pupillary pathway and its abnormality.

1. PUPILLARY
PATHWAY
Dr Shreeji
Shrestha…..

2. Development
•pupillary membrane is formed by the condensation of
2nd wave mesodermal tissue surrounding the margin of
the optic cup and tunica vasculosa lentis.
• The peripheral part of the pupillary membrane gets
vascularised.
•The central part is eventually completely absorbed
forming the pupil.
•Pupil is formed by the complete absorption of the central
part of pupillary membrane

3. • Pupillary membrane begins
to degenerate at to degenerate at 8th month
• Iris stroma and dilator muscle
is I'm is immature hence pupil remain
co nstri constricted at birth

4. Persistent pupillary membrane
Polycoria
Iris coloboma- associated with CHARGE syndrome, turner , klinefelter
Aniridia

5. Acquired causes of pupil irregularity
• Blunt trauma - focal tear in sphincter muscle
• Iridodialysis - outer edge of iris is torn from ciliary
attachment
• Synechiae - IO inflammation can damage iris
leading adherence to lens or cornea
• Neovascularization- distort iris and impair reactivity
• Surgical procedure in anterior segment, cataract
• Tadpole pupil- focal spasm of iris dilator muscle
• Midbrain corectopia- rostral midbrain disease

6. PUPIL
● Round in shape and relatively equal in size
● Located inferonasally to the centre of cornea
● Normal pupil range from 3 to 4mm in ambient light
conditions
◦ Miotic pupil- less than 2mm
◦ Mydriatic pupil- greater than 7mm

7. PUPIL SIZE
● Determined by
◦ Level of retinal illumination
◦ Level of arousal
◦ Amount of ambient light
◦ Age
◦ Small pupil: Sleep, infants, old age
◦ Large pupil: Excitement, arousal,seizures,
increased IOP

9. Pupil Contraction and Dilation
● Controlled by two muscles of iris
◦ Sphincter muscle (pupil constriction)
●Innervated by the parasympathetic nerve
◦ Dilator muscle (pupil dilation)
●Innervated by the sympathetic nerve

10. FUNCTIONS OF PUPIL
•Pupil movement in response to changing light
intensity helps in optimizing retinal illumination to
maximize the visual perception
•Improves the image quality of the retina when the steady
state pupil diameter is small.
•Small pupil increases the depth of focus of the eye’s
optical system similar to pinhole effect of camera by
limiting rays entering cornea

13. Pupillary reflex
● Light reflex
● Near reflex
● Psychosensory reflex

14. Llight reflex
Preganglionic parasympathetic fibers
Postganglionic parasympathetic fibers
Contraction of sphincter muscle

15. Clinical aspect
Left Right
Damage to left optic nerve/pretectal nucleus
light in LE- no direct plus consensual light
reflex in right eye
Light in right eye- direct + consensual light
reflex present
Damage to left EWN/ occulomotor nerve/ ciliary
ganglion
Light in LE light in RE
LE- no change LE - no change
RE- pupil constrict. RE- constrict

16. Accommodation reflex
• Def- ability of eye to see near object when
focusing on far object
• Stimulus- sudden exposure of eye to near object
• Response- constriction of pupil
Convergence of eyeball
Increase curvature of lens

17. Near reflexshort ciliary nerve
Contraction of ciliary muscle- increase in curvature
Contraction of constrictor pupillae- constrict pupilContraction of MR- convergence of eyeball

18. Dilatation has 2 causes:
•Simply abolition of light reflex with consequent relaxation
of the sphincter pupillae
•Contraction of dilator pupillae supplied by sympathetic
nervous system
Darkness reflex

19. Psychosensory reflex
•Dilatation of pupil in response to sensory and psychic
stimuli
•Mechanism of psychosensory reflexes is a cortical one
and apparently the pupil dilatation in these results from 2
components-
✓Sympathetic discharge to the dilator pupillae
✓Inhibition of parasympathetic discharge to the sphincter
pupillae.

20. Abnormal Pupillary Reactions
● Afferent pupillary defect
• Total afferent pathway defect (TAPD) or Amaurotic pupil
• Relative afferent pathway defect (RAPD) or Marcus Gunn pupil
• Wernicke’s hemianopic pupil
● Efferent pupillary defect
• Tonic pupil
• oculomotor nerve palsy
• Pharmacologic mydriasis
● Light near dissociation
• Argyll Robertson pupil

21. TAPD/amaurotic pupil
• Caused - complete optic nerve or retinal lesion
Total blindness on affected side
• Ctd by:
direct light reflex on affected side - abs
consensual light reflex on normal side- abs
When the normal eye is stimulated, both pupils react normally
near reflex - normal
Diffuse illumination - both pupil are equal

22. Relative afferent pathway defect / Marcus gunn pupil
Paradoxical response of pupil to light -relative measurement of
input of one eye compared to other eye
Cause - incomplete nerve lesion or. a
severe retinal disease
Central serous retinopathy or cystoid macular edema
Central or branch retinal vein/artery occlusion
Retinal detachment
Anterior ischemic optic neuropathy
Optic neuritis
Compressive optic neuropathy
Intraocular hemorrhage-AC or vitreous

23. RAPD grading
Grade 1+: A weak initial pupillary constriction
followed by greater redilatation
Grade 2+: An initial pupillary stall followed by greater
redilatation
Grade 3+: An immediate pupillary dilatation
Grade 4+: No reaction to light

24. Measurement of RAPD
Neutral density filters
● Estimation of the amount of RAPD is in log units using
NDF placed infront of better eye and provides idea of how
much visual field damage is present.
● NDF balances asymmetry of pupil btn 2 eyes
● Loss of central 5º of visual field results in RAPD of 0.3 log
units.
● Loss of entire central field 10º causes RAPD of 0.6-0.9
log units.

26. • Tilting test:
If very small asymmetry is suspected (eg hippus) confirm
by tilting the RAPD to right and left using 0.3 log unit filters.
• Infrared videography:
helps to examine both pupil clearly in dark and to
establish dilatation lag of horner’s pupil.
• Computerized pupillometry: helps to record dynamics of
pupil movement and analyzed by software
• Pupil perimetry: Video camera is pointed at pupil and
amplitude of each light reaction is measured

27. Wernicke hemianopia pupil
• Cause- optic tract lesion
• Light reflex- ipsilateral direct & contralateral
consensual absent when light shown in termporal
half of affected retina & nasal half of opposite
side

28. Efferent pupillary defect
● Interferes with contraction or dilatation of pupil due
to the damage in midbrain, peripheral nerves that
supply iris muscles, or in the iris muscles itself
causing anisocoria
● Damage to parasympathetic or sympathetic nerves
that supply iris

29. Anisocoria equal in both dim & bright light: -
Physiologic/primary Anisocoria: 20% of the individuals
Difference in pupil diameter<1.0mm
Anisocoria greater in dim light( if iris dilated is
paretic or sympathetic palsy)
● Mechanical anisocoria: Previous trauma/ surgery
Inflammation
● Pharmacological anisocoria: Unilateral use of
medications like pilocarpine
● Horner syndrome

30. Physiologic anisocoria
● Dim light- right pupil is slightly larger than left
● Bright light both pupil constricts
● After instillation of cocaine both pupil dilates

31. Sympathetic Pathway

32. Horner syndrome
● Lesion at any point along oculosymphathetic pathway
• Characterized by : 1) ptosis - paralysis of muller muscle
2) miosis - paralysis of dilator pupillae
3) anhidrosis - reduced sweating on face
and neck when lesion is below SCG
4) apparent enophthalmos
5) Dilation lag : when lights are turned off
the horner’s pupil dilates more slowly than normal pupil does
6) Heterochromia irides: when
sympathetic innervation is interrupted early in life
7) light reflex and Near reflex - normal
● Anisocoria is more apparent in dim illumination.

33. Causes of Horner syndrome

34. Pharmacological Tests for horner syndrome
● Cocaine 4 or 10%: instilled in both eyes
Cocaine blocks reuptake of noradrenaline so causes pupillary
dilatation
In Horner syndrome no NA is secreted in first place so no effect seen
Result: Normal pupil dilate but Horner pupil does not dilate.
● Apraclonidine 0.5% or 1.0%
Alpha-1 agonist
In sympathetic denervated eyes, dilator muscle develops
adrenergic supersensitivity causing pupillary dilatation
Result: Horner pupil dilates but normal pupil is unaffected

35. • Hydroxyamphetamine test - localize site of lesion
A. Postganglionic - pupil will not dilate at all
B. Preganglionic / central lesion - pupil will dilate
normally
• Decentralization supersensitivity - Horner pupil
dilate more than normal - preganglionic

36. Central Preganglionic Postganglionic
Hypothalamic signs:
disturbed sleep,
temperature
Lungs and breast
malignancy has spread
to thoracic outlet
Ipsilateral vascular
headache
Brainstem- vertigo,
sensory deficit
history of injury /
surgery in neck, chest
tumor in cavernous
sinus associated III, IV,
VI palsy
Meningeal signs
Anhydrosis, brachial
plexus palsy, vocal
cord palsy
ICA dissection:
face/neck pain
neck bruit
Retinal artery
occlusion

37. Tonic pupil
● Traumatic iridoplegia (sphincter rupture, pigment
dispersion, angle recession)
● Angle-closure glaucoma (ischemia of the iris
sphincter)
● Fixed pupil after anterior segment surgery
● Bound down iris (synechia) after iritis
● Pharmacologic pupil- mydriatic medications
● Adie tonic pupil
● Third nerve palsy
Anisocoria Greater in Bright Light(iris sphincter is par

38. Adie’s tonic pupil
•Caused by denervation of the post ganglionic supply of
the sphincter pupillae and ciliary muscle
•which may follow viral illnessUsually unilateral
•Typically affects healthy young women (U/L)
•Affected pupil is large and irregular
•Light reflex is absent
•Near reflex is slow and tonic
•Accomodative paresis
•May be associated with mild regional
impairment of corneal sensations
•May be associated with
absent knee jerk

39. Third nerve palsy
● Pupillary dysfunction associated with ptosis and limitation
of extraocular mobility
● pupil mid-dilated Maximum anisocoria occurs in bright
light
● Aneurysms at the junction of internal carotid and posterior
communicating artery must be excluded
● 0.125% pilocarpine no constriction but constrict with 1%

41. Light near dissociation
Condition where light reflex is absent or sluggish but near response is normal

42. Argyll Robertson pupil
•Caused by the lesion in the region of tectum
•Usually bilateral but asymmetrical
•Pupils small in size and irregular
•Light reflex is absent but near reflex is present
•Pupils dilate very poorly with mydriatics

43. Pharmacology
Miotics
•Parasympathomimetics (sphincter stimulators):
i. Direct acting: pilocarpine
ii. Indirect acting or cholinesterase inhibitors: physostigmine
•Sympatholytics
1. Alpha adrenergic blocker: phenoxybenzamine and tolazoline
•Others miotics: histamine, morphine
Mydriatics
•Sympathomimetics: adrenaline, phenylephrine,
hydroxyamphetamine, cocaine
•Parasympatholytic: atropine, homatropine, tropicamide,
cyclopentolate.

44. Ciliospinal reflex
• B/l pupillary dilatation on nociceptive stimulation
on skin of neck
• Mediated by 2nd and 3rd order sympathetic
nerve

45. Other Pupillary Disorders
● Benign Episodic Pupillary Mydriasis- Young, healthy
individuals with headache, episodic mydriasis lasting
from minutes to hours, mild blurring of vision &
periocular discomfort
● Paradoxical Pupillary Reactions-
congenital stationary night blindness, congenital
achromatopsia. or dominant optic atrophy

48. References
• Alders physiology
• American academy of ophthalmology-
neuroophthalmology
• Wolf's anatomy of eye
• Anatomy and physiology of eye- A K khurana