This lecture is based on post-graduate medical students of Ophthalmology (DO. DCO. MS. FCPS) topic Neuro-ophthalmology

2. Anterior Ischaemic Optic Neuropathy: Aetiopathogenesis
Ischaemic optic neuropathy, producing an altitudinal field defect, has been
recognized for many years as a complication of severe anemia or after a
massive haemorrhage. Patients suffering from a neglected acute attack of
angle-closure glaucoma are also likely to develop ischaemic neuropathy with
subsequent optic atrophy.
The condition, however, may arise spontaneously and the clinical entity
comprises sudden loss of vision, initially associated with swelling of the optic
disc (Fig. 22.7) which resolves to optic atrophy within a month or two leaving
a permanent visual defect (Parsons’ 354)

3. Anterior Ischaemic Optic Neuropathy: Aetiopathogenesis
It is due to interference with the blood supply of the posterior ciliary artery to
the anterior part of the optic nerve, producing a post-laminar infarct, without
necessarily involving the central retinal artery.
The underlying aetiology leading to anterior ischaemic optic neuropathy (AION)
can be either inflammatory or non-inflammatory. Based on this, ischaemic optic
neuropathy is broadly classified into two categories:
(i) arteritic and
(ii) non-arteritic.

4. Non-arteritic anterior ischaemic optic neuropathy
(NAION)
Non-arteritic anterior ischaemic optic neuropathy (NAION) is caused
by occlusion of the short posterior ciliary arteries resulting in partial
or total infarction of the optic nerve head.
Predispositions include structural crowding of the optic nerve head so
that the physiological cup is either very small or absent,

5. Predispositions factors
hypertension (very common),
diabetes mellitus,
hyperlipidaemia,
collagen vascular disease,
antiphospholipid antibody syndrome,
hyperhomocysteinaemia,
sudden hypotensive events,
cataract surgery,
sleep apnoea syndrome and
erectile dysfunction. Patients are usually over the age of 50, but are typically
younger than those who develop arteritic ION

6. Diagnosis: Symptoms & Signs
Symptoms
Sudden painless monocular visual loss; this is frequently discovered
on awakening, suggesting a causative role for nocturnal hypotension.
Signs
VA is normal or only slightly reduced in about 30%. The remainder has
moderate to severe impairment.
Visual field defects are typically inferior altitudinal but central,
paracentral, quadrantic and arcuate defects may also be seen

7.  Dyschromatopsia is usually proportional
to the level of visual impairment, in
contrast to optic neuritis in which colour
vision may be severely impaired when
VA is reasonably good.
 Diffuse or sectoral hyperemic disc
swelling, often associated with a few
peripapillary splinter haemorrhages
 Disc swelling gradually resolves and
pallor ensues 3–6 weeks after onset.
Arteritic anterior
ischaemic optic neuropathy
showing
typical disc oedema with
splinter haemorrhage.

8. Investigation & Prognosis
Investigation should include blood pressure, a fasting lipid profile and
blood glucose. It is also very important to exclude occult giant cell
arteritis with symptomatic enquiry and testing as appropriate.
Atypical features may prompt special investigations, such as
neuroimaging.
Prognosis: Improvement in vision is common although recurrence
occurs in about 6%. About 50% of eyes achieve 6/9 or better, though
25% will only reach 6/60 or worse.

9. Fellow eye
Fellow eye.
Involvement of the fellow eye occurs in about 10% of patients after 2
years and 15% after 5 years. When the second eye becomes involved,
optic atrophy in one eye and disc oedema in the other gives rise to the
‘pseudo-Foster Kennedy syndrome’.

10. Treatment
There is no definitive treatment.
Optic nerve fenestration has not been shown to be of benefit.
Some authorities advocate short-term systemic steroid treatment.
Any underlying systemic predispositions should be treated.
Although aspirin is effective in reducing systemic vascular events and is
frequently prescribed in patients with NAION,
it does not appear to reduce the risk of involvement of the fellow eye.

11. Arteritic anterior ischaemic optic neuropathy
(AAION)
Arteritic anterior ischaemic optic neuropathy (AAION) is caused by
giant cell arteritis (GCA). About 50% of patients with GCA have
polymyalgia rheumatica (PMR) at diagnosis, while around 20% of PMR
patients will develop GCA.
The severity and extent of involvement are associated with the quantity
of elastic tissue in the media and adventitia and intracranial arteries are
usually spared as they possess little elastic tissue.

12. Diagnosis of giant cell arteritis
GCA is a granulomatous necrotizing arteritis with a predilection for
large and medium-size arteries, particularly the major aortic branches
and
the superficial temporal (STA),
ophthalmic,
posterior ciliary and
proximal vertebral arteries.

13. Risk factors
Smoking,
low body mass index and
early menopause may be independent risk factors.
Patients are usually elderly (average 70 years) and the condition is
extremely rare under the age of 50.
Women are affected four times more commonly than men.

14. Symptoms
Scalp tenderness, first noticed when combing the hair, is common.
Headache, which may be localized to the frontal, occipital or temporal areas
or be more generalized.
Jaw claudication (cramp-like pain on chewing), caused by ischaemia of the
masseter muscles, is virtually pathognomonic.
Non-specific symptoms such as weight loss, fever, night sweats, malaise and
depression are common.
Double vision may occur.

15. Other features
Superficial temporal arteritis is characterized by thickened, tender,
inflamed and nodular arteries (Fig. 19.14B), though the signs may be
subtle.
Pulsation is initially present, but later ceases, a sign strongly suggestive
of GCA, since a non-pulsatile superficial temporal artery is highly
unusual in a normal individual.
Ocular motor palsies, including a pupil-involving third nerve palsy, can
manifest.
Scalp gangrene may occur in very severe cases.

16. Giant cell arteritis: Investigation
Erythrocyte sedimentation rate (ESR) is often very high, with a level of >60
mm/hr., although in approximately 20% of patients it is normal, even low–
normal.
C-reactive protein (CRP) is invariably raised and may be helpful when ESR is
equivocal.
Full blood count: elevated platelets and normocytic normochromic anemia are
commonly present.
Liver function tests are abnormal in one-third.

17. Giant cell arteritis: Investigation
Autoantibodies are normal.
Temporal artery biopsy (TAB) should be performed if GCA is
suspected. Steroid treatment should never be withheld pending biopsy,
which should ideally be performed within 3 days of commencing
steroids.
Systemic steroid administration of duration greater than 7–10 days
may suppress histological evidence of active arteritis although this is
not invariable. In patients with ocular involvement it is advisable to
take the biopsy from the ipsilateral side. The ideal location is the
temple because it lessens the risk of major nerve damage.

18. Giant cell arteritis: Investigation
At least 2.5 cm of artery should be collected and serial sections
examined because of the phenomenon of ‘skip’ lesions in which inflamed
segments of arterial wall are interspersed with histologically normal
areas. A negative TAB should not prevent ongoing treatment in the
presence of a convincing clinical picture of GA as 15% have normal
histology; a contralateral biopsy may be positive in 5% following a
negative initial biopsy

19. Giant cell arteritis: Investigation
• Colour Doppler and duplex ultrasonography shows a hypoechoic halo
around the superficial temporal artery lumen in around 75% due to
oedema in the artery wall, and may be pathognomonic. There is some
evidence that this provides a valid non-invasive alternative to TAB.
Doppler imaging is also a useful aid to locating the artery for biopsy
when it cannot be palpated.

20. Giant cell arteritis: Investigation
• Extra cranial large vessel imaging. Aortic imaging with
ultrasonography, MRA or positron emission tomography (PET)
scanning may be used to exclude aortic aneurysm or dissection due to
aortitis. Serial long-term imaging is increasingly being advocated to
exclude these potentially life-threatening complications, the risk of
which has now been demonstrated to be substantially increased in and
following GCA.

21. Giant cell arteritis: Investigation
Shoulder joint imaging. Recent work suggests that particular
inflammatory features in the shoulder joints on MRI and
ultrasonography may be useful diagnostically in PMR.

22. Treatment of giant cell arteritis without AAION
Treatment in the absence of visual symptoms is with oral prednisolone.
An initial dose of 1 mg/kg/day is typical, the subsequent duration of
treatment being governed by the response of symptoms and the level of
the ESR or CRP; symptoms may recur without a corresponding rise in
ESR or CRP and vice versa. Most patients need treatment for 1–2 years,
although some may require

23. indefinite maintenance therapy. Rapid tapering should generally not
occur, with added caution when the dose is reduced to below about 10
mg a day. CRP may play an important role in monitoring
disease activity, as the level seems to fall more rapidly than the ESR in
response to treatment

24. Arteritic anterior ischaemic optic neuropathy (AAION)
Arteritic anterior ischaemic optic neuropathy (AAION) affects 30–50%
of untreated patients with GCA, of whom one-third develop involvement
of the fellow eye, usually within a week of the first. Posterior ischaemic
optic neuropathy is much less common.

25. Symptoms: AAION
Sudden, profound unilateral visual loss not uncommonly preceded by
transient visual obscurations (amaurosis fugax) and sometimes by double
vision.
Periocular pain is common.
Other GCA symptoms are common; most cases of AAION occur within a few
weeks of the onset of GCA, although at presentation about 20% do not have
systemic symptoms, Simultaneous bilateral involvement is rare but rapid
involvement of the second eye, with resultant total blindness, should always
be regarded as a substantial risk

26. Signs: AAION
Severe visual loss is the rule, commonly to only perception of light or worse.
A strikingly pale ‘chalky white’ oedematous disc is particularly suggestive of
GCA.
Over 1–2 months, the swelling gradually resolves and severe optic atrophy
ensues.
Prognosis is very poor. Visual loss is usually permanent, although, very
rarely, prompt administration of systemic steroids may be associated with
partial recovery.

28. Treatment: AAION
Treatment is aimed at preventing blindness of the fellow eye, as visual loss
in the index eye is unlikely to improve even with immediate treatment; the
second eye may still become involved in 25% despite early steroid
administration. The regimen is as follows:
Intravenous methylprednisolone, 500 mg to 1 g/day for 3 days followed by
oral prednisolone 1–2 mg/kg/day.
After 3 more days the oral dose is reduced to 50–60 mg (not less than 0.75
mg/kg) for 4 weeks or until symptom resolution and ESR/CRP normalization.

29. Treatment: AAION
A typical subsequent regimen consists of reducing the daily dose by 10
mg/day every 2 weeks until 20 mg/day is reached,
with tapering afterwards titrated against ESR/CRP and symptoms, e.g.
2.5 mg reduction every 2–4 weeks to 10 mg then a 1 mg reduction
every 1–2 months.

30. Treatment: AAION Following guideline should be
followed when prescribe steroid for a long time
Enteric-coated prednisolone may be appropriate,
Steroid treatment should be accompanied by bone and gastrointestinal
protection, e.g. a weekly bisphosphonate, calcium/vitamin D supplementation
and a proton pump inhibitor.
Monitoring A full blood count, ESR/ CRP, urea and electrolytes, random
glucose and blood pressure should be checked at each visit. Every 1–2 years, a
chest X-ray or more sophisticated imaging should be performed to exclude an
aortic aneurysm and bone mineral density should be assessed.

31. Treatment: AAION
Antiplatelet therapy, e.g. aspirin 600 mg stat then 100 mg/day.
Any significant symptomatic relapse should be treated with an aggressive
increase in steroid dose; intravenous methylprednisolone should be given if
visual disturbance occurs.
Immunosuppressives such as methotrexate may be used as adjuncts in
steroid-resistant cases or as steroid-sparing agents when extended
treatment is required, though with caution as their benefit is considerably
less proven than that of steroids.
Biological blockers have not been shown to have a definite protective effect.

32. Other manifestations
Cilioretinal artery occlusion may be combined with AAION
Central retinal artery occlusion is often combined with occlusion of a
posterior ciliary artery – with resultant choroidal hypoperfusion – as
the two can arise from the ophthalmic artery by a common trunk.
Ocular ischaemic syndrome due to involvement of the ophthalmic
artery is rare.
Pseudo-Foster Kennedy syndrome (From Kanski 9 th edition)

33. Posterior ischemic optic neuropathy (PION)
(PION) is much less common than the anterior variety. It is caused by
ischaemia of the retrolaminar portion of the optic nerve supplied by the
surrounding pial capillary plexus, which in turn is supplied by pial
branches of the ophthalmic artery. The diagnosis of PION should be
made only after other causes of retrobulbar optic neuropathy, such as
compression or inflammation, have been excluded. Initially, the optic
disc appears normal but pallor develops over weeks.

34. Operative (perioperative) PION develops following a variety of surgical
procedures, most notably involving the heart and the spine. It occurs in
about 0.02% of these procedures.
The major risk factors appear to be anemia and intraoperative
hypovolaemic hypotension. Bilateral involvement is common and the
visual prognosis is typically poor. Prompt blood transfusion and
treatment of facial/orbital swelling may be of benefit.

35. Arteritic PION is associated with giant cell arteritis and carries a poor
visual prognosis.
Non-arteritic PION is associated with the same systemic risk factors as
NAION, but is not associated with a crowded optic disc. The visual
prognosis is similar to NAION. Some practitioners prescribe a short
course of high-dose systemic steroid in early cases.

36. Clinical Features Distinguishing Arteritic from Non-Arteritic Anterior
Ischaemic Optic Neuropathy (AION)
Common features to
both
Arteritic AION Non-Arteritic AION
1) Sex ratio Female> Male Female = Male
2) Vision Loss • Sudden
• Reduced colour
vision
• Altitudinal or
central field
defect
• Usually severe
• Up to 76%
• <6/60
• Occasionally
progressive
• Usually moderate
• Up to 61% .
• >6/60
• non-progressive
3) Ocular pain Usually painless May be present Rare
4) Prior episodes of
amaurosis
Uncommon Occasionally Rare
5) Laterality Initially unilateral
but may
become bilateral
Fellow eye affected
in up to 95% within
days to weeks
Fellow eye affected
in ,30%
within months to
years

37. Clinical Features Distinguishing Arteritic from Non-Arteritic Anterior
Ischaemic Optic Neuropathy (AION)
6) Optic
disc
Oedema and
pallor of the
disc; may be
sectoral, flame
shaped
haemorrhages
Pale .hyperemic oedema
Cup normal
Hyperemic .pale
oedema
Cup small
7) Other
symptoms
and signs
• Headache
• Scalp tenderness; palpable,
tender, non-pulsatile temporal
Artery
• Proximal muscle and joint,
aches ‘polymyalgia rheumatica’
• Anorexia, weight loss, fever
• Jaw claudication
• Cranial nerve palsies
• Associated
hypertension in
40% of patients
• Diabetes in up to
24%
• Shock (acute
systemic
hypotension)
• Nocturnal
hypotension

38. Clinical Features Distinguishing Arteritic from Non-Arteritic Anterior Ischaemic
Optic Neuropathy (AION)
1) ESR Usually .40 mm in first
hour
Mean 20–40 mm in first hour
2) Temporal
artery biopsy
Giant cell
granulomatous
vasculitis
involving all coats of the
vessel wall
Not indicated if features do
not suggest arteritis
3) Fluorescein
angiogram
Disc and choroidal
filling delay
Disc filling delay
4) Natural
history
Improvement rare,
fellow eye involvement
in up to 95%
Improvement in up to 43%,
fellow eye affected in ,30%
5) Treatment Corticosteroids Not proved to be effective
Levodopa–carbidopa
combination for 3 weeks and
then double dose for 1 month
reported to be beneficial