2. NEURO OPHTHALMOLOGY
Topics covered in this lecture are:
Pupillary disorders
Neuro motility disorders
Optic nerve disease
Visual field defects
3. PUPILLARY PATHWAYS
Anatomy and physiology
The iris controls the size of the pupil. It contains
two groups of smooth muscle fibres:
Sphincter pupillae innervated by the parasympathetic
nervous system
Dilator pupillae innervated by the sympathetic
nervous system
Pupil size (normal 2-6 mm) depends on the
balance between sympathetic and
parasympathetic tone
4. PUPILLARY DISORDERS
Anisocoria
= unequal pupils
A 1-2mm difference in pupil size can be physiological
Check in bright and dark room to ascertain which pupil is
abnormal
If one pupil is abnormally constricted the anisocoria will increase
when lights dimmed
If one pupil is abnormally dilated the anisocoria will decrease
when lights dimmed
Physiological anisocoria will remain unchanged
8. Horner’s syndrome
Lesion of the sympathetic pathway in head and
neck
Miosis, ptosis and anhidrosis
Myriad of causes including Pancoast apical lung
tumour
Diagnosis
Cocaine drops dilate normal pupil but not Horner’s
pupil
Hydroxyamphetamine drops locate the lesion as pre-
ganglionic (dilates pupil) or post-ganglionic (does not
dilate)
Further investigations directed by history and exam
9. Relative afferent pupillary defect
Caused by optic nerve lesion or severe
retinal damage, i.e. a lesion anterior to
optic chiasm
Can be elicited by SWINGING FLASH
LIGHT TEST
If the light source is “swung” from eye to eye,
dwelling 2-3 secs on each, the affected pupil
will paradoxically dilate
10. Adies pupil
Unilateral dilated pupil
Benign condition usually affecting young women
Onset is acute and may cause blurring
Absent light response; response to
accomodation slow but present = light near
dissociation
If associated with reduced or absent limb
reflexes = Holmes Aides syndrome
No known cause
12. Argyll Robertson pupil
Pupils irregular, small and difficult to dilate with
drops
Seen in neurosyphilis
Light near dissociation present
Near response present, light response absent
13. NEUROMOTILITY DISORDES
Related anatomy and physiology
Six muscles control eye movements:
1. Superior rectus
2. Medial rectus
3. Inferior rectus
4. Inferior oblique
(All the above muscles innervated by the 3rd nerve)
5. Superior oblique - innervated by 4th nerve
6. Lateral rectus - innervated by the 6th nerve
The oblique muscles move the eye up (Inferior oblique) or down (superior
oblique) when it is turned in
The superior and inferior recti move the eye up (SR) and down (IR)
The lateral and medial recti abduct (move out) and adduct (move in) the eye
respectively
Eye movements are examined in the six different directions of gaze
representing individual muscle action
14. Third nerve palsy
Clinical features:
Ptosis
Eye down and out
Limited elevation, adduction and depression
Pupil sparing or pupil involving (pupil fixed and
dilated)
Pupil involving third nerve palsy = PCA
aneurysm until proven otherwise. Life
threatening neurosurgical emergency
16. SIXTH NERVE PALSY
Clinical features
Esotropia (convergent squint) in the primary
position, due to unopposed action of the medial
rectus muscle
Marked limitation of abduction
Horizontal diplopia (double vision)
18. FOURTH NERVE PALSY
Clinical features:
Affected eye is hypertropic, i.e. at higher position
than the unaffected eye
Hypertropia increases on tilting the head to the
ipsilateral shoulder
Vertical diplopia
Patient adopts a compensatory head tilt to the
opposite side to prevent diplopia
19. FOURTH NERVE PALSY
Causes:
Congenital – may not develop until adult life
Acquired
Trauma
Microvascular disease
Aneurysms and tumours rare
20. Myasthenia gravis
Autoimmune disorder of the
neuromuscular junction
Systemic and ocular features
Ptosis, ophthalmoloplegia and weak
orbicularis muscle
Fatigable, asymmetrical, variable
Tensilon test confirms diagnosis
25. ANTERIOR ISCHAEMIC OPTIC
NEUROPATHY
1. Arteritic
Giant cell arteritis causes occlusion of
posterior ciliary arteries of optic nerve
Untreated can cause sudden bilateral
blindness
Never miss this diagnosis
2. Non-arteritic
26. Giant cell arteritis
Occlusive vasculitis of ophthalmic artery and its
branches
Elderly
Symptoms
Bilateral irreversible visual loss if untreated
Temporal tenderness
Jaw claudication
Scalp tenderness
Headache
Constitutional symptoms, eg weight loss, anorexia
Signs
Variable visual acuity but often severe vision loss
Pale optic disc with diffuse edema and haemorrhages
later optic atrophy
Thickened non pulsatile temporal artery
27. Giant cell arteritis
Investigations (urgent)
ESR raised > 60 mm/hr (normal = half the age for men
and half the age plus 10 for women)
C reactive protein (CRP) raised
Temporal artery biopsy - histology confirms diagnosis
Treatment
Aim is to prevent blindness in the fellow eye
Initial treatment is with high dose intravenous
methylprednisolone then oral prednisolone 60 mg
daily.Taper oral steroids gradually
28. Non arteritic anterior ischaemic
anterior optic neuropathy
Clinical features
- Age group affected usually is 45-65 yrs
- Altitudinal visual field defect
- Visual loss of variable degree
- Swollen optic disc with edema /splinter haemorrhages
- Normal ESR and CRP
- Hypertension
Treatment
- Treat underlying vascular disorders (Hypertension ,
Diabetes,Hyperlipidemia )
- Aspirin to prevent further vascular events
29. Papilloedema
Bilateral optic disc swelling due to
raised intracranial pressure
Clinical features
- Visual acuity usually normal
- May be associated with transient visual loss
- Enlargement of the blind spot
- Swollen discs
- Optic atrophy if chronic
32. PAPILLOEDEMA
Causes
-Intracranial space occupying lesions, e.g. tumour,
Haemotoma
-Any lesion causing hydrocephalus in adults e.g..
Meningitis and subarachnoid haemorrhage
- Venous obstruction caused by thrombosis in the venous
sinuses
- Benign intra cranial hypertension
Differential diagnosis
- Malignant hypertension (always check blood pressure)
33. OPTIC NERVE DISEASE
Optic atrophy
- Caused by damage to the nerve fibres at
any point between the ganglion cells of
the retina and lateral geniculate body
- Irreversible loss of vision
35. OPTIC ATROPHY
Causes
1. Retinal
Central retinal artery occlusion
Retinitis pigmentosa
2. Optic nerve
Anterior Ischaemic optic neuropathy
Optic neuritis
Glaucoma
Chronic papilloedema
Toxic e.g. Methyl alcohol, ethyl alcohol, tobacco and ethambutol.
Tumour e.g. optic nerve glioma or meningioma
Trauma
Leber’s Hereditary optic neuropathy
3. Chiasm
Any cause of chiasmal compression e.g. pituitary adenoma, craniopharyngioma
36. VISUAL FIELD DEFECTS
Central scotoma
Characteristic of most optic nerve lesions, e.g. optic neuritis
Arcuate scotoma
The scotoma extends from the blind spot above or below fixation
following the course of nerve fibres. Characteristically seen in
glaucoma.
Bitemporal hemianopia
Loss of temporal half of the visual field bilaterally. Seen in chiasmal
compression by tumours, e.g. pituitary adenoma
Homonymous hemianopia
Any visual pathway lesion posterior to the optic chiasm, e.g. stroke,
tumour
37. VISUAL FIELD DEFECTS
Left homonomous
hemianopia
Bitemporal hemianopia
Monocular blindness
Monocular constricted field
e.g. retinitis pigmentosa
Right nasal field defect,
usually due to retinal
disease or glaucoma