iris and pupils NBEO.txt
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Where is the pupil located relative to the iris?
Nasal and inferior to iris center
Where is the pupil thickest?
In the collarette
What zones do the collarettes divide?
- Pupillary zone
- Ciliary zone
Where is the thinnest part of the iris?
The iris root, located in the ciliary zone
What does the iris root do?
Attaches the ciliary zone of the iris to the ciliary body
What part of the iris is continuous with the stroma of the ciliary body?
Where is the major circle of the iris located?
In the ciliary body
Where is the minor circle of the iris located?
In the iris stroma, at the level of the collarette
What innervates the Iris sphincter muscle?
What innervates the iris dilator muscle?
What chemical receptors are found on the dilator muscle?
Where is the iris sphincter muscle located within the iris?
Where is the iris dilator muscle found within the iris?
What forms the pupillary ruff?
Pigmented posterior epithelium
What causes iris color?
Due to the amount of pigmentation of melanocytes in the anterior border layer of the iris
What forms the blood aqueous barrier?
- Iris vessels
- Endothelium of Schlemm's canal
- Non-pigmented ciliary epithelium
How is uveitis related to the blood aqueous barrier?
Uveitis occurs due to a breakdown of the BAB
What type of pupillary defects are afferent?
- Light-near dissociation
What should you consider if anisocoria is worse in the dark?
- Horner's syndrome
- Posterior synechiae
- Argyll Robertson
What 3 things is Argyll Robertson pupil associated with?
Where would there be a lesion found in Argyll Robertson pupil?
What does the tectotegemental tract do?
Carries information from the pretectal nucleus to Edinger-Westphal nuclei
What pupil disorder presents with anisocoria worse in the dark but has normal accommodative response?
Argyll Robertson pupil
What should you consider if anisocoria is worse in light conditions?
- Adie's Tonic pupil
- Something involving CN3
If you suspect Adie's Tonic pupil, but it constricts after 0.125% pilocarpine, what should you consider?
Where would a lesion be located in Adie's Tonic pupil?
What condition would you suspect if there was anisocoria worse in the light together with poor light/near response?
Adie's Tonic pupil
If you suspect Adie's tonic pupil, but it fails to constrict with pilocarpine what should you consider?
- Due to trauma of sphincter muscles
- Due to pharmacologic agent
What are 3 the typical signs seen in Horner's syndrome?
- Mitotic pupil (anisocoria) worse in dim illumination
Where is the most common location of a lesion in Horner's syndrome?
Pancoast tumor in the apex of the lung
What chemical agents are used to diagnose Horner's syndrome?
Cocaine or apraclonidine
What chemical agent is used to determine location after Horner's syndrome has been diagnosed?
If a Horner's pupil dilates with hydroxyamphetamine where should you suspect a lesion?
Preganglionic, 1st or 2nd order
If a Horner's pupil does not dilate with hydroxyamphetamine, where should you suspect a lesion?
Postganglionic, 3rd order
What is the 1st order sympathetic pathway of the eye?
Preganglionic fibers begin at hypothalamus and descend and synapse at ciliospinal center of budge
What is the 2nd order sympathetic pathway of the eye?
Preganglionic fibers from the ciliospinal center of budge course across the apex of the lung, ascend, and synapse in the superior cervical ganglion
What is the 3rd order sympathetic pathway of the eye?
- Postganglionic signal from the superior cervical ganglion ascend the internal carotid and innervates:
- Muller's muscle on the upper eyelid
- Iris dilator and ciliary muscle via the LPCN
- Choroidal and conjunctival blood vessels via SPCN
- Vasoconstriction of lacrimal gland via petrosal nerve
How are CSR and the sympathetic system related?
CSR is believed to be a hyperactivity of sympathetic system localized in the retina, causing bruch's membrane damage
Where is the near pupil reflex controlled?
Frontal eye fields
What part of the pupillary pathway is used for pupil constriction?
- Edinger-Westphal nuclei
- Ciliary ganglion
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