Wei-Han Chua

Myopia and associated pathological complications.

Besides the direct economic and social burden of myopia, associated ocular complications may lead to substantial visual loss. In several population and clinic‐based cohorts, case–control and cross‐sectional studies, higher risks of posterior subcapsular cataract, cortical and nuclear cataract in myopic patients were reported. Patients with high myopia (spherical equivalent at least –6.0 D) are more susceptible to ocular abnormalities. The prevalent risks of glaucoma were higher in myopic adults, and risks of chorioretinal abnormalities such as retinal detachment, chorioretinal atrophy and lacquer cracks increased with severity of myopia and greater axial length. Myopic adults were more likely to have tilted, rotated, and larger discs as well as other optic disc abnormalities. Often, these studies support possible associations between myopia and specific ocular complications, but we cannot infer causality because of limitations in study methodology. The detection and treatment of possible pathological ocular complications is essential in the management of high myopia. The ocular risks associated with myopia should not be underestimated and there is a public health need to prevent the onset or progression of myopia.

Atropine for the treatment of childhood myopia: safety and efficacy of 0.5%, 0.1%, and 0.01% doses (Atropine for the Treatment of Myopia 2).

PURPOSE Our previous study, Atropine for the Treatment of Myopia 1 (ATOM1), showed that atropine 1% eyedrops were effective in controlling myopic progression but with visual side effects resulting from cycloplegia and mydriasis. The aim of this study was to compare efficacy and visual side effects of 3 lower doses of atropine: 0.5%, 0.1%, and 0.01%. DESIGN Single-center, double-masked, randomized study. PARTICIPANTS A total of 400 children aged 6-12 years with myopia of at least -2.0 diopters (D) and astigmatism of -1.50 D or less. INTERVENTION Children were randomly assigned in a 2:2:1 ratio to 0.5%, 0.1%, and 0.01% atropine to be administered once nightly to both eyes for 2 years. Cycloplegic refraction, axial length, accommodation amplitude, pupil diameter, and visual acuity were noted at baseline, 2 weeks, and then every 4 months for 2 years. MAIN OUTCOME MEASURES Myopia progression at 2 years. Changes were noted and differences between groups were compared using the Huber-White robust standard error to allow for data clustering of 2 eyes per person. RESULTS The mean myopia progression at 2 years was -0.30±0.60, -0.38±0.60, and -0.49±0.63 D in the atropine 0.5%, 0.1%, and 0.01% groups, respectively (P=0.02 between the 0.01% and 0.5% groups; between other concentrations P > 0.05). In comparison, myopia progression in ATOM1 was -1.20±0.69 D in the placebo group and -0.28±0.92 D in the atropine 1% group. The mean increase in axial length was 0.27±0.25, 0.28±0.28, and 0.41±0.32 mm in the 0.5%, 0.1%, and 0.01% groups, respectively (P < 0.01 between the 0.01% and 0.1% groups and between the 0.01% and 0.5% groups). However, differences in myopia progression (0.19 D) and axial length change (0.14 mm) between groups were small and clinically insignificant. Atropine 0.01% had a negligible effect on accommodation and pupil size, and no effect on near visual acuity. Allergic conjunctivitis and dermatitis were the most common adverse effect noted, with 16 cases in the 0.1% and 0.5% atropine groups, and no cases in the 0.01% group. CONCLUSIONS Atropine 0.01% has minimal side effects compared with atropine at 0.1% and 0.5%, and retains comparable efficacy in controlling myopia progression.

Atropine for the Treatment of Childhood Myopia: Effect on Myopia Progression after Cessation of Atropine

PURPOSE The aim of this study was to assess the effect on myopia progression after cessation of topical atropine treatment. DESIGN Parallel-group, placebo-controlled, randomized, double-masked study. PARTICIPANTS Four hundred children aged 6 to 12 years with refractive error of spherical equivalent -1.00 to -6.00 diopters (D) and astigmatism of -1.50 D or less. INTERVENTION No intervention was administered. Subjects were followed up for 12 months after stopping treatment, which consisted of either 1% atropine or vehicle eyedrops once nightly for 2 years. Only 1 eye of each subject was chosen through randomization for treatment. MAIN OUTCOME MEASURES The main efficacy outcome measures were change in spherical equivalent refraction as measured by cycloplegic autorefraction and change in ocular axial length as measured by ultrasonography. RESULTS After cessation of atropine drops, the mean progression in the atropine-treated group was -1.14+/-0.80 D over 1 year, whereas the progression in placebo-treated eyes was -0.38+/-0.39 D (P<0.0001). However, after 3 years of participation in the trial (with 2 years on atropine treatment), eyes randomized to atropine have less severe myopia than other eyes. Spherical equivalent was -4.29+/-1.67 D in the atropine-treated eyes compared with -5.22+/-1.38 D in the placebo-treated eyes (P<0.0001). Spherical equivalents in atropine-untreated and placebo-untreated eyes were -5.00+/-1.62 D and -5.28+/-1.43 D, respectively. Over the 3 years, the increase in axial length of the atropine-treated eyes was 0.29+/-0.37 mm compared with 0.52+/-0.45 mm in the placebo-treated eyes (P<0.0001). After cessation of atropine, the amplitude of accommodation and near visual acuity returned to pretreatment levels. CONCLUSIONS After stopping treatment, eyes treated with atropine demonstrated higher rates of myopia progression compared with eyes treated with placebo. However, the absolute myopia progression after 3 years was significantly lower in the atropine group compared with placebo.

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.

Atropine for the Treatment of Childhood Myopia: Changes after Stopping Atropine 0.01%, 0.1% and 0.5%

PURPOSE To study the change in spherical equivalent and other ocular parameters 1 year after stopping the administration of atropine. DESIGN Prospective randomized double-masked clinical trial. METHODS We assigned 400 myopic children, 6 to 12 years of age, to receive atropine 0.5%, 0.1% or 0.01% for 24 months, after which medication was stopped. Parents and children gave informed consent to participate in the research. Children were reviewed at 26, 32 and 36 months, and changes in cycloplegic spherical equivalent (SE), axial length (AL), visual acuity, pupil size, and accommodation were assessed. RESULTS Of the children, 356 (89%) entered into the washout phase. At entry, there was no significant difference in age, gender, SE, or AL among the children in the various atropine groups. Over the following 12 months, myopic progression was greater in the 0.5% eyes (-0.87 ± 0.52 D), compared to the 0.1% (-0.68 ± 0.45 D) and 0.01% eyes (-0.28 ± 0.33 D, P < 0.001). AL growth was also greater in the 0.5% (0.35 ± 0.20 mm) and 0.1% (0.33 ± 0.18 mm) eyes, compared to the 0.01% eyes (0.19 ± 0.13 mm, P < 0.001). Pupil size and near visual acuity returned to pre-atropine levels in all groups, but accommodation at 36 months was less in the 0.5% eyes (13.24 ± 2.72 D) compared to the 0.1% (14.45 ± 2.61 D) and 0.01% eyes (14.04 ± 2.90 D, P < 0.001). The overall increase in SE over the entire 36 months in the 0.5%, 0.1% and 0.01% groups was -1.15 ± 0.81 D, -1.04 ± 0.83 D and -0.72 ± 0.72 D, respectively (P < 0.001). CONCLUSION There was a myopic rebound after atropine was stopped, and it was greater in eyes that had received 0.5% and 0.1% atropine. The 0.01% atropine effect, however, was more modulated and sustained.

Myopia and night lighting in children in Singapore

AIM To examine the role of night time lighting and myopia in children in Singapore METHODS A cross sectional study was conducted on 1001 children in two Singapore schools. Cycloplegic refraction and A-scan biometry measurements were made in both eyes. A detailed questionnaire was completed by the parents to obtain information on night time lighting, near work activity, educational and demographic factors. RESULTS There was no difference in myopia prevalence rates in children exposed to night time light (33.1%) compared with children who slept in the dark (31.4%) before age 2. In addition, vitreous chamber depth was not related to night light (p=0.58) before age 2. These results remained even after controlling for near work. CONCLUSION Myopia is not associated with night light in Asian populations.

Sensitivity and specificity of visual acuity screening for refractive errors in school children.

Purpose. To examine the optimal cutoff point for the use of the visual acuity test to screen for refractive errors in schoolchildren. Methods. In a sample of schoolchildren between 7 and 9 years old, visual acuity testing was performed using modified ETDRS charts monocularly without optical aids by trained personnel. Cycloplegic autorefraction was performed in each eye. The screening efficacy of using various cutoff points for referring children for further optometric/ophthalmic assessment was studied. Myopia was defined as a spherical equivalent of at least −0.5 D, hyperopia a spherical equivalent of at least +2.0 D, and astigmatism a cylinder of at least −1.0 D in at least one eye. The sensitivity, specificity, and predictive values were calculated using each patient as a case; a receiver operator curve was plotted. Results. A total of 1028 children were tested. A satisfactory sensitivity/specificity profile was obtained using a referral criterion of visual acuity worse than or equal to 0.28 logarithm of the minimum angle of resolution in at least one eye. In this scenario, the sensitivity and specificity of this screening test were 72% (95% confidence interval [CI], 68 to 76) and 97% (95%CI, 95 to 98), respectively. The positive and negative predictive values were 96% (95%CI, 93 to 98) and 78% (95%CI, 75 to 82), respectively. Conclusions. The modified ETDRS visual acuity chart can be used to predict refractive errors in schoolchildren in Singapore in a sensitive and specific manner using a referral criterion of worse than or equal to 0.28 logarithm of the minimum angle of resolution.

Diffuse lamellar keratitis after laser in situ keratomileusis associated with surgical marker pens

PURPOSE: To describe a series of cases of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK) associated with intraoperative use of a surgical marker pen. SETTING: Singapore National Eye Centre, Singapore, Singapore. METHODS: A review of all 115 patients (125 eyes) who had myopic LASIK from July 23 to July 26, 2007, was performed to determine whether eyes in which the Codman surgical marker pen (Johnson & Johnson Medical) was used intraoperatively developed postoperative DLK. RESULTS: Nine of 12 eyes that had LASIK or flap relifting with a Codman surgical marker pen developed grade 1 to grade 3 DLK on the first postoperative day. The 113 other eyes that had LASIK in the same week with another brand of surgical marker pen (Securline, Precision Dynamics Corp.) did not develop DLK. All eyes with DLK were treated with intensive topical steroid therapy. The DLK resolved in 2 eyes after the steroid treatment; 7 eyes required flap relifting with interface irrigation. One month postoperatively, 6 eyes with DLK had an uncorrected visual acuity of 6/7.5 or better. Two eyes developed central corneal scarring with consecutive hyperopia with a best corrected visual acuity of 6/12 after 1 month. CONCLUSIONS: There was a strong association between the occurrence of DLK after LASIK with the use of the Codman surgical marker pen. One or more constituents of the ink in the Codman pen may have been responsible for this series of cases.

Performance of the Hansatome microsuction ring for laser in situ keratomileusis in eyes with narrow palpebral apertures

Purpose: To evaluate the performance of a new microsuction ring during laser in situ keratomileusis (LASIK) in eyes with narrow palpebral apertures. Setting: Singapore National Eye Centre, Singapore, Republic of Singapore. Methods: Laser in situ keratomileusis was performed sequentially in both eyes of 33 Chinese patients. A randomization table was used to determine the control and test eyes. A standard suction ring (20.3 mm diameter) was used in control eyes, and a microsuction ring (19.0 mm diameter) was used in test eyes. Corneal flaps were created using the Hansatome® microkeratome (Baush & Lomb). The following ring performance parameters were evaluated: flap diameter deviation (actual minus nominal flap diameter), ease of suction ring application, adequacy of suction, and overall microkeratome performance. Parameters 2 to 4 were rated by the surgeons using a subjective 1 to 100 scale. Results: The mean flap diameter deviation was 0.45 mm in the control eyes and 0.22 mm in the study eyes; the mean difference was 0.23 mm (95% confidence interval, 0.39‐0.07) (P<.001). For ease of application, the mean score of the microsuction ring was 100 and of the standard suction ring, 89.9. For adequacy of suction, the mean score of the microsuction ring was 99.7 and of the standard suction ring score, 98.2 (P = .13). The mean overall microkeratome performance score using the microsuction ring was 99.4 and using the standard suction ring, 94.6 (P = .011). Conclusion: The Hansatome microsuction ring was easy to apply during LASIK in eyes with narrow palpebral apertures, and there appeared to be no compromise of ring performance and safety.