can help you with pupil abnormalities

1. Pupil
By
Staff Members
Ophthalmology Department
Zagazig University
2022

2. I am
Dr Ahmed Elsayed
Assistant lecturer of Ophthalmology /
Zagazig University
And You ?
Group A7

3. Rules

4. PUPILLARY LIGHT REFLEX
Definition :
When light falls on one eye, pupil of this
eye become smaller (Direct light reflex)
and also pupil of the other eye (Indirect,
consensual or crossed light reflex).

5. Pathway of pupillary light reflex :
• Stimulus : light.
• Receptors : Rods and cones in the retina.
• Afferent : Axons of ganglion cells → Optic
nerve → Chiasma → In the chiasma, the nasal
fibers cross to reach the optic tract of the
opposite side (First crossing). The temporal
fibers pass directly into the optic tract of the
same side. → Fibers leave tract at its
posterior third → Mid-brain and relay in the
pre-tectal nucleus → Edinger-Westphal
nucleus on both sides (Second crossing).

6. • Centre: Edinger-Westphal nucleus (Part of III
nerve nucleus).
• Efferent : III nerve with parasympathetic
fibers → Ciliary ganglion → Post ganglionic
fibers enter the eye (in short ciliary nerves)
to supply sphincter pupille muscle.
• N.B: Consensual reaction is due to crossing
of the fibers in the Chiasma and in Midbrain.
N.B: Consensual reaction is due to crossing of the
fibers in the Chiasma and in Midbrain.

9. Technique of pupillary light
reaction
 The illumination room is reduced and, the patient should
be instructed to look at a distant object to reduce
accommodation and bright light is directed on the side
of the patient’s eye (Avoid standing in front of the patient
or placing the light in the front of the eye, this will
stimulate accommodation and hence miosis).
 Placing the light on side of one eye gives direct pupillary
light reaction (Constriction of the pupil) in this eye and
consensual pupillary light reaction (Constriction of the
pupil) in the other eye.

10. Technique of pupillary light
reaction
 Repeat in other eye.
 Movement of the light to and fro between the eyes
gives Swinging flashlight test (Constriction of both
pupil). If one pupil dilates instead of constricts, this is
an afferent pupil defect indicating a serious retinal or
optic nerve problem.

12. Group interaction

13. Check list
Reduction of room illumination
the patient should be instructed to look at a distant
object to reduce accommodation
Bright light is directed on the side of the patient’s eye
while observing the size of the patient’s pupil
Repeat the test in other eye
Swinging flashlight by moving the light to and fro
between both eyes
Interpretation of the result

14. NEAR REACTION
When a near object is viewed, three
related reflexes occur :
1. Convergence, by contraction of the two
medial recti muscle.
2. Miosis, by contraction of the sphincter
pupillae muscle.
3. Accommodation, by contraction of ciliary
muscle.
 All three reflexes are mediated by III nerve.

15. Technique of accommodation (near
response) test
 Ask the patient to look from the distance fixation to near object,
both pupils should constrict equally.

16. Pathway :
• Stimulus : Blurring of the image.
• Receptors: Rods and cones.
• Afferent : Rods and cones → Optic nerve →
Chiasma → Optic tract → Lateral geniculate
body → Optic radiation → Occipital cortex
→ Frontal cortex → internal capsule →
Edinger Westphal nucleus.
• Centre : Edinger Westphal nucleus.
• Efferent: Same as in the light reflex.

18. ABNORMAL PUPILLARY
REACTION
Relative afferent pupillary defect (RAPD,
Marcus Gunn pupil) :
It is a sign caused by unilateral :
a- Partial optic nerve lesion.
b- Severe retinal disease.

19. b- “Swinging flashlight test” : When
swinging the light from the unaffected
to the affected eye , the abnormal pupil
dilates instead of constricting.
It is characterized by :
a- Vision in the affected eye is markedly
diminished while vision in the another
eye is normal.

22. • It is characterized by :
- Involved eye is completely blind (NO PL).
- Loss of direct and consensual reaction on
stimulation of the affected eye while both
reactions are intact on stimulation of the
normal eye.
- Near reflex is normal in both eyes.
Absolute afferent pupillary defect (amaurotic
pupil) :
• It is caused by a complete optic nerve lesion
or central retinal artery occlusion.

28. Questions
Dr : Ahmed Elsayed Mohamed
 Ahmad.m.1991@Hotmail.com
 00201147110558