Pupil
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Transcript of Pupil
Normal pupilVaries with:
• Age,
• Person to person
• emotional state
• Level of alertness
• Degree of
accommodation
• Ambient room light.
Normal diameter: 3-4
mm.
• small (infants, &
elderlies).
• large (childhood &
middle-aged).
• Balance between
sphincter & dilator.
• Supranuclear control
(frontal & occipital).
Normal pupil• Hippus: responses to
respiration.
• Physiological (essential) anisocoria: 20-40% of GP.
• Mydriatics & cycloplegics work more on blue eyes > brown.
• Constriction: activation of circular sphincter pupillae (parasympathetic).
• Dilatation: contraction of the radiating dilator pupillae (sympathetic).
• Near response:Convergence, ↑ Accommodation, Miosis
Pupillary Light
reflex pathways
• Light reflex: Afferent arc: retina ON 20% OC (axons from nasal retina cross, axons from temporal retina remain uncross) OTbrachium of superior colliculus before LGN pretectal nuclei (50% IL & 50% CL via posterior commisure) 1st order neuron Edinger Westphal nucleus –pupiloconstrictor nucleus – 2nd order neuron.
Pupillary Light
reflex pathways
• Efferent arc: join with
somatic motor IIICN
fibers in brainstem on
its medial side-
preganglionic
ciliary ganglion
ciliary nerves –post-
ganglionic sph
pupillae.
Sympathetic nervous system
• Hypothalamus
ciliospinal center of
Budge in C8
sympathetic chain
superior cervical
(stellate) ganglion
sympathetic plexus of
ICA ophthalmic
artery ciliary
ganglion ciliary
nerves dilator
pupillae.
Near Response pathway
• Retina occipital cortex occipito-
bulbar pathway modify EOM
EWN III CN.
• Anisocoria: Physio or Patho (efferent
defect or local iris pathology).
• APD: Swinging flashlight test.
Miosis• Bright illumination
• Sleep
• Old age,
• Forced lid closure,
• Iritis,
• Pontine lesion,
• sympathetic chain lesion,
• Miotics (sympatholytics, parasympathomimetics
• Narcotics X pethidine.
Mydriasis
• Poor illumination
• Emotional stimuli
• Pain
• Mydriatics (sympathomimetics, & parasympatholytics)
• III CN disturbances ( ICP with tentorial coning)
• Trauma
• Toxic
• Infective conditions-botulism & diphtheria.
Afferent Pupillary Defect
• RAPD:
Unilateral ↓Va sine RAPD:
• Refractive error
• Cloudy media
• Amblyopia
• Hysteria
• Malingering
• Macular lesion
• Chiasmatic lesion.
RAPD sine ↓Va:
• Lesion of brachium of superior colliculus (thalamic hg).
Amaurotic pupillary defect:
• in severe unilat retinal or optic nerve dz…..
Pupillary Light-Near Dissociation
• Light stronger > Near response as miotic, the reverse is known as light-Near Dissociation
• Causes: APD, CG & MB lesions, CNS syphilis, DM, chr alcoholism, encephalitis, MS, CNS deg. dz, MB tumors & infarcts, Lesion at periaqueductal gray matter of MB.
Argyl-Robertson Pupil (ARP)
• C/F: Pupil size < 3 mm (miotic), light reaction absent, accommodation reaction present (ARP), bilateral, irregular eccentric & dilate poorly with mydriatics-iris atrophy,
• Incomplete: slow response to light
• unilateral
• Causes: CNS syphilis + tabes dorsalis /general paresis, DM, chr alcoholism, encephalitis, MS, CNS deg. dz, MB tumors. Lesion at periaqueductal gray matter of MB.
Tonic pupil• C/F: L – N D, slow contraction of sphincter
to near stimulation –abnormal constrictor
mechanism, segmental iris constriction
Vermiform movements of edge.
• Acute stage : pupillary dilatation.
• Adie’s syndrome : Tonic pupil with absent
deep tendon reflexes.
Tonic pupil
• Damage to ciliary ganglion or short ciliary nerves (30 nn for Near response , 1 n for light reflex) by trauma or inflame… 0.1% Pilo test constriction (denervation hypersensitivity), if normal it is not affected.
• Coccaine drops diltation. Dilates slowly in dark & promptly to mydriatcs. young girls.
• Bilateral tonic pupils autonomic neuropathy.
Horner’s syndrome
Lesions of the sympathetic pathway:
• Central (post hypothalamus Br stem
C8-T2),
• Preganglionic (SC SCG) &
• Post-ganglionic SCG Carotid plexus Va
orbit) Muller’s muscle & Iris dilator.
Horner’s syndrome
C/F:
• Meiosis
• Ptosis
• Anhydrosis: absence of
facial & nuchal sweating
IL
• Heterochromia irides
(cong. Melanocyte
immaturation bluer
iris).
Horner’s syndrome
• Etiology;
• Central:
Brainstem infarct (Stroke)
Lateral medullary infarction (Wallenburg Syndrome)
Syringomyelia
Cervical cord tumor
Tabes dorsalis
Lyme dz
Vertebral artery dissection
Horner’s syndrome
• Preganglionic:
Cervical rib
Cervical vertebral #
Apical pulmonary lesion eg br Ca (Pancoast syndrome)
Brachial plexus injury.
Cervical spine abn
Neuroblastoma
Horner’s syndrome
• Postganglionic:
Dissecting aneurysm of
carotid or subclavian
a.
Carotid a injury high in
the neck
Cluster headaches
Pharmacology
Parasympathomimetics (miotics):
• Direct: Pilocarpine, Carbachol,
Acetylcholine.
• Indirect: Eserine, Edrophonium,
Echothiophate, Isofluorophate.
Sympatholytics (Miotics):
• Guanethidine, Dibenzyline, Tolazoline.
Pharmacology
Parasympatholytics (mydriatics):
• Direct: Atropine, Homatropine,
Scopolamine, Cyclopentolate,
Tropicamide.
Sympathomimetics (mydriatics):
• Direct : Epinephrine, Phenylephrine
• Indirect : Epinephrine, Cocaine.