When patients present with a change in vision, ask:
• Did the change in vision start suddenly or gradually?
• How is the vision affected (loss of vision, cloudy vision,
• Is it one or both eyes that are affected?
• Is the whole or only part of the visual field affected?
• If partial, which part of the visual field is affected?
• whether anything started the pain
• about the character of the pain
• if the pain is exacerbated or relieved by any factors
• whether the pain is associated with any other symptoms.
The cornea is one of the most highly innervated regions of the
body. When the corneal nerves are activated, this leads to pain,
the sensation of foreign body, reflex watering and photophobia.
There are, however, many other causes of a painful eye. Box
8.3 summarises the history and examination findings associated
8.1 Common causes of an acute change in vision
Cause Clinical features Cause Clinical features
• 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
• Acute, painless loss of vision
• Greater risk if hypertensive
• Haemorrhages, exudates and tortuous retinal veins
• Sudden painless loss of central vision
• Haemorrhage at the macula (Fig. 8.7E)
• Association with flashing lights or floaters
• History of a curtain coming across vision
• Myopic patients at greater risk
• Pale raised retina usually with a retinal tear (Fig. 8.7B)
• Painless loss of upper or lower visual field
• Increased risk in vasculopaths
• Examination may reveal optic disc swelling
• Acute, painless loss of vision
• Increased risk in vasculopaths
• Examination: pale retina with a cherry red spot at the
• Pain exacerbated by eye movement
• Swollen optic disc in optic neuritis (Fig. 8.7F) or
normal appearances in retrobulbar neuritis
• Corneal opacity may be visible (e.g. Fig. 8.7D)
• Painless loss of vision for minutes
• History of cardiovascular disease
• May have associated atrial fibrillation or carotid bruit
Cerebral infarct • May have associated headache and/or neurological
• Usually specific field defects dependent on how the
visual pathway is affected (Fig. 8.5)
• If post chiasmal visual pathway affected, bilateral
Migraine • Gradually evolving usually bilateral visual loss
• Vision loss is usually preceded by visual aura
• Vision usually returns to normal after hours
RAPD, relative afferent pupillary defect (p. 162).
8.2 Common causes of a gradual loss of vision
Refractive error • No associated symptoms
• Vision can be improved by pinhole (Fig. 8.4D)
Glaucoma • Usually bilateral but asymmetric loss of visual field
• Cupped optic discs on examination
Cataract • Gradual clouding of vision
• May be associated with glare
• Examination: clouding of the pupil and altered red
• Central vision reduced or distorted
• Haemorrhages and exudates at the macula on
• Gradual unilateral loss of vision
• Pale optic disc on examination (Fig. 8.8D)
• Gradual bilateral symmetric loss of peripheral
• Nyctalopia (poor vision in dim light)
• Examination: bone spicule fundus, attenuated
blood vessels and waxy optic disc (Fig. 8.8E)
E Wet age-related macular degeneration. F Swollen optic nerve head in acute optic neuritis.
peripherally in association with a ring scotoma and symptoms of night blindness.
8.2 Common causes of a gradual loss of vision – cont’d
• Gradual loss of central vision
• Examination: drusen, atrophy and pigmentation at
Ocular examination: redness and swelling of lid
Ocular examination: foreign body visible or found
Ulcer on cornea, which can be highlighted with
fluorescein staining (see Fig. 8.7D)
Ocular examination: white infiltrate may be visible
Scleritis Severe pain that keeps the patient awake at night
Association with recent infection, surgery or
Ocular examination: scleral injection
Possibly, haloes seen around lights
Association with nausea and vomiting
Ocular examination: fixed mid-dilated pupil, hazy
RAPD, relative afferent pupillary defect (p. 162).
Conjunctivitis Increased clear or purulent discharge
Ocular examination: ciliary flush
Optic neuritis Reduction in vision
Reduction in colour sensitivity
Constant pain worsened by eye movement
Ocular examination: swollen disc in optic neuritis
(see Fig. 8.7F), normal disc in retrobulbar neuritis
Orbital cellulitis Constant ache around the eyes
Association with a recent viral infection
Ocular examination: conjunctival chemosis and
injection, restricted eye movements; in severe cases,
Symptoms of hyperthyroidism (p. 197)
Ocular examination: lid retraction, proptosis,
restricted eye movements and conjunctival injection,
conjunctival chemosis (see Fig. 10.4)
8.4 Common causes of a red eye
Possibly, more frequent occurrence at certain times
Viral conjunctivitis Watery discharge
Ocular examination: gland swelling and follicles
Ocular examination: may reveal subconjunctival
Acute-onset reduction in vision
Ocular examination: fixed, mid-dilated pupil with a
Ocular examination: ciliary flush
Episcleritis Focal or diffuse injection
Possible association with a nodule
Scleritis Focal or diffuse injection
Association with recent infection, surgery or
Severe pain that keeps the patient awake at night
Dry eyes Gritty or burning sensation
Ocular examination: corneal fluorescein staining
Ocular examination: mildly raised conjunctiva with a
Ocular examination: ulcer seen on fluorescein
May be associated with a white corneal infiltrate
RAPD, relative afferent pupillary defect (p. 162).
8.4 Common causes of a red eye – cont’d
Orbital cellulitis Usual occurrence in young children
Recent history of intercurrent viral illness
Ocular examination: reduced vision and colour
vision, proptosis, eye movement restriction; in
Ocular examination: lid retraction, proptosis,
conjunctival injection and chemosis (see Fig. 10.4)
• Internuclear ophthalmoplegia
• Severe orbital cellulitis or
Fig. 8.10 Third nerve palsy. A Complete ptosis in right III nerve
palsy. B The same patient looking down and to the left. The right eye
is unable to adduct or depress due to a complete right III nerve palsy. It
remains in slight abduction due to the unopposed action of the right
lateral rectus muscle and an intact VI nerve. From Forbes CD, Jackson
WF. Color Atlas of Clinical Medicine. 3rd edn. Edinburgh: Mosby; 2003.
Fig. 8.9 Sixth nerve palsy causing weakness of the lateral rectus
muscle. The patient is attempting to look to the left.
Ask the patient whether they have any known ophthalmic
conditions. Enquire specifically about amblyopia, which is 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 the last time they had their
eyes checked for refractive correction. Ask about any previous
eye operations that may also affect vision.
Focus on systemic diseases that can affect the eyes directly or
as a side effect of treatment, in particular:
• a history of diabetes or hypertension, especially in the
context of visual loss or double vision
• thyroid disease in the context of red, swollen eyes and
• asthma, chronic obstructive pulmonary disease (COPD) or
peripheral vascular disease if starting glaucoma medication.
The eyes may be affected by medication given for other conditions
(such as glaucoma exacerbated by conjunctival absorption of
nebulised anticholinergic drugs in COPD). Medication given for
the eyes (such as beta-blocker eye drops) can aggravate other
Ask about a history of hay fever and allergies if the patient
Several eye diseases have an inherited predisposition. Ask
specifically about a history of glaucoma in first-order relatives.
Genetic diseases affecting the eyes include retinitis pigmentosa
(see Fig. 8.8E). Patients with thyroid eye disease may have a
positive family history of autoimmune disease.
Visual impairment has a wide range of effects on daily life.
• Daily activities requiring good vision: reading, television,
• Occupation: certain professions, including drivers of heavy
goods vehicles and pilots, require specific visual acuity criteria.
• Smoking and alcohol use: this may affect vascular and
optic nerve function within the eye.
8.6 Common causes of increased discharge from the eyes
Yellow or green sticky discharge
Ocular examination: conjunctival chemosis and injection
Possible malposition of the lid
Possible positive fluorescein staining
Possible history of hay fever or atopy, or recent start of
Blepharitis Mild injection of lids
Watering increased in the wind
Improvement with tear supplements
Ocular examination: early break-up time (<3 seconds)
with fluorescein staining of tear film
8.7 Common causes of periorbital swelling
Inflammatory Granulomatous polyangiitis
Vascular Caroticocavernous fistula
Pseudoproptosis Ptosis Severe viral
Carefully and systematically examine:
• facial asymmetry and dysmorphic features
• eyelid position and periocular skin
• position and symmetry of gaze (any squint/strabismus?).
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 is using a Snellen chart,
which displays a random selection of letters at diminishing font
size 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.
• Use a backlit Snellen chart positioned at 6 metres and dim
• Cover one eye and ask the patient to read the chart from
the top down until they cannot read any further. Repeat
• If the patient cannot see the largest font, reduce
the test distance to 3 metres, then to 1 metre if
• 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
• 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
• 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 they wear them) to correct any
residual refractive error (see Fig. 8.4D).
• If the visual acuity is not improved with a pinhole, this
indicates the presence of eye disease not related to the
refractive apparatus alone, such as retinal or optic nerve
• Note that 6/6 is regarded as normal vision; in the UK,
6/12 or better with both eyes is the requirement for
• 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
The physical examination • 161
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
Direct and consensual light reflex
• 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
• 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.
Orbit and periorbital examination
• Observe the face and orbit for asymmetry and any obvious
abnormality, including swelling, erythema or any other skin
• Look for any abnormality in the position of the lids and
• Look for any asymmetry in the position of the eyeballs.
Eyeball protrusion (proptosis) is best detected by looking
• Palpate around the orbital rim and orbit, looking for any
• Check eye movements (Fig. 8.11).
• Use an ophthalmoscope (Fig. 8.12) to look for optic disc
First inspect generally for squint and ptosis. Examine pupil shape
and symmetry. Physiological anisocoria (unequal pupil size) is
seen in 20% of the population.
The eyes should be assessed to determine which is the abnormal
• With the patient fixating at a point in the distance, increase
and decrease the illumination and look for any change in
Neurogenic Horner’s syndrome Ptosis, miosis, eye
Myogenic Myotonic dystrophy Frontal balding, sustained
Myasthenia gravis History of variable
Mechanical Eyelid tumour Evident on inspection
Trauma Scarring/history of trauma
Degenerative Levator aponeurosis
Fig. 8.12 Ophthalmoscopy. Ask the patient to focus on a distant target.
To examine the left eye, use your left eye to look through the
ophthalmoscope and left hand to hold it, index finger on the wheel. Hold
the patient’s head with your free hand. Gradually move in to visualise the
optic disc. Rotate the wheel to obtain a clear, focused image.
Fig. 8.11 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 ask them if they see the target as double.
Move the target to the six positions of gaze (blue arrows).
This is a mid-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. It typically
affects young women and is benign. When associated with
diminished Achilles tendon reflexes, it is referred to as Holmes–
The pupil is small and irregular, and reacts to accommodation
but not light. This is classically the result of neurosyphilis. There
are other causes of light-near dissociation, however, including
diabetes mellitus, severe optic nerve disease and midbrain
The normal visual field extends 160 degrees horizontally and
130 degrees vertically. Fixation is the very centre of the patient’s
visual field. The physiological blind spot is located 15 degrees
temporal to the point of visual fixation and represents the entry
of the optic nerve head into the eye.
The aim of the visual field examination is to test the patient’s
visual fields against your own (making the assumption that you
have normal visual fields). The visual field can be tested using
the fingers for gross examination. Finer examination can be
performed using a small hatpin.
• Check visual acuity and ensure that the patient has at
least enough vision to count fingers.
• Sit directly facing the patient, about 1 metre away.
• 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 across to your opposite eye; you
should also close your other eye.
• Hold your hands out and 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 the plane
exactly halfway between yourself and the patient. Wiggle
your fingertip and ask the patient to point to it when they
first see it (Fig. 8.13). If the patient fails to notice your finger
when it is clearly visible to you, their field is reduced in
• Test all four quadrants 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 (again always in the plane
halfway between you and the patient). Ask the patient to
say when they first see the target.
• Undertake this for all four quadrants, testing each eye
• To assess very early visual field loss, repeat the same test
using a red hatpin or a red Neurotip (Fig. 8.14).
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.
• Move the light briskly from one eye to the other, but place
it on each eye for a minimum of 3 seconds.
In normal patients, this results in symmetrical constriction of
both pupils. In RAPD, light in the affected eye causes weaker
constriction (apparent dilatation) compared to light shone in the
• Ask the patient to look at a close fixation target (do not
use a light source) after fixating on a distant target.
• There should be constriction of the pupil 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
Pupillary examination will distinguish the various causes of
anisocoria, as described here.
Horner’s syndrome is the clinical picture resulting from dysfunction
of sympathetic nerve supply to the eye, which originates in the
hypothalamus and emerges in the root of the neck before
innervating the pupil (see Fig. 8.6B). Damage at any point in
this pathway will result in Horner’s syndrome. On examination,
there is a constricted pupil (loss of sympathetic dilator tone) and
a partial ptosis resulting from denervation of Müller’s muscle
in the upper eyelid. There may also be anhydrosis (loss of
sweating) on the affected side. Diagnosis may be confirmed by
administering cocaine eye drops, which will cause pupil dilatation
in the unaffected pupil but no dilatation on the affected side.
Causes of Horner’s syndrome include demyelination, neck trauma/
surgery, apical lung tumour (Pancoast tumour) and carotid artery
• Mechanical, e.g. secondary to
posterior synechiae in iritis or
• Late-stage Adie’s tonic pupil
with a constricting agent (e.g.
The physical examination • 163
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
• To confirm the presence of a squint, perform the cover/
• Ask the patient to look at the pen torch at all times and
• 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).
• It is important to show 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
• 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
• To test the blind spot, place a red-tipped target
equidistant between the patient and yourself at the visual
• Move the target temporally until it disappears.
• Then move the target slowly up and down, as well as from
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 are normally parallel in all positions of gaze except
for convergence. Any misalignment is referred to as a squint
(strabismus). Squints are described as manifest (tropia) if present
with both eyes open, or latent (phoria) if revealed only by covering
one eye. In addition, they can be concomitant (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 commonly the result of paralysis of particular
• Sit directly facing the patient, approximately 1 metre away
• 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
Fig. 8.13 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 wiggle 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
Fig. 8.14 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
The direct ophthalmoscope is a useful tool for assessing both the
anterior and the posterior segments of the eye. Pharmacological
pupil dilatation is essential for a thorough fundus examination,
though the optic disc can be examined sufficiently without
• Ask the patient to sit upright and look at a distant target.
• When using the direct ophthalmoscope to examine
the patient’s right eye, hold it in your right hand and
use your right eye to examine. Hold it in your left
hand and use your left eye to examine the patient’s
• Place your free hand on the patient’s forehead and brow,
as this will steady the head and improve your
proprioception when moving closer to the patient with the
• Rotate the ophthalmoscope lens to +10. This will allow
a magnified view of the anterior segment. You will be
able to examine the eyelid margins, conjunctiva, cornea
and iris. If epithelial defects are suspected, fluorescein can
be administered and a cobalt blue filter used to reveal
• To examine the fundus, dial the lens back to 0.
• With your hand on the forehead and the brow, use the
ophthalmoscope to see the red reflex (red light reflected
off the retina) at a distance of about 10 cm. When the red
reflex is in focus, look for opacities and determine whether
they are static or mobile. Static opacities are usually due
to cataract changes, while mobile opacities indicate
• Slowly move the ophthalmoscope closer to the patient
almost to the point that your forehead touches your
thumb, which is resting on the patient’s forehead and
• Turn the lens dial until the optic disc comes into focus; if it
does not, focus on a blood vessel.
• The optic disc can usually be located easily; if not, follow a
blood vessel centrally (in the direction opposite to its
• Examine the optic disc, paying particular attention to its
shape, colour, edges and cup size.
• Follow each blood-vessel arcade and examine each of the
• To examine the macula, ask the patient to look directly at
The normal retina looks different in Asian and Caucasian
Swelling of the optic disc is a very important clinical sign.
Causes of unilateral and bilateral optic disc swelling, and their
distinguishing features, are summarised in Box 8.10.
A variety of diseases that can damage the optic nerve cause
an abnormally pale optic disc (see Fig. 8.8D). The differential
diagnosis of optic disc pallor is summarised in Box 8.11.
• Conversely, if the eye moves outwards when the
contralateral 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
• The alternating cover test involves covering the eyes
alternately 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.
• In the same seating position, ask the patient to look at a
target or pen-torch light about 50 cm away.
• Ask them to say if and when they experience diplopia.
• Starting from the primary position, move the target in the
six positions of gaze (see Fig. 8.11) and up and down.
• If diplopia is present, ask whether this is horizontal, vertical
• Determine where the image separation is most
• Look for nystagmus and determine whether the eye
Interpretation of any limitation of excursion is made by
reference to the functions of the extraocular muscles (see
Oculocephalic (doll’s-eye) reflex
This reflex is the ability of the eyes to remain fixated while the
head is turned in the horizontal plane (Fig. 8.15). An impaired
reflex indicates a brainstem abnormality.
• With the patient supine, ask them to look at your face.
Gently turn their head from side to side, noting the
• This can also be performed on a comatose patient.
Nystagmus is continuous, uncontrolled movement of the eyes.
Biphasic or jerk nystagmus is the most common type. It is
characterised by slow drift in one direction, followed by fast
correction/recovery in the opposite direction. The direction of the
fast phase designates the direction of the nystagmus. If there
are equal oscillations in both directions, it is called pendular
Nystagmus commonly indicates vestibular disease, and the
examination sequence and differential diagnosis are covered
Diabetes mellitus leads to a wide range of important abnormalities
in the retina, which are summarised on Fig. 8.17.
The eye also provides an opportunity to view the effects of
hypertension on the microvasculature. The retinal arteries are
effectively arterioles. Chronic arteriosclerosis with vessel-wall
thickening and hyalinisation appears as widening of the arterioles,
arteriovenous nicking where arterioles cross venules, and a ‘silver
and copper wiring’ light reflex.
More acute changes can also be seen in malignant hypertension.
Various grading systems have been created to try to link retinal
findings to end-organ damage. The retinal appearances in
hypertension are illustrated in Fig. 8.18 and classified using the
Modified Scheie classification:
• Grade 1: barely detectable arteriolar narrowing.
• Grade 2: obvious retinal arteriolar narrowing with focal
• Grade 3: grade 2 plus retinal haemorrhages, exudates,
cotton-wool spots or retinal oedema.
• Grade 4: grade 3 plus optic disc swelling.
Inherited retinopathies result from a wide range of genetic
mutations. The most common inherited retinopathy is retinitis
pigmentosa, which causes symptoms of nyctalopia (difficulty
seeing in dim light) and tunnel vision. Examination reveals a
pale optic disc, attenuated arterioles and bone-spicule retinal
Appropriate initial tests for a variety of common presenting eye
problems are summarised in Box 8.12.
Fig. 8.16 The normal fundus. A Caucasian. B Asian.
8.10 Causes of optic disc swelling
8.11 Differential diagnosis of optic disc pallor
• Congenital optic atrophy, including Leber’s and Behr’s
• End-stage papilloedema • Devic’s disease
• Central retinal artery occlusion • Giant cell arteritis
• Meningitis • Postoptic neuritis
photocoagulation in treated proliferative diabetic retinopathy.
disease with a swollen optic disc and macular exudate.
Refraction Refractive error, cataract and corneal disorders
Fluorescein staining Corneal epithelial disease
Schirmer’s test Dry eyes, Sjögren’s syndrome
Nasolacrimal duct washout Watery eyes
Blood pressure Hypertensive retinopathy, retinal vein occlusion
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