A collection of studies on the biometry of myopic and non-myopic eyes

Abstract

At present, a wealth of interest surrounds the epidemiology of ametropia and ocular structural and functional correlates across the spectrum of refractive error. Myopia is the most common ocular condition globally, and its prevalence is continuing to increase. Myopia is not a purely refractive condition, being a major cause of visual impairment and blindness worldwide. Consequently, numerous studies have investigated various optical and non-optical interventions to limit its progression in childhood. This thesis describes the correlates of structural and functional parameters on the development of myopia in children. The investigation of these differences is expected to aid a deeper understanding of the aetiology of ametropia and subsequently assist with myopia amelioration The data presented within form a collection of cross-sectional cohort studies, investigating ocular parameters of children and young adults with normally developing eyes and children with peripheral retinal anomalies. Measures of central and peripheral refractive error, visual fields, fundus imaging and ocular biometry are analysed and discussed. This thesis demonstrates that gender and ethnicity do not appear to have a significant influence on refractive error: axial length ratio. Furthermore, the distribution and degree of corneal or refractive astigmatism in children appears linked to increasing spherical hypermetropia and is not influenced by ethnicity, gender or axial length. Pilot work also suggests that Retinitis Pigmentosa and Congenital Stationary Night Blindness are appropriate models for the investigation of the retinal periphery’s role in myopia development. The final study contained within found a reduction in foveal light sensitivity correlated with increasing myopia, perhaps suggestive of an increase in photoreceptor spacing. It is, therefore, recommended that normative refractive, astigmatism and axial length data should be tailored to individual characteristics. Future large-scale longitudinal studies should be designed to develop growth curves for axial length and refractive error such as those available for anthropometric characteristics.