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174 • THE VISUAL SYSTEM
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8.1 Common causes of an acute change in vision
Cause Clinical features Cause Clinical features
Unilateral
Giant cell
arteritis
Central retinal
vein occlusion
Retinal
detachment
Central retinal
arterial
occlusion
Corneal
disease
Bilateral
Giant cell
arteritis
Raised
intracranial
pressure
RAPD, Relative afferent pupillary defect (p. 182).
• Painless loss of vision
• Age >50 years
• Weight loss
• Loss of appetite, fatigue
• Jaw or tongue claudication
• Temporal headache
• Pale or swollen optic disc
• RAPD
• Acute, painless loss of vision
• May have RAPD if severe
• Greater risk if hypertensive
• Haemorrhages, exudates and tortuous retinal veins
(Fig. 8.7A)
• Painless loss of vision
• Association with flashing lights or floaters
• History of a curtain coming across vision
• Myopic patients at greater risk
• RAPD if macula is involved
• Pale raised retina usually with a retinal tear (Fig. 8.7B)
• Acute, painless loss of vision
• Carotid bruit may be heard
• RAPD
• Increased risk in vasculopaths
• Examination: pale retina with a cherry red spot at the
fovea (Fig. 8.7C)
• Usually painful
• Foreign body sensation
• Corneal opacity may be visible (e.g. Fig. 8.7D)
• Painless loss of vision
• Age >50 years
• Weight loss
• Loss of appetite, Fatigue
• Jaw or tongue, claudication
• Temporal headache
• Pale or swollen optic disc
• Headache
• Often asymmetric
• Pulsatile tinnitus
• Swollen optic discs
Vitreous
haemorrhage
Wet age-related
macular
degeneration
Anterior ischaemic
optic neuropathy
Optic neuritis/
retrobulbar neuritis
Amaurosis fugax
Cerebral infarct
Migraine
• Painless loss of vision
• Risk in proliferative diabetic retinopathy
• History of flashing lights or floaters may precede
haemorrhage in posterior vitreous detachment
• Poor fundus view on examination
• Reduction or loss of the red reflex
• Usually no RAPD if retina is intact
• Sudden painless loss of central vision
• Age >55 years
• Increased risk in smokers
• Haemorrhage at the macula (Fig. 8.7E)
• Painless loss of upper or lower visual field
• Increased risk in vasculopaths
• Examination may reveal optic disc swelling
• Visual reduction over hours
• Usually aged 20–50
• Pain exacerbated by eye movement
• RAPD
• Reduced colour sensitivity
• Swollen optic disc in optic neuritis (Fig. 8.7F)or
normal appearances in retrobulbar neuritis
• Painless loss of vision for minutes
• History of cardiovascular disease
• May have associated atrial fibrillation or carotid
bruit
• Normal ocular examination
• May have associated headache and/or
neurological signs
• Usually specific field defects dependent on how
the visual pathway is affected (Fig. 8.5)
• Normal fundus examination
• If post chiasmal visual pathway affected, bilateral
visual field abnormalities
• Gradually evolving usually bilateral visual loss
• Vision loss is usually preceded by visual aura
• Normal ocular examination
• Ocular examination: normal
• Vision usually returns to normal after hours
• Is pain exacerbated or relieved by anything?
• Any other associated features (e.g. change in vision, red eye,
discharge, photophobia, watering eye)?
The most common cause of a painful eye is corneal irritation
from a foreign body or infection. The cornea is one of the most
highly innervated parts of the body. When the corneal nerves are
activated, a patient experiences foreign body sensation, pain,
reflex watering and photophobia. There are, however, many
other causes of a painful eye. Box 8.3 summarises the history
and examination findings associated with a painful eye.
A
Patient history • 175
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C
B
8
D
Fig. 8.8 Common causes of a gradual loss of vision. A Cataract. B Altered red reflex in cataract. C Dry age-related macular degeneration. D
Compressive optic neuropathy. Optic nerve sheath meningioma causing optic disc pallor and increased disc cupping with sparing of the outer optic nerve rim.
Retinitis pigmentosa: a triad of optic atrophy, attenuated retinal vessels and pigmentary changes. The latter typically start peripherally with an associated ring
scotoma and symptoms of night blindness.
8.2 Common causes of a gradual loss of vision
Cause Clinical features
Refractive error
Glaucoma
Cataract
Diabetic
maculopathy
Compressive
optic neuropathy
Retinitis
pigmentosa
Dry age-related
macular
degeneration
• No associated symptoms
• Normal ocular examination
• Vision can be improved by pinhole (Fig. 8.4D)
• Usually bilateral but asymmetric loss of visual field
• Cupped optic discs on examination
• Gradual clouding of vision
• May be associated with glare
• Usually seen in the elderly
• Examination: clouding of the pupil and altered red
reflex (Fig. 8.8A and B)
• History of diabetes
• Central vision reduced or distorted
• Haemorrhages and exudates at the macula on
examination (Fig. 8.17A)
• Gradual unilateral loss of vision
• Pale optic disc on examination (Fig. 8.8D)
• Gradual bilateral symmetric loss of peripheral
visual field
• Nyctalopia (poor vision in dim light)
• Family history
• Examination: bone spicule fundus, attenuated blood
vessels and waxy optic disc (Fig. 8.8E)
• Gradual loss of central vision
• Usually bilateral
• Examination: drusen, atrophy and pigmentation at
the macula (Fig. 8.8C)
E
E
Red eye
The eye is covered in a network of vessels in the conjunctiva,
episclera and sclera. Ciliary vessels are also found around
the cornea. Dilatation or haemorrhage of any of these vessels
can lead to a red eye. Additionally, in uveitis, acute angleclosure glaucoma and corneal irritation, the ciliary vessels
around the cornea become more prominent (‘ ciliary flush’).
The appearance is distinct from conjunctivitis, in which
there is classically a relative blanching of vessels around the
cornea.
Ask:
• Is there any pain or photophobia?
• Is vision affected? If so, how?
• Has there has been any recent trauma or foreign body?
• Is the eye itchy?
• Is there any discharge? If so, what kind (e.g. watery, sticky,
clear, yellow)?
• Has there been any recent contact lens use?
Box 8.4 summarises the features of the common causes of a
red eye on history and examination.
Double vision (diplopia)
Ask:
• Does the double vision occur with one eye open or only with
both eyes open? Binocular double vision is caused by an
176 • THE VISUAL SYSTEM
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8.3 Causes and distinguishing features of a painful eye
Cause History Examination
Blocked gland on lid
Corneal foreign body
Corneal infection
Scleritis
Angle-closure
glaucoma
Conjunctivitis
Uveitis
Optic neuritis
Orbital cellulitis
Thyroid eye disease
• Pain on lid • Tenderness to touch
• Foreign body sensation
• Watery eye
• Photophobia
• Foreign body sensation
• Photophobia
• Severe pain disturbing sleep
• Association with recent infection, surgery or rheumatic
disease
• Constant pain around eye
• Acute reduction in vision
• Haloes seen around lights
• Associated nausea and vomiting
• Clear or purulent discharge
• Vision usually unaffected
• Floaters
• Blurry vision
• Photophobia
• Reduction in vision
• Reduction in colour sensitivity
• Constant pain, worsened by eye movement
• Constant ache around eyes
• Reduced vision
• Double vision
• Associated with recent infection/sinus blockage
• Symptoms of hyperthyroidism (p. 222)
• Sore, gritty eyes
• Double vision
• Redness and swelling of lid
• Foreign body visible or found under the eyelid
• Red eye
• Corneal ulcer, (highlighted with fluorescein stain (Fig. 8.7D)
• White infiltrates may be visible
• Eye is sore to touch
• Scleral injection
• Fixed mid-dilated pupil, hazy cornea and usually a cataract
• Red eye
• Ciliary flush
• Swollen disc in optic neuritis (Fig. 8.7F), normal disc in retrobulbar
neuritis
• Conjunctival chemosis and injection
• Restricted eye movements
• Severe cases: visual reduction with RAPD
• Lid retraction
• Proptosis
• Restricted eye movements
• Conjunctival injection or chemosis (Fig. 10.2B)
RAPD, Relative afferent pupillary defect (p. 182).
imbalance in eye movement between the eyes. Monocular
diplopia results from intraocular disease in one eye.
• What is the character of the double vision (e.g. are images
seen side by side, one above the other or at an angle)?
• Has there been any recent trauma?
In binocular diplopia, test the eye movements (Fig. 8.9) and
use your knowledge of the function of the extraocular muscles
(see Fig. 8.2) to work out which cranial nerve is affected.
The causes of double vision are summarised in Box 8.5 and
Figs. 8.10 and 8.11.
Discharge
Ocular discharge results from either an increase in production or
a decrease in drainage from the ocular surface. Irritation of
corneal nerves activates cranial nerve V(I), resulting in a reflex
tearing response.
Tears normally drain from the ocular surface through the
puncta, small openings to the medial end of the upper and lower
eyelid, into the nasolacrimal duct, which opens below the inferior
turbinate in the nasal cavity. Consequently, blockage of tear
drainage or an abnormal lid position can also result in excessive
discharge.
Ask:
• Is the discharge clear or opaque? If opaque, what colour?
• Is the discharge watery or sticky?
• Is the discharge associated with any other features (e.g. pain,
foreign body sensation, red eye or itchiness)?
The clinical features of different types of eye discharge are
summarised in Box 8.6.
8.4 Common causes and distinguishing features of a red eye
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Causes History Examination
Allergic conjunctivitis
Viral conjunctivitis
Bacterial conjunctivitis
Trauma
Acute angle-closure
glaucoma
Acute anterior uveitis
Episcleritis
Scleritis
Dry eyes
Subconjunctival
haemorrhage
Corneal ulcer/abrasion
Orbital cellulitis
Thyroid eye disease
• Itchy eyes
• Clear discharge
• May be seasonal
• Watery discharge
• Possible itch
• Usually bilateral
• Purulent discharge
• Pain
• History of trauma • May reveal subconjunctival haemorrhage or
• Acute reduction in vision
• Pain
• Blurring of vision
• Haloes seen around lights
• Nausea
• Gradual onset of pain
• Photophobia
• Floaters
• Red eye without pain
• Vision not affected
• Focal or diffuse injection
• Vision may be affected
• Association with recent infection, surgery or rheumatic disease
• Severe pain disturbing sleep
• Gritty or burning sensation
• Watery eyes
• No pain
• Vision unaffected
• Vision usually reduced
• Foreign body sensation
Photophobia
•
• Watering
• Usually affects young children
• Recent intercurrent viral illness
• Vision may be affected
• Possible double vision
• Chronic red eyes
• Sore, gritty sensation
• Foreign body sensation
• Double vision
• Conjunctival injection
• Swollen conjunctiva
• Gland swelling and follicles under lid
• Purulent discharge
injection
• Fixed, mid-dilated pupil with a hazy cornea
• Ciliary flush
• Focal or diffuse injection
• Possible association with a nodule
• Eye painful to touch
• Corneal fluorescein staining
• Mildly raised conjunctiva with a bleed
• Ulcer seen on fluorescein staining (Fig. 8.7D)
• May be associated with a white corneal infiltrate
• Reduced vision and colour vision
• Proptosis
• Eye movement restriction
• In severe cases, RAPD
• Lid retraction
• Proptosis
• Conjunctival injection and chemosis (see Fig. 10.2B)
Patient history • 177
8
RAPD, Relative afferent pupillary defect (p. 182).
Swollen eyes
The orbit is enclosed by bone on all sides, except anteriorly. As a
result, orbital swelling can lead to the anterior displacement of
the globe and proptosis.
Ask if the swelling is:
• Unilateral or bilateral?
• Acute or gradual in onset?
• Associated with pain?
• Associated with itch or irritation?
• Associated with double vision?
Box 8.7 summarises the common causes of swollen
eyes.
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8.5 Causes of double vision
Monocular
• High astigmatism
• Corneal opacity
• Abnormal lens
• Iris defect
Binocular
• Myasthenia gravis (p. 190)
• VI nerve palsy (Fig. 8.10)
• IV nerve palsy
• III nerve palsy (Fig. 8.11)
• Internuclear ophthalmoplegia
• Thyroid eye disease (see Fig. 10.2A,B)
• Complex or combined palsy
• Severe orbital cellulitis or orbital inflammation
Past ocular history
Ask the patient whether they have any known ophthalmic conditions. Enquire specifically about amblyopia (a reduction in vision
in one eye from childhood), as this may limit best-corrected visual
acuity. Check whether the patient normally wears glasses or
contact lenses, and ask about the last time they had their eyes
checked for refractive correction. Also ask about any previous
eye surgery, as this may also limit vision.
Past medical history
Focus on systemic diseases that can affect the eyes. In particular:
• a history of diabetes or hypertension, especially in the context
of visual loss
• thyroid disease in the context of red, swollen eyes or double
vision.
Drug and allergy history
8.6 Common causes of increased discharge from the
eyes
Causes Clinical features
Bacterial
conjunctivitis
Viral
conjunctivitis
Blocked tear
duct
Trichiasis/
foreign body
Allergic
conjunctivitis
Blepharitis
Poor tear film/
dry eyes
Mendelian inherited eye disease is retinitis pigmentosa (see
Fig. 8.8E).
• Red eye
• Yellow or green sticky discharge
• Vision usually unaffected
• Red eye
• Clear, watery discharge
• Occasionally itchy eyes
• Vision usually unaffected
• Ocular examination: conjunctival chemosis and
injection
• White eye
• Clear, colourless tearing
• Possible occluded punctum
• Possible malposition of the lid
• Foreign body sensation
• Clear discharge
• Positive fluorescein staining
• Red eyes
• Itchy eyes
• Clear discharge
• Possible history of hay fever or atopy, or recent
start of eye medication
• Mild injection of lids
• Deposits on lashes
• Constant tearing
• Watering increased in the wind
• Improvement with tear supplements
• Ocular examination: early break-up time (<3
seconds) with fluorescein staining of tear film
The eyes may, rarely, be affected by medication prescribed for
other medical conditions. For example, oral glucocorticoids can
cause glaucoma and cataract. Additionally, medication prescribed to treat eye conditions (such as beta-blocker eye drops)
can aggravate systemic conditions like asthma.
Ask about a history of allergies, including hay fever, if the pa-
tient has itchy or red eyes.
Family history
Several eye diseases can be inherited. Ask specifically about a
history of glaucoma in first-order relatives. The most common
Social history
Visual impairment can affect activities of daily living. If vision is
reduced, ask about:
• Daily activities requiring vision, such as reading, television,
sport, hobbies and driving.
• Effects on occupation. Certain professions are required to
meet specific visual standards, including drivers of heavy
goods vehicles and pilots.
• Smoking and alcohol. These may affect retinal vascular disease and optic nerve function.
8.7 Common causes of periorbital swelling and proptosis
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Category Causes Clinical features
Infective
Inflammatory
Neoplastic
Systemic
Vascular
Pseudoproptosis
• Orbital cellulitis • Rapid onset unilateral swelling and erythema
• Granulomatous polyangiitis
• Idiopathic orbital inflammatory disease
• Vasculitis
• Orbital tumours
• Lymphoma
• Metastases
• Thyroid eye disease • Bilateral asymmetric periocular swelling
• Caroticocavernous fistula • Unilateral proptosis with conjunctival swelling
• Orbital varices • Intermittent unilateral swelling and proptosis associated with Valsalva manoeuvre
• Ptosis • Asymmetric palpebrae aperture
• Severe viral conjunctivitis • Bilateral conjunctival injection and oedema associated with serous discharge
• Myopia • Significant difference in prescription between the two eyes
• Lid retraction • Difference in height of palpebral aperture between the two eyes
• Pyrexia and signs of sepsis
• Restricted ocular movements
• Optic nerve compression in severe cases
• Proptosis with conjunctival redness and swelling is seen.
• Restricted eye movements
• In severe cases optic nerve compression
• Gradual onset unilateral periocular swelling.
• Not inflamed and rarely any erythema
• Restricted eye movements
• Associated proptosis and reduced ocular movements.
• Most cases are not associated with inflammation
• Reduced ocular movements
• Patient aware of a bruit
• Occasional pain
• The eye with the more minus prescription will look more prominent
The physical examination • 179
8
The physical examination (Video 17)
General examination
Carefully and systematically examine:
• posture and gait
• head position
• facial asymmetry and dysmorphic features
• eyelid position and periocular skin
• position and symmetry of gaze (any squint/strabismus?).
Visual acuity
The assessment of visual acuity is mandatory in all ophthalmic
patients. Each eye must be tested separately. The most
commonly used method of testing distance visual acuity uses a
Snellen chart, which displays a random selection of letters in
diminishing font sizes in successive lines. Ask patients to wear
their distance spectacles if they usually require them. Near/
reading spectacles should be worn only when testing reading
vision.
Examination sequence (Video 17A)
• Use a backlit Snellen chart positioned at 6 metres and dim
the room’s lighting.
• Cover one eye and ask the patient to read the chart from the
top down until they cannot read any further. Repeat for the
other eye.
• If the patient cannot see the largest font, reduce the test
distance to 3 metres, then to 1 metre if necessary.
• If they still cannot see the largest font, document instead
whether they can count fingers, see hand movement or just
perceive the difference between light and dark.
• On the Snellen chart, lines of decreasing font size are
numbered according to the distance in metres that a person
with normal vision could read them. Express visual acuity as
the distance at which text is read (usually 6 metres) over the
number of the smallest font line read correctly on the chart. For
example, 6/60 means that the patient sees at 6 metres the font
size that is seen at 60 metres by a person with normal vision.
• If the patient cannot read down to line 6 (6/6), place a pinhole
directly in front of the eye (with the patient keeping their usual
spectacles on, if used) to correct any residual refractive error
(see Fig. 8.4D).
• If visual acuity is not improved with a pinhole, this indicates the
presence of eye disease not related to the refractive apparatus
alone, such as amblyopia, or retinal or optic nerve pathology.
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• Assess near vision with a similar test using text of reducing
font size held at a comfortable reading distance. It is important to consider the need for reading spectacles in patients
over the age of 40 years because of presbyopia (age-related
deterioration in near vision).
Fig. 8.9 Testing the six positions of gaze. Sit facing the patient, 1 metre
away. Perform the test with both eyes open. Hold a pen torch or target in front
of the patient and move it to the six positions of gaze (blue arrows). Ask if they
see the target as double.
Fig. 8.10 L sided sixth nerve palsy causing weakness of the lateral
rectus. The patient is attempting to look left.
A
Orbit and periorbital examination
Examination sequence (Video 17B)
• Observe the face and orbit for asymmetry and any obvious
abnormalities, including swelling or erythema.
• Look for abnormalities in the position of the lids, such as
ptosis (Box 8.8).
• Look for asymmetry in the position of the eyeballs. Eyeball
protrusion (proptosis) is best detected by examining the head
from above.
• Palpate around the orbital rim and orbit and look for any
masses.
• Check eye movements (see Fig. 8.9).
• Use an ophthalmoscope (Fig. 8.12) to look for optic disc
swelling from compression.
Pupils (Video 17C)
Inspect first for squint and ptosis, which may reveal the cause
of abnormal pupils. Examine pupil shape and symmetry.
Physiological anisocoria (unequal pupil size) is seen in 20% of
the population.
Anisocoria
Assess which is the abnormal pupil.
B
Fig. 8.11 Third nerve palsy. A Complete ptosis in R third nerve palsy. B
The same patient looking down and left. The affected R eye is unable to
adduct or depress and remains slightly abducted due to unopposed action of
the lateral rectus. From Forbes CD, Jackson WF. Color Atlas of Clinical
Medicine. 3rd ed, Edinburgh: Mosby; 2003.
Examination sequence
• With the patient fixating at a point in the distance, increase
and decrease the illumination and look for any change in the
degree of anisocoria.
If the degree of anisocoria is greater in brighter lighting, then it
is the larger pupil that is abnormal; if it is more pronounced in dim
lighting, the smaller pupil is the abnormal one. An equal degree of
anisocoria in all levels of lighting indicates physiological
anisocoria.
Direct and consensual light reflex
Examination sequence
• With the patient fixating on a point in the distance and in
ambient lighting, shine a bright light from the temporal side
into one eye and look for constriction of the ipsilateral pupil.
The physical examination • 181
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8.8 Causes of eyelid ptosis
Associated distinguishing
Cause Diagnosis
Neurogenic Horner’s
Myogenic Myotonic
Neuromuscular
junction
Mechanical Eyelid tumour Evident on inspection
Degenerative Levator
• To test the consensual reflex, assess the pupil response in
the contralateral pupil when light is directed towards the
ipsilateral pupil. Repeat for the other pupil.
syndrome
Cranial nerve III
palsy
dystrophy
Chronic
progressive
external
ophthalmoplegia
Oculopharyngeal
dystrophy
Myasthenia gravis History of variable muscular
Eyelid
inflammation/
infection
Trauma Scarring/history of trauma
aponeurosis
degeneration
Long-term contact
lens wear
features
Ptosis, miosis, eye movement
spared (Fig. 5.10, p. 96)
Dilated pupil, eye movements
affected ( Fig. 8.11)
Frontal balding, sustained
handgrip
Bilateral ptosis and impairment
of eye movements, often
without diplopia, sparing of
pupil reflexes
History of swallowing
abnormalities
fatigue
Evident on inspection
Often unilateral, eye movement
normal
History of contact lens use
Relative afferent pupillary defect
Relative afferent pupillary defect (RAPD) is an important clinical
sign that occurs when disease of the retina or optic nerve reduces the response of the eye to a light stimulus. Testing for
RAPD is an extension of the direct and consensual light
responses.
8.9 Causes of anisocoria
Dilated pupil Clinical features
• Physiological • Normal pupillary reactions
• Cranial nerve III palsy • Pupil dilated and unresponsive to light
• Trauma • History of significant ocular trauma
• Adie’ s tonic pupil • Slow to react to light
• Pharmacological
treatment with a
dilating agent (e.g.
tropicamide or
atropine)
Constricted pupil
• Physiological • Normal pupil reactions
• Horner’ s syndrome • Partial ptosis
• Mechanical (e.g.
secondary to posterior
synechiae in iritis or
trauma)
• Late-stage Adie’s tonic
pupil
• Pharmacological
treatment with a
constricting agent (e.g.
pilocarpine)
• Seen in 20% of population
• Partial or complete ptosis
• Eye deviated down and out
• Rupture of pupillary sphincter muscle
sometimes seen on slit lamp
examination
• Vermiform movement of the iris seen on
slit lamp examination.
• Constricts with dilute pilocarpine
(0.125%)
• Unreactive dilated pupil, resolves with
time
• History of pharmacological administration
• Seen in 20% of population
• Ipsilateral anhidrosis
• Anisocoria more pronounced in dim light
• History of trauma or iritis
• Pupil margin may be irregular
• Small slowly reactive pupil
• History of the pupil being the larger one
in the past
• Unreactive constricted pupil that will
dilate with time
• History of pharmacological
administration
Accommodation
8
Examination sequence
• Use a bright light source.
• Maintain the light on each eye for a minimum of 3 seconds,
then move it between the eyes briskly.
In normal patients, the RAPD test results in symmetrical
constriction of both pupils. If an RAPD is present, the pupil will
dilate when the light is shone in the affected eye.
Examination sequence
• Ask the patient to look at a distant target and then to quickly
focus on a close fixation target (do not use a light source).
• The pupils will constrict on near gaze.
• Failure to constrict to light but constriction on near gaze is
referred to as light-near dissociation.
There are many causes of a dilated or constricted pupil
(Box 8.9).
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Horner’s syndrome
Horner’s syndrome results from a dysfunction of the sympathetic
supply to the eye. The sympathetic innervation of the eye originates in the hypothalamus and emerges in the root of the neck
before innervating the pupil (see Fig. 8.6B). Damage at any
point along this pathway will result in Horner’s syndrome. On
examination, the pupil will be constricted (loss of sympathetic
dilator tone) and have a partial ptosis resulting from denervation
of Müller’s muscle in the upper eyelid (see Fig. 5.10,p.96).
There may also be anhidrosis (loss of sweating) on the affected
side.
The diagnosis of Horner’s syndrome can be confirmed by
administering drops of the alpha-2 adrenergic agonist apraclonidine to both eyes. This causes reversal of pupil constriction in
the affected eye and no change in the unaffected eye. This results in a reduction of anisocoria (difference in pupil size between
the eyes). Causes of Horner’s syndrome include demyelination,
neck trauma/surgery, apical lung tumour (Pancoast tumour) and
carotid artery dissection.
Adie’s pupil
Adie’s pupil is a dilated pupil that responds poorly to both light
and accommodation. With time, however, the affected pupil can
become constricted. Adie’s pupil is thought to result from
parasympathetic pathway dysfunction in the orbit leading to a
lack of pupil constriction. It typically affects young women and is
benign. When associated with diminished Achilles tendon reflexes, it is referred to as Holmes-Adie syndrome.
Examination sequence (Video 17D)
• Check visual acuity and ensure that the patient has at least
enough vision to count fingers.
• Sit about 1 metre away directly facing the patient and at the
same height.
• With your eyes and the patient’s eyes open, ask the patient to
look at your face and comment on whether they have any
difficulty seeing parts of your face.
• Ask the patient to keep looking straight at your face. Test
each eye separately. Ask the patient to close or cover one
eye and look directly at your opposite eye; you should similarly close your contralateral eye.
• Bring an extended finger in from the periphery towards the
centre of the visual field. For an accurate assessment of the
patient’s fields, it is vital that the testing finger is always kept in a
plane exactly halfway between yourself and the patient. Wiggle
your fingertip and ask the patient to say when they first see it
(Fig. 8.12). If the patient fails to notice your finger when it is
clearly visible to you, their field is reduced in that area.
• Test all four quadrants separately, testing each eye separately.
• More subtle visual field defects can be elicited using a small
white hatpin or a white Neurotip. With the patient looking
directly at your eye, bring the white target in from the periphery to the centre (always in the plane halfway between
you and the patient). Ask the patient to say when they first
see the target.
Argyll Robertson pupil
Argyll Robertson pupils are bilaterally small and irregular and
react to near accommodation but not to light (‘light-near dissociation’). These pupils are classically the result of neurosyphilis;
however, they can also occur in diabetes mellitus, severe optic
nerve disease and midbrain lesions.
Visual fields
The normal visual field extends 160 degrees horizontally and 130
degrees vertically. The physiological blind spot is located
approximately 15 degrees temporal to the point of visual fixation
and represents the entry of the optic nerve head into the eye.
Theaimofthevisualfield examination is to test the patient’svisual fields against your own (assuming that you have normal visual
fields). The visual field can be tested using the fingers for gross
examination. Finer examination is performed using a hatpin.
Fig. 8.12 Confrontation visual field testing. Sit facing the patient, 1 metre
away. To compare your visual field (assumed normal) with the patient’s,
present a white target or your fingers at a point equidistant between yourself
and the patient in the periphery. Bring the target inwards in the direction of the
blue arrows, asking the patient to alert you when they first see it. Test each
eye separately.
The physical examination • 183
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open or latent (phoria) if revealed only by covering one eye. In
addition, they can be conc om itan t (where the angle of squint
remains the same in all positions of gaze) or incomitant (where
the angle of squint deviation is greatest in a single position of
gaze). The latter is comm on ly the result of extraocular muscle
paralysis.
Detection of a squint
Examination sequence
Fig. 8.13 Testing the central visual field. Sit facing the patient, 1 metre
away. Present a red target at a point equidistant between yourself and the
patient in the periphery, starting when you can first see the target as red. Bring
the target inwards in the direction of the blue arrows, asking the patient to alert
you when they first see the target as red. Test each eye separately.
• Check all four quadrants, testing each eye separately.
• To assess very early visual field loss, repeat the same test
using a red hatpin or a red Neurotip (Fig. 8.13).
• It is important to sho w the patient the red target and ask
them to report what colour they see. A dull or pale red
suggests colour desaturation, which may indicate optic
nerve dysfunction.
• When testing each quadrant with a red target, be sure to
explain to the patient that they should say when they first see
that the target is red and not when they first see it. The target
may be visualised before they appreciate the red colour.
• To test the blind spot, place a red-tipped target equidistant
between the patient and yourself at the visual fixation point.
• Move the target temporally from central fixation until it
disappears.
• Once you have identified the blind spot, move the target
slowly up and down and side to side until it reappears. This
allows you to compare the patient’s blind spot with yours.
Ocular alignment and eye movements
The eyes normally move in the same direction (conjugate
motion) in all positions of gaze except during convergence. Any
misalignment is referred to as a squint (strabismus). Squints
are described as ma nif est (tropia) if present wit h both eyes
• Sit directly facing the patient, approximately 1 metre away
and at a similar height.
• Check visual acuity as part of the examination.
• Look for any abnormal head posture, such as head tilts (seen
in cranial nerve IV palsy) or head turns (cranial nerve VI palsy).
These signs may be subtle.
• Hold a pen torch directly in front of the patient and instruct
them to look at the light. Observe the reflection of the light on
the cornea in relation to the pupil. The reflections should be
symmetrical between the two eyes. Ask the patient if they see
a single or double light. If they see double, this may indicate
the presence of a squint, but not seeing double does not
exclude a squint. If the reflection is on the nasal aspect of the
pupil in one eye, this suggests that the eye is deviated outwards and is described as an exotropia.
• To confirm the presence of a squint, perform the cover/un-
cover test:
• Ask the patient to look at the pen torch at all times and
then cover one eye.
• Look at the uncovered eye for any movement. It may be
helpful to repeat this several times.
• Inward movement of the uncovered eye suggests that it
was positioned abnormally outwards and is described as
an exotropia (divergent manifest squint).
• Conversely, if the eye moves outwards when the contra-
lateral eye is covered, this suggests that it was abnormally
positioned inwards and is described as an esotropia
(convergent manifest squint).
• Repeat the cover/uncover test for the other eye.
• Failure of an eye to move despite an obvious corneal light
reflex may indicate that the eye has such poor vision that it
cannot take up fixation or else it is restricted from moving.
• The alternating cover test involves covering the eyes alter-
nately and quickly while the patient is fixated on the pen
torch. Leave the cover on each eye for about 2 seconds but
move between the eyes in less than 1 second. The movement is repeated multiple times. This test will help to elicit
latent squint.
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