VERU have developed new ways of assessing and exploring aberrations both on the lenses and on the patient. Our studies have developed in vitro and in vivo tests to assess the performance of existing and prototype lenses and in materials with the objective being to investigate how the composition and structural morphology of contact lens polymers affects on-eye performance.
Instrumentation now permits a comprehensive biometric and optical aberration analysis of the anterior segment of the eye. This enables an analysis of the extent of corneal defomation during disease progression in cases of keratoconus. Typical assessment includes Topography and Optical Coherence Tomography imaging (AtlasTM and VisanteTM (Zeiss)), on-eye and off-eye aberration measurement. To enable the impact of aberration management we need to understand how lens position on eye affects the efficacy of the optical design. A common method to maintain lens orientation (prism ballast) has been found to produce the aberration coma as soon as the lens itself decentres.
A large study was undertaken to assess the optical aberrations of a population of unaided myopic patients. The aberrations of six different commonly worn contact lens products were then measured and then combined with the aberrations obtained from the first study. Our conclusions were that many producers had over estimated the magnitude and direction of a specific aberration (for example spherical aberration) which would undermine any visual benefit. In addition other effects were observed on-eye which could well be associated with tear-film changes on the anterior surface of the contact lens.
Research techniques have been developed centred on the investigation of synthetic hydrogels primarily developed for use in ophthalmic applications. A range of techniques have been successfully applied to probe internal structural dimensions and transport properties include various forms of Nuclear Magnetic Resonance, Impedance Spectroscopy, Differential Interference Contrast Microscopy (DIC) and surface studies applying Fourier Transform Infra Red Spectroscopy.Multi-dimensional NMR has permitted a greater insight in to the distribution of water in hydrogels with added information with regard to water confined in nano-channels. The interconnectivity of the hydrogel has been investigated by impedance spectroscopy and our research has confirmed that this is the major rate limiting parameter with regard to hydrogel dehydration and initial drug release. The novel application of DIC microscopy to investigate transparent hydrogels has confirmed the existence of micro-scale domains in certain heterogeneous materials such as silicone hydrogels. This knowledge is already assisting with the modelling of uptake and release studies and with material spoliation studies.
VERU Professor Bourne leads the Vision Loss Experts Group (VLEG) which is part of the Global Burden of Disease Study (GBD). VLEG compiled the most up-to-date statistics ever generated on the prevalence of global blindness, facilitating the analysis of trends and risk factors, and producing detailed future projections. VLEG data has been described as “a critical contribution to our understanding of present and future health priorities for countries and the global community” (Editor-in-Chief, The Lancet).
The findings have directly impacted on healthcare policymakers and professionals, charities and economic analysts, both in the UK and overseas. It has increased their awareness of global eye care issues. These users have applied this increased awareness at a global level. The data has become a significant resource in health analyses by economists and healthcare planners such as PriceWaterhouse Coopers and the World Economic Forum, enabling these organisations to provide recommendations for eye-health policies and practices. These reports predict the socio-economic impact of visual impairment in the world and provide an insight into the economic return from investments in eye-health treatment programmes.
These in turn have informed the development of healthcare planning nationally and internationally. In addition, the research findings were used by NGOs and opinion leaders in ophthalmology at the Congress of the International Agency for the Prevention of Blindness (IAPB), informing discussion of blindness prevention strategies. This led directly to the development of an Action Plan for the Prevention of Avoidable Blindness and Visual Impairment (2014 - 2019) by the WHO. Furthermore, the World Bank, as part of its mission to alleviate poverty, has adopted the data to inform funding priorities for health care projects in developing countries. It has also had an impact at a national level, where VLEG findings drew attention to the absence of reliable data, subsequently leading to the commissioning of a detailed countrywide National Eye Survey of Trinidad and Tobago (NESTT), worth £350k, in order to identify and address eye health priorities. The richness and detail of VLEG data enables its users (government policymakers and non-governmental organisations) in countries worldwide to obtain location-relevant information, rather than relying upon data from neighbouring regions, or data that has been collapsed across regions. This provides a more accurate view of the specific issues faced by each country which, due to differing risk factors, may differ markedly from their neighbours. For example, users can assess the impact of gender, age, ethnicity and other predictive variables in their region to establish specific eye care priorities. Where data was found to be sparse (e.g. the Caribbean), this has stimulated governments to commission new, country-based population studies. Finally, the data has also formed the basis of training events with key policymakers and healthcare professionals, impacting on their professional practice.