Your eyesight may become blurry and your eyes may become very sensitive to light and glare for up to six hours. We recommend that you bring a pair of sunglasses to help with the sensitivity to light.
You must not drive a vehicle or operate machinery until you feel that you can see clearly.
https://phw.nhs.wales/services-and-teams/screening/diabetic-eye-screening-wales/about-diabetic-eye-screening/your-appointment/