Relative Afferent Pupillary Defect (RAPD)

What's going on?

The patient has a pupil abnormality, indicative of severe diffuse retinal disease or optic nerve disease. Patients do not get RAPDs with lesions behind the optic chiasm. The key is the underlying cause for the optic nerve or retinal malfunction. Optic nerve lesions may be inflammatory, compressive, infective or traumatic

If I examine the patient what will I find?

See Pupil examination.

What if I've diagnosed it?

Depending on the suspected cause, the patient should be referred to the hospital eye service.

If you suspect giant cell arteritis and the vision is reduced, the patient should be referred immediately. Taking blood for inflammatory indices – (ESR/CRP) – will be valuable, but send the blood samples with the patient, so they can be processed in the hospital and the results made immediately available.

If you suspect an optic neuritis, the patient should be referred immediately but assessment the following day is acceptable (soon).

What will the hospital do?

Try to find the cause of the retinal or optic nerve lesion. If a diffuse retinal disease is responsible, this is usually clinically evident from fundoscopy. Electrodiagnostic tests, which assess the function of the retina and optic nerve, may help find the exact location of the pathology. If a compressive lesion is suspected, then neuro-imaging is required.

What do I need to do?

The underlying cause may require an assessment from a systemic point of view.