3. Function of The Pupil
• The pupil serves an important function to the eye ,
as it controls the amount of the light that enters the
eye , and it does so by the help of the Iris:
• Sphincter muscle(constrictor) Dilator muscle
4. Physiology of The Pupil
• Knowing the physiology
is must :
• The parasympathetic
pathway :controls the
muscle , serves as the
pupillary light reflux :
• Also as near , orbicularis
5. The Pupillary light reflux pathway :
Afferent pathway -
2- optic chiasm
3- optic tract
4-the pretectal nucleus (lying in the dorsal midbrain).
Efferent pathway: (The parasympathetic)
1- Edinger-Westphal nucleus
2- the third cranial nerve out to
3-the ciliary ganglion
4-short ciliary nerves to both constrictors of the eye.
6. The Sympathetic Pathway
• The sympathetic
pathway controls the
dilator papillae muscle :
• For withdrawal ,
emotional fear and
7. The pathway of The Sympathetic
• -The central first neuron begins in the posterior
hypothalamus, the ciliospinal center (C8-T2)in the
cervical spinal cord
• -The preganglionic second neuron
• Through sympathetic trunk to the superior
• -The postganglionic third neuron extends a
neural plexus along the internal carotid artery,
ophthalmic artery, and long ciliary nerves to the
dilator pupillae muscle .
8. Let’s Start to evaluate the Pupil
• General examination of the patient
• Provide helpful clues as to what is going on,
particularly where there is an underlying
• Telltale neck scar and associated ptosis in
patients with Horner's syndrome or a
neurosurgical scar in patients with a 3rd nerve
9. Pupil Examination
• Important terminologies :
• Examination consists of four steps :
Unequal pupils size
Equal pupils size
10. 1-Pupil Observation
• Start by a general observation, noting
1. The shape
2. The size of the pupil in ambient bright light.
Size is measured in millimetres and the
normal pupil ranges from 1-8 mm.
3. The symmetry.
11. 2-Light reflex test
• Used to assess the integrity of the pupillary
light reflex pathway.
• Direct light reflex :
The examined eye is constricted when the light
• Indirect (consensual) light reflex :
The fellow eye will constrict.
(don’t stand in the front of the patient!!)
13. 3- Swinging Flashlight Test
• Also known as (Marcus gunn test).
• Used to compare between direct and
consensual light reflex.
• It’s preformed by equal exposure of light to
• Normally both pupils should be of the same
size and constricted.
• Abnormally if the pupil dilate if light is shown.
14. • That’s caused by withdrawal reflex of the
• Called as RAPD (relative afferent pupillary
15. Near Reflex
• Used to test accommodation.
• Preformed by asking the patient to fixed at
distant the to bring it to a near object (arm’s
• Normally the pupil will have a brisk
• Near-light dissociation =significant better
pupillary near reflex than light reflex.
16. Normal Pupil Reactions
• Will be :
•Pupils Equal Round and
Responsive to Light and
•Negative Marcus Gunn response
17. Diagnosis Keys
• Determine which pupil is abnormal.
• Search for associated signs.
Disorders of the pupil may result from:
• Ocular disease.
• Disorders of the controlling neurological
• Pharmacological action.
• This is physiological in about 20% of people.
• How to assess it :
• An affected Large Pupil has poor constriction
in a well lit room.
• An affected small pupil has poor dilatation in
well lit room.
19. The abnormally reacting pupil
1- Light reflex test :
From severe optic nerve
The patient will be blind in
one eye .
No reaction when the
affected side is
20. The abnormally Reacting Pupil
2- Swinging flashlight test
:when the pupil exhibits
an RAPD, it is described
as a Marcus Gunn pupil.
• Optic nerve disease,
central retinal artery or
vein, A mild RAPD may
in amblyopia .
22. Diseases affecting the pupils
• Congenital :
1. Aniridia : bilateral
2. Coloboma : partial
absence of pupil.
3. Leukocoria : White
or congenital cataract)
23. Diseases affecting the pupils
• Acquired :
matrix material deposited on
the anterior lens.
2. Sphincter tear: due to
3. Synechiae : post. between
iris +lens or ant. Between
iris and cornea.
24. Diseases affecting the pupils
• Neurological :
1- Horner’s syndrome :
disruption of the sympathetic
nerves supplying the eye.
Triad of :
• Partial ptosis (upper eyelid
• Miosis (pupillary constriction).
• Enophthalmos .
• (Normal pupillary reaction)
• Causes :
Many causes :
1. Central : Multiple
sclerosis, spinal cord
3. Postganglionic : internal
28. 3- Adie's tonic pupil:
Tonically dilated pupil
Caused by infection to
29. 4-Argyll Robertson pupils:
They are characterized by
irregular pupils showing
Difficult to dilate.
30. Drugs Affecting Pupil
•Mydriatics (bilateral or
• Topical : sympathomimetics
and antimuscarinics (eg,
•Miotics (bilateral or unilateral)
• Topical : muscarinic
agonists (eg, pilocarpine).
• Systemic: opiates (eg,
31. Remember :
• Take a good history to help exclude an ocular
cause for the pupillary changes and to see if a
medical condition exists which may contribute
to the pupillary problem.
• Determine whether it is the small or the large
pupil that is abnormal.
• Search for associated signs that may help
make a diagnosis.