Requirement for and optimisation of premium intraocular lenses

Abstract

Premium intraocular lenses (IOLs) aim to surgically correct astigmatism and
presbyopia following cataract extraction, optimising vision and eliminating the need for cataract surgery in later years. It is usual to fully correct astigmatism and to
provide visual correction for distance and near when prescribing spectacles and
contact lenses, however for correction with the lens implanted during cataract surgery, patients are required to purchase the premium IOLs and pay surgery fees
outside the National Health Service in the UK. The benefit of using toric IOLs was thus demonstrated, both in standard visual tests and real-world situations. Orientation of toric IOLs during implantation is critical and the benefit of using
conjunctival blood vessels for alignment was shown. The issue of centration of IOLs relative to the pupil was also investigated, showing changes with the amount
of dilation and repeat dilation evaluation, which must be considered during surgery
to optimize the visual performance of premium IOLs. Presbyopia is a global issue, of growing importance as life expectancy increases,
with no real long-term cure. Despite enhanced lifestyles, changes in diet and improved medical care, presbyopia still presents in modern life as a significant visual impairment. The onset of presbyopia was found to vary with risk factors including alcohol consumption, smoking, UV exposure and even weight as well as age. A new technique to make measurement of accommodation more objective and robust was explored, although needs for further design modifications were
identified. Due to dysphotopsia and lack of intermediate vision through most multifocal IOL designs, the development of a trifocal IOL was shown to minimize
these aspects. The current thesis, therefore, emphasises the challenges of premium IOL surgery
and need for refinement for optimum visual outcome in addition to outlining how premium IOLs may provide long-term and successful correction of astigmatism
and presbyopia.

Date of Award	17 Dec 2012
Original language	English
Supervisor	James Wolffsohn (Supervisor) & Leon Davies (Supervisor)