How poor eyesight can lead to traffic cráshes

In the past couple of months, Emeka Mayaka, one of the PD editors, has ceased driving his car at night. His eyes cannot tolerate piercing lights from oncoming cars.

Mayaka has worn glasses all his adult life and while they have helped him achieve vision competency, he now recognises that some tasks are becoming more difficult to fulfill.

“I have never found myself in big trouble. I made a deliberate decision to avoid endangering myself and other road users. I don’t drive in misty environments either, and I usually seek the help of friends or relatives when traveling long distances by road,” he says.

Mayaka’s case gives a snapshot of drivers who have acknowledged their vision challenges and have made a prudent decision to withdraw from road usage. Many drivers are yet to do this.

A recent eye screening exercise conducted in five counties on drivers of Public Service Vehicles (PSV) revealed that at least 40 per cent of the drivers tested had unattended eye problems, yet they were still ferrying passengers from different parts of the country.

“It is worrying that of the 900 drivers we screened, at least 300 were on the road with eye problems,” explains Gakari Thomas an optometrist based in Nairobi and organising secretary of the Optometrist Association of Kenya.

Refractive disorders

 The leading cause of these problems is refractive disorders, which include, myopia (near-sightedness) hyperopia(far-sightedness), pres-byopia (loss of near vision), and astigmatism (irregular shape of the cornea), all of which can be corrected by the use of prescribed glasses.

The screening which was conducted last year was sponsored by the Optometrist Association of Kenya and covered Nairobi, Eldoret, Nakuru Kakamega, Kisii, and Mombasa counties.

“With these defects (refractive disorders) the driver may not see oncoming vehicles in good time and this reduces reaction time, such as overtaking. At the same time drivers with light sensitivity issues are not wearing anti-glare glasses,” said Gakari.

Gakari noted that during the screening, drivers were unwilling to seek eye care as this would be an admission of an eye condition that would jeopardise their source of employment if their employers found out.

According to The Lancet, a medical journal, people with poor central visual acuity are 46 per cent more likely to have a road traffic crash than people with normal vision in low middle income countries.

The 2021 paper titled ‘Vision impairment and traffic safety outcomes in low-income and middle-income countries’ further says there is a high prevalence of vision disorders among drivers and poor adherence to vision-related driving licensure requirements.

Dr Ashok Shah, a consultant ophthalmic surgeon based in Nairobi says the minimum vision requirement for driving or better known as vision acuity(sharpness of vision ) is 6/12 or above in the best eye, with or without glasses.

He adds that at this vision level, the driver can see clearly and far enough. Also, people with one eye can drive provided they meet the minimum vision requirements.

Drivers sight not measured

“There is a lack of statistical evidence to show the relationship between road accidents and vision impairments in the country because drivers are not tested after accidents occur. But we can presume the various eye defects we see impact driving,” he says.

The surgeon says some medical conditions that may undermine a person’s vision on the road include glaucoma, tumor of the brain and patients who have had laser eye treatment for diabetic eye disease.

“Some eye defects may deny a person’s field of vision, meaning one is not able to see on the sides of the eyes when facing forward. This is to imply if you are driving you may not see overtaking cars,” he said.

Diseases that affect the retina can also cause an eye defect and subsequently undermine vision.

 Age-related eye complications such as age-related macular degeneration (AMD), which affects older people, may also render their vision unsuitable for driving.

“It would be good if citizens aged 65 years and above have their vision tested before having their licenses renewed because at this age, their vision starts to deteriorate,” said Dr Shah

The 2022 Kenya Health Demographic Survey (KHDS) singled out difficulty seeing as the most prevalent disability in the population with the burden being heavier on those aged 50 years and above.

Dr Shah further says that motorists should wear protective eye shields because when driving, objects or insects can suddenly enter the eye, increasing the risk of an injurious road crash.

And like Gakari, Dr Shah has observed unwillingness among drivers to seek medical eye care.

“We sometimes see patients who are working as drivers whose vision is not good, but they are reluctant to wear glasses. We still do not understand why there is this reluctance, because it is not an issue of affordability because glasses cost as low as Sh890 a pair,” he said.

Self declaration

According to the Traffic Act, a motor vehicle license can fail to be granted if an applicant fails to make a declaration of an application form of a disease or disability they have or do not have, which may cause harm to the public or is unable to read with glasses a motor vehicle whose identification plate is at a distance of twenty-five meters.

Medics say questions concerning the enforcement of the standards are critical. For example, will drivers undergo regular screening of visual function and and if so, from what age and within what intervals? This requires insight into the prevalence of impairments, the costs involved in screening and the sensitivity and specificity of tests.

It is not clear whether the National Transport and Safety Authority (NTSA) which is mandated to issue road licenses has adequate regulations to deter licensing of people with severe uncorrected eye defects.

The authority did not respond to queries by the time of going to press.