PAPILLOEDEMA

The terms papilloedema and disc oedema look alike
and per se mean swelling of the optic disc. However,
arbitrarily the term ‘papilloedema’ has been reserved
for the passive disc swelling associated with
increased intracranial pressure which is almost always
bilateral although it may be asymmetrical. The term
‘disc oedema or disc swelling’ includes all causes of
active or passive oedematous swelling of the optic
disc.
Causes of disc oedema
1. Congenital anomalous elevation (Pseudopapilloedema)
2. Inflammations
Papillitis
Neuroretinitis
3. Ocular diseases
Uveitis
Hypotony
Vein occlusion
4. Orbital causes
Tumours
Graves’ orbitopathy
Orbital cellulitis
5. Vascular causes
Anaemia
Uremia
Anterior ischaemic optic neuropathy
6. Increased intracranial pressure
See causes of papilloedema
Etiopathogenesis of papilloedema
Causes. As discussed above, papilloedema occurs
secondary to raised intracranial pressure which may
be associated with following conditions:
1. Congenital conditions include aqueductal
stenosis and craniosynostosis.
2. Intracranial space-occupying lesions (ICSOLs).
These include brain tumours, abscess,
tuberculoma, gumma, subdural haemotoma and
aneurysms. The ICSOLs in any position excepting
medulla oblongata may induce papilloedema.
Papilloedema is most frequently associated with
tumours arising in posterior fossa, which obstruct
aqueduct of Sylvius and least with pituitary
tumours. Thus, the ICSOLs of cerebellum,
midbrain and parieto-occipital region produce
papilloedema more rapidly than the mass lesions
of other areas. Further, the fast progressing lesions
produce papilloedema more frequently and acutely
than the slow growing lesions.
3. Intracranial infections such as meningitis and
encephalitis may be associated with papilloedema.
4. Intracranial haemorrhages. Cerebral as well as
subarachnoid haemorrhage can give rise to
papilloedema which is frequent and considerable
in extent.
5. Obstruction of CSF absorption via arachnoid
villi which have been damaged previously.
6. Tumours of spinal cord occasionally give rise to
papilloedema.
7. Idiopathic intracranial hypertension (IIH) also
known as pseudotumour cerebri,is an important
cause of raised intracranial pressure. It is a poorly
understood condition, usually found in young
obese women. It is characterised by chronic
headache and bilateral papilloedema without any
ICSOLs or enlargement of the ventricles due to
hydrocephalus.
8. Systemic conditions include malignant
hypertension, pregnancy induced hypertension
(PIH) cardiopulmonary insufficiency, blood
dyscrasias and nephritis.
9. Diffuse cerebral oedema from blunt head trauma
may causes papilloedema
Unilateral versus bilateral papilloedema. Disc
swelling due to ocular and orbital lesions is usually
unilateral. In majority of the cases with raised
intracranial pressure, papilloedema is bilateral.
However, unilateral cases as well as of unequal
change do occur with raised intracranial pressure. A
few such conditions are as follows:
1. Foster-Kennedy syndrome. It is associated with
olfactory or sphenoidal meningiomata and frontal
lobe tumours. In this condition, there occurs
pressure optic atrophy on the side of lesion and
papilloedema on the other side (due to raised
intracranial pressure).
2. Pseudo-Foster-Kennedy syndrome. It is
characterised by occurrence of unilateral
papilloedema associated with raised intracranial
pressure (due to any cause) and a pre-existing
optic atrophy (due to any cause) on the other
side.
Pathogenesis. It has been a confused and
controversial issue. Various theories have been put
forward and discarded from time to time. Till date,
Hayreh’s theory is the most accepted one. It states
that, ‘papilloedema develops as a result of stasis of
axoplasm in the prelaminar region of optic disc, due
to an alteration in the pressure gradient across the
lamina cribrosa.’
Increased intracranial pressure, malignant
hypertension and orbital lesions produce disturbance
in the pressure gradient by increasing the tissue
pressure within the retrolaminar region. While, ocular
hypotony alters it by lowering the tissue pressure
within the prelaminar area.
Thus the axonal swelling in prelaminar region is
the initial structural alteration, which in turn produces
venous congestion and ultimately the extracellular
oedema. This theory discards the most popular view
that the papilloedema results due to compression of
the central retinal vein by the raised cerebrospinal
fluid pressure around the optic nerve.
Evolution and recovery. Papilloedema usually
develops quickly, appearing within 1-5 days of raised
intracranial pressure.
In cases with acute subarachnoid haemorrhage it
may develop even more rapidly (within 2-8 hours).
However, recovery from fully developed papilloedema
is rather slow. It takes about 6-8 weeks to subside
after the intracranial pressure is normalised.
Clinical features
[A] General features. Patients usually present to
general physicians with general features of raised
intracranial pressure. These include headache,
nausea, projectile vomiting and diplopia. Focal
neurological deficit may be associated.
[B] Ocular features. Patients may give history of
recurrent attacks of transient blackout of vision
(amaurosis fugax). Visual acuity and pupillary
reactions usually remain fairly normal until the late
stages of diseases when optic atrophy sets in.
Clinical features of papilloedema can be described
under four stages: early, fully developed, chronic and
atrophic.
1. Early (incipient) papilloedema
Symptoms are usually absent and visual acvity is
normal.
Pupillary reactions are normal.
Ophthalmoscopic features of early papilloedema
are (Fig. 12.11A): (i) Obscuration of the disc
margins (nasal margins are involved first followed
by the superior, inferior and temporal) (ii) Blurring
of peripapillary nerve fibre layer. (iii) Absence of
spontaneous venous pulsation at the disc
(appreciated in 80% of the normal individuals).
(iv) Mild hyperaemia of the disc. (v) Splinter
haemorrhages in the peripapillary region may be
present.
Visual fields are fairly normal.
2. Established (fully developed) papilloedema
Symptoms. Patient may give history of transient
visual obscurations in one or both eyes, lasting
a few seconds, after standing. Visual acuity is
usually normal,
Pupillary reaction remain fairly normal,
Ophthalmoscopic features (Fig. 12.11B): (i)
Apparent optic disc oedema is seen as its forward
elevation above the plane of retina; usually up to
1-2 mm (1 mm elevation is equivalent to +3
dioptres). (ii) Physiological cup of the optic disc
is obliterated. (iii) Disc becomes markedly
hyperaemic and blurring of the margin is present
all-around. (iv) Multiple soft exudates and
superficial haemorrhages may be seen near the
disc. (v) Veins becomes tortuous and engorged.
(vi) In advanced cases, the disc appears to be
enlarged and circumferential greyish white folds
may develop due to separation of nerve fibres by
the oedema. (vii) Rarely, hard exudates may radiate
from the fovea in the form of an incomplete star.
Visual fields show enlargement of blind spot.
3. Chronic or long standing (vintage) papilloedema
Symptoms. Visual acuity is variably reduced
depending upon the duration of the papilloedema.
Pupillary reactions are usually normal
Ophthalmoscopic features (Fig. 12.11C). In this
stage, acute haemorrhages and exudates resolve,
and peripapillary oedema is resorbed. The optic
disc gives appearance of the dome of a champagne cork. The central cup remains
obliterated. Small drusen like crystalline deposits
(corpora amylacea) may appear on the disc
surface.
Visual fields. Blind spot is enlarged and the
visual fields begin to constrict.
4. Atrophic papilloedema
Symptoms. Atrophic papilloedema develops after
6-9 months of chronic papilloedema and is
characterized by severely impaired visual acuity.
Pupillary reaction. Light reflex is impaired.
Ophthalmoscopic features (Fig. 12.11D)
It is characterised by greyish white discoloration
and pallor of the disc due to atrophy of the neurons
and associated gliosis. Prominence of the disc
decreases in spite of persistent raised intracranial
pressure. Retinal arterioles are narrowed and veins
become less congested. Whitish sheathing develops
around the vessels.
Visual fields. Concentric contraction of peripheral
fields becomes apparent as atrophy sets in.
Differential diagnosis
Papilloedema should be differentiated from pseudopapilloedema
and papillitis. Pseudopapilloedema is
a non-specific term used to describe elevation of the
disc similar to papilloedema, in conditions such as
optic disc drusen, hypermetropia, and persistent
hyaloid tissue. The differentiating points between
papilloedema, papillitis and pseudopapilloedema
(pseudopapillitis) due to hypermetropia are
enumerated in Table 12.2.
Treatment and prognosis
It is a neurological emergency and requires immediate
hospitalisation. As a rule unless the causative disease
is treatable or cerebral decompression is done, the
course of papilloedema is chronic and ultimate visual
prognosis is bad.
Feature Papilloedema Papillitis Pseudopapillitis
1. Laterality Usually bilateral Usually unilateral May be unilateral
or bilateral
2. Symptoms
(i) Visual acuity Transient Marked loss of Defective vision
attacks of blurred vision of depending upon
vision sudden onset the degree of
Later vision refractive error
decreases due to
optic atrophy
(ii) Pain and tenderness Absent May be present Absent
with ocular movements
3. Fundus examination
(i) Media Clear Posterior Clear
vitreous haze
is common
(ii) Disc colour Red and juicy Marked Reddish
appearance hyperaemia
Disc margins Blurred Blurred Not well defined
Disc swelling 2-6 dioptres Usually not Depending upon the
more than degree of
3 dioptres hypermetropia
(iii) Peripapillary oedema Present Present Absent
(iv) Venous engorgement More marked Less marked Not present
(v) Retinal haemorrhages Marked Usually not present Not present
(vi) Retinal exudates More marked Less marked Absent
(vii) Macula Macular star may be Macular fan may be Absent
present present
4. Fields Enlarged Central scotoma No defect
blind spot more for colours
5. Fluorescein angiography Vertical oval Minimal No leakage of dye
pool of dye leakage of dye
due to leakage

OPTIC NEURITIS

Optic neuritis includes inflammatory and demyelinating
disorders of the optic nerve.
Etiology
1. Idiopathic. In a large proportion of cases the
underlying cause is unidentifiable.
2. Hereditary optic neuritis (Leber’s disease)
3. Demyelinating disorders are by far the most
common cause of optic neuritis. These include
multiple sclerosis, neuromyelitis optica (Devic’s
disease) and diffuse periaxial encephalitis of
Schilder. About 70% cases of established multiple
sclerosis may develop optic neuritis.
4. Parainfectious optic neuritis is associated with
various viral infections such as measles, mumps,
chickenpox, whooping cough and glandular fever.
It may also occur following immunization.
5. Infectious optic neuritis may be sinus related
(with acute ethmoiditis) or associated with cat
scratch fever, syphilis (during primary or
secondary stage), lyme disease and cryptococcal
meningitis in patients with AIDS.
6. Toxic optic neuritis (see toxic amblyopias).
Clinical profile
Anatomical types. Optic neuritis can be classified
into three anatomical types:
Papillitis. It refers to involvement of the optic
disc in inflammatory and demyelinating disorders.
This condition is usually unilateral but sometimes
may be bilateral.
Neuroretinitis refers to combined involvement of
optic disc and surrounding retina in the macular
area.
Retrobulbar neuritis is characterized by
involvement of optic nerve behind the eyeball.
Clinical features of acute retrobulbar neuritis are
essentially similar to that of acute papillitis except
for the fundus changes and ocular changes
described below.
Symptoms. Optic neuritis may be asymptomatic or
may be associated with following symptoms:
Visual loss. Sudden, progressive and profound
visual loss is the hallmark of acute optic neuritis.
Dark adaptation may be lowered.
Visual obscuration in bright light is a typical
symptom of acute optic neuritis.
Impairment of colour vision is always present in
optic neuritis. Typically the patients observe
reduced vividness of saturated colours.
Movement phosphenes and sound induced
phosphenes may be percieved by patients with
optic neuritis. Phosphenes refer to glowing
sensations produced by nonphotic or the so
called inadequate stimuli.
Episodic transient obscuration of vision on
exertion and on exposure to heat, which recovers
on resting or moving away from the heat
(Uhthoff’s symptom) occurs in patient with
isolated optic neuritis.
Depth perception, particularly for the moving
object may be impaired (Pulfrich’s phenomenon).
Pain. Patient may complain of mild dull eyeache.
It is more marked in patients with retrobulbar
neuritis than with papillitis. Pain is usually
aggravated by ocular movements, especially in
upward or downward directions due to
attachment of some fibres of superior rectus to
the dura mater.
Signs are as follows:
1. Visual acuity is usually reduced markedly.
2. Colour vision is often severely impaired.
3. Pupil shows ill-sustained constriction to light.
Marcus Gunn pupil which indicates relative
afferent pupillary defect (RAPD) is a diagnostic
sign. It is detected by the swinging flash light
test (see page 474).
4. Ophthalmoscopic features. Papillitis is
characterised by hyperaemia of the disc and
blurring of the margins. Disc becomes oedematous
and physiological cup is obliterated. Retinal veins
are congested and tortuous. Splinter haemorrhages
and fine exudates may be seen on the disc.
Slit-lamp examination may reveal inflammatory
cells in the vitreous. Inflammatory signs may also
be present in the surrounding retina when papillitis
is associated with macular star formation and the
condition is labelled as ‘neuroretinitis’ (Fig. 12.8).
In majority of the cases with retrobulbar neuritis
fundus appears normal and the condition is
typically defined as a disease where neither the
ophthalmologist nor the patient sees anything.
Occasionally temporal pallor of the disc may be
seen.
5. Visual field changes. The most common field
defect in optic neuritis is a relative central or
centrocaecal scotoma. Other field defects noted
rarely include: paracentral nerve fibre bundle
defect, a nerve fibre bundle defect extending up
to periphery and a nerve fibre bundle defect
involving fixation point and periphery. The field
defects are more marked to red colour than the
white.
6. Contrast sensitivity is impaired.
7. Visually evoked response (VER) shows reduced
amplitude and delay in the transmission time.
Differential diagnosis
Papillitis should be differentiated from
papilloedema and pseudo-papilloedema (see
Table 12.2).
Acute retrobulbar neuritis. It must be differentiated
from malingering, hysterical blindness,
cortical blindness and indirect optic neuropathy.
Evolution, recovery and complications
In optic neuritis, typically, the visual acuity and colour
vision is lost progressively over 2-5 days. The rate of
visual recovery is slower than the rate of visual loss
and usually takes between 4 and 6 weeks. About 75
to 90 percent cases get good visual recovery.
However, recurrent attacks of acute retrobulbar
neuritis are followed by primary optic atrophy and
recurrent attack of papillitis are followed by
postneuritic optic atrophy leading to complete
blindness.
Treatment
Efforts should be made to find out and treat the
underlying cause. There is no effective treatment for
idiopathic and hereditary optic neuritis and that
associated with demyelinating disorders.
Corticosteroid therapy may shorten the period of
visual loss, but will not influence the ultimate level of
visual recovery in patients with optic neuritis. Optic
neuritis treatment trial (ONTT) group has made
following recommendations for the use of
corticosteroids:
1. Oral prednisolone therapy alone is contraindicated
in the treatment of acute optic neuritis, since, it
did not improve visual outcome and was
associated with a significant increase in the risk
of new attacks of optic neuritis.
2. A patient presenting with acute optic neuritis
should have brain MRI scan. If the brain shows
lesions supportive of multiple sclerosis (MS),
regardless of the severity of visual loss, each
patient should receive immediate intravenous
methylprednisolone (1 gm daily) for 3 days
followed by oral prednisolone (1 mg/kg/day) for
11 days. This therapy will delay conversion to
clinical MS over the next 2 years.
3. Indications for intravenous methylprednisolone
in acute optic neuritis patients with a normal
brain MRI scan are:
Visual loss in both eyes simultaneously or
subsequently within hours or days of each
other.
When the only good eye is affected.
When the slow progressive visual loss
continues to occur.

PUPILLARY REFLEXES AND THEIR ABNORMALITIES

PUPILLARY REFLEXES
Light reflex
When light is shone in one eye, both the pupils
constrict. Constriction of the pupil to which light is
shone is called direct light reflex and that of the other
pupil is called consensual (indirect) light reflex. Light
reflex is initiated by rods and cones.
Pathway of light reflex (Fig. 12.6). The afferent fibres
extend from retina to the pretectal nucleus in the midbrain.
These travel along the optic nerve to the optic
chiasma where fibres from the nasal retina decussate
and travel along the opposite optic tract to terminate
in the contralateral pretectal nucleus. While the fibres
from the temporal retina remain uncrossed and travel
along the optic tract of the same side to terminate in
the ipsilateral pretectal nucleus.
Internuncial fibres connect each pretectal nucleus
with Edinger-Westphal nuclei of both sides. This
connection forms the basis of consensual light reflex.
Efferent pathway consists of the parasympathetic
fibres which arise from the Edinger-Westphal nucleus
in the mid-brain and travel along the third
(oculomotor) cranial nerve. The preganglionic fibres
enter the inferior division of the third nerve and via
the nerve to the inferior oblique reach the ciliary
ganglion to relay. Post-ganglionic fibres travel along
the short ciliary nerves to innervate the sphincter
pupillae.
Near reflex
Near reflex occurs on looking at a near object. It
consists of two components: (a) convergence reflex,
i.e., contraction of pupil on convergence; and
(b) accommodation reflex, i.e., contraction of pupil
associated with accommodation.
Pathway of convergence reflex (Fig. 12.7). Its afferent
pathway is still not elucidated. It is assumed that the
afferents from the medial recti travel centrally via the
third nerve to the mesencephalic nucleus of the fifth
nerve, to a presumptive convergence centre in the
tectal or pretectal region. From this the impulse is
relayed to the Edinger-Westphal nucleus and the
subsequent efferent pathway of near reflex is along
the 3rd nerve. The efferent fibres relay in the
accessory ganglion before reaching the sphincter
pupillae.
Pathway of accommodation reflex (Fig. 12.7). The
afferent impulses extend from the retina to the
parastriate cortex via the optic nerve, chiasma, optic
tract, lateral geniculate body, optic radiations, and
striate cortex. From the parastriate cortex the impulses
are relayed to the Edinger- Westphal nucleus of both
sides via the occipito-mesencephalic tract and the
pontine centre. From the Edinger-Westphal nucleus
the efferent impulses travel along the 3rd nerve and
reach the sphincter pupillae and ciliary muscle after
relaying in the accessory and ciliary ganglions.
Psychosensory reflex
It refers to dilatation of the pupil in response to
sensory and psychic stimuli. It is very complex and
its mechanism is still not elucidated.
ABNORMALITIES OF PUPILLARY REACTIONS
1. Amaurotic light reflex. It refers to the absence of
direct light reflex on the affected side (say right eye)
and absence of consensual light reflex on the normal
side (i.e., left eye). This indicates lesions of the optic
nerve or retina on the affected side (i.e., right eye),
leading to complete blindness. In diffuse illumination
both pupils are of equal size.
2. Efferent pathway defect. Absence of both direct
and consensual light reflex on the affected side (say
right eye) and presence of both direct and consensual
light reflex on the normal side (i.e., left eye) indicates
efferent pathway defect (sphincter paralysis). Near
reflex is also absent on the affected side. Its causes
include: effect of parasympatholytic drugs (e.g.,
atropine, homatropine), internal ophthalmoplegia,
and third nerve paralysis.
3. Wernicke’s hemianopic pupil. It indicates lesion
of the optic tract. In this condition light reflex
(ipsilateral direct and contralateral consensual) is
absent when light is thrown on the temporal half of
the retina of the affected side and nasal half of the
opposite side; while it is present when the light is
thrown on the nasal half of the affected side and
temporal half of the opposite side.
4. Marcus Gunn pupil. It is the paradoxical response
of a pupil of light in the presence of a relative afferent
pathway defect (RAPD). It is tested by swinging flash
light test. For details see page 474.
5. Argyll Robertson pupil (ARP) . Here the pupil is
slightly small in size and reaction to near reflex is
present but light reflex is absent, i.e., there is light
near dissociation (to remember, the acronym ARP may
stand for ‘accommodation reflex present’). Both pupils
are involved and dilate poorly with mydriatics. It is
caused by a lesion (usually neurosyphilis) in the
region of tectum.
6. The Adie’s tonic pupil. In this condition reaction
to light is absent and to near reflex is very slow and
tonic. The affected pupil is larger (anisocoria). Its exact
cause is not known. It is usually unilateral, associated
with absent knee jerk and occurs more often in young
women. Adie’s pupil constricts with weak pilocarpine
(0.125%) drops, while normal pupil does not.