Overview

During a dilated-eye exam, eye drops are used to enlarge (dilate) your pupils. This means the doctor can get good photos of the back of your eyes.  

Your doctor will decide which drops you need. This would be either phenylephrine 2.5% drops, or tropicamide (0.5% or 1%) drops.

Side effects

Dilation eye drops can blur your vision and make you sensitive to bright light. You might find it helpful to wear sunglasses.

You might also have temporary stinging and a dry mouth after using the eye drops.

The effects of the drops normally last 2 to 4 hours, but can be up to 6 hours.

You should not drive or operate heavy machinery until your sight returns to normal and your eyes are comfortable. 

When to get help

Very rarely, the drops can cause a sudden, dramatic rise in pressure within your eye (acute glaucoma). This will need to be treated quickly in an eye unit.

If you get any other symptoms that you are concerned about, please contact your GP.

Information on other possible side effects is available in the patient leaflet that comes with your medicine. Please ask our staff if you would like a copy.

You can find emergency departments with an attached eye casualty at these hospitals:

• St Thomas’ Hospital, Eye Casualty, Ground Floor, South Wing, Westminster Bridge Road, London, SE1 7EH
• King’s College Hospital, Denmark Hill, London SE5 9RS
• St George’s Hospital, Blackshaw Road, London SW17 0QT
• King’s Hospital, First Floor, Normanby Building during the day, or main Emergency Department out of hours
• Queen Mary’s Hospital, 2nd floor, B block, Frognal Avenue, Sidcup
  DA14 6LT. Monday to Friday, 8am to 4pm.