I'm still only a nursing student, but this is right up my alley. My current job is working with a neuro-ophthalmologist. While we don't see this everyday, (and we don't see pedi pts), we do see a fair amount this, along with other people sent over from neurology/ other eye doctors for consultation for other pupil problems. It should be noted that 10% of the population has anisocoria
(unequal pupil sizes). It is considered physiologic if < 1mm, or essential (i.e. benign) if >1mm but drug testing doesn't uncover a defect.Typically, once Horner's is confirmed, that's it. No big whoop. If it was not congenital than we refer back to the appropriate service to treat the underlying cause/disease.
I always get a kick out of calling down to the pharmacy to order the testing gtts, which are a 10% cocaine solution. Everybody around me and on the other end of the phone just stops what they're doing and stares at me! Complete stunned silence! LOL
From one of my reference books:
"Sympathetic pupil defects
Sympathetic pupil defects have increased anisocoria in
dim illumination. Because of the iris dilator muscle is defective, the
smaller pupil is the abnormal one. It stays small when a it should enlarge, because the radial muscle fibers that should contract to enlarge the pupil cannot because they are paretic. Called Horner's Syndrome, this is the only situation in which a pupil defect is caused by a sympathetic pathway. Several defects are caused by the parasympathetic pathway.
Horner's Syndrome
This may result from a lesion anywherein the sympathetic nervous system. It is usually unilateral. Characteristics are:
1. Miosis because the iris dialtor does not contract.
2. Ptosis from lack of tone in Mueller's muscle.
3. Anhydrosis (absense of sweating on th eface and neck) on the involved side from affected sympathetic fibers from the external carotid plexus.
If sweating is intact, then the sympathetic fibers traveling with the external carotid arteries are intact, suggesting Horner's syndrome with 3rd neron (postganglionic) damage, because a central or preganglionic Horner's syndrome effect would destroy the sympathetic fibers before they branch off to the external carotid arteries." *
Here's a good link that explain's Horner's and also talks about testing to confirm Horner's and determine where the problem area is. In particular I think that the OP will find the second paragraph of interest:
http://www.revoptom.com/HANDBOOK/sect6g.htm
and there are some pictures at this site under neuro-ophthalmology:
http://www.redatlas.org/main.htm
* from: Fundamentals for Ophthalmic Technical Personnel by Barbara Cassin. Published by W.B. Saunders Co. page 172