Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Pupillary Size PowerPoint PPT presentation
Normal pupil
Normal pupil is round, regular, centered in the iris and 3-5mm in
size. In old age the size is <3mm.
In bright light, the pupil constricts to a minimum diameter of 2
mm and in dark, it dilates to about 8mm.
Pupils are examined for any difference in their size under
normal illumination.
Size of the pupil changes due to the action of 2 muscles, the
circumferential sphinter pupillae which is innervated by
parasympathetic nervous system and radial dilator pupillae
which has alpha adrenergic sympathetic receptors which
respond to changes in sympathetic tonus and changes in the
blood level of circulating catacholamines.
Pathway of ocular
sympathetic fibres
HYPOTHALAMUS (1ST ORDER NEURONS)
BRAINSTEM
INTERMEDIOLATERAL HORN OF SPINAL CORD AT C8 AND T1
LEVEL
2ND ORDER NEURON FROM C8 & T1 GO TO SUPERIOR
SYMPATHETIC GANGLION
3RD ORDER NEURON FROM THERE IS CARRIED AROUND
CAROTID ARTERY TO THE OPHTHALMIC DIVISION OF 5TH
CRANIAL NERVE
NASOCILIARY NERVE
LONG CILIARY NERVE
OCULOPUPILLARY FIBRES
SUPPLY DILATOR PUPILLAE AND MULLER'S MUSCLE OF UPPER EYELID
Miosis
If pupillary size is <3mm, it is called miosis.
Causes of unilateral miosis
1. Irritation of parasympathetic
2. Horner's syndrome (due to oculosympathetic paresis)
Central horners syndrome (1st order neuron). Hypothalamic
lesion, tumor, hemorrhage, brainstem stroke, lateral medullary
syndrome, syringomyelia
Bronchogenic carcinoma - pancoast's tumor (tumor of
pulmonary apex) in advanced stages can compress cervical
sympathetic (2nd order neuron).
Metastatic carcinoma of neck - Rowland Payne syndrome
(Disrupting the oculosympathetic nerve, vagus nerve and
phrenic nerve).
T1 radiculopathy
Post ganglionic - carotid artery disease (aneurysm) at
cavernous sinus.
Readers paratrigeminal syndrome (painful Horner's syndrome )
- due to compression of 5th cranial nerve by ICA aneurysm.
Parkinson's syndrome - 6th nerve lesion + Horners syndrome
Causes for bilateral miosis
Old age
Argyll Robertson pupil (lesions like neurosyphillis
in the region of tectum.)
Pontine haemorrhage
Iritis
Organophosphorus or alcohol poisoning
Application of pharmacological miotics like
pilocarpine.
Overdose of neostigmine.
Pin point pupil
PUPILLARY SIZE 1MM OR LESS IS KNOWN AS PIN POINT PUPIL.
Causes for pin point pupil
? PONTINE HAEMORRHAGE
? ORGANOPHOSPHORUS OR ALCOHOL
POISONING
? CLONIDINE AND TETRAHYDRAZOLINE
? APPLICATION OF PILOCARPINE DROPS
? MORPHINE OR BARBITURATE
POISONING
? HEAT STROKE
Pathway of ocular
parasympathetic fibres
AFFERENT: FROM RETINA THROUGH OPTIC NERVE
TO THE PRETECTAL NUCLEUS OF MIDBRAIN
PRETECTAL NUCLEUS CONNECT WITH EDINGER
WESTPHAL NUCLEUS OF BOTH SIDES.
EFFERENT: PARASYMPATHETIC FIBRES ARISES FROM
THE EDINGER-WESTPHAL NULEUS IN THE MIDBRAIN
AND TRAVEL ALONG THE 3RD CRANIAL NERVE. THE
PREGANGLIONIC FIBRES ENTER THE INFERIOR
DIVISION IF THE 3RD NERVE AND VIA THE NERVE TO
INFERIOR OBLIQUE REACH THE CILIARY GANGLION
TO RELAY. POST GANGLIONIC FIBRES TRAVEL
ALONG THE SHORT CILIARY NERVES TO INNERVATE
THE SPHINCTER PUPILLAE.
Mydriasis
If size of the pupil is >5mm, it is known as mydriasis.
Causes of unilateral mydriasis
3rd nerve palsy.
Adie's pupil or myotonic pupil.(post ganglionic
parasympathetic pupil omotor damage)
Optic atrophy
Acute congestive glaucoma.
Head injury
Tentorial herniation (same side)
Causes of bilateral mydriasis
Childhood, anxiety or fear
Application of mydriatic (atropine)
Datura poisoning
Deep coma
Severe raised intracranial tension.
Cerebral anoxia
Death
Hippus
It is the alternating dilatation and constriction of
pupil.
Causes
Autonomic imbalance
recovering 3rd nerve lesion
Chorea
Anisocoria (unequal pupils)
The eyes should be assessed to determine which is the abnormal
pupil.
Causes
commonest cause is the application of mydriatic to one eye.
Unilateral sympathetic paralysis or irritation
unilateral 3rd nerve lesion as in brain stem damage, transtentorial
herniation
pressure effect on 3rd nerve in tumor or aneurysm
Blindness in one eye
Encephalitis
Iritis
severe head injury
Holmes - Adie pupil
Meningioma
migraine
This post was last modified on 12 August 2021