The Power Of The Pupil

Kelly A. Malloy, OD, FAAO, Diplomate, Neuro-Ophthalmic Disease

Course Description: This course highlights both the afferent as well as the efferent pupillary function and demonstrates the magnitude of information that can be gained from proper and careful pupil testing. Testing techniques are reviewed, and interpretation of the results in combination with other clinical findings is stressed. A case-based approach aids in the understanding of the importance of pupil testing in diagnosing multiple neuro-ophthalmic disease processes affecting both the afferent and efferent visual system.

Course Learning Objectives:

  1. To develop a systematic approach to pupil testing.
  2. To properly and thoroughly evaluate both the afferent and the efferent pupillary function.
  3. To be able to accurately interpret the results of pupil testing in terms of both a relative afferent pupillary defect and anisocoria.
  4. To understand when the pupil findings suggest a neuro-ophthalmic disease process that requires further work-up / evaluation.

Course Outline:

I.The Relative Afferent Pupillary Defect

a.Suggests asymmetric disease

b.Not related to anisocoria

c.Relatively unaffected by media opacities

d.Signature of optic neuropathy

  1. An RAPD can ONLY occur with lesions at on anterior to the Lateral Geniculate Nucleus (LGN) !

II.PUPIL TESTING TECHNIQUE

a.PERSONALLY perform pupil testing

b.Do test prior to ANY drop instillation

c.Test to be done in the dark

d.Patient to fixate at distance

e.Use a bright light (transilluminator) directed into the pupil

f.Shine the light onto each eye for an equal amount of time

g.Check the direct response to light in each eye

h.CHECKING FOR A RELATIVE AFFERENT PUPILLARY DEFECT

i.Perform BOTH the 1 SECOND AND 3 SECOND Swinging Flashlight Test

1.1 second test only picks up large RAPDs

2.3 second test is necessary to detect small RAPDs

-the endpoint is pupillary ESCAPE, not pupil size

  1. An RAPD can ONLY occur with lesions at on anterior to the Lateral Geniculate Nucleus (LGN) !

III.RAPD GRADING

a.1-4+ scale

i.1+ = EARLY RELEASE / ESCAPE OF PUPIL

ii.2+ = NO INITIAL MOVEMENT FOLLOWED BY EARLY RELEASE

iii.3+ = IMMEDIATE RELEASE OF PUPIL

iv.4+ = AMAUROTIC PUPIL ASSOCIATED WITH NO LIGHT PERCEPTION

b.“MEASURING THE RAPD”

i.Neutral Density Filters (0.3, 0.6, 0.9, 1.2, 1.8)

c.SUPPORT WITH OTHER TESTS of AFFERENT NERVE FUNCTION / DISC APPEARANCE

i.BRIGHTNESS SENSE COMPARISON

ii.COLOR VISION / DESATURATION

iii.VISUAL FIELD

  1. Visual acuity
  2. optic disc appearance

IV.RAPD and Optic Tract Lesions

a.Ipsilateral ST/IT pallor ( I/S arcuate VF defects)

b.Contralateral band pallor (temporal VF defect)

i.From nasal macular fibers (papillomacular bundle)

c.May have small RAPD in contralateral eye

  1. An RAPD can ONLY occur with lesions at on anterior to the Lateral Geniculate Nucleus (LGN) !

d.Incongruous homonymous hemianopia

e.Bow tie optic atrophy contralateral to tract lesion

V.Inverse / Reverse RAPD Testing

a.When 1 pupil does not respond to light

b.Need to compare the direct and the consensual response to light

VI.The Near-Accommodative Response (“Near Synkinesis”)

a.If pupils do not react well to light, you MUST test the near response

i.Accommodation

ii.Convergence

iii.Miosis

b.LIGHT/NEAR DISASSOCIATION PUPILS

  1. pupils react better to near stimulus than to light
  2. 5 causes of light-near disassociation
  3. AMAUROTIC (blind eye)
  4. TONIC (Adie’s as well as other causes of tonic pupil)
  5. ARGYLL ROBERTSON (syphilis)
  6. TECTAL (Dorsal Midbrain Syndrome)
  7. ABERRANT REGENERATION OF CN III

VII.ANISOCORIA

a.Is this physiologic or pathologic anisocoria?

b.Is the anisocoria greater in bright or dim illumination?

i.= difference in bright and dim = physiologic

ii.> BRIGHT = PARASYMPATHETIC

iii.> DIM = OCULOSYMPATHETIC

iv.> BRIGHT, < DIM = BOTH, TONIC

c.Is the abnormal pupil smaller or larger?

i.Larger Pupil is Abnormal

1.Muscle – sphincter tears, synechia

2.Junction – pharmacologic dilation

3.Nerve – CN III, tonic pupil

4.Brain – dorsal midbrain syndrome, uncal herniation

ii.Smaller pupil is abnormal

1.Horner Syndrome

2.Argyll Robertson Pupil

d.Are there other associated problem?

i.Lids / Motility

VIII.TONIC PUPIL

a.ADIE”S TONIC PUPIL = idiopathic

b.NEUROPATHIC TONIC PUPIL

i.SARCOID

ii.SYPHILIS

iii.DIABETES

c.Pharmacologic Testing for Tonic Pupil

i.Weak (1/8 or 1/10) pilocarpine

ii.Miosis owing to “denervation supersensitivity”

iii.Acquired phenomenon

iv.“3 S’s” seen with slit lamp examination

1.Sector paralysis

2.Stromal spread

3.Stromal steaming

v.Other Clinical Features of tonic pupil

1.“Flat” edges

2.“Vermiform” iris movement

3.Poor response to light near or LND

4.“Dilation lag” following prolonged near effort

5.“Paradoxical Pupil” - aniso greater in light dim

IX.ARGYLL-ROBERTSON PUPIL

a.MIOSIS (2.5 mm in dark)

b.ABSENT DIRECT LIGHT RESPONSE BRISK NEAR RESPONSE (LND)

c.ETIOLOGY = TREPONEMA PALLIDUM (SYPHILIS)

i.WORK-UP FOR ARGYLL-ROBERTSON PUPILS

1.BOTH RPR AND FTA-ABS

2.NEURO-IMAGING

3.LUMBAR PUNCTURE (VDRL)

4.LYME TITER

ii.Treatment for neuro-syphilis

1.IV penicillin x 14 days

X.DORSAL MIDBRAIN SYNDROME

a.Feature of Dorsal Midbrain Syndrome

i.Tectal Pupils - Mid-Dilated, Poorly Reactive To Light, Better To Near

ii.Upgaze Paresis (Downgaze Paresis, Or Both)

iii.Convergence Retraction Nystagmus

iv.Eyelid Retraction

b.Cause of Dorsal Midbrain Syndrome

i.Pinealoma

ii.tumors, mets, AVM, III ventricle, infarct, MS, syphilis

iii.aqueductalstenosis

iv.herniation

XI.CN III PALSY

a.Ptosis

b.Mid-dilated pupil ?

i.Pupil involved = ANEURYSM (86%) (MEDICAL EMERGENCY)

ii.Pupil Spared = VASCULOPATHIC (77%)

•DOES NOT APPLY IF:

– COMPLICATED CNIII

– INCOMPLETE CNIII

– RELATIVE SPARING

– 20-50 YEARS OF AGE

c.Reduced response to light & near

d.External ophthalmoplegia (up, down & in)

e.Complete vs. incomplete

f.Aberrant regeneration

  1. Features
  2. Lid elevation on downgaze
  3. Lid elevation on medial gaze
  4. light-near disassociation
  5. Causes
  6. Aneurysm
  7. Tumor
  8. Trauma
  9. NEVER vasculopathic!!!!
  1. CN III PALSY WORK-UP
  2. 20-50 years of age

–CT, MRI, MRA, Angiogram

ii.50+ Years of age (pupil, palsy, pain)

–NEUROIMAGING

–VASCULOPATHIC EVALUATION

iii. if painful or pupil involvement, is a MEDICAL EMERGENCY!!!

XII.HORNER SYNDROME

a.Features

i.MIOSIS

1.RESPONSES INTACT

2.ANISOCORIA > DIM

3.“LAZY DILATOR”

4.NO COCAINE DILATION (not available)

ii.PTOSIS

1.1-2 mm

iii.(ANHYDROSIS)

b.New Diagnostic Test For Horner Syndrome

i.0.5% or 1.0% Apraclonidine (Iopidine)

1.Alpha agonist

2.Weak alpha 1 agonist

3.No effect on normal pupil

4.Dilates Horner pupil (supersensitivity – MUST NOT USE ANY DROPS PRIOR TO TEST)

5.Look for REVERSAL OF ANISOCORIA (indicates a positive test)

c.HORNER SYNDROME LOCALIZATION

i.Brainstem (CN IV, APD, INO)

ii.Spine (phrenic nerve)

iii.brachial plexus

iv.apex of lung (Pancoast tumor)

v.neck (carotid dissection)

vi.base of skull

vii.cavernous sinus

viii.Horner syndrome in kids – need to consider neuroblastoma

d.Carotid Artery Dissection (MEDICAL EMERGENCY)

i.Need to consider this diagnosis in EVERY PAINFUL HORNER’s

ii.Can occur with or without trauma

iii.Medical Emergency

iv.Horner’ s with eye, head, neck pain

v.Pt to hospital immediately (MRI, MRA, CTA, angiogram)