I don't like to post too many stories about crashes because I don't think it's constructive to make cycling look more dangerous than it is.
But stories like this one, involving a driver who was being treated for cataracts and glaucoma, coming hot on the heels of the news that the killer of Eilidh Cairns was driving with defective eyesight, represent an issue that needs action.
It seems obvious that anyone with defective eyesight should not be driving. But there is no system to ensure that such people are prevented from getting behind the wheel. There must be thousands of people knowingly driving with substandard eyesight every day, simply because it is so easy for them to do so undetected, and if like many people they are car-dependent, they don't want to give up driving. It's very easy for such people to go into denial and tell themselves "It'll be OK if I only drive in daylight; I'm probably safer than a boy-racer."
At the very least, professional drivers (cab drivers, HGV and van drivers) should have to take an eye test regularly and submit the results to the DVLA and to their employer.
With private individuals it is less simple because there are issues of doctor-patient confidentiality. However, it is possible to give people a strong nudge towards notifying the DVLA. Eye specialists and opticians should be required to make clear to the patient that they are breaking the law by failing to notify the DVLA of their condition, and present them with a simple form to sign on the spot, which the practitioner can then mail to the DVLA.
You could call this preventative medicine.