CS2: Pupil Testing

Afferent Testing

(transillumintor)

pupillary reaction to light

pupillary reaction to near

when we observe the pupillary reaction to light we look at

- the direct reaction of light

- consensual reaction of light

-comparison of direct and consensual light reaction (testing for RAPD)

Efferent testing

(measuring stick)

- pupil size

in bright and in dim

reaction to light/near

afferent testing

pupil size

efferent

Bright light

iris constrictor/parasympathetic

Dim light

iris dilator/sympathetic

Afferent limb of the light reflex pathway

light reflex --> nasal fibers cross --> optic tract --> brachium of superior colliculus -->pretectal nucleus -->cross at the posterior commisure and some uncrossed --> Edinger-Westphal Nucleus

the light pathway does not use

the lateral geniuclate nucleus

Efferent limb of reflex pathway

Leaves midbrain

autonomic - parasympathetic

travels w CN3

synapse in the ciliary ganglion

travel with ciliary nerves

stimulus to one eye causes

both pupils to constrict because of the crossing

Near visual pathway

near target --> nasal fibers cross --> LGN --> Visual Cortex --> there is some pathway to EW nucleus --> travels w 3 --> synapse in ciliary ganglion --> short cilliary --> sphoncter

PERRLA (+/-) RAPD

P+ pupils

E = equal

R = round

RL= reactive to light

A = reactive to accommodation

RAPD = relative afferent pupillary defect

SEE slides for procedure

anisocoria

unequal pupil size

difference in pupil size is equal in both bright and dim illumination

physiologic anisocoria

difference greater in DIM

problem dilator --> sympathetics

difference greater in bright illumination

problem with constrictor - parasympathetics

See procedure

when do we asses pupillary reaction to near stimulus

only necessary if poor light reaction

if a pat has less than a 4 reaction to light

test the near stimulus (A) to see if the response is greater for near

evaluate for pupillary constriction when looking at near thumb OR look at dilation when look far

near synkinesis triad

accommodation

convergence

miosis (constriction)

Light-near dissociation

if the pupillary reaction is greater for an accommodative target than for a light stimulus

Light/near dissociation pupils can be caused by

- amaurotic (blind eye)

- tonic pupil

- ARGYLL ROBERTSON PUPIL (neuro-syphilis)

- TECTAL PUPIL (Dorsal Midbrain Syndrome)

• ABERRANT REGENERATION OF CN III

Near pathway also sends innervation to the ___ for convergence

subnucleus for medial rectus

in the ciliary ganglion there are more neurons for

accommodation than for iris constrictor

1 second Swinging flashlight test

Turn all lights off and shine light in each eye for 1 second at a time swinging back and forth

you are only looking at the eye which you are shining the light

If there is any dilation or constriction note RAPD

Normal/ small RAPD response is that both pupils remain constricted equally for the duration of the test

this means there is no large RAPD

Marcus Gunn Pupil

other eye is occluded

relative afferent pupillary defect / thompson arch opthalmol 1976

the consensual response induced by the good eye is greater than the direct response produced by the diseased eye

3 second swinging flash light test

dark

looking at the eye in which you are shining

at one time does the pupil start to dilate

normal response = time to escape is equal

the eye with the faster escape at the RAPD

Pupil pitfalls

- keeping light on each eye for differnt times

- light shinning into both eyes

- holding light at different distances

- not shining directly into pupil (especially when there is an eye turn)

on 3 second swiningt flashlight test, If one pupil has a faster escape, this represents a

small relative afferent pupillary defect

The relative afferent pupillary defect

damage to afferent visual system

asymmetric disease

not related to anisocoria

relatively unaffected by media opacities

signature of optic neuropathy

RAD occurs with lesion

anterior to the LGN

retina

ON

optic chiasm

Optic tract

(usually)

RAPD may indicate

asymltruc optic nerve disease

significant asymmetric retinal disease

optic chiasm

optic tract

NOT PRESENT IN AMBLYOPIA

RAPD = asymetric optic neuropathy

- compression

- inflammation

- infarction

-demyelination

-glaucome

-trauma

-papilledema

Retinao causes of RAPF

CRAO

CRVO

Macular disease (rare)

retinal detachment (large!! amcular nvolvement)

RAPD optic tract

bow tie optic atrophy contralateral to tract lesion

small RAPD in contralateral to the lesion

can only see on 3 second test

could also impact corticospinals -->contralateral spastic paralysis

lack of RAPD

does not mean normal

its just not asymmetric

RAPD grading 1+

early release/escape of pupil

small

2 sec

RAPD grading 2+

no initial movement followed by early release

small

3 sec

RAPD grading 3+

immediate release of pupil

1 second

RAPD grading 4+

Amaurotic pupil associated with no light perceptionm

1 second

We can measure the RAPD with a

neutral density filter

Neutral density filter

0.3, 0.6, 0.9, 1.2

Put the NDF over the good eye

increase until the time to escape is the same

(the brain is perceiving the same amount of light from both eyes)

Tilting

use of 0.3 NDF to tease out a subtle RAPD

will not do the same thing on both eyes

is it really a RAPD?

support with subjective test of afferent nerve function

brightness sense comparison

color vision/ desaturation

contract sensitivity

visual field

the difference in the amount of visual filed damage in each eye should be equal to the measured degree of RAPD

mean damage OD - mean damge OS

divid by 10

is equal to the log unit NDF

inverse/ reverse RAPD

when 1 pupil does not respond to light we can still check

need to compare the direct and consensual response to light getting all of the information from 1 eye

ANISOCORIA

anisocoria

unequal pupil size

EFFERENT

Pathologic Anisocoria

unequal difference between eyes in BOTH bright and dim

Physiologic anisocoria

equal difference btw eyes in BOTH bright and dim illumination

physiologic anisocoria ____&

17%

only 5% have difference of

1 mm

which pupil is abnormal

measure pupil sizes in BOTh bright and dim light

Anisocoria greater in bright

iris sphincter is not working (not constricting)

parasympathetic

larger pupil is abnormal

Anisocoria in Dim

iris dilator is not working (not dilating)

sympathetic

smaller pupil is abnormal

anisocoria in bright and dim

physiologic

if pathologic think about where the damage can be

1. Mescle

2. Junction (drops)

3. nerve

4. Brain

EFFERENT VISUAL SYSTEM

If the abnormal pupil is too large: Muscle

synechia (iris stuck to lens)

trauma

If the abnormal pupil is too large: Junction

drops (dilating)

If the abnormal pupil is too large: Nerve

CN III palsy (from parasympathetics traveling with CN III)

Tonic pupil (lesion of ciliary ganglion)

If the abnormal pupil is too large: Brain

Tectal Pupil

Uncal herniation (compression of CNIII and parasympathetic)

If the abnormal pupil is too Small: Muscle

ciliary muscle spasm

If the abnormal pupil is too small: junction

mitotic eye drops

If the abnormal pupil is too small: nerve

horner's syundrome

If the abnormal pupil is too small: brain

argyll-Robertson

Horner's syndrome

oculosympathetic paresis

oculosympathetic pathway

starts in the hypothalamus --> spinal cord --> synapse in the centrla horn of grey --> synapse in the superior ervical ganglion --> travels with ICA --> enters orbit and travels with the long/short ciliary nerves --> dilator

1st and 2nd order neurons

pre ganglionic

3rd order

post ganglionic

Horner's syndrome triad

miosos (small pupil)

ptosis (droopy lid)

anhydrosis (lack of sweating)

another sign og Horners syndrome is

dilation lag

reluctant dilator

anisocria > 5sec than at 12 secs

Old gold standard to test for Horner's syndrome

Cocaine drops

cocain blcolks re-uptake of norepinephrine at nerve terminal causing a healthy eye to dialte

a postive Horner Syndrom results in No dilation

used in infants under 6 mos and somtimes under 2

New diagnostic test for Horner's syndrome

0.5% or 1% Apralinidine

0.5% or 1% Apralinidine

no effect on normal pupil

weak alpha 1 agonist

Dilates Horner Pupil (supersensitivity)

look for reversal of anisocria

Horner's eye and apraclonidine

Horner eye has alpha 1 receptors upregualted due to the reduced amount of norepinephrine

apraclonidine is a wawek alpha 1 agonist that will not effect a normal eye

however the horner syndrome yeye will dialte becuase it is starved (upregualted alpha 1 recpetsr)

will call small eye to dilate!

Paredrine Test (both eyes dilate)

negative for 3rd orfer neuron horners

or acute 3rd order

Paredrine Test (only normal eyes dilate)

non acute 3rd order

1.0% Phenylepherine

endpoint is reversal of anisocoria in POSTGANGLIONIC Horners (3rd order Horner eye dilates) - Pre-ganglionic (1st and 2nd order Horner) would not dilate

Painful Horner's syndrome

consider carotid artery dissection

(tear)

Medical EMergency

CN III Palsy

larger pupil!

anisocoria in light

CN 3 innervates

medial rectus, superior rectus, inferior rectus, inferior oblique, levator

parasympathetis travel with

causes of CNII

aneurysm (PCOM)

vasculopathic (diabetes and high blood pressure )

we can use the pupil as a guide when

its complete CN III

lid all the way down

concern for aneurysm

if the pupil is invilved

anuerysm

if the pip is not involved

vsculopathic

DOES NOT APPLY IF

complicated CN3

incomplete CN3

relative sparing

20-50 years

Pain in CN3 palsy

Aneurysm!!!

diabetes

oituitary apoplexy

giant cell

cavernous synus

Aberrant regneration of CN III

anuerysm tumor, trama

Light-near dissociation

Pseduo-graefe sign (tell pt to look down and eyelid goes up)

Eyelid synkinesia (look in and eyelid shoots up)

Aberrant regneration of CN III is NEVER

vasculopathic

Argyll Robertson Pupil

no anisocoria

small in bright and dim

Argyll Robertson Pupil

Light near dissociation

small mitic pupil no karger than 2.5

unilateral or bilteral

Argyll Robertson Pupil most common caused by

neuro syphilis

dorsal midbrain syndrome (tectal pupils)

mid dilated

light near dissociation

no anisocoria

upgaze/down gaze paresis

eyelid retraction

Tonic pupil

pilocarpine is an eyedrop used to contrict the pupils

weak pilo

will not constrict a normal pupil but will constrict a tonic

Tonic Pupil

funny looking pupil

mid dilated

light near dissociation

3 S

secrtor paralyis

stromal spreading

stromal steaming