. A disproportionate, stratified, clustered, random sampling procedure was used to select the names of 2000 Chinese people aged 40 to 79 years from the 1996 electoral register in the Tanjong Pagar district of Singapore. Selected subjects underwent a comprehensive interview and ocular examination. Pterygium was diagnosed and graded clinically as grade 1 (transparent), 2 (intermediate), and 3 (opaque). Risks factors associated with pterygium and grade 3 pterygium were evaluated with logistic regression models. RESULTS: From a total of 1717 eligible subjects, 1232 (71.8%) were examined. There were 120 people with either unilateral (n = 70) or bilateral (n = 50) pterygium, equivalent to an overall prevalence of 6.9% (95% confidence interval [CI], 5.2, 8.8) in the Chinese population aged 40 and older. The prevalence increased linearly with age (chi-square test of trend P <.001) and was higher among men than women (age-adjusted odds ratio [OR], 4.2; 95% CI, 2.5, 6.9). Men aged 70 and above had the highest overall prevalence of 25.4% (95% CI, 18.2, 19.4), but pterygium was not seen in women aged 40 to -49 years. In multivariate analysis, ptergyium was independently associated with increasing age (OR, 7.8; 95% CI, 3.2, 18.8 for persons 70 to 81 years, compared with 40 to 49 years), male sex (OR, 5.1; 95% CI, 2.9, 9.3) and certain occupations; factory workers, production workers and machine operators (OR, 3.1; 95% CI, 1.5, 6.3), as well as laborers and agricultural workers (OR, 3.3; 95% CI, 1.6, 7.0) had higher risks, compared with professionals and office workers. Grade 3 pterygium (n = 36) was also independently associated with male sex (OR, 11.6; 95% CI, 3.5, 38.6) and similar occupations but was not related to age. CONCLUSIONS: The prevalence of pterygium in Singapore is 7% among Chinese aged 40 years and older. Independent associations with increasing age, male sex, and occupations linked to outdoor work and other exposures suggest a multifactorial cause of this condition.

Adult↗
PubMed2001

Natural history of trachomatous scarring in The Gambia: results of a 12-year longitudinal follow-up.

PURPOSE: The sight-threatening complications of trachoma are trichiasis and corneal opacity, and these remain the world's most common cause of preventable blindness. The aim of the study was to investigate the rate of progression of trachomatous conjunctival scarring to trichiasis and corneal opacity and to investigate risk factors for such progression. DESIGN: A 12-year, longitudinal study of the incidence and risk factors for the development of trichiasis and corneal opacity in a cohort of patients initially identified with trachomatous scarring in The Gambia. PARTICIPANTS: Six hundred thirty-nine subjects with some degree of trachomatous scarring were identified from the 1986 survey, and attempts were made to trace all these subjects. METHODS: Successfully traced subjects were interviewed, examined, and graded for trachoma. MAIN OUTCOME MEASURES: (1) Twelve-year rates of progression. (2) Risk factors for progression of disease. RESULTS: Three hundred twenty-six of six hundred thirty-nine (51%) subjects were traced and examined, 108 (17%) had died, and 205 (32%) were lost to follow-up. After 12 years, 6.4% (95% confidence interval [CI], 4.0-9.97) of scarred subjects had trichiasis develop, 5.96% (95% CI, 3.67-9.42) had corneal opacity develop, 16.51% (95% CI, 12.71-21.13) had visual impairment/blindness develop, and 2.5% (95% CI, 1.2-5.0) had corneal visual impairment/blindness develop. Mandinka ethnicity was a risk factor for trichiasis (odds ratio [OR], 4.3; 95% CI, 1.3-14.4), and trichiasis at baseline was a risk factor for corneal opacity (OR, 8.4; 95% CI, 1.8-39.2). History of lid surgery for trichiasis was associated with corneal opacity at follow-up (OR, 4.4; 95%CI, 1.4-14.0). Older age was a significant risk factor for development of trichiasis, corneal opacity, and visual loss (OR, 1.07; 95% CI, 1.01-1.12). Bilateral cataract was present in 40% of traced subjects and was associated with the incidence of visual impairment/blindness (OR, 9.4; 95%CI, 4.5-19.6) CONCLUSIONS: This is the first study to demonstrate the link between trichiasis and future corneal opacity, and it provides the rationale for performing lid rotation surgery on patients with trichiasis who do not yet have corneal opacity. The association between corneal opacity at follow-up and previous surgery among trichiasis patients suggests late presentation as a problem. The planning of surgical services will be aided by the incidence figures generated by this study.

Adolescent↗
PubMed2001

Glaucoma in East Greenlandic Inuit--a population survey in Ittoqqortoormiit (Scoresbysund).

PURPOSE: To determine the prevalence of primary angle-closure glaucoma (PACG) in an isolated Greenlandic Inuit community and to examine the anatomical risk factors for this disease. METHODS: All individuals aged > or =40 years were examined. Visual acuity, refractive error, anterior chamber depth (ACD), intraocular pressure (IOP), gonioscopy, and optic disc characteristics were recorded. RESULTS: Seventy-nine individuals (65% response rate) were examined. Mean IOP was 12.0 mmHg. ACD was shallow and decreased with age and hypermetropia. ACD was deeper than observed in the same community in 1981 and another East Greenland population in 1970. Two subjects had definite PACG (2.5 %). CONCLUSION: This is the first study to use applanation tonometry in a Greenland population and confirms a low IOP as found in other populations of Inuit and Mongolians. ACD measured in 1998 was deeper than in 1981 in the same community which may represent a cohort effect indicating a secular change.

Adult↗
PubMed2001

Trial of the Trachoma Rapid Assessment methodology in The Gambia.

PURPOSE: To test the validity and repeatability of a newly designed Trachoma Rapid Assessment (TRA) methodology. METHOD: Results from an initial TRA in 20 villages (TRA1) are compared with those of a second validation TRA (TRA2) after 6 weeks in 13 villages, randomly selected out of the original 20, conducted by different field staff. Findings of TRA1 and TRA2 are compared with those of a door-to-door survey of the entire population of all 13 villages. RESULTS: There is a considerable amount of variation between the results of TRA1 and TRA2 and between the results of both TRA's and the door-to-door survey. Even indicators that should have remained the same, like distance to Primary Health Centre or distance to trichiasis surgery facility, scored differently. CONCLUSIONS: The TRA methodology is easy to use and the results are quickly available. The scoring system indicates which intervention(s) of the SAFE strategy are needed and facilitates priority setting. The definition of some indicators, like availability and use of latrines, may need modification. In some cases, the scoring system seems to exaggerate differences between the actual findings. The consistency between two TRA's in the same village is low and the accuracy in measuring the actual situation is doubtful.

Anti-Bacterial Agents↗
PubMed2001

Long term clinical outcome of a randomised controlled trial of anterior chamber lenses after high volume intracapsular cataract surgery.

BACKGROUND: Age related cataract remains the major cause of blindness throughout the world. In many countries, the majority of cataract surgery continues to be done by the intracapsular cataract extraction (ICCE) method. The results of a large randomised controlled trial of multiflex open loop anterior chamber intraocular lenses (ACIOL) were reported from a busy eye hospital in Nepal. METHODS: There was a randomised controlled trial of 2000 people with bilateral cataract reducing vision to less than 6/36. Interventions were ICCE with an ACIOL compared with ICCE with aphakic spectacles (+11 dioptres). Participants were followed at discharge, 6 weeks, 1 year, and 1 1/2-5 years after surgery. Visual acuity and clinical outcome were measured. A poor outcome was defined as vision <6/60. RESULTS: Visual outcome was comparable in the two groups. More of the control group experienced functional blindness due to loss of aphakic spectacles at 1 year. The majority of cases of poor outcome occurred in the first year after surgery. There was no indication of any lens related problems after 1 year. CONCLUSION: Multiflex open loop anterior chamber lenses are safe for up to 1 year of follow up when used by experienced surgeons, and the available evidence of 2-5 years of follow up suggests that the complication rate is reasonably low. An ACIOL at the time of cataract surgery offers benefits over routine ICCE surgery with aphakic spectacle correction as it avoids the problem of replacing lost and broken spectacles.

Adult↗
PubMed2001

Glaucoma in China: how big is the problem?

AIMS: To derive preliminary estimates for the number of adults in China suffering from glaucoma, and project the burden of visual morbidity attributable to primary and secondary glaucoma. METHODS: Age and sex specific data from two population surveys were applied to US Census Bureau population estimates for urban and rural China. It was assumed that data from Singapore were representative of urban China, and those from Mongolia were representative of rural China. RESULTS: It was estimated that 9.4 million people aged 40 years and older in China have glaucomatous optic neuropathy. Of this number, 5.2 million (55%) are blind in at least one eye and 1.7 million (18.1%) are blind in both eyes. Primary angle closure glaucoma (PACG) is responsible for the vast majority (91%) of bilateral glaucoma blindness in China. The number of people with the anatomical trait predisposing to PACG (an "occludable" drainage angle) is in the region of 28.2 million, and of these 9.1 million have significant angle closure, indicated by peripheral anterior synechiae or raised intraocular pressure. CONCLUSIONS: This extrapolation of data from two east Asian countries gives an approximate number of people in China suffering from glaucoma. It is unlikely that this crude statistical model is entirely accurate. However, the authors believe the visual morbidity from glaucoma in China is considerable. PACG is probably the leading cause of glaucoma blindness in both eyes, and warrants detailed investigation of strategies for prevention.

Adult↗
PubMed2001

Prolonged enoxaparin therapy to prevent venous thromboembolism after primary hip or knee replacement. Enoxaparin Clinical Trial Group.

BACKGROUND: Patients undergoing hip or knee joint replacement are at risk for venous thromboembolic complications for up to twelve weeks postoperatively. We evaluated the efficacy and safety of a prolonged post-hospital regimen of enoxaparin, a low-molecular-weight heparin, in this patient population. METHODS: Following elective total hip or knee replacement, 968 patients received subcutaneous enoxaparin (30 mg twice daily) for seven to ten days, and 873 were then randomized to receive three weeks of double-blind outpatient treatment with either enoxaparin (40 mg once daily) or a placebo. The primary efficacy end point was the prevalence of objectively confirmed venous thromboembolism or symptomatic pulmonary embolism during the double-blind phase of treatment. RESULTS: Of the 873 randomized patients, 435 underwent elective total hip replacement and 438 underwent elective total knee replacement. Enoxaparin was superior to the placebo in reducing the prevalence of venous thromboembolism in patients treated with hip replacement: 8.0% (eighteen) of the 224 patients treated with enoxaparin had venous thromboembolism compared with 23.2% (forty-nine) of the 211 patients treated with the placebo (p < 0.001; odds ratio, 3.62; 95% confidence interval, 2.00 to 6.55; relative risk reduction, 65.5%). Enoxaparin had no significant benefit in the patients treated with knee replacement: thirty-eight (17.5%) of the 217 patients treated with enoxaparin had venous thromboembolism compared with forty-six (20.8%) of the 221 patients treated with the placebo (p = 0.380; odds ratio, 1.24; 95% confidence interval, 0.76 to 2.02; relative risk reduction, 15.9%). Symptomatic pulmonary embolism developed in three patients, one with a hip replacement and two with a knee replacement; all had received the placebo. There was no significant difference in the prevalence of hemorrhagic episodes or other types of toxicity between the enoxaparin and placebo-treated groups. CONCLUSIONS: Prolonging enoxaparin thromboprophylaxis following hip replacement for a total of four weeks provided therapeutic benefit, by reducing the prevalence of venous thromboembolism, without compromising safety. A similar benefit was not observed in patients treated with knee replacement.

Adult↗
PubMed2001

Variations in ocular biometry in an adult Chinese population in Singapore: the Tanjong Pagar Survey.

PURPOSE: To describe the variation in ocular biometry in adult Chinese individuals in Singapore. METHODS: This study was a population-based, cross-sectional survey of adult Chinese persons aged 40 to 81 years residing in Tanjong Pagar district, Singapore. Axial ocular dimensions, including axial length (AL), anterior chamber depth (ACD), lens thickness (LT), and vitreous chamber depth (VCD) were measured using an A-scan ultrasound device. Corneal curvature (CC) and noncycloplegic refraction were measured with an autorefractor, with refraction further refined subjectively. Lens nuclear opacity (NO) was graded clinically using the modified Lens Opacity Classification System III (LOCS III) score. RESULTS: A total of 1717 subjects were eligible for the survey, of whom 1232 (71.8%) participated. Biometric and refraction data were available for 1004 (58.5%) phakic subjects. The AL, ACD, LT, VCD, CC, and LOCS III scores were 23.23 +/- 1.17 mm, 2.90 +/- 0.44 mm, 4.75 +/- 0.47 mm, 15.58 +/- 1.11 mm, 7.65 +/- 0.27 mm, and 3.2 +/- 0.9 (mean +/- SD), respectively. On average, people aged 40 to 49 years, when compared with those 70 to 81 years, had longer ALs (mean difference, +0.58 mm), deeper ACDs (+0.52 mm), longer VCDs (+0.72 mm), but thinner lenses (-0.70 mm) and less severe NO (-1.7 LOCS III score). CCs did not vary significantly with age. After controlling for age, women had shorter ALs and VCDs, shallower ACDs, but thicker lenses and steeper CCs than men. The variation in noncycloplegic refraction with age was nonlinear. Among people aged 40 to 59 years, a higher prevalence of hyperopia was seen in older compared with younger persons (on average, a difference of +1.3 D for every 10-year difference in age, P: < 0.001), explained principally by shorter AL (and VCD) in older persons. Among those 60 to 81 years, this pattern was not obvious (a difference of -0.03 D for every 10-year difference in age, P: = 0.12), as NO became an additional determinant of refraction, with greater degrees of NO in older person's driving refraction in the "minus" direction. CONCLUSIONS: Ocular dimensions vary with age and gender in adult Chinese persons in Singapore. The variation in noncycloplegic refraction in people 40 years and older may be explained by differences in axial lengths (principally vitreous chamber depths) between older and younger persons and, from 60 years onwards, differences in lens nuclear opacification as well.

Adult↗
PubMed2001

The relationship between ocular dimensions and refraction with adult stature: the Tanjong Pagar Survey.

PURPOSE: To describe the association of ocular dimensions and refraction with adult stature. METHODS: This was a population-based cross-sectional survey of adult Chinese aged 40 to 81 years residing in the Tanjong Pagar district in SINGAPORE: As part of the examination, ocular dimensions, including axial length, anterior chamber depth, lens thickness, and vitreous chamber depth, were measured using an A-mode ultrasound device. Corneal radius and refraction were determined with an autorefractor, with refraction further refined subjectively. Height (in meters) and weight (in kilograms) were measured using a standardized protocol, and body mass index (BMI) was calculated as weight divided by the square of the height (kilograms per square meter). RESULTS: Data on ocular biometry, refraction, height, and weight were available on 951 (55.4%) participants with phakic eyes. After controlling for age, sex, education, occupation, housing type, income, and weight, it was found that taller persons were more likely to have longer axial lengths (+0.23 mm longer axial length, for every 0.10 m difference in height), deeper anterior chambers (+0.07 mm), thinner lenses (-0.09 mm), longer vitreous chambers (+0.26 mm), and flatter corneas (+0.09 mm longer corneal radius), although refractions were similar. In contrast, heavier persons tended to have more hyperopic refractions (+0.22 D for every 10 kg difference in weight, +0.56 D for every 10 kg/m(2) difference in BMI) but similar ocular dimensions. CONCLUSIONS: Adult height is independently related to ocular dimensions, but does not appear to influence refraction. Thus, although taller persons are more likely to have longer globes, they also tend to have deeper anterior chambers, thinner lenses, and flatter corneas. Conversely, weight is independently related to refraction, although the exact biometric component responsible for this association is not apparent.

Adult↗