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Consultant Ophthalmologist,
Cataract & Refractive Surgeon

BMedSci BM BS MRCS MRCSEd MRCOpth FRCOphth MMedLaw PgD Cataract & Refractive Surgery

Traumatic Mydriasis

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What's going on?

A blunt injury to the eye has ruptured the pupil sphincter muscle. The pupil will not be able to react properly to light and will remain larger than that of the other eye at all levels of illumination (anisocoria). It will, however, still react briskly to light but will not be able to constrict as much as the normal eye. Vision may be slightly down.

If I examine the patient, what will I find?

One pupil will be larger than the other, but there will be no RAPD detected on swinging flashlight testing. If you look very closely using the ophthalmoscope as a magnifying glass, you may see some irregularity of the pupil margin related to the position of the rupture.

What if I've diagnosed it?

If there are no other features, such as hyphaema or ocular pain, and vision is good, the patient should be referred to the hospital eye service as a soon via letter.

What will the hospital do?

A thorough assessment will be done of the front and back of the eye to ensure no other damage has occurred.

What do I need to do?

The patient should be told to minimise the risk of further injury. If the injury was sports-related, the patient should be advised about protective measures such as wearing goggles.

What to tell the patient

They have had a permanent injury that will not resolve. They may suffer from photophobia and glare caused by too much light entering their eye through their dilated pupil.