Vision and Balance Changes After Bilateral Implantation of Toric IOLs

Cataracts are the major cause of blindness in the world. Cataract surgery, being the most performed surgery in the world today, provide correction by extracting the natural lens from its capsular bag and replaced by an artificial intraocular lens (IOL) implantation. In the UK, almost all patients undergoing cataract surgery by the NHS are given monofocal intraocular lenses (IOLs) which do not correct corneal astigmatic error. It is estimated that around 20% of the population has over 1.50DC of corneal astigmatism. Uncorrected astigmatism not only increase spectacle dependency and reduce quality of life post surgically, but it also adversely affects the overall economic costs. Specialised toric IOLs offer the opportunity to correct pre-existing corneal astigmatism. Previous work has shown a link between reduced vision and balance or mobility. Full correction of refractive error may have greater impact on lifestyle than previously thought.

This is a single centre, parallel randomized controlled trial study comparing the dynamic stability and visual outcomes of cataract patient with astigmatism implanted with mono-focal Toric versus non-Toric IOLs.

140 cataracts patients with astigmatism awaiting cataract correction surgery at the Royal Eye infirmary of the University Hospitals of Plymouth NHS Trust will be recruited in this study over a two year period. The participants will be randomly assigned to be implanted with either Toric IOLs or standard non-Toric IOLs. Three additional study visits will be arranged for them. One visit before the cataract surgery, second visit at three to six months after the first eye cataract surgery and third visit at three to six months after the second eye cataract surgery. The primary assessment outcome is dynamic balance measured by movement sensors (accelerometer) during walk and turn, crossing over obstacle and stair walking. The secondary outcomes include eye tracking during movement activities, visual functions, risk of fall questionnaires and vision-specific quality of life questionnaire.

This project is funded by Carl Zeiss Meditec AG, led by the University of Plymouth and sponsored by University Hospitals Plymouth NHS Trust . The project also involves collaboration with the University of Glasgow and the Plymouth Marjon University.

Eligibility Criteria:
Inclusion Criteria:

* bilateral significant corneal astigmatism \>1.0D
* on waiting list for bilateral cataract surgery in NHS

Exclusion Criteria:

* pre-existing eye pathology which may be aggravated by intraocular implant
* previous intraocular/ corneal surgery
* History of uveitis, glaucoma, proliferative diabetic retinopathy or IDDM, pseudoexfoliation, macular degeneration that may affect potential best corrected visual acuity of 20/40 or better
* Micropthalmia
* corneal decompensation or endothelial insufficiency
* pars planitis
* high myopia
* participants using a systematic medication that is known to cause ocular side effects
* participated in a concurrent clinical trial or have participated in an opthalmology clinical trial within the last 30 days
* unable or not willing to cooperate for the follow up period
* pregnant women
* unable to give informed consent
* unable to walk with or without walking aids independently for at least 20m
* unable to walk up/down stairs independently using aids or handrail