Once you've successfully passed your driving test you're eligible to hold your licence until you're 70, unless:
You lose it through a driving conviction
Your health affects your driving ability
Some health conditions still allow for a long and fruitful driving life. Others, unfortunately, do not.
It's your duty to keep the DVLA informed of your health, and failure to do so can incur a significant fine.
It's also essential that you inform your car insurance provider so that they're aware of your new driving situation and are able to consider any possible risks it may pose.
You can be fined up to £1,000 if you do not tell about a medical condition that affects your driving. You may be prosecuted if you’re involved in an accident as a result.
Assessing fitness to drive: a guide for medical professionals