Biomedical subjects

Donald T H Tan

Publications and source records attributed to Donald T H Tan.

At least 19 recordsLinked to original sources

PubMed2006

Evaluation of keratoconus in Asians: role of Orbscan II and Tomey TMS-2 corneal topography.

PURPOSE: To evaluate the corneal topographic patterns of Asian patients with keratoconus (KC). DESIGN: Prospective observational case-control study. METHODS SETTING: Institutional. STUDY POPULATION: A total of 116 patients (both eyes included) with KC were recruited. The control group consisted of 70 laser in-situ keratomileusis (LASIK) candidates with myopia. Patients with previous ocular surgery and trauma were excluded. OBSERVATION PROCEDURE: Corneal topography was performed using the Tomey KC screening system (Topographic Modeling System, software version 2.4.2J, Tomey Corp, Nagoya, Japan) and Orbscan II corneal topography system (Bausch & Lomb Surgical, Orbtek Inc, Salt Lake City, Utah, USA). MAIN OUTCOME MEASURES: Videokeratographic variables were analyzed and the eyes were grouped into KC, KC suspect, and control groups. RESULTS: The corneal topographic patterns of 196 eyes were analyzed. The topographic patterns displayed by Tomey (TMS-2N) and Orbscan II were similar. The majority of eyes with KC (71.2%) and KC suspect (70%) had asymmetric bowtie patterns. Thirteen indices of TMS-2N were analyzed and the means of the indices were found to be significantly higher in eyes in the KC group than the KC suspect group (P < .001). Fourteen indices of Orbscan II were analyzed. Eyes in the KC suspect group had higher mean posterior elevation (46 +/- 17 microm), 3 mm irregularity (2.44 +/- 1.36 diopters [D]), 5 mm irregularity (2.61 +/- 1.19 D) and had thinner corneas (mean 504.4 +/- 40.4 microm) than normal eyes (26 +/- 8 microm, 1.05 +/- 0.37 D, 1.38 +/- 0.39 D, and 554.0 +/- 25.0 microm, respectively). CONCLUSION: Corneal topography pattern recognition combined with quantitative diagnostic indices is useful for the screening and classification of KC with the Orbscan II being more sensitive in screening for KC than TMS-2N.

Adolescent↗

PubMed2006

An outbreak of Fusarium keratitis associated with contact lens wear in Singapore.

CONTEXT: Fungal keratitis is a potentially blinding condition that is rarely seen with contact lens wear. OBJECTIVE: To describe a nationwide outbreak of fungal keratitis caused by Fusarium species among contact lens wearers in Singapore. DESIGN, SETTING, AND PATIENTS: Nationwide, hospital-based case series. All cases of fungal keratitis among contact lens wearers in all ophthalmology departments in Singapore were reviewed along with the charts of all contact lens wearers with culture-proven fungal keratitis from March 2005 through May 2006. A standardized telephone interview was conducted to obtain additional clinical information. MAIN OUTCOME MEASURE: Diagnosis of Fusarium keratitis associated with contact lens wear. RESULTS: During the study period, 66 patients (68 affected eyes) were diagnosed with Fusarium keratitis associated with contact lens wear; the estimated annual national incidence is 2.35 cases per 10,000 contact lens wearers (95% confidence interval, 0.62-7.22). Patients ranged in age from 13 to 44 years (mean [SD], 27.1 [8.4] years), of which 32 (48.5%) were men. The vast majority (65 patients; 98.5%) wore soft, disposable contact lenses; 62 patients (93.9%) reported using 1 brand of contact lens cleaning solution (ReNu, Bausch & Lomb, Rochester, NY), including 42 patients (63.6%) who recalled using ReNu with MoistureLoc. Most patients (81.8%) reported poor contact lens hygiene practices, including overnight use of daily wear contact lenses (19.7%), and use of contact lenses past the replacement date (43.9%). The final best-corrected visual acuity ranged from 20/20 to 20/80. Five patients (5 eyes; 7.4%) required emergency therapeutic or tectonic corneal transplantation. CONCLUSIONS: A new and evolving epidemic of Fusarium keratitis associated with contact lens wear was found in Singapore. Physicians and eye care practitioners worldwide need to be aware of the likelihood of similar outbreaks emerging among contact lens wearers.

Adolescent↗

PubMed2006

Mutations in sodium-borate cotransporter SLC4A11 cause recessive congenital hereditary endothelial dystrophy (CHED2).

Congenital hereditary endothelial dystrophy (CHED) is a heritable, bilateral corneal dystrophy characterized by corneal opacification and nystagmus. We describe seven different mutations in the SLC4A11 gene in ten families with autosomal recessive CHED. Mutations in SLC4A11, which encodes a membrane-bound sodium-borate cotransporter, cause loss of function of the protein either by blocking its membrane targeting or nonsense-mediated decay.

Amino Acid Substitution↗

PubMed2006

Inferior corneal decompensation following laser peripheral iridotomy in the superior iris.

PURPOSE: To describe a previously unreported clinical entity of inferior corneal decompensation occurring as a long-term complication of superior laser peripheral iridotomy. DESIGN: Retrospective, non-comparative observational case series. METHODS: Chart review of 14 subjects (16 eyes) with inferior corneal decompensation. RESULTS: All patients were Chinese, most were females (71.4%), and the mean age was 69.5 +/- 8.1 year. The mean interval from iridotomy to the onset of inferior corneal decompensation was 66.1 +/- 34.0 months. The most common indication for laser iridotomy was for prophylaxis, either in the fellow eye of acute angle closure (43.8%) or for occludable angles (12.5%). CONCLUSIONS: Corneal decompensation in the inferior part of the cornea at a site remote from the iridotomy is a rare but important complication of laser iridotomy. Because many of the laser iridotomies were performed prophylactically in eyes without glaucoma, patients may need to be warned of this risk.

Aged↗

PubMed2006

Evaluation of Orbscan II corneal topography in individuals with myopia.

PURPOSE: To evaluate Orbscan II (Bausch & Lomb, Orbtek Inc., Salt Lake City, UT) corneal topography in individuals with myopia. DESIGN: Retrospective, observational, consecutive, clinical case series. PARTICIPANTS: One hundred forty eyes of 70 persons with myopia. METHODS: Manifest refraction results and the Orbscan II corneal topographic maps were reviewed retrospectively. MAIN OUTCOME MEASURES: Refractive powers and the following test indices produced by Orbscan II were analyzed: anterior elevation best-fit sphere (BFS), posterior elevation BFS, maximum posterior elevation (Max PE), radius of Max PE, maximum keratometry, minimum keratometry, astigmatism, 3-mm irregularity, 3-mm mean power, 3-mm astigmatism, 5-mm irregularity, 5-mm mean power, 5-mm astigmatism, corneal diameter, pupil diameter, thinnest pachymetry, and anterior chamber depth. The correlations between right eyes and left eyes and between indices were explored. RESULTS: Of the 140 eyes, the mean manifest refraction was -5.27+/-2.19 diopters (D; range, -10.50 to 0.00 D), the mean Max PE was 28+/-7 mum, and the mean maximum keratometry was 44.5+/-1.5 D. Correlation coefficient analyses of Orbscan II quantitative indices combined with pattern recognition showed that there were high degrees of correlations between the right and left eyes of each individual patient. Maximum posterior elevation, corneal irregularity, and thinnest pachymetry did not vary with the degree of maximum keratometry. CONCLUSIONS: This article provides a detailed description and analysis of Orbscan II corneal topography of a normal population with myopia. This helps in establishing normal standards in Orbscan II corneal topography that will aid in preoperative assessment in refractive surgery.

Adult↗

PubMed2006

Modified automated lamellar therapeutic keratoplasty for keratoconus: a new technique.

PURPOSE: To describe a modified automated lamellar therapeutic keratoplasty (ALTK) technique for the treatment of keratoconus. METHODS: The ALTK procedure was modified to include the use of a Hanna trephine system to control donor and recipient diameters and was performed in 2 stages. The recipient corneal lamellar bed was first prepared by creating a laser in situ keratomileusis (LASIK) flap at a preset depth that was left to heal over. The second stage involved the use of a Hanna trephination system to perform central trephination within the lamellar flap and transplantation of a donor lamellar graft that was fashioned to precisely match the recipient corneal bed, again using the Hanna donor punch to create a central trephination within the lamellar button obtained with the ALTK unit. RESULTS: The modified ALTK procedure effectively treated a patient with moderate keratoconus with a best-corrected visual acuity of 20/80, despite rigid gas-permeable contact lenses. Postoperatively, there was a significant reduction in the irregular astigmatism, and visual acuity improved to 20/25. There were no complications, and the ALTK interface remained clear throughout the 20-month follow-up period. CONCLUSIONS: ALTK combined with Hanna trephination enables precise control of both depth and diameter of lamellar dissection during surgery, removes the need for any form of manual dissection, and may therefore improve optical and visual outcomes in lamellar keratoplasty.

Adult↗

PubMed2006

The development of a serum-free derived bioengineered conjunctival epithelial equivalent using an ultrathin poly(epsilon-caprolactone) membrane substrate.

PURPOSE: To evaluate the use of an ultrathin poly(epsilon-caprolactone) (PCL) membrane as a substrate for the development of a serum-free-derived conjunctival epithelial equivalent. METHODS: Ultrathin PCL membranes 6 microm in thickness were prepared by solvent casting and biaxial stretching and analyzed by atomic force microscopy (AFM), scanning electron microscopy (SEM), tensile testing, and water-contact angle measurement. Rabbit conjunctival epithelial cells were cultivated on sodium hydroxide (NaOH)-treated PCL membranes and untreated PCL membranes in serum-free medium. The proliferative capacity of cultivated cells was analyzed with a bromodeoxyuridine (BrdU) ELISA proliferation assay. Conjunctival equivalents were xenografted into severe combined immune-deficient (SCID) mice. Immunostaining for tissue-specific and basement membrane-related proteins was performed. RESULTS: After biaxial stretching, the tensile strength of PCL membranes increased from 21 to 42 MPa, with a Young's modulus of 225 MPa. AFM and SEM showed that biaxially stretched PCL membranes consisted of closely packed microfibrils. PCL membranes supported the attachment and proliferation of conjunctival epithelial cells to form confluent stratified epithelial sheets. Surface modification with NaOH resulted in greater hydrophilicity and cellular proliferation than that of untreated membranes. Transplanted conjunctival equivalents underwent greater proliferation and stratification in vivo. Cultivated conjunctival cells expressed K4, K19, MUC5AC, and Ki67, whereas collagen IV and integrin beta4 were detected at the basement membrane junction. CONCLUSIONS: An ultrathin PCL membrane was shown to be biocompatible, mechanically strong enough to stand up to handling, and able to support conjunctival epithelial cell proliferation. This membrane may have potential for use as a scaffold matrix for tissue-engineered conjunctival equivalents.

Amnion↗

PubMed2006

A cohort study of incident myopia in Singaporean children.

PURPOSE: To determine the risk factors of incident myopia in a school-based cohort study in Singaporean children. METHODS: A 3-year prospective cohort study was conducted in Singaporean school children aged 7 to 9 years in three schools at entry. Chinese children without myopia at baseline (n = 994) were included in the analysis. The main outcome was incident myopia, defined as spherical equivalent (SE) at least -0.75 D based on cycloplegic autorefraction. Other definitions of incident myopia, at least -0.5 D and at least -1.0 D, were also assessed. RESULTS: After controlling for school, age, gender, income, reading in books per week and intelligence quotient (IQ) test scores, we found the relative risk (RR) of incident myopia defined as -0.75 D to be 1.55 (95% confidence interval [CI] 1.18-2.04) for two versus no myopic parents. The multivariate RR of myopia for IQ in the third versus first tertile was 1.50 (95% CI, 1.19-1.89). However, the RR of incident myopia was 1.01 (95% CI, 0.97-1.05) for every unit increase in books read per week. Similar results were obtained with definitions of -0.5 and -1.0 D for incident myopia. CONCLUSIONS: These data provide new prospective evidence of essential links between parental myopia, IQ scores and subsequent myopia development. However, reading in books per week was not associated with incident myopia.

Child↗

PubMed2006

Myopia, axial length, and OCT characteristics of the macula in Singaporean children.

PURPOSE: The purpose of this study was to evaluate the associations between macular volume and thickness, as assessed by optic coherence tomography (OCT), with refraction and axial length (AL) in children. METHODS: A total of 104 Chinese school children (51 girls and 53 boys) 11 to 12 years of age were randomly selected from one school during the 2005 examination in the Singapore Cohort Study of the Risk Factors for Myopia (SCORM). Cycloplegic autorefraction was performed to obtain refraction (defined as spherical equivalent [SE]) and ultrasound biometry performed to obtain the AL. Macular volume and thickness were then measured (StratusOCT3; Carl Zeiss Meditec, Dublin, CA). RESULTS: Children with moderate myopia (SE at least -3.0 D) tended to have smaller total macular volume and thinner quadrant-specific macular thickness (except in the inferior and superior inner quadrants), followed by children with low myopia (-0.5 -0.5 D). Total macular volume was positively associated with SE (beta=1.58, 95% CI, 0.84 to 2.32, standardized beta=0.14, P<0.001) and negatively associated with AL (beta=-1.20, 95% CI, -1.62 to -0.79, standardized beta=0.45, P<0.001) in multiple linear regression models controlling for age and gender. CONCLUSIONS: In children, increasing axial myopia was associated with reduced macular volume and thickness. These findings suggest that early anatomic changes may be present in the retinas of children with axial myopia.

Anthropometry↗

PubMed2006

Higher order ocular aberrations in eyes with myopia in a Chinese population.

PURPOSE: To describe the characteristics of higher order ocular aberrations of adult Chinese eyes with myopia. METHODS: Higher order aberrations in consecutive right eyes of 166 Chinese patients with myopia who enrolled for preoperative assessment for LASIK were retrospectively reviewed. Wavefront aberrations were measured with the Bausch & Lomb Zywave over a 6-mm dilated pupil. The correlations between higher order aberrations and myopia, astigmatism, and age, respectively, were analyzed. RESULTS: Mean patient age was 32.1 +/- 6.2 years, the mean refractive error was sphere -5.23 +/- 1.79 diopters (D) and cylinder -1.29 +/- 0.98 D. The mean of the total higher order root-mean-square (RMS) (third to fifth order) was 0.49 +/- 0.16 microm. Third-order RMS was largest (mean 0.37 +/- 0.16 microm), followed by fourth-order RMS (mean 0.29 +/- 0.11 microm). For individual higher order Zernike coefficients, spherical aberration (C4(0)) predominated with a mean of 0.23 +/- 0.14 microm. No correlation was found between total higher order RMS and myopia or between total higher order RMS and age. Small but statistically significant relationships were found in the following groups: age and vertical primary coma (C3(-1))(r=-0.206, P=.008); age and spherical aberration (C4(0)) (r=0.196, P=.012); and myopia and horizontal trefoil (C3(3)) (r=-0.158, P=.042). CONCLUSIONS: Higher order aberrations varied among individuals with myopia. Third-order RMS was the predominant higher order aberration. Spherical aberration and vertical primary coma increased slightly with age. Our study helps establish ocular aberration standards for Chinese refractive surgery candidates.

Adult↗

PubMed2006

Enhancement of the mechanical and biological properties of a biomembrane for tissue engineering the ocular surface.

INTRODUCTION: In this study, we have developed and optimised a novel gelatin-chitosan (GC) substrate for use as a cellular carrier for tissue-engineered conjunctival epithelium. MATERIALS AND METHODS: The substrate was fabricated by casting and the mechanical properties of the substrate, including tensile strength and elongation, were measured. Using the MTT, cell proliferation assay with rabbit conjunctival fibroblasts, we optimised the G:C ratio to enhance cytocompatibility. Rabbit conjunctival epithelial cells were immunostained using monoclonal antibodies for keratin 4 and pancytokeratin to investigate the biological effects of the GC substrate on the proliferation and differentiation of epithelial cells. RESULTS: We found that increasing the amount of gelatin resulted in an increase in elasticity (from 1:9 to 1:1 ratio), reaching a maximum (101.89% +/- 7.13%) at a ratio of 1:1. The MTT assay showed that the proliferation of conjunctival fibroblasts significantly increased from 0.068 +/- 0.017 to 0.177 +/- 0.011 (P = 0.014) as the gelatin was increased from 20% (1:4) to 50% (1:1). Additional studies using tissue-cultured conjunctiva explants showed that these explants grew well on the substrate, forming a multilayered epithelium. Cell morphology on this substrate was similar to that of cells grown on culture dishes alone. Positive staining of keratin 4 and pancytokeratin indicated that the substrate supported normal differentiation of conjunctival epithelial cells. CONCLUSION: By enhancing the proportion of gelatin, both the mechanical and biological properties of the chitosan substrate were improved. The results also suggest that this GC biomembrane may be a useful candidate for reconstructive tissue engineering of the conjunctiva.

Animals↗

PubMed2006

Characterisation of human tear proteins using high-resolution mass spectrometry.

INTRODUCTION: The proteins found in tears play an important role in maintaining the ocular surface and changes in tear protein components may reflect changes in the health of the ocular surface. Proteomics provides a comprehensive approach for cataloguing all the proteins of the tear proteome, which will help to elucidate disease pathogenesis, make clinical diagnoses and evaluate the influence of medications on the structure, composition and secretion of tear proteins. In this study, an alternative proteomic strategy was investigated to explore the human tear proteome. MATERIALS AND METHODS: Tear samples were obtained from patients who had pterygium and were collected on the first day and third day after pterygium surgery. Tears pooled from 6 patients were used in the analysis. Reverse-phase high-pressure liquid chromatograph (RPHPLC) was used as the first step to separate intact proteins into 21 peaks. Each fraction was then tryptic-digested and analysed by nanoLC-nano-ESI-MS/MS to characterise the protein components in each fraction. RESULTS: In total, 60 tear proteins were identified with high confidence, including well-known abundant tear proteins, and tear-specific proteins such as lacritin and proline-rich proteins. Among them, proline-rich protein 5 was found for the first time in tear fluid. A large number of plasma proteins were also observed in tear fluid. CONCLUSIONS: The results showed that the proteomic strategy used in this study was successfully applied to analyse tear proteome.

Eye Proteins↗

PubMed2005

Autologous cultivated conjunctival transplantation for pterygium surgery.

PURPOSE: To investigate the safety and efficacy of autologous cultivated conjunctival transplantation for the treatment of primary pterygium. DESIGN: Prospective nonrandomized clinical trial. METHODS: Forty patients with primary pterygium were recruited. Excision of the pterygium was followed by reconstruction using a serum-free derived autologous cultivated conjunctival equivalent in 22 patients (group A) and conventional denuded amniotic membrane transplantation in 18 patients (group B). In group A patients, conjunctival epithelial equivalents were constructed by the ex vivo expansion of conjunctival epithelial cells on human amniotic membranes (HAM). The main outcome measures were conjunctival epithelialization, recurrence, survival analysis, and incidence of complications. RESULTS: The mean follow-up was 14.1 +/- 3.9 months (range, 12 to 25 months). Complete epithelialization was achieved within five days after surgery in group A patients compared with approximately three weeks for group B patients. The proportion of patients that had true recurrences was 22.7% in group A and 25.0% in group B. The mean time to recurrence was 4.8 +/- 1.6 months in group A and 5.0 +/- 2.9 months in group B. No ocular complications were noted in group A, while one eye (6.0%) in group B developed scleral necrosis associated with a persistent epithelial defect. CONCLUSIONS: Transplantation of an autologous cultivated conjunctival epithelial sheet facilitated early postoperative epithelialization and recovery, and may aid in preventing serious complications associated with simple denuded HAM transplantation, such as scleral necrosis and secondary infection. This may provide a novel method for conjunctival epithelial replacement in the treatment of ocular surface disorders.

Adult↗

PubMed2005

Autologous cultivated conjunctival transplantation for recurrent viral papillomata.

PURPOSE: To describe the use of an autologous serum-free derived cultivated conjunctival epithelial equivalent in the treatment of extensive recurrent viral papillomata. DESIGN: Interventional case report. METHODS: A 10-year-old child with extensive recurrent viral papillomata involving the superior and inferior tarsal, forniceal, and bulbar conjunctiva underwent surgical excision of all diseased areas and double freeze-thaw cryotherapy. Autologous serum-free cultivated conjunctival equivalents were used to reconstruct the ocular surface and conjunctival fornices. RESULTS: Almost complete epithelialization was achieved within 5 days postoperatively. A good cosmetic and functional result was obtained, and no recurrences or cicatricial complications developed during 12-month follow-up. CONCLUSION: Transplantation of autologous cultivated conjunctiva was effectively used in the reconstruction of the ocular surface after extensive excision of recurrent viral papillomata. This modality of treatment may be useful in the treatment of ocular surface disorders in which extensive conjunctival and fornix reconstruction is required.

Amnion↗

PubMed2005

Prevalence and causes of amblyopia in a population-based study of young adult men in Singapore.

PURPOSE: To determine the prevalence and causes of amblyopia in young adult Chinese, Indian, and Malay men in Singapore. DESIGN: A population-based cross-sectional study. METHODS: Best-corrected visual acuities of all Singaporean men born in the years 1978 to 1983 were measured before enlistment into military service. Those with BCVA of 6/12 or worse were examined by an ophthalmologist for the presence of amblyopia and other causes. RESULTS: Of the 122,596 men examined, there were 428 with amblyopia, an overall prevalence of 0.35%. The prevalence was similar among Chinese (0.34%), Malays (0.37%), and Indians (0.41%, P = .52). Anisometropic amblyopia was the most common type of amblyopia and strabismic amblyopia was more common in Indians. There were little racial differences in the prevalence of meridional or form deprivation amblyopia. CONCLUSION: The overall prevalence of amblyopia was low and was similar among the three racial groups in young adult Singaporean males.

Adolescent↗

PubMed2005

One-year multicenter, double-masked, placebo-controlled, parallel safety and efficacy study of 2% pirenzepine ophthalmic gel in children with myopia.

OBJECTIVE: To evaluate the safety and efficacy of the relatively selective M(1)-antagonist, pirenzepine ophthalmic gel (gel), in slowing the progression of myopia in school-aged children. DESIGN: Parallel-group, placebo-controlled, randomized, double-masked study. PARTICIPANTS: Three hundred fifty-three healthy children, 6 to 12 years old, with a spherical equivalent (SE) of -0.75 to -4.00 diopters (D) and astigmatism of <or=1.00 D. Subjects underwent a baseline complete eye examination, and regular examinations over a 1-year period. The study was conducted at 7 academic centers and clinical practices in Asia. INTERVENTION: Subjects received 2% gel twice daily (gel/gel), 2% gel daily (evening, placebo/gel), or vehicle twice daily (placebo/placebo) in a 2:2:1 ratio, respectively, for 1 year. MAIN OUTCOME MEASURE: Spherical equivalent under cycloplegic refraction. RESULTS: At study entry, mean SE refraction was -2.4+/-0.9 D. At 12 months, there was a mean increase in myopia of 0.47 D, 0.70 D, and 0.84 D in the gel/gel, placebo/gel, and placebo/placebo groups, respectively (P<0.001 for gel/gel vs. placebo/placebo). Discontinued from the study for adverse events were 11% (31/282) of pirenzepine-treated subjects. Of the 15 serious adverse events reported in 12 subjects (all in the active groups), none was ophthalmic in nature, all subjects recovered, and only 1 (abdominal colic preceded by a flu) was judged possibly related to treatment. CONCLUSIONS: Gel (2% twice daily) was effective and relatively safe in slowing the progression of myopia over a 1-year treatment period.

Adolescent↗

PubMed2005

Compressive C-shaped lamellar keratoplasty: a surgical alternative for the management of severe astigmatism from peripheral corneal degeneration.

OBJECTIVE: To describe a compressive lamellar surgical technique for treating severe astigmatism in peripheral corneal ectasia. DESIGN: Retrospective, noncomparative, interventional case series. PARTICIPANTS: Four eyes of 3 patients with either pellucid or Terrien's marginal corneal degeneration were included in this series. METHODS: C-shaped lamellar keratoplasty using multiple trephines of different sizes, with deliberate undersizing of the donor graft for a controlled compressive effect, was performed on these patients. MAIN OUTCOME MEASURES: Visual acuity outcome and refraction were measured at different intervals at up to 40 months of follow-up. RESULTS: All eyes achieved Snellen visual acuity of 20/40 or better and stable astigmatism ranging from 0 to -2.75 diopter cylinder within 6 months, with no recurrence of corneal thinning or peripheral corneal vascularization. CONCLUSIONS: Compressive C-shaped lamellar keratoplasty is able to reduce severe corneal astigmatism in peripheral corneal ectasia and can result in good visual and refractive outcomes with early visual rehabilitation.

Astigmatism↗

PubMed2005

Incidence and progression of myopia in Singaporean school children.

PURPOSE: To determine the incidence and progression rates of myopia in young Singaporean children. METHODS: A prospective cohort study, the Singapore Cohort Study of the Risk Factors for Myopia (SCORM), was conducted in two schools in Singapore (1999-2002). Children aged 7 to 9 years (n=981) were followed up over a 3-year period. Cycloplegic autorefraction and biometry parameter measures were performed annually, according to the same protocol. RESULTS: The 3-year cumulative incidence rates were 47.7% (95% confidence interval [CI]: 42.2-53.3), 38.4% (95% CI: 31.4-45.4), and 32.4% (95% CI: 21.8-43.1) for 7-, 8-, and 9-year-old children, respectively. The 3-year cumulative incidence rates were higher in Chinese (49.5% vs. 27.2%) and in 7-year-old compared with 9-year-old children at baseline (47.7% vs. 32.4%), though the latter relationship was of borderline significance after adjustment for race, gender, amount of reading (books/week), and parental myopia (P=0.057). Premyopic children with greater axial lengths, vitreous chamber depths, and thinner lenses were more prone to the development of myopia, after controlling for age, gender, race, reading, and parental myopia. The 3-year mean cumulative myopia progression rates were -2.40 D (95% CI: -2.57 to -2.22) in 7-year-old myopic children, -1.97 (95% CI: -2.16 to -1.78) in 8-year-olds, and -1.71 (95% CI: -1.98 to -1.44) in 9-year-olds. CONCLUSIONS: Both the incidence and progression rates of myopia are high in Singaporean children.

Age Distribution↗