Are there any opticians or similar in here?

[gingergingerginger]

Does anyone know anything about relative afferent pupil defect?

It's usually a sign of optic neuritis (inflammation of one of the optic nerves).

When you shine a light into someone's left eye, the left pupil constricts (direct response) but the right pupil also constricts (consensual response). If you move the light from the left to the right eye, both pupils remain constricted. The reflex is mediated by impulses going in to the brain via the optic nerve from the side where the light is shone and returning to the eyes via the oculomotor nerves on both sides.

If someone has a damaged optic nerve (or, more rarely, retina), the input to the brain from the optic nerve is less and therefore the signal returning to the eye is less. Consequently, when you move the light from the unaffected eye to the affected eye the pupils appear to dilate because the constriction in response to a light shone in the affected eye is smaller than the constriction in response to a light shone in the unaffected eye.

See en.wikipedia.org/wiki/Marcus_Gunn_pupil

Thank you. That's really helpful.

The optician noticed RAPD in my 7 year old son. How serious is this? Can it have a benign cause? Can the optician get it wrong?

@gingergingerginger

I'm afraid I'm not qualified to answer those questions. I'm not trying to avoid answering: I simply don't know. (I'm a scientist rather than a healthcare practitioner.) I presume the optometrist suggesting taking your son to see a doctor. Does he have any visual problems or was this the only unusual thing the optometrist found?

Thanks, it's ok. He doesn't have any visual problems. This was noticed because I took him in with unequal pupils.

Sorry to bump, but does anyone else know anything about this. Particularly why he would have uneven pupils and then show RAPD. My understanding is that they are separate and unrelated???

Could the optician have got it wrong?