Ischaemic Optic Neuropathies Flashcards
What is ischaemic optic neuropathy?
How common is it?
Different types?
Ischaemia of optic nerve which leads to death of ganglion cells
· Ischaemic optic neuropathy is the most common optic nerve disorder in patients over age 50 years
· Ischaemic optic neuropathy is generally categorized as anterior (affecting the optic disc) versus posterior (retrobulbar) and as arteritic versus nonarteritic
Exam plan?
Exam Plan
1. Visual Acuity
o Habitual VA with PH
- Preliminaries
a. Confrontations
o To screen for an gross VF defects
b. Pupils
o Expect an afferent pupillary defect for asymmetrical or unilateral presentation
c. EOM & CT
o Worsening pain on eye movement would indicate optic neuritis
d. Red Cap – Colour Vision
o To screen of ONH and Macular involvement
o For asymmetrical or unilateral presentation
e. Amsler
o To screen for macula involvement
o Assist in differentiating vision loss from macula pathologies
- Refraction
o To assess if V can be improved with new Rx
o Only to be performed if there is improvement with PH - Near VA
o To assess macula involvement - IOP
o Pre and post dilation IOP - SLE
o Check Van Herrick – Gonio if indicated
o To assess the possibility of corneal involvement or involvement of the anterior segment that may have contributed to the symptoms - DFE
o To assess the posterior pole and peripheral retina
o Helps differentiate from peripheral retinal conditions such as retinal tears, detachments or vitreous haemorrhages - Visual Fields
o Variable defects seen in optic neuropathies - OCT
o To confirm any optic nerve oedema - Fundus Photography
o Record Keeping
o Allows us to compare with past presentations and future presentations
Signs and symptoms of AAION
- GCA usually presents a number of symptoms before any loss of vision occurs.
- About 80% of those affected will feel unwell for some time with any of the following:
o Pain in the temples
o Pain when chewing
o Scalp pain or tingling
o Neck pain
o Muscle aches and pains, particularly in the upper legs or arms
o General fatigue
o Loss of appetite
o Unexplained loss of weight
o Fever - Key Vision Related Symptoms
o Painless, temporary blurriness or loss of vision lasting several minutes or hours before vision loss becomes permanent.
Temporary Vision Loss should be treated as a warning signal
Signs:
• Reduced VA
o More severe than NAION
o Can result in no light perception
• Dyschromatopsia (diminished colour vision)
• Afferent pupillary defect
• Optic disc oedema
o Tends to be pallid as opposed to hyperaemic (AAION)
• Peripapillary splinter haemorrhage
o Peripapillary splinter or flame haemorrhages and dilated telangiectatic capillaries is common
• VF loss o Classically inferior altitudinal VF Loss o Inferior nasal defect o Central scotoma o Generalised depression
What tests need to be considered when testing for GCA?
Questions to ask
- Presence of headache, scalp tenderness and jaw claudication
Tests - Blood Tests o Erythrocyte Sedimentation Rate (ESR) o C – Reactive Protein - Temporal Artery Biopsy
What is AAION?
- Is a dangerous condition caused by inflammation of arteries supplying blood to the optic nerve.
What percentage of patients with vision loss that have GCA are caused by AION?
80%
What is GCA? (GIANT CELL ARTERITIS)
causes inflammation of medium- and large-sized arteries.
- GCA is potentially fatal and can damage the entire optic nerve head leading to permanent, massive vision loss if not diagnosed and treated quickly.
What age is AAION most likely to affect?
Female to male ratio?
those over 55 years of age
3 more likely in women than men
Process of GCA?
- ONH Ischaemia > ONH Swelling > Necrosis of ONH
RISK factors of NAION?
- Obstructive sleep apnoea
- Smoking
- Diabetes
- High Blood Pressure
- High Cholesterol
- Other forms of Cardiovascular Disease
- Anaemia or other Blood Disorders
Signs and symptoms of NAION
Symptoms
- Monocular vision loss over hours to days
- Typically unilateral
- Pain is unlikely
Signs
- Reduced VA
o Less severe than AAION
o Can range from 6/6 to light perception
- Dyschromatopsia (diminished colour vision)
- Afferent pupillary defect
- Optic disc oedema
o Tends to be hyperaemic as opposed to pallid (AAION) - Peripapillary splinter haemorrhage
o Peripapillary splinter or flame hemorrhages and dilated telangiectatic capillaries is common - Small optic cup, nerve fiber crowding in the unaffected eye
o Denoted as “Disc at Risk” - VF loss
o Classically inferior altitudinal VF Loss
o Inferior nasal defect
o Central scotoma
o Generalised depression
What causes Posterior Ischaemic optic Neuropathy?
• PION is believed to result from an infarction of the retrobulbar optic nerve and is distinguished clinically from AION by a normal-appearing optic nerve head.
Signs and symptoms of PION?
- Sudden, painless, monocular vision loss
- Afferent pupillary defect
- Acquired colour vision deficiency
- VF loss altitudinal defect or central scotoma
- Normal appearing ONH
Diagnostic criteria of PION?
There is no confirmatory diagnostic test for PION, which is a diagnosis of exclusion
Diagnostic Criteria:
• Acute deficit in visual acuity and/or visual field
• Ipsilateral relative afferent pupillary defect unless bilateral
• Normal optic disc appearance at onset of visual loss
• Exclusion of other causes (retinal vascular occlusion, glaucoma, chorioretinal scars)
• Exclusion of other causes of optic neuropathy such as compression, demyelination, or inflammation with neuroimaging, preferably brain magnetic resonance imaging (MRI) with gadolinium
• Abnormal visual evoked response, either absent or decreased amplitude
• Normal electroretinogram
• Development of optic disc pallor within four to eight weeks of onset
Management
Perioperative PION
No treatment for perioperative PION
Vision loss does not typically improve significantly
Arteritic PION
Corticosteroids
Non – Arteritic PION
Occasionally use corticosteroids – but not recommended if GCA has been excluded
