48% improvement in driving for people that have received cataract surgery
By Holly Giles
The development of a cataract is a natural occurrence through the process of ageing. It is when the clear lens of the eye becomes cloudy making it harder to see. Sufferers often develop near-sightedness, a loss of clarity of vision and are more influenced by the glare of bright lights when driving at night. It is predicted that by the age of 80 over half of us will have developed cataracts, so it therefore makes sense that over 330,000 cataract operations are performed annually in the UK. Matthew Groski, an opthalmologist in New York, explained: “Cataracts are one of the leading causes of blurry vision in patients over 50. Other symptoms of cataracts like glare, halos, double vision, loss of contrast sensitivity, dimness of vision or difficulties with depth perception can lead to trouble reading or difficulty driving.”
Groski describes the operation as a “low risk, quick and efficient procedure” and is currently the only way of treating cataracts. Ophthalmologists perform the surgery separately for each eye, with the worst eye being treated first. 60% of patients find a satisfactory increase in vision from the first surgery and do not require the second. The remaining 40%, however, have the second eye done also, leading to a 98% success rate in the surgery’s improvement of vision. Many patients claim a drastic improvement in their vision after the surgery and many no longer require glasses. But until now it has been unproven scientifically if there was an improvement in the quality of vision.
Last week researchers at the University of Western Australia tried to answer this question using a driving simulator before and after surgery. They tested the driving performance of 44 patients before they had the surgery, after the first eye has been operated on and then again after the second. The driving simulator assesses a variety of variables including adjusted speed limits, traffic densities, intersections and pedestrian crossings. After the first surgery had been performed the frequency of near misses and crashes decreased by 35% and after the second surgery the figure fell further to 48%. It has been predicted that the decreases in near misses is due to an increase in contrast sensitivity, improving depth perception.
Dr Jonathon Ng, leading this research, said: “While visual acuity – how well one sees the eye chart – is an important method to assess a person’s fitness to drive, it’s an incomplete assessment. Quality of vision is also an important indicator. Improved contrast sensitivity and better night vision improves drivers’ safety on the road. In Australia and other countries, people often wait months to receive government funded surgery after a cataract is diagnosed. These results highlight the importance of timely cataract surgery in maintaining safety and continued mobility and independence in older adult drivers.”
The investigation does have obvious limitations due to its sample size of 44. Further studies with more participants and using a simulator able to test driving at night as well as in the day are needed to conclusively determine the effects of cataract surgery on driving. It does, however, raise issues regarding whether older drivers should be more closely monitored on the road in line with declining cognitive abilities, slower reaction times and visual impairment. This is necessary to ensure the safety of fellow drivers and pedestrians. The importance of these findings is reinforced by ophthalmologist Dr Mark Fromer: “[this] improved vision as a result of cataract surgery in the elderly population likely represents a significant reduction in economic societal costs, injuries and deaths related to traffic-related injuries”. The research is ongoing and the team remain hopeful that with a larger sample size the impact of cataract surgery can be observed clearly – no pun intended.