Question About Pupillary Accomodation

[AnnTaylor]

Hi,

Does anyone know the significance of this:

You shine a light in a pt's eye...You keep the light on the pupil...initially the pupil constricts a little, but then dilates back to its normal size immediately after constricting...and stays unconstricted with the light remaining on it...shouldn't it STAY constricted for the entire duration of the time light is shining on it?

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[typhoonegator]

Yep, it should stay constricted. Hippus, the phenomenon of repeated constriction and dilation to light exposure, can be a normal variant, which could be explained by an under-dampened light reflex. Hippus should be a bilateral phenomenon, whereas in a unilateral situation failure to constrict could be due to a ciliary problem, Adie's, etc. Hey, maybe he's herniating.

Accomodation is a near reflex, which is independent of the light reflex (hence the concept of light-near dissociation). Try not to mix up the terms.

 

[maddog2020]

What you are describing is called pupillary escape. This is a normal phenomenon usually seen in younger people.

If you use a penlight that is not very bright and the other eye is kept relatively dark, you may see initial constriction followed by redilation. There are a lot of theories about why this happens. A good neurologist will use a very bright pocket light and keep the batteries topped off. 🙂

 

[Nirv]

It's normal to do that. Most people's don't back to the full size so quickly however. More common in younger like prior poster mentioned. Poster probably meant the pupil is accomodating to the light, and not the technical convergence.

 

[danielmd06]

I always wondered why this happened! I need to get a new battery.