Correction: Selective laser trabeculoplasty: past, present, and future.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Cycloplegic refraction in preschool children: comparisons between the hand-held autorefractor, table-mounted autorefractor and retinoscopy.

AIMS: It is common for refraction to be measured using different testing methods in children, with much debate still ongoing on the preferred method. Therefore, we compared cycloplegic refraction measurements using three objective methods in a large cohort of children. METHODS: We present the findings from a total of 51 children who were recruited and examined as part of the Strabismus, Amblyopia and Refractive error in Singapore preschool children (STARS) study. Each child underwent a comprehensive eye examination, which included cycloplegic refraction using a hand-held autorefractor (Retinomax), a table mounted autorefractor (Canon FK-1) and streak retinoscopy. Spherical equivalent (SE) was calculated as (sphere + half of minus cylinder) and astigmatism was determined using the negative cylindrical component. RESULTS: The current study sample consisted of 29 boys and 22 girls aged between 24 and 72 months (mean age 52.3 months). The mean spherical equivalent (SE) using the table-mounted autorefractor (1.03 +/- 1.64 D) was not significantly different from the streak retinoscopy (1.09 +/- 1.58 D, p = 0.66). However, the mean SE using the hand-held Retinomax (0.80 +/- 1.43 D) was significantly different (more 'minus'p = 0.0004) to streak retinoscopy. The astigmatism measured using the hand held (-0.89 +/- 0.51 D) and table-mounted autorefractor (-0.83 +/- 0.61 D) were significantly greater than that obtained with streak retinoscopy (-0.58 +/- 0.56, p = 0.0003). CONCLUSIONS: The table-mounted autorefractor provided a reading more similar to that of streak retinoscopy than to that of the hand-held autorefractor. However, there were only small differences in mean SE (<0.32 D) between the hand-held Retinomax and the other methods, which will have implications in research investigations of refractive error.

Selective laser trabeculoplasty: past, present, and future.

Over the past two decades, selective laser trabeculoplasty (SLT) has increasingly become an established laser treatment used to lower intraocular pressure in open-angle glaucoma and ocular hypertensive patients. In this review we trace the origins of SLT from previous argon laser trabeculoplasty and review the current role it has in clinical practice. We outline future directions of SLT research and introduce emerging technologies that are further developing this intervention in the treatment paradigm of glaucoma.

Defining myopia using refractive error and uncorrected logMAR visual acuity >0.3 from 1334 Singapore school children ages 7-9 years.

AIM: To determine the association of spherical equivalent (SE) with low uncorrected visual acuity (VA) along with a proposed definition for myopia using logMAR VA >0.3 as the criteria. METHODS: 1334 Chinese schoolchildren (mean age 7.8; range 7-9 years) were enrolled in the study after those who had hyperopia > or =+2.00 dioptres (D) and astigmatism > = -2.00 D were excluded. Uncorrected logMAR VA was measured for both eyes. Cycloplegia autorefraction was achieved by the instillation of three drops of 1% cyclopentolate 5 minutes apart. The average of five successful consecutive refraction and keratometry readings were obtained with calibrated Canon RK5 autokeratorefractometers by well trained optometry students, at least 30 minutes after the instillation of the third drop of cyclopentolate. SE cut-off points (-0.25 D, -0.5D, -0.75 D, -1.0 D) were evaluated. RESULTS: Using different SE cut-off points, the myopia prevalence rates of this sample of schoolchildren varied from 45.8% (SE at least -0.25 D) to 30.7% (SE at least -1.0 D). The cut-off point of > or =-0.75 D had a sensitivity and specificity of 91.8% (95% CI, 89.2 to 94.4) and 93.7% (95% CI, 92.1 to 95.3), respectively, to predict low vision defined as uncorrected logMAR VA > 0.3 (either eye). The next best cut-off point of -0.5D had a higher sensitivity (93.3%), but lower specificity (87.9%). CONCLUSIONS: The cut-off points of -0.75D and -0.5D in SE refraction are appropriate for the prediction of uncorrected logMAR VA worse than 0.3, which is the criterion for the US common state adult driver licensing standard.

Visual acuity after acute primary angle closure and considerations for primary lens extraction.

BACKGROUND/AIM: Primary lens extraction has been advocated for acute primary angle closure (APAC), but it is not known if this is warranted in all cases. The aim of this study was to investigate the visual acuity (VA) of APAC eyes shortly after resolution of the acute episode in order to assess the appropriateness of performing such surgery in this condition. METHODS: This was a prospective observational case series. As part of a randomised controlled trial comparing phacoemulsification and laser iridotomy, 135 consecutive APAC subjects over a 2 year period underwent subjective refraction and measurement of Snellen VA once the acute episode had resolved with reduction of intraocular pressure (IOP) and improved corneal clarity. RESULTS: Subjects were predominantly Chinese (95.6%) and female (79.3%), with a mean age of 63.6 (SD 9.6) years. When assessed 1.7 (2.7) days after presentation, the majority of APAC cases (50.4%) had good VA (6/12 or better), with more than a quarter of cases having VA of 6/7.5 or better. Poor VA was associated with duration of symptoms (p = 0.04, OR = 4.1, 95% CI 1.1 to 15.7) and time taken to resolution of APAC (p = 0.04, OR = 2.2, 95% CI 1.02 to 4.6), but not with sex (p = 0.31), age (p = 0.26), duration from presentation to measurement of visual acuity (p = 0.53), or presenting IOP (p = 0.73). CONCLUSION: Within days after APAC, more than half of APAC affected eyes had good VA (6/12 or better). The role of lens extraction in the management of APAC warrants further debate, especially for eyes with good VA.

Uncorrected refractive error in Singapore teenagers.

AIM: To study the prevalence rate of uncorrected refractive error and associated risk factors among Singapore schoolchildren aged 12-16 years (grade 7). METHODS: A cross sectional study of 628 participants (participation rate 99.8%) was conducted in two schools. An interviewer led questionnaire asking about sociodemographic variables and risk factors was administered. Refractive errors were measured using a table mounted autorefractor. Participants with habitual visual acuity (VA) of 0.2 logMAR or worse underwent subjective refraction. Uncorrected refractive error was defined as improvement of at least 0.2 logMAR in best corrected visual acuity after subjective refraction. RESULTS: The prevalence rate of uncorrected refractive error was 22.3% (95% confidence interval (CI) 19.0% to 25.5%). The multivariate adjusted odds ratio of uncorrected refractive error in students with the lowest academic ability was 2.24 (95% CI 1.34 to 3.73). Increasing time interval since the last visit to an eye care provider increased the risk of uncorrected refractive error (trend p = 0.001). CONCLUSION: Uncorrected refractive error was a significant problem among Singapore students aged 12-16 years (grade 7). Uncorrected refractive error was more common among students with low academic ability or those who had not visited an eye care provider for a long time.

Utility values among glaucoma patients: an impact on the quality of life.

AIM: To ascertain utility values and associated quality of life with different severity and duration of glaucoma among Indian patients. METHODS: Utility values of 105 consecutive patients with primary glaucoma of at least 12 months' duration were evaluated in a cross sectional study. Utility values were ascertained in five groups using both the time-trade off and standard gamble methods: group 1 (best corrected visual acuity in the better eye of 6/9 or better), group 2 (best corrected visual acuity in the better eye of 6/18 to 6/12), group 3 (best corrected visual acuity in the better eye of 6/36 to6/24), group 4 (best corrected visual acuity in the better eye of 3/60 to 6/60), and group 5 (best corrected visual acuity in the better eye of 3/60 or worse). RESULTS: The mean utility value for the glaucoma group as a whole was 0.64 (SD 0.69; 95% confidence interval (CI), 0.58 to 0.70) with the time-trade off method and 0.86 (SD 1.00; 95% CI, 0.81 to 0.90) with the standard gamble method for a gamble of death and 0.97 (SD 1.00; 95% CI, 0.94 to 0.99) for a gamble of blindness. The mean utility results by the time-trade off method were as follows: group 1 = 0.66, group 2 = 0.66, group 3 = 0.62, group 4 = 0.55, and group 5 = 0.61. The utility value was much lower (0.46) in those with no formal education or only primary education compared to those with postgraduate education (0.75) (p = 0.038). Those patients with glaucoma of less than 5 years' duration had a utility score of 0.62 while those with glaucoma for more than 10 years had a score of 0.74 (p = 0.40). CONCLUSIONS: Visual acuity loss occurring secondary to glaucoma is associated with a substantial decrease in patient utility value (and quality of life) in a developing country like India. The utility value is directly dependent on the degree of visual acuity loss associated with the disease and educational status and not on the duration of disease, the number of medications, or the visual field indices.

Eye growth changes in myopic children in Singapore.

AIMS: To assess the longitudinal changes in biometric parameters and associated factors in young myopic children aged 7--9 years followed prospectively in Singapore. METHODS: Children aged 7--9 years from three Singapore schools were invited to participate in the SCORM (Singapore Cohort study Of the Risk factors for Myopia) study. Yearly eye examinations involving biometry measures were performed in the schools. Only myopic children (n=543) with 3 year follow up data were included in this analysis. RESULTS: The 3 year increases in axial length, anterior chamber depth, lens thickness, vitreous chamber depth, and corneal curvature were 0.89 mm, -0.02 mm, -0.01 mm, 0.92 mm, and 0.01 mm, respectively. Children who were younger, female, and who had a parental history of myopia were more likely to have greater increases in axial length. After adjustment for school, age, sex, race, parental myopia and reading in books per week, the age (p<0.001), sex (p=0.012), and parental myopia (p=0.027) remained significantly associated with the 3 year change in axial length. Reading in books per week, however, was not associated with axial length change. Children with faster rates of progression of myopia had greater increases in axial length (Pearson correlation coefficient (r)=-0.69) and vitreous chamber depth (r=-0.83). CONCLUSIONS: The 3 year change in axial length of Singapore children aged 7--9 years at baseline was high and greater in younger children, females, and children with a parental history of myopia. Myopia progression was driven largely by vitreous chamber depth increase.

Choroidal expansion as a mechanism for acute primary angle closure: an investigation into the change of biometric parameters in the first 2 weeks.

BACKGROUND/AIM: Choroidal expansion with anterior movement of the lens was recently proposed as a mechanism for acute primary angle closure (APAC). The aim of this study was to compare the biometric parameters, central anterior chamber depth, limbal chamber depth, lens thickness, and lens position, within 24 hours of presentation and 2 weeks later in eyes with APAC. METHODS: This was a prospective observational case series of 41 subjects with APAC. Subjects who presented with APAC were treated with medical therapy followed by laser iridotomy (LI) in both eyes once the acute attack was broken. Ocular biometry was performed in affected and fellow eyes before LI (baseline) and then 2 weeks later. Optical pachymetry was used to measure central anterior chamber depth (ACD) and the limbal chamber depth (LCD) was graded at the slit lamp. A-scan ultrasound was used to measure lens thickness (LT) and axial length (AL). Lens position (LP) was defined as ACD +(1/2)LT. RESULTS: The majority of subjects were Chinese (83%) and female (61%), and the mean age was 60.4 (SD 10.3) years. In affected eyes, the ACD was 1.81 (0.29) mm before and 1.80 (0.28) mm 2 weeks after LI (p = 0.63), while in fellow eyes, the ACD was 1.83 (0.29) mm and 1.81 (0.38) mm, respectively (p = 0.21). There was no significant change in lens position, relative lens position, or axial length in both affected and fellow eyes over the 2 weeks. CONCLUSIONS: There was no change observed in central anterior chamber depth, lens thickness, or lens position at the time of the acute attack compared to 2 weeks later in both APAC affected and fellow eyes. The findings do not support the hypothesis of lens movement due to choroidal expansion in APAC.

Utility values and myopia in teenage school students.

AIM: To ascertain the utility values of myopic teenage students in Singapore. METHODS: Children (n=699) aged 15-18 years with myopia (spherical equivalent (SE) at least -0.5 dioptres (D)) in two high schools in Singapore were recruited. Information on time trade-off (years of life willing to sacrifice for treatment of myopia) and standard gamble for blindness (risk of blindness from therapy willing to sacrifice for treatment of myopia) utility values, demographic, and socioeconomic status data were obtained. RESULTS: The time trade-off and standard gamble for blindness utility values were 0.93 (95% confidence interval (CI) 0.93 to 0.94) and 0.85 (95% CI 0.84 to 0.86), respectively. Children with presenting better eye logMAR visual acuity >0.3 had lower time trade-off utility values (mean 0.92 versus mean 0.94), after adjusting for race and sex. There were dose-response relations between standard gamble for blindness values and total family income, as well as both utility values and educational stream (all p values for trend <0.01), after controlling for the same factors. CONCLUSION: The utility values in myopic students were higher for teenagers with better presenting visual acuity, children who wore spectacles or contact lenses, higher total family income, more "academic" schooling stream, and who were non-Muslims.

Intraocular pressure associations with refractive error and axial length in children.

AIM: To assess whether intraocular pressure (IOP) is associated with refractive error or axial length in children. METHODS: Of subjects from the Singapore Cohort Study of the Risk Factors for Myopia (SCORM), 636 Chinese children aged 9-11 years from two elementary schools underwent non-contact tonometry, cycloplegic autorefraction, and A-scan biometry during 2001. For analyses, refractive error was categorised into four groups; hypermetropia (spherical equivalent refraction (SE) > or = +1.0D), emmetropia (-0.5D

Myopia: attempts to arrest progression.

Previous studies have evaluated the efficacy of several interventions to decrease the progression of myopia. These include devices that alter the perception of the visual environment and pharmacological treatments. There is no conclusive evidence thus far that alteration of the pattern of spectacle wear, bifocals, ocular hypotensives, or contact lenses retards the progression of myopia. Several randomised clinical trials have demonstrated that the rate of progression of myopia is lower in children given atropine eye drops than those given placebo. However, atropine is associated with short term side effects such as photophobia and possible long term adverse events including light induced retinal damage and cataract formation. Other more selective antimuscarinic agents such as pirenzipine are presently being evaluated. Further well conducted randomised clinical trials with large sample sizes and adequate follow up designed to evaluate treatments to retard the progression of myopia should be conducted, since the identification of an effective intervention may have a greater public health impact on the burden and morbidity from myopia than the few treatments currently available.

Causes of low vision and blindness in rural Indonesia.

AIM: To determine the prevalence rates and major contributing causes of low vision and blindness in adults in a rural setting in Indonesia METHODS: A population based prevalence survey of adults 21 years or older (n=989) was conducted in five rural villages and one provincial town in Sumatra, Indonesia. One stage household cluster sampling procedure was employed where 100 households were randomly selected from each village or town. Bilateral low vision was defined as habitual VA (measured using tumbling "E" logMAR charts) in the better eye worse than 6/18 and 3/60 or better, based on the WHO criteria. Bilateral blindness was defined as habitual VA worse than 3/60 in the better eye. The anterior segment and lens of subjects with low vision or blindness (both unilateral and bilateral) (n=66) were examined using a portable slit lamp and fundus examination was performed using indirect ophthalmoscopy. RESULTS: The overall age adjusted (adjusted to the 1990 Indonesia census population) prevalence rate of bilateral low vision was 5.8% (95% confidence interval (CI) 4.2 to 7.4) and bilateral blindness was 2.2% (95% CI 1.1 to 3.2). The rates of low vision and blindness increased with age. The major contributing causes for bilateral low vision were cataract (61.3%), uncorrected refractive error (12.9%), and amblyopia (12.9%), and the major cause of bilateral blindness was cataract (62.5%). The major causes of unilateral low vision were cataract (48.0%) and uncorrected refractive error (12.0%), and major causes of unilateral blindness were amblyopia (50.0%) and trauma (50.0%). CONCLUSIONS: The rates of habitual low vision and blindness in provincial Sumatra, Indonesia, are similar to other developing rural countries in Asia. Blindness is largely preventable, as the major contributing causes (cataract and uncorrected refractive error) are amenable to treatment.

Awareness of glaucoma, and health beliefs of patients suffering primary acute angle closure.

AIM: To evaluate the factors associated with lack of awareness of glaucoma and late presentation to the doctor in Singapore Chinese patients with acute angle closure (AAC) METHODS: A prospective, hospital based case series of 105 patients aged 35 years and above who presented with a first attack of AAC in a tertiary hospital in Singapore was conducted. A research assistant interviewed all patients face to face in clinic and recorded demographic factors, awareness of glaucoma, and subjective barriers to seeing a doctor. The time from onset of symptoms to presentation at the clinic was noted. RESULTS: Overall, 22.9% of patients had heard of glaucoma. The multivariate adjusted odds ratio (OR) of unawareness of glaucoma in older people (> 60 years) was 1.5 (95% confidence interval (CI) 0.5 to 4.6), 3.2 (95% CI 1.1 to 9.2) for adults who were not working, and 13.8 (95% CI 1.3 to 146.7) for patients who had less than a pre-university education. A significant proportion (31.7%) of patients presented to the doctor 24 hours or more after symptoms occurred. In a multiple logistic regression model, the adjusted OR of late presentation was 8.5 (95% CI 1.04 to 69.5) if there was no car access, 5.0 (95% CI 1.0 to 24.6) if the patients spoke Chinese, and 3.3 (95% CI 0.9 to 11.9) if there was nobody to accompany to hospital. CONCLUSION: Glaucoma awareness among patients suffering AAC was not high. Lack of awareness was associated with increasing age, lack of formal education, and unemployment. A significant proportion of patients seek medical attention late. Risk factors for late presentation include lack of car access, nobody to accompany the patient, and speaking the Chinese language primarily. Health education programmes may help increase the knowledge and awareness of glaucoma.

Intraocular pressure and visual field loss in primary angle closure and primary open angle glaucomas.

AIM: To compare the correlation between visual field loss and the pretreatment intraocular pressure (IOP) in primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG). METHODS: In a cross sectional observational study of 74 patients (43 PACG, 31 POAG), pretreatment IOP was measured at presentation, before treatment was initiated. The severity of visual field loss was assessed by AGIS score, mean deviation (MD), pattern standard deviation (PSD), and corrected pattern standard deviation (CPSD). Glaucomatous optic neuropathy was assessed from simultaneous stereo disc photographs. RESULTS: There was a stronger correlation between pretreatment IOP and the extent of visual field loss in PACG subjects than in those with POAG for both MD (PACG: Pearson correlation coefficient (r) = 0.43, p = 0.002; r(2) = 0.19), (POAG: r = 0.21, p = 0.13; r(2) = 0.04) and AGIS score (PACG: r = 0.41, p = 0.003; r(2) = 0.17), (POAG: r = 0.23, p = 0.19; r(2) = 0.05 respectively). No such associations were seen for pattern standard deviation (PSD) or corrected pattern standard deviation (CPSD) in either group (p> 0.29). Both horizontal and vertical cup-disc ratio were well correlated with severity of field loss but not with presenting IOP for either diagnosis. CONCLUSIONS: This is consistent with the hypothesis of a greater IOP dependence for optic nerve damage in PACG than POAG and, conversely, a greater importance of other, less pressure dependent mechanisms in POAG compared to PACG.

Pterygium in Indonesia: prevalence, severity and risk factors.

AIM: To determine prevalence rates, severity, and risk factors for pterygium in adults in provincial Indonesia and to validate a clinical grading scheme in a population based setting. METHODS: A population based prevalence survey of 1210 adults aged 21 years and above was conducted in five rural villages and one provincial town in Riau province, Sumatra, Indonesia, an area near to the equator. A one stage household cluster sampling procedure was employed: 100 households were randomly selected from each village or town. Pterygia were graded for severity (T1 to T3, by visibility of episcleral vessels) and the basal and apical extent measured by an ophthalmologist (GG) with a hand held slit lamp. Refraction was measured by hand held autorefractor (Retinomax). Face to face household interviews assessed outdoor activity, occupation, and smoking. The participation rate was 96.7%. RESULTS: The mean age was 36.6 years (SD 13.1), 612 were male. The age adjusted prevalence rate of any pterygium was 10.0% (95% confidence intervals (CI) 8.2 to 11.7) and of bilateral pterygia was 4.1% (95% CI 2.9 to 5.3). There was a significant dose-response relation with age (2.9% (95% CI 0.4 to 5.8) for 21-29 years versus 17.3% (95% CI 10.4 to 24.2) 50 years and above; p for trend <0.001) and occupations with more time outdoors (p for trend = 0.02). This was true for both sexes, all grades of lesion (T1 to T3), and bilateral disease. A multivariate logistic regression model showed pterygium was independently related to increasing age and outdoor activity 10 years earlier. The mean basal diameter = 3.3 mm (SD 1.51, range 0.1-9.5) and extent from limbus = 1.4 mm (SD 1.18, range 0.1-8.0). Higher grade pterygia were larger for basal and apical extent (p for trend <0.001). The presence of pterygium was associated with astigmatism (defined as cylinder at least -0.5 dioptres (D); p <0.001). This association increased with increasing grade of lesion (p for trend <0.001). Median cylinder for those with pterygium (-0.50 D) was greater than for those without (-0.25D), (p <0.001), and increased with higher grade of lesion (p for trend <0.001). For eyes with pterygia, magnitude of astigmatism was associated with greatest extent from the limbus, (p = 0.03), but not basal width (p = 0.99). CONCLUSIONS: There is a high prevalence rate of pterygia in provincial Sumatra. The independent increase with age and past outdoor activity (a surrogate for sun exposure) is consistent with previous findings. Clinical grading of pterygium morphology by the opacity of the lesion was a useful additional marker of severity.

Prevalence and risk factors associated with dry eye symptoms: a population based study in Indonesia.

AIM: To determine the prevalence and identify associated risk factors for dry eye syndrome in a population in Sumatra, Indonesia. METHODS: A one stage cluster sampling procedure was conducted to randomly select 100 households in each of the five rural villages and one provincial town of the Riau province, Indonesia, from April to June 2001. Interviewers collected demographic, lifestyle, and medical data from 1058 participants aged 21 years or over. Symptoms of dry eye were assessed using a six item validated questionnaire. Presence of one or more of the six dry eye symptoms often or all the time was analysed. Presence of pterygium was documented. RESULTS: Prevalence of one or more of the six dry eye symptoms often or all the time adjusted for age was 27.5% (95% confidence interval (CI) 24.8 to 30.2). After adjusting for all significant variables, independent risk factors for dry eye were pterygium (p<0.001, multivariate odds ratio (OR) 1.8; 95% CI 1.4 to 2.5) and a history of current cigarette smoking (p=0.05, multivariate OR 1.5; 95% CI 1.0 to 2.2). CONCLUSIONS: This population based study provides prevalence rates of dry eye symptoms in a tropical developing nation. From our findings, pterygium is a possible independent risk factor for dry eye symptoms.

Prevalence and risk factors for refractive errors and ocular biometry parameters in an elderly Asian population: the Singapore Longitudinal Aging Study (SLAS).

PURPOSE: To determine the prevalence rates of refractive errors and pattern of ocular biometry in a multi-ethnic elderly Asian population. METHODS: A population-based study of 1835 residents aged 55-85 years, evaluating the refractive error and ocular biometry parameters, including axial length (AL) and anterior chamber depth. RESULTS: The age-standardized prevalence of myopia, hyperopia, astigmatism, and anisometropia were 30.0% (95% confidence interval (CI): 29.6, 30.4), 41.5% (95% CI: 41.1, 41.9), 43.5% (95% CI: 43.1, 44.0), and 22.1% (95% CI: 21.7, 22.4), respectively. Male gender (P=0.02), age ≥ 75 years (P=0.033), and higher educational level (P<0.001) were significantly associated with higher rates of myopia in multivariate analyses. The prevalence of astigmatism was higher in persons with diabetes (odds ratio (OR) 1.4, 95% CI: 1.03, 1.90, P=0.031). AL was longer in Chinese than other ethnic groups (23.7 vs 23.4 mm, P=0.018), and in men compared with women (24.2 vs 23.4 mm, P<0.001). AL was associated with increasing height (AL increased by 0.3 mm for every 10 cm increase in height, P<0.001). CONCLUSION: There is a high prevalence of myopia in elderly Singaporeans, consistent with trends seen in younger populations in Asia. Male gender and higher education were independent risk factors for myopia. These data suggest that higher rates of myopia in East Asians compared with Caucasians may not be a recent phenomenon.

Breastfeeding and association with refractive error in young Singapore Chinese children.

PURPOSE: The objective of this study was to investigate an association between spherical refractive error and breastfeeding. METHODS: Strabismus, amblyopia, and refractive errors in Singaporean preschoolers (STARS) is a cross-sectional population-based study of 3009 Chinese children aged 6-72 months conducted between June 2006 and September 2008 in Singapore. Parents were asked about the history of breastfeeding in face-to-face interviews. Children without cycloplegia or without refraction assessment were excluded. The final sample analysed was 2639 children (1375 male, 1264 female). RESULTS: Out of those who were breastfed, 842 (41.3%) were breastfed for more than 3 months and 599 (29.4%) were breastfed longer than 6 months. The prevalence of myopia, defined as the spherical equivalent refraction of the right eye of at least -0.5 dioptres (D), was 11.3% (95% CI (10.1, 12.5)). The mean spherical equivalent refraction of breastfed children was 0.12 D higher than that of children who were not breastfed (P-value=0.03). Breastfeeding, however, was not associated with myopia (adjusted OR=0.85; 95% CI (0.62, 1.18)). CONCLUSIONS: The results show that breastfeeding is associated with more hyperopic spherical equivalent refraction in young Chinese children in Singapore.

Prevalence and causes of decreased visual acuity in Singaporean Chinese preschoolers.

AIMS: To describe the prevalence and causes of decreased visual acuity (VA) in Singaporean Chinese children. METHODS: A population-based survey of Singaporean Chinese children aged 6 to 72 months was conducted. Participants underwent an orthoptic evaluation, cycloplegic refraction and biometric measurements. A sub-group of children aged 30 to 72 months with presenting logMAR VA were included in this analysis. Retesting was performed on the same day or another day by predefined criteria with best refractive correction. Decreased VA was defined as worse than 20/50 (0.4 logMAR) for ages 30 to 47 months and worse than 20/40 (0.3 logMAR) for ages 48 to 72 months. RESULTS: The study examined 3009 children (participation rate 72.3%) of which 2017 children aged 30 to 72 months were eligible for VA testing and completed in 1684 (83.5%). In children aged 30-47 months, the prevalence of decreased presenting VA was 2.1%, and in children 48-72 months, it was 2.05%, with no significant difference between boys and girls in both age groups (p=0.15 and p=0.85). Causes for decreased presenting VA in those 30-47 months were refractive error (7/11, 63.6%), amblyopia (1/11, 9.1%) and "no explanation" (3/11, 27.3%), and 17/24 (70.8%), 5/24 (20.8%) and 2/24 (8.3%), respectively, for those aged 48-72 months. The types of refractive error were astigmatism (15/24, 62.5%), myopia (6/24, 25.0%), hyperopia (2/24, 8.3%) and hyperopia with astigmatism (1/24, 4.2%). CONCLUSIONS: The prevalence of decreased VA among Singaporean Chinese preschoolers is low, with uncorrected refractive error being the main cause in both children 30-47 and 48-72 months.