Dana Robaei

Ethnic differences in refraction and ocular biometry in a population-based sample of 11-15-year-old Australian children

PurposeTo examine the prevalence of refractive error and distribution of ocular biometric parameters among major ethnic groups in a population-based sample of 11–15-year-old Australian children.MethodsThe Sydney Myopia Study examined 2353 students (75.3% response) from a random cluster-sample of 21 secondary schools across Sydney. Examinations included cycloplegic autorefraction, and measures of corneal radius of curvature, anterior chamber depth, and axial length.ResultsParticipants mean age was 12.7 years (range 11.1–14.4); 49.4% were female. Overall, 60.0% of children had European Caucasian ethnicity, 15.0% East Asian, 7.1% Middle Eastern, and 5.5% South Asian. The most frequent refractive error was mild hyperopia (59.4%, 95% confidence interval (CI), 53.2–65.6), defined as spherical equivalent (SE) +0.50 to +1.99 D. Myopia (SE−0.50 D or less) was found in 11.9%, 95% (CI 6.6–17.2), and moderate hyperopia (SE⩾+2.00 D) in 3.5%, 95% (CI 2.8–4.1). Myopia prevalence was lower among European Caucasian children (4.6%, 95% CI 3.1–6.1) and Middle Eastern children (6.1%, 95% CI 1.3–11.0) than among East Asian (39.5%, 95%, CI 25.6–53.5) and South Asian (31.5%, 95%, CI 21.6–41.4) children. European Caucasian children had the most hyperopic mean SE (+0.82 D) and shortest mean axial length (23.23 mm). East Asian children had the most myopic mean SE (−0.69 D) and greatest mean axial length (23.86 mm).ConclusionThe overall myopia prevalence in this sample was lower than in recent similar-aged European Caucasian population samples. East Asian children in our sample had both a higher prevalence of myopia and longer mean axial length.

Evidence of Arteriolar Narrowing in Low-Birth-Weight Children

Background— Cardiovascular disease may have its origins in utero, but the influence of in utero growth on microvascular structure in children is unknown. We hypothesized that poor in utero growth is associated with narrower arteriolar caliber, which may help explain the established association of low birth weight with hypertension and cardiovascular disease in adulthood. Methods and Results— We examined the relation of birth weight and other markers of in utero growth to microvascular caliber in the retina in a population-based study of 1369 6-year-old children in Sydney, Australia (Sydney Childhood Eye Study). Birth weight, birth length, and head circumference were obtained from parental records. Retinal arteriolar and venular calibers were measured from digitized retinal photographs by a validated computer-assisted method. Lower birth weight, shorter birth length, and smaller head circumference were associated with narrower retinal arteriolar caliber. Each kilogram decrease in birth weight was associated with a 2.3-&mgr;m (95% CI 0.6 to 3.9, P=0.01) narrower retinal arteriolar caliber after controlling for age, gender, ethnicity, height, body mass index, axial length, mean arterial blood pressure, and prematurity. Similar associations were observed between shorter birth length and smaller head circumference with narrower retinal arteriolar caliber. Conclusions— Children who had lower birth weight, shorter birth length, and smaller head circumference had narrower retinal arteriolar calibers. These data support the concept that poor in utero growth may have an adverse influence on microvascular structure.

Prevalence and associations of anisometropia and aniso-astigmatism in a population based sample of 6 year old children

Aim: To study the distribution of anisometropia and aniso-astigmatism in young Australian children, together with clinical and ocular biometry relations. Method: The Sydney Myopia Study examined 1765 predominantly 6 year old children from 34 randomly selected Sydney schools during 2003–4. Keratometry, cycloplegic autorefraction, and questionnaire data were collected. Results: Spherical equivalent (SE) anisometropia (⩾1 dioptre) prevalence was 1.6% (95% confidence interval (CI) 1.1% to 2.4%). Aniso-astigmatism (⩾1D) prevalence was 1.0% (CI: 0.6% to 1.6%). Both conditions were significantly more prevalent among moderately hyperopic (SE ⩾2.0D) than mildly hyperopic (SE 0.5–1.9D) children. Myopic children (SE ⩽−0.5D) had higher anisometropia prevalence. Neither condition varied by age, sex, or ethnicity. In multivariate analyses, anisometropia was significantly associated with amblyopia, odds ratio (OR) 29, (CI: 8.7 to 99), exotropia (OR 7.7, CI: 1.2 to 50), and neonatal intensive care unit (NICU) admission (OR 3.6, CI: 1.1 to 12.6). Aniso-astigmatism was significantly associated with amblyopia (OR 8.2, CI: 1.4 to 47), maternal age >35 years (OR 4.0, CI: 1.3 to 11.9), and NICU admission (OR 4.6, CI: 1.2 to 17.2). Anisometropia resulted from relatively large interocular differences in axial length (p<0.0001) and anterior chamber depth (p = 0.0009). Aniso-astigmatism resulted from differences in corneal astigmatism (p<0.0001). Conclusion: In this predominantly 6 year old population, anisometropia and aniso-astigmatism were uncommon, had important birth and biometry associations, and were strongly related to amblyopia and strabismus.

Socio-economic, familial and perinatal factors associated with obesity in Sydney schoolchildren.

Aim:  To examine associations between socio‐economic, familial and perinatal factors with overweight/obesity in 6‐ and 12‐year‐old schoolchildren.

The impact of topical corticosteroid use before diagnosis on the outcome of Acanthamoeba keratitis.

OBJECTIVE To examine the impact of topical corticosteroid use before the diagnosis of Acanthamoeba keratitis (AK) on final visual outcomes and to determine the prognostic factors predicting poorer outcomes. DESIGN Cohort study. PARTICIPANTS A total of 209 eyes of 196 patients with retrievable medical records, diagnosed with AK at Moorfields Eye Hospital, London, between January 1991 and April 2012. One eye was randomly excluded from analysis in the 13 cases of bilateral AK. METHODS Patient demographic, initial clinical examination findings, and management details were collected. The outcomes of patients treated with topical corticosteroids before diagnosis of AK were compared with those not treated with topical corticosteroids before diagnosis. A multivariable logistic model, optimized for prior corticosteroid use, was used to derive the odds ratios (ORs) of a suboptimal visual outcome. MAIN OUTCOME MEASURES Suboptimal visual outcome was defined as final visual acuity (VA) ≤ 20/80, corneal perforation, or need for keratoplasty. RESULTS Acanthamoeba keratitis was diagnosed on microbiological culture in 94 eyes (48.0%), on histopathologic examination in 27 eyes (13.8%), on confocal microscopy in 38 eyes (19.4%), and on the basis of a typical clinical course and response to treatment in 37 eyes (18.9%). Final VA and prior corticosteroid use data were available for 174 eyes (88.8%). In multivariable analysis, corticosteroid use before diagnosis was associated with suboptimal visual outcome (OR, 3.90; 95% confidence interval [CI], 1.78-8.55), as were disease stage 3 at presentation (OR, 5.62; 95% CI, 1.59-19.80) and older age (60+ years) at diagnosis (OR, 8.97; 95% CI, 2.13-37.79). CONCLUSIONS Corticosteroid use before diagnosis of AK is highly predictive of a poorer visual outcome. This is largely due to the initial misdiagnosis of AK as herpetic keratitis. It is important to include AK in the differential diagnosis of keratitis in all contact lens users with keratitis, particularly before making a diagnosis of herpes keratitis and before the use of topical corticosteroids in the therapy of any indolent keratitis.

Therapeutic and Optical Keratoplasty in the Management of Acanthamoeba Keratitis : Risk Factors, Outcomes, and Summary of the Literature

OBJECTIVE To report the risk factors for and outcomes of therapeutic and optical keratoplasty in the management of Acanthamoeba keratitis (AK). DESIGN Retrospective case series. PARTICIPANTS A total of 50 eyes of 196 patients with retrievable medical records, diagnosed with AK at Moorfields Eye Hospital, London, underwent keratoplasty between January 1991 and April 2012. METHODS Patient demographics, initial clinical examination findings, and management details were collected. The ophthalmic characteristics of patients who underwent keratoplasty for AK were compared with those who did not. Patients undergoing therapeutic keratoplasty were compared with those undergoing optical keratoplasty for baseline characteristics, management details, and visual outcomes. A multivariate logistic model was used to derive the odds ratios of a poor visual outcome in all keratoplasty patients. MAIN OUTCOME MEASURES Poor visual outcome was defined as final visual acuity of 20/200 or worse. Secondary outcomes of interest included number of clinic visits and the need for additional intraocular surgery. RESULTS Of the 196 AK patients, a total of 50 patients (25.5%) underwent penetrating or anterior lamellar keratoplasty, 10 of whom (20%) underwent repeat procedures. Of these 50 patients, 26 (52%) had therapeutic keratoplasty, predominantly for corneal perforation. The remaining 24 patients (48%) underwent optical keratoplasty for visual rehabilitation. Thirty-seven (80.4%) patients in the keratoplasty group initially were misdiagnosed as having herpes simplex keratitis versus 59 (41.8%) patients who did not require a keratoplasty (P < 0.001). Final visual outcomes were significantly better in the optical group compared with the therapeutic group, with 13 (54.2%) achieving visual acuity of 20/30 or better versus 7 (26.9%), respectively. On multivariate analysis, beginning therapy at a hospital other than Moorfields and undergoing a therapeutic, rather than an optical, keratoplasty were associated significantly with a poor visual outcome from keratoplasty. CONCLUSIONS The prognosis of keratoplasty differs markedly when performed for therapeutic purposes compared with visual rehabilitation. Where possible, keratoplasty should be delayed until such time as the eye is uninflamed and medically cured of Acanthamoeba.

Corneal blindness: a global problem.

Corneal blindness is an important, yet underreported cause of avoidable visual impairment worldwide, especially in developing countries. The World Health Organisation (WHO) estimates that corneal opacities (including trachoma) accounted for 7% of the world’s blind population in 2010, making it the 3rd most common cause of blindness. Although cataracts and glaucoma (in the elderly) are more common causes of visual impairment, corneal blindness affects all age groups and is a leading cause of irreversible visual impairment. An eye blind from scarring and vascularisation of the cornea, usually remains blind for life. In this issue of Clinical and Experimental Ophthalmology, Wang et al. present findings on corneal blindness from a large, population-based study of visual impairment in rural Heilong-Jiang province, China. Although there are numerous population-based studies detailing the major causes of blindness and low vision in both the developed and developing world, few published reports have thus far attempted to detail the different causes of corneal blindness. Rapoza et al. reported corneal infections (including trachoma) to be the leading cause of unilateral and bilateral corneal blindness in Central Tanzania, followed by vitamin A deficiency and measles. Unilateral corneal opacification had similar causes, with the important addition of trauma. Bowman et al. replicated these results in a population-based study in Gambia. Wang et al. here present findings on a large sample of 10 384 participants, representative of the rural Northern Chinese population, with a high overall response rate of 88.1%. Blindness was defined according to WHO criteria as a visual acuity of less than 3/60. All respondents underwent a screening examination, including measurement of best-corrected visual acuity (BCVA). Those achieving BCVA < 6/18 were subsequently referred for a more detailed examination. Although anterior segment examination was performed with a slit-lamp biomicroscope, fundus examination was carried with a hand-held ophthalmoscope only, without pupillary dilatation. This may have resulted in misclassification of the cause of blindness in a proportion of patients. Despite this shortcoming, the study presents some important findings. First, the majority (40%) of corneal blindness in this sample was acquired in childhood. Second, trauma (an entirely avoidable) cause of corneal blindness accounted for a third of all cases. Corneal opacification is the 3rd commonest cause of childhood blindness worldwide, after non-corneal causes such as congenital cataract and glaucoma. Unlike trachomatous corneal opacification, which results from repeated episodes of trachoma infection, corneal blindness in childhood is often due to a single episode of infection, such as ophthalmia neonatarum resulting from Neisseria gonorrhoea and Chlamydia trachomatis infections acquired from the mother’s genital tract at birth. During infancy and childhood, measles is another important cause of corneal blindness in the developing world, the impact of which is mediated through multiple mechanisms, including induction of acute vitamin A deficiency, measles keratitis, secondary bacterial or herpetic keratitis as well as the use of harmful traditional medicines. The WHO has ranked trachoma, corneal opacities, as well as childhood blindness, as priority eye diseases. Blind children have a lifetime of increased morbidity ahead of them. In addition, that lifetime can be very short, with up to 60% of blind children dying within 1 year of becoming blind. In this issue, Wang et al. report trauma as the second most common cause of corneal blindness in their population. In fact, corneal ulceration in developing countries is now considered a ‘silent epidemic’. Superficial corneal injuries from agriculture or domestic incidents led to blinding corneal ulceration due to delayed presentation and treatment. Indeed, in the developing world the majority of corneal ulcerations are the result of minor trauma and foreign bodies. This highlights the importance of public health education programs, targeting highrisk populations such as males, farmers and people with lower education. These programmes need to emphasize the importance of workplace safety, and timely hospitalization for corneal ulceration. In a previous study, also from China, Zhang and Wu demonstrated a lack of knowledge and awareness

Impact of amblyopia on vision at age 12 years: findings from a population-based study

AimsTo report prevalence of amblyopia and long-term impact of its treatment on vision in a population-based sample of 12-year-old Australian children.MethodsLogarithm of minimum angle of resolution (logMAR) visual acuity (VA) was measured in 2353 children (response rate 75.3%); visual impairment was defined as VA<6/12. Amblyopia was defined using various criteria of best-corrected VA, together with an amblyogenic factor and absence of significant organic pathology. Corroborative historical data on previous diagnosis and treatment were obtained from parental questionnaires.ResultsForty-four children (1.9%) were diagnosed with amblyopia, unilateral in 40 and bilateral in four. Isolated anisometropia was the most frequent cause (41%), followed by strabismus (25%), combined anisometropia and strabismus (23%), and high ametropia (9%). Myopia, hyperopia, and astigmatism were present in 28, 51, and 44% of amblyopic children, respectively, compared to 12, 4, and 9% of non-amblyopic children. Mean best-corrected VA in amblyopic eyes was 44.5 logMAR letters (Snellen equivalent 6/9), range: 11–60 letters. Most children with amblyopia (84%) had been treated. Only 27% were visually impaired in their amblyopic eye.ConclusionsThis report documents a low amblyopia prevalence in a population of 12-year-old Australian children. Amblyopic visual impairment was infrequent in this sample despite absence of mandatory vision screening.

The Impact of Topical Corticosteroids Used in Conjunction with Antiamoebic Therapy on the Outcome of Acanthamoeba Keratitis

PURPOSE To examine the impact of topical corticosteroid use after the start of antiamoebic therapy (AAT) on the outcomes of Acanthamoeba keratitis (AK) therapy. DESIGN Cohort study. PARTICIPANTS A total of 196 patients diagnosed with AK at Moorfields Eye Hospital, London, between January 1991 and April 2012. In 13 patients with bilateral AK, 1 eye was randomly excluded from analysis. METHODS Patient demographics and clinical examination findings were collected both at the start of AAT and subsequently at the time that topical corticosteroid therapy was initiated. Preliminary a priori investigations were used to identify effect modifiers/confounders and extreme associations requiring consideration in multivariate regression modeling. A multivariable logistic model, optimized for assessment of corticosteroid use after the start of AAT, was used to estimate the odds ratios (ORs) of a suboptimal outcome. MAIN OUTCOME MEASURES Suboptimal outcome was defined as final visual acuity ≤20/80, corneal perforation, or the need for keratoplasty. RESULTS In multivariable analysis, restricted to 129 eyes (1 eye per patient) free of scleritis and hypopyon at the start of AAT, topical corticosteroids were not associated with worse outcomes (OR, 1.08; 95% confidence interval [CI], 0.39-3.03), even when corticosteroids had been used before the start of AAT. Risk factors significantly associated with worse outcomes were topical corticosteroid use before the start of AAT (OR, 3.85; 95% CI, 1.35-11.03), a corneal ring infiltrate (together with at least 1 other feature of AK) present at the start of AAT (OR, 5.89; 95% CI, 1.17-29.67), and age ≥33 years at the start of AAT (OR, 4.02; 95% CI, 1.46-11.06). CONCLUSIONS Many corneal specialists currently are uncertain about the risk benefit associated with the use of topical corticosteroids for the management of inflammatory complications of AK. The evidence from this study gives clinicians and patients reassurance that the potential benefits of topical corticosteroid therapy, for treating pain and discomfort, are not associated with worse outcomes when initiated after starting modern AAT. Other potential benefits, in terms of resolution of inflammatory complications, will not be demonstrated without a carefully designed randomized clinical trial.

Can Information on the Purpose of Spectacle Use and Age at First Use Predict Refractive Error Type

Purpose: To assess the sensitivity and specificity of predicting refractive error type using information from a four-item questionnaire on the purpose of spectacle use and age at first use. Methods: The Sydney Myopia Study examined 1,740 year 1 (78.9% response) and 2,353 year 7 students (75.3% response) from a random cluster sample of 34 primary and 21 secondary schools across Sydney. Parents of participants completed a four-item questionnaire that sought data on parental spectacle use, age at first use, and purpose of use (for clear distant vision, close work, or both). Prescriptions were obtained for 720 of 3,209 (22%) parents (73% of those approached) for validation. A receiver operating characteristic (ROC) curve was used to determine the optimal cutoff age for spectacle use in myopia classification. Results: Using the ROC curve, a cutoff age of 30 years at first spectacle use produced the highest accuracy in determining myopia. We combined information on the purpose for using spectacles (for distant and near vision) and age of first use at 30 years or younger to determine myopia, otherwise hyperopia. Validated against prescriptions, the sensitivity and specificity of these predictions were 0.89 and 0.83, respectively, for myopia. The specificity was 0.92 for hyperopia and 0.80 for astigmatism, though corresponding sensitivities were lower at 0.23 and 0.46, respectively. Conclusions: In a sample of the parents of Sydney Myopia Study participants, information on the purpose of spectacle use with an age-at-first-use criterion can identify myopic refractive error with reasonable sensitivity and specificity. This four-item questionnaire may assist future epidemiological studies of screening for myopia.