Trans 017 Neurooptha part 2 Flashcards
FUNCTIONS OF THE PUPIL
- Control in retinal illumination
- Reduction in optical aberration
- Depth of Focus
CLINICAL IMPORTANCE of the pupil
- Objective indicator of Light Input
- Anisocoria
- Pharmacological Indicator
- Indicated level of wakefulness
Direct light vs Consensual vs Near Reflex
DIRECT light reflex - Constriction of the pupil that was shined with light
✓ CONSENSUAL light reflex - Constriction of the other pupil without direct shining of light
✓ NEAR reflex - Constriction of the pupil without stimulation of light but when you focus at near objects
Two components of near reflex?
Convergence and Accomodation
Convergence of visual axis and associated constriction of pupil
When you’re looking at a far object and then suddenly you focus on the near object, your eyes will converge; this is accompanied by automatic constriction of pupil
Convergence reflex
Increased accommodation and associated constriction of pupil
Your lens will change in shape, especially hen you’re younger than 40 years old without the need for eyeglasses, they can see clearly at far and can see clearly at near, and that’s because of your accommodation; there is constriction of your ciliary muscles that will change the shape of your lens; part of this reflex is the constriction of pupil.
Accomodation reflex
Near Reflex Triad consists of:
o Increased Accommodation
Lens will change in shape to make it like a magnifying glass
o Convergence of Visual Axis
o Constriction of pupils
how to do the near reflex test?
- Instruct the patient to look at the distant target
- The examiner holds up a target containing fine detail approximately 25cm from the patient
- Ask the patient to fixate the near target and look for pupil constriction
- Note the speed of the constriction and the roundness of each pupil
AFFERENT PUPILLARY REFLEX is assessment of what to what?
Assessment of afferent input from the retina, optic nerve, and chiasm, optic tract and midbrain till LGB (Lateral Geniculate Body)
cause a reduction in pupil contraction when one eye is stimulated by light compared with when the opposite eye is stimulated by light.
may be associated with visual field or electroretinographic asymmetries between the two eyes
• Asymmetrical differences in retinal appearance or optic nerve appearance may occur
RAPD
Some causes of RAPD
- Optic neuritis
- Anterior ischemic optic neuropathy
- Compressive optic neuropathy
- Glaucoma
- Optic Nerve Tumors
- Orbital Diseases
- Ischemic Retinal Diseases: CRAO, CRVO, BRAO, BRAVO
- Ocular Ischemic Syndrome
- Central Serous Retinopathy or Crystoid Macular Edema
- Retinal Detachment
- Chiasmal Compression
- Optic Tract Lesion
- Post Geniculate Damage
- Midbrain tectal Damage
is defined by a difference in the size of the two pupils of 0.4 mm or greater.
Anisocoria
It should be considered a neurosurgical emergency if a patient has anisocoria with
acute onset of third-nerve palsy (“frozen eye”) and associated with headache or trauma.
If the difference in pupil size in both light and dark illumination is constant, then it is called
Physiologic or Essential anisocoria
DISORDERS CHARACTERIZED BY ANISOCORIA
- Horner’s syndrome
- Adie’s tonic syndrome
- Third-nerve palsy
- Adrenergic mydriasis
- Anticholinergic mydriasis
- Argyll Robertson pupils
- Local iris disease (e.g., sphincter atrophy, posterior synechiae, pseudoexofoliation syndrome)
- Hutchinson’s pupil
- Bernard’s syndrome
OCULOMOTOR NERVE PALSY WITH OR WITHOUT PUPIL INVOLVEMENT is a surgical emergency, true or false?
True
• The most common site of an intracranial aneurysm causing third nerve palsy is:
o The posterior communicating artery
o Internal carotid artery and basilar artery
The origin of Inferior Oblique is the
Medial orbital wall
Structures passing through the annulus:
- Oculomotor nerve (Superior an Inferior Divisions)
- Abducens nerve
- Optic nerve
- Nasociliary nerve
- Ophthalmic artery
What if there is tumor inside the annulus of Zinn? Everything is compressed; When there is inflammation, there will be edema and swelling thereby causing compression; we call it the
Orbital Apex Syndrome.
inserts closest to the limbus and is therefore susceptible to injury during anterior segment surgery
Medial rectus
Paralysis of Lateral rectus due to damage to Abducent nerve leads to
Medial Squint
Damage to Trochlear nerve cause paralysis of superior oblique muscle causing
diplopia while looking downwards.
Most common cause of acute optic neuropathy in over 50 years of age
• It is due to ischemia of anterior part of optic nerve head
• Involvement of posterior ciliary artery circulation
• Considered in differential diagnosis of sudden vision loss
• Visual field loss always present
Not all the visual field, but part of the visual field.
Anterior ischemic optic neuropathy
2 types of AION
Arteritic and non arteritic
arteritic vs non arteritic AION
• Arteritic o Most serious type o Mainly due to giant cell arteritis • Non-arteritic o Most common o Consist of all other cause than GCA
PATHOGENESIS:
• Occlusion of short posterior ciliary artery ->
• Decreased blood supply to optic nerve head ->
• Infarction of optic nerve head
RISK FACTORS:
• Multifactorial
• Nocturnal arterial hypotension play very important role
Parang sa CVA din”
which pathogenesis and risk factors?
Anterior AION
• Sudden painless monocular loss of Visual Acuity
• Visual field defect usually inferior altitudinal but can be central, paracentric, arcuate
• Dyschromatopsia
First thing affected before visual acuity is the color perception whatever condition it is”
• Diffuse or sectoral disc swelling (pallid edema) Optical Disc of other eye is typically small or absent cup
• Frequently associated with splinter hemorrhages.
clinical features of what disease?
AION
Isang clue na AION siya is the presence of ________ This is used to distinguish AION from Optic Neuritis.
flame shaped hemorrhages on the optic disc margins or splinter hemorrhages.
what lab test to rule out AION?
ESR
a- agonist eyedrops that is neuroprotective. More on the recovery of the optic nerve.
Topical - Brimonidine
- Uncommon
- Caused by retrobulbar optic neuritis ischemia (supplied by pial arteries)
- Diagnosed only after exclusion of other retrobulbar optic neuropathy
PION
• Sudden painless unilateral or bilateral vision loss
• Relative Afferent Pupillary Defect
• Absence of optic disc edema
• Optic atrophy ensues in 4-6 weeks
After 1 month or 2 months, the optic disc becomes pale and that is atrophy already”
clinical features of?
PION
is defined as “a condition causing a relatively rapid onset of visual failure, in which no evidence for a toxic vascular or compressive etiology can be discovered and where local retinal lesion have been excluded.”
• It is characterized by inflammation, demyelination and neurodegeneration
Optic neuritis
Used when Optic Disc appears normal
Retrobulbar Neuritis
when Optic Disc or Nerve Head is inflamed
Papillitis
Used for inflammation of both intravascular Optic Nerve & Peripapillary Retina
Neuroretinitis
Inflammatory involvement of Optic Nerve Sheath without inflammation on Nerve.
Optic Perineuritis
When unilateral or bilateral Optic Nerve is involved. Cranial nerves are normal.
Acute Demyelinating Optic Neuritis
SYMPTOMS:
• Loss of Central Vision & pain in and around the affected eye, increased by eye movements.
• Loss of visual acuity is noted in majority
• Vision loss is typically abrupt, over several hours to several days. Loss of Color vision
• Progression for few days to a week
• Degree of Visual loss varies from Minimal reduction to complete blindness
• Loss of portion of peripheral field on one side
Basically this is what you call hemianopsia”
• Mostly unilateral, bilateral in children
• Photopsias, may occur. Flashing Black Squares, Flashes of lights, showers of sparks.
PION
- Visual Acuity is reduced in almost all.
- Varies from Mild Reduction to No Light Perception
- Contrast Sensitivity & Color Vision is impaired in All.
- Visual Field loss is Mild to Severe. May be Diffuse or Focal
- Can involve Central or Peripheral Field
- Afferent Pupillary Defect in All (RAPD)
- Disc Swelling. Optic Disc is Slightly or Markedly Blurred
- Disc Swelling sometimes very severe and mimic Papilledema
- Degree of Disc Swelling does not correlate with loss of Visual Acuity
- Peripapillary Hemorrhages are less common
- Some have normal optic disc (Retrobulbar Neuritis)
- Fellow Eye may show abnormalities in Acuity, Color Vision and Disc Appearance
PION
