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2. PHD Thesis / Tesis PHD
3. Faculty of Health Sciences / Fakulti Sains Kesihatan

Title:	Intervention strategies using multifocal soft contact lenses to reduce progression of myopia in schoolchildren
Authors:	Kareem Fawzi A. Allinjawi (P65539)
Supervisor:	Sharanjeet Kaur, Professor Dr.
Keywords:	Myopia Contact lenses Dissertations, Academic -- Malaysia
Issue Date:	6-Jun-2017
Description:	Myopia, the most common type of refractive error, starts at early childhood and continues to progress until late teenage. High degree of myopia leads to serious ocular pathologies and could cause visual impairment. Clinical characteristics, such as accommodation response/lag and phoria, in children with myopia have been shown to be important in management and the control of myopia progression. Meanwhile, animal studies have highlighted the importance of peripheral refraction (PR) in myopia progression. The difference in refractive error between center and peripheral retina, known as RPRE, has been suggested to have an impact on myopia progression. Myopes have been found to have a positive RPRE, called hyperopic defocus, at the retinal periphery whereas hyperopes and emmetropes have a negative RPRE, called myopic defocus. Correction using Multifocal soft contact lens (MFCL) has been shown to reduce the hyperopic defocus in adult myopes. The present study aimed to investigate the effect of MFCLs on myopia progression in myopic schoolchildren aged between 13 to 15 years old. The study was divided into 2 phases. In phase 1, a cross-sectional study was conducted to evaluate the clinical characteristics, center refraction and PR of 27 myopic right eyes at baseline (with no correction), with single vision soft contact lenses (SVCL), two different designs of MFCL (MultiStage and ProClear) with addition power (ADD) of +1.50D, and four different ADD (+1.50D, +2.50D, +3.00D and +3.50D) for ProClear MFCL. The main objectives of the Phase 1 were to determine the optimal design and the optimal ADD of MFCL. The results of Phase 1 showed that for ADD of +1.50D, using a narrow junction zone and wider spherical near zone, as seen in MultiStage MFCL, could reduce peripheral hyperopic defocus better compared to a design with progressive increase of ADD, as seen in the ProClear MFCL. The results also showed that a +3.00D ADD for the ProClear MFCL was the optimal ADD as it could invert the hyperopic defocus at the peripheral retina into myopic defocus while maintaining near normal Lag of accommodation (1.10 ± 0.83D) and exophoria (-0.31 ± 2.49PD). In phase 2, a prospective longitudinal study of duration 18 months was performed to observe the progression of myopia in myopic schoolchildren (n=37) wearing SVCL, Multistage +1.50D MFCL, and ProClear +3.00D MFCL. Assessment of contact lenses fitting was first done to obtain best fit. Center refraction and PR, axial length (AL) as well as corneal curvature (CC) were measured at every visit (baseline, 6, 12 and 18 months). After 18 months of wearing contact lenses, the results showed that SVCL group had progressed by - 0.57 ±1.68D compared with Multistage +1.50D MFCL group -0.35 ±1.44D, and ProClear +3.00D MFCL group -0.19 ±1.16D. One-way ANOVA (using Bonferroni correction) showed that there was a statistically significant difference in myopia progression between the SVCL group and the MFCL groups (MultiStage, p = 0.03; ProClear, p < 0.001). Corresponding axial length changes were 0.228 ±0.89 mm, 0.157 ±1.34 mm, and 0.084 ±1.02 mm, respectively. The estimated control of the myopia progression in children wearing Multistage +1.50D was 38.6%, and 66.6% with Proclear +3.00D MFCL, in comparison to children who wore SVCL over 18 months of treatment. There was also no statistically significant change in CC between the 3 groups. Classification of RPRE curves were also done by calculating area under curve. Our analysis revealed five different pattern curves (Type A, B, C, D and E) in myopic eyes. We noticed that myopia progression could be reduced with any MFCL used in this study for Type A, and best with ProClear MFCL for Types B, C and D. Hence, understanding the difference in the curve patterns, and link it with the suitable treatment strategies using MFCL might lead to promising myopia control results among the myopic school children.,Doktor Falsafah
Pages:	200
Call Number:	WW320.A437i 2017 9
Publisher:	UKM, Kuala Lumpur
Appears in Collections:	Faculty of Health Sciences / Fakulti Sains Kesihatan

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