Examination of the Eyes and Vision – OSCE Guide

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Assessment of the eyes and vision frequently appears in OSCEs and you’ll be expected to pick up the relevant clinical signs using your examination skills. This guide provides a step-by-step approach to examining the eyes, assessing vision and performing fundoscopy. It also includes a video demonstration.


Introduction

Introduce yourself to the patient including your name and role.

Confirm the patient’s name and date of birth.

Briefly explain what the examination will involve using patient-friendly language.

Gain consent to proceed with the examination.

Position the patient sitting on a chair.

Wash your hands.

Ask if the patient has any pain before proceeding.


Gather equipment

  • Snellen chart
  • Ishihara chart
  • Fine print reading chart
  • Pinhole
  • Hatpin
  • Ophthalmoscope
  • Pen torch
  • Mydriatic eye drops

Visual acuity

Assessment of visual acuity (distance)

Begin by assessing the patient’s visual acuity using a Snellen chart. If the patient normally uses distance glasses, ensure these are worn for the assessment.

1. Stand the patient at 6 metres from the Snellen chart.

2. Ask the patient to cover one eye and read the lowest line they are able to.

3. Record the lowest line the patient was able to read (e.g. 6/6 (metric) which is equivalent to 20/20 (imperial)).

4. You can have the patient read through a pinhole to see if this improves vision (if vision is improved with a pinhole, it suggests there is a refractive component to the patient’s poor vision).

5. Repeat the above steps with the other eye.

Recording visual acuity

  • Visual acuity is recorded as chart distance (numerator) over the number of the lowest line read (denominator).
  • If the patient reads the 6/6 line but gets 2 letters incorrect, you would record as 6/6 (-2).
  • If the patient gets more than 2 letters wrong, then the previous line should be recorded as their acuity.
  • When recording the vision it should state whether this vision was unaided (UA), with glasses or with pinhole (PH).

Further steps for patients with poor vision

If the patient is unable to read the top line of the Snellen chart at 6 metres (even with pinhole) move through the following steps as necessary:

1. Reduce the distance to 3 metres from the Snellen chart (the acuity would then be recorded as 3/denominator).

2. Reduce the distance to 1 metre from the Snellen chart (1/denominator).

3. Assess if they can count the number of fingers you’re holding up (recorded as “Counting Fingers” or “CF”).

4. Assess if they can see gross hand movements (recorded as “Hand Movements” or “HM”).

5. Assess if they can detect light from a pen torch shone into each eye (“Perception of Light”/”PL” or “No Perception of Light”/”NPL”).

Assessment of near vision

Assess the patient’s near vision using a near vision chart. If the patient normally uses reading glasses, ensure these are worn for the assessment.

Fine print reading

1. Ask the patient to cover one eye.

2. Then ask the patient to read a paragraph of small print in a book or newspaper.

3. Repeat the assessment on the other eye.

  • Assess near vision with fine print reading
    Assess near vision with fine print reading
Causes of decreased visual acuity

Decreased visual acuity has many potential causes including:

  • Refractive errors
  • Amblyopia
  • Ocular media opacities such as cataract or corneal scarring
  • Retinal diseases such as age-related macular degeneration
  • Optic nerve (CN II) pathology such as optic neuritis
  • Lesions higher in the visual pathways

Optic nerve (CN II) pathology usually causes a decrease in acuity in the affected eye. In comparison, papilloedema (optic disc swelling from raised intracranial pressure), does not usually affect visual acuity until it is at a late stage.


Colour vision assessment

Colour vision can be assessed using Ishihara plates, each of which contains a coloured circle of dots. Within the pattern of each circle are dots which form a number or shape that is clearly visible to those with normal colour vision and difficult or impossible to see for those with a red-green colour vision defect.

How to use Ishihara plates

If the patient normally wears glasses for reading, ensure these are worn for the assessment.

1. Ask the patient to cover one of their eyes.

2. Then ask the patient to read the numbers on the Ishihara plates. The first page is usually the ‘test plate’ which does not test colour vision and instead assesses contrast sensitivity. If the patient is unable to read the test plate, you should document this.

3. If the patient is able to read the test plate, you should move through all of the Ishihara plates, asking the patient to identify the number on each. Once the test is complete, you should document the number of plates the patient identified correctly, including the test plate (e.g. 13/13).

4. Repeat the assessment on the other eye.

  • Assess colour vision using an Ishihara chart at arms length
    Assess colour vision using an Ishihara chart at arms length

Visual fields

This method of assessment relies on comparing the patient’s visual field with your own and therefore for it to work:

  • you need to position yourself, the patient and the target correctly (see details below).
  • you need to have normal visual fields and a normal-sized blindspot.

Visual field assessment

1. Sit directly opposite the patient, at a distance of around 1 metre.

2. Ask the patient to cover one eye with their hand.

3. If the patient covers their right eye, you should cover your left eye (mirroring the patient).

4. Ask the patient to focus on part of your face (e.g. nose) and not move their head or eyes during the assessment. You should do the same and focus your gaze on the patient’s face.

5. As a screen for central visual field loss or distortion, ask the patient if any part of your face is missing or distorted. A formal assessment can be completed with an Amsler chart.

6. Position the hatpin (or another visual target) at an equal distance between you and the patient (this is essential for the assessment to work).

7. Assess the patient’s peripheral visual field by comparing to your own and using the visual target. Start from the periphery and slowly move the target towards the centre, asking the patient to report when they first see it. If you are able to see the target but the patient cannot, this would suggest the patient has a reduced visual field.

8. Repeat this process for each visual field quadrant, then repeat the entire process for the other eye.

9. Document your findings.

  • Assess the patient's peripheral visual fields
    Assess the patient's peripheral visual fields
Types of visual field defects
  • Bitemporal hemianopia: loss of the temporal visual field in both eyes resulting in central tunnel vision. Bitemporal hemianopia typically occurs as a result of optic chiasm compression by a tumour (e.g. pituitary adenoma, craniopharyngioma).
  • Homonymous field defects: affect the same side of the visual field in each eye and are commonly attributed to stroke, tumour, abscess (i.e. pathology affecting visual pathways posterior to the optic chiasm). These are deemed hemianopias if half the vision is affected and quadrantanopias if a quarter of the vision is affected.
  • Scotoma: an area of absent or reduced vision surrounded by areas of normal vision. There is a wide range of possible aetiologies including demyelinating disease (e.g. multiple sclerosis) and diabetic maculopathy.
  • Monocular vision loss: total loss of vision in one eye secondary to optic nerve pathology (e.g. anterior ischaemic optic neuropathy) or ocular diseases (e.g. central retinal artery occlusion, total retinal detachment).

Blind spot

A physiological blind spot exists in all healthy individuals as a result of the lack of photoreceptor cells in the area where the optic nerve passes through the optic disc. In day to day life, the brain does an excellent job of reducing our awareness of the blind spot by using information from other areas of the retina and the other eye to mask the defect.

Blind spot assessment

1. Sit directly opposite the patient, at a distance of around 1 metre.

2. Ask the patient to cover one eye with their hand.

3. If the patient covers their right eye, you should cover your left eye (mirroring the patient).

4. Ask the patient to focus on part of your face (e.g. nose) and not move their head or eyes during the assessment. You should do the same and focus your gaze on the patient’s face.

5. Using a red hatpin (or alternatively, a cotton bud stained with fluorescein/pen with a red base) start by identifying and assessing the patient’s blind spot in comparison to the size of your own. The red hatpin needs to be positioned at an equal distance between you and the patient for this to work.

6. Ask the patient to say when the red part of the hatpin disappears, whilst continuing to focus on the same point on your face.

7. With the red hatpin positioned equidistant between you and the patient, slowly move it laterally until the patient reports the disappearance of the top of the hatpin. The blind spot is normally found just temporal to central vision at eye level. The disappearance of the hatpin should occur at a similar point for you and the patient.

8. After the hatpin has disappeared for the patient, continue to move it laterally and ask the patient to let you know when they can see it again. The point at which the patient reports the hatpin re-appearing should be similar to the point at which it re-appears for you (presuming the patient and you have a normal blind spot).

9. You can further assess the superior and inferior borders of the blind spot using the same process.

  • Assess the patient's blind spot
    Assess the patient's blind spot
Causes of an enlarged blind spot

An enlarged blind spot is typically associated with a swollen optic disc (papilloedema) which is most often caused by raised intracranial pressure (e.g. brain tumour, hypertensive crisis, intracranial haemorrhage).


Inspect the external eye

To inspect the external eye, ask the patient to focus on a fixed object in the distance (e.g. light switch) and use the light of the fundoscope to carefully examine the eyelids, eyelashes, conjunctiva, sclera, cornea, iris and pupil.

General inspection

Inspect the eye for signs of pathology:

  • Eyelids: note any lumps (benign or malignant), oedema, cellulitis and entropion/ectropion.
  • Eyelashes: inspect for loss of eyelashes (can be associated with malignant lesions) or trichiasis (inturning of the eyelashes).
  • Diffuse conjunctival injection (redness): dilated inflamed blood vessels across the majority of the conjunctiva. Typically associated with bacterial, viral and allergic conjunctivitis.
  • Circumciliary injection: dilated inflamed blood vessels affecting the conjunctiva in a circular pattern around the cornea suggesting intraocular inflammation. Typically associated with keratitis, acute angle-closure glaucoma and uveitis.
  • Discharge: watery discharge is typically associated with allergic conjunctivitis, viral conjunctivitis or normal physiological production (e.g. reaction to a corneal abrasion/foreign body). Purulent discharge is more likely to be associated with bacterial conjunctivitis.
  • Hyphema: an inferior settled layer of blood in the anterior chamber typically occurring as a result of trauma.
  • Hypopyon: an inferior settled layer of ‘pus’ (white cells and debris) in the anterior chamber. Typically associated with severe corneal ulcers or endophthalmitis, but can also occur secondary to anterior uveitis.
  • Periorbital erythema and swelling: a feature of preseptal cellulitis (anterior to the orbital septum) or orbital cellulitis (posterior to the orbital septum).
  • Pupillary abnormalities: can include abnormal size, shape and asymmetry (see below).
  • Foreign bodies: may be visible on the surface of the eye or embedded within the cornea or sclera. Associated clinical features include redness, pain, watering and a ‘foreign body sensation’.
  • Corneal abrasion: redness, pain, watering and photophobia are common clinical features. Epithelial defects can be very hard to see with the naked eye but stain brightly with fluorescein drops and a cobalt blue light.
  • Corneal ulcer: typical clinical features include pain, watering, photophobia and a staining epithelial defect with associated haziness (infiltrates). The infiltrate may appear fluffy and irregular.

Inspect the pupil

The pupil is the hole in the centre of the iris that allows light to enter the eye and reach the retina.

Assess pupil size

  • Normal pupil size varies between individuals and depends on lighting conditions (i.e. smaller in bright light, larger in the dark).
  • Pupils are usually smaller in infancy and larger in adolescence.

Assess pupil shape

  • Pupils should be round, abnormal shapes can be congenital or due to pathology (e.g. posterior synechiae associated with uveitis).
  • Peaked pupils in the context of trauma are suggestive of globe injury.

Assess pupil symmetry

  • Note any asymmetry in pupil size between the pupils (anisocoria). This may be longstanding and non-pathological or relate to actual pathology. If the pupil is more pronounced in bright light this would suggest that the larger pupil is the abnormal pupil, if more pronounced in dark this would suggest the smaller pupil is abnormal.
  • Examples of asymmetry include a large pupil in oculomotor nerve palsy and a small and reactive pupil in Horner’s syndrome.

Inspect the eyelids

  • Assess lid position: ptosis can be a sign of Horner’s syndrome (often very subtle ptosis) and oculomotor nerve palsy (can vary from partial to complete ptosis).
  • Assess the lid margins: crusting and inflamed lid margins are associated with blepharitis.
  • Inspect the pupils
    Inspect the pupils
Causes of red eye

Below is a non-exhaustive list of causes of red eye, with their associated clinical features.

Painless red eye:

  • Conjunctivitis: diffuse conjunctival injection (unilateral or bilateral), discharge, swollen conjunctiva (chemosis) and debris. Bacterial conjunctivitis typically has more purulent discharge than viral or allergic conjunctivitis.
  • Subconjunctival haemorrhage: a flat, bright red patch on the conjunctiva with sharply defined borders and normal conjunctiva surrounding it.
  • Episcleritis: sectoral area of subconjunctival injection (unilateral). The subconjunctival injection in episcleritis is superficial and, as a result, moveable with a swab (using topical anaesthesia) pressed gently on the conjunctiva.
  • Dry eye: caused by deficiencies in tear production and maintenance secondary to conditions such as blepharitis (obstruction of meibomian glands). Clinical features include diffuse conjunctival injection (unilateral or bilateral), inflamed lid margins with crusting and matted eyelashes.

Painful red eye:

  • Scleritis: deep pinkish localised conjunctival injection (unilateral), visual acuity may be reduced, minimal watery discharge, photophobia and a tender globe (causing the patient to wake at night). Symptoms tend to progressively worsen and individuals commonly have other connective tissue diseases.
  • Uveitis: circumciliary conjunctival injection (unilateral), hazy cornea, distorted pupil, hypopyon, reduced visual acuity, watery discharge, photophobia and pain are common clinical features.
  • Corneal abrasion: eye redness, pain, watering and photophobia are common clinical features. Epithelial defects can be very hard to see with the naked eye but stain brightly with fluorescein drops and a cobalt blue light.
  • Corneal ulcer: typical clinical features include pain, watering, photophobia and a staining epithelial defect with associated haziness (infiltrates). The epithelial defect may appear fluffy, irregular and apparent even without a slit lamp.
  • Acute angle-closure glaucoma (AACG): typical clinical features include significant pain leading to vomiting, circumciliary conjunctival injection (unilateral), reduced visual acuity, photophobia, haloes in vision, hazy cornea and a mid-dilated unreactive pupil.
  • Foreign bodies: may be visible on the surface of the eye or embedded within the cornea or sclera. Associated clinical features include redness, pain, watering and a ‘foreign body sensation’. Foreign bodies may be hidden under the top and bottom of the eyelid.

Pupillary reflexes

With the patient seated, dim the lights in the assessment room to allow you to assess pupillary reflexes effectively.

Direct pupillary reflex

Assess the direct pupillary reflex:

  • Shine the light from your pen torch into the patient’s pupil and observe for pupillary restriction in the ipsilateral eye.
  • A normal direct pupillary reflex involves constriction of the pupil that the light is being shone into.

Consensual pupillary reflex

Assess the consensual pupillary reflex:

  • Once again shine the light from your pen torch into the same pupil, but this time observe for pupillary restriction in the contralateral eye.
  • A normal consensual pupillary reflex involves the contralateral pupil constricting as a response to light entering the eye being tested.
  • Assess direct and consensual pupillary light reflexes
    Assess direct and consensual pupillary light reflexes

Swinging light test

Move the pen torch rapidly between the two pupils to check for a relative afferent pupillary defect (see more details below).

  • Perform the swinging light test
    Perform the swinging light test

Accommodation reflex

1. Ask the patient to focus on a distant object (clock on the wall/light switch).

2. Place your finger approximately 20-30cm in front of their eyes (alternatively, use the patient’s own thumb).

3. Ask the patient to switch from looking at the distant object to the nearby finger/thumb.

4. Observe the pupils, you should see constriction and convergence bilaterally.

  • Assess the accommodation reflex
    Assess the accommodation reflex
Pupillary light reflex

Each afferent limb of the pupillary reflex has two efferent limbs, one ipsilateral and one contralateral.

The afferent limb functions as follows:

  • Sensory input (e.g. light being shone into the eye) is transmitted from the retina, along the optic nerve to the ipsilateral pretectal nucleus in the midbrain.

The two efferent limbs function as follows:

  • Motor output is transmitted from the pretectal nucleus to the Edinger-Westphal nuclei on both sides of the brain (ipsilateral and contralateral).
  • Each Edinger-Westphal nucleus gives rise to efferent nerve fibres which travel in the oculomotor nerve to innervate the ciliary sphincter and enable pupillary constriction.

Normal pupillary light reflexes rely on the afferent and efferent pathways of the reflex arc being intact and therefore provide an indirect way of assessing their function:

  • The direct pupillary reflex assesses the ipsilateral afferent limb and the ipsilateral efferent limb of the pathway.
  • The consensual pupillary reflex assesses the contralateral efferent limb of the pathway.
  • The swinging light test is used to detect relative afferent limb defects.
Abnormal pupillary responses
  • Relative afferent pupillary defect (Marcus-Gunn pupil): normally light shone into either eye should constrict both pupils equally (due to the dual efferent pathways described above). When the afferent limb in one of the optic nerves is damaged, partially or completely, both pupils will constrict less when light is shone into the affected eye compared to the healthy eye. The pupils, therefore, appear to relatively dilate when swinging the torch from the healthy to the affected eye. This is termed a relative…. afferent… pupillary defect. This can be due to significant retinal damage in the affected eye secondary to central retinal artery or vein occlusion and large retinal detachment; or due to significant optic neuropathy such as optic neuritis, unilateral advanced glaucoma, compression secondary to tumour or abscess and ischaemic optic neuropathy.
  • Unilateral efferent defect: commonly caused by extrinsic compression of the oculomotor nerve, resulting in the loss of the efferent limb of the ipsilateral pupillary reflexes. As a result, the ipsilateral pupil is dilated and non-responsive to light entering either eye (due to loss of ciliary sphincter function). The consensual light reflex in the unaffected eye would still be present as the afferent pathway (i.e. optic nerve) of the affected eye and the efferent pathway (i.e. oculomotor nerve) of the unaffected eye remain intact.
  • Relative afferent pupillary defect
    Relative afferent pupillary defect 15

Assessment of strabismus

Light reflex test (a.k.a. corneal reflex test or Hirschberg test)

1. Ask the patient to focus on a target approximately half a metre away whilst you shine a pen torch towards both eyes.

2. Inspect the corneal reflex on each eye:

  • If the ocular alignment is normal, the light reflex will be positioned centrally and symmetrically in each pupil.
  • Deflection of the corneal light reflex in one eye suggests a misalignment.

Cover test

The cover test is used to determine if a heterotropia (i.e. manifest strabismus) is present.

1. Ask the patient to fixate on a target (e.g. light switch).

2. Occlude one of the patient’s eyes and observe the contralateral eye for a shift in fixation:

  • If there is no shift in fixation in the contralateral eye, while covering either eye, the patient is orthotropic (i.e. normal alignment).
  • If there is a shift in fixation in the contralateral eye, while covering the other eye, the patient has a heterotropia.

3. Repeat the cover test on the other eye.

The direction of the shift in fixation determines the type of tropia; the table below describes the appropriate interpretation.

Interpretation of the cover test

Direction of eye at rest The direction of shift in fixation of the unoccluded eye when the opposite eye is occluded Type of tropia present
Temporally (i.e. laterally or outwards) Nasally (i.e. medially or inwards) Exotropia
Nasally (i.e. medially or inwards) Temporally (i.e. laterally or outwards) Esotropia
Superiorly (i.e. upwards) Inferiorly (i.e. downwards) Hypertropia
Inferiorly (i.e. downwards) Superiorly (i.e. upwards) Hypotropia
Cover test interpretation
Cover test interpretation

Eye movements

Briefly assess for abnormalities of eye movements which may be caused by underlying cranial nerve palsy (e.g. oculomotor, trochlear, abducens, vestibular nerve pathology).

1. Hold your finger (or a pin) approximately 30cm in front of the patient’s eyes and ask them to focus on it. Look at the eyes in the primary position for any deviation or abnormal movements.

2. Ask the patient to keep their head still whilst following your finger with their eyes. Ask them to let you know if they experience any double vision or pain.

3. Move your finger through the various axes of eye movement in a ‘H’ pattern.

4. Observe for any restriction of eye movement and note any nystagmus (which may suggest vestibular nerve pathology or stroke).

Actions of the extraocular muscles
  • Superior rectus: primary action is elevation, secondary actions include adduction and medial rotation of the eyeball.
  • Inferior rectus: primary action is depression, secondary actions include adduction and lateral rotation of the eyeball.
  • Medial rectus: adduction of the eyeball.
  • Lateral rectus: abduction of the eyeball.
  • Superior oblique: depresses, abducts and medially rotates the eyeball.
  • Inferior oblique: elevates, abducts and laterally rotates the eyeball.
  • Assess eye movements
    Assess eye movements

Fundoscopy

Ophthalmoscope overview

Parts

  • Viewing window: this is where you look through to observe the eye.
  • Filter switch: allows you to select a light filter (e.g. blue cobalt light).
  • Aperture dial: adjust the size of the light beam.
  • Diopter dial: adjusts the lens used to view the eye.
  • Diopter power display: shows the current lens being used.
  • Rheostat: adjusts the intensity of the light beam.
  • On/off switch: turns the device on and off.

Aperture size (beam size)

  • Micro aperture: used for viewing the fundus through very small undilated pupils.
  • Small aperture: used for viewing the fundus through an undilated pupil.
  • Large aperture: used for viewing the fundus through a dilated pupil and for the general examination of the eye.
  • Slit aperture: can be helpful in assessing contour abnormalities of the cornea, lens and retina as it makes elevation easier to see.

Filter

  • Cobalt blue filter: used to look for corneal abrasions or ulcers with fluorescein dye.
  • Red-free filter: used to look at the centre of the macula and other vasculature in more detail.
  • Practitioner side of the ophthalmoscope
    Practitioner side of the ophthalmoscope

Explanation

Explain the process of fundoscopy to the patient to ensure they are aware of what to expect during the assessment.

Example explanation

“I will be using a magnifying tool called an ophthalmoscope to look at the front and back of your eyes with the lights off.”“To do this, I’ll need to get quite close to your face. I’ll place a hand on your forehead to prevent us from bumping into each other.”

“I’ll also be using some eye drops to dilate your pupils and to highlight any problems. The dilating drops will cause your vision to be temporarily blurry and you’ll be more sensitive to light, so you’ll not be able to drive for several hours afterwards.”

Preparation for fundoscopy

1. It is essential to darken the room for the examination. Make sure the patient is positioned seated prior to turning out the lights to avoid accidents.

2. Dilate the patient’s pupils using short-acting mydriatic eye drops such as tropicamide 1%.  You will be unable to monitor pupil reactions once dilating drops have been applied, furthermore assessing vision, colour vision, double vision and visual fields will be less accurate once drops are instilled.

3. Ask the patient to look straight ahead for the duration of the examination (asking the patient to fixate on a distant target such as a light switch can cause confusion if you then obstruct the view of this target).

Assess the red reflex

Ophthalmoscope settings

To set up the ophthalmoscope for assessing the red reflex adjust the diopter dial to correct for your refractive error so that you can see the patient and their eye clearly from a distance:

  • If you have normal visual acuity, you can set the diopter dial to 0.
  • If you have a refractive error but are planning to wear glasses/contact lenses that correct this when using the ophthalmoscope you can also set it to 0.
  • If you have a refractive error and are not going to wear your glasses/contact lenses you should adjust the diopter dial to match your prescription (e.g. -2).

How to assess for the red reflex

1. Look through the ophthalmoscope, shining the light towards the patient’s eye at a distance of approximately one arm’s length.

2. Observe for a reddish/orange reflection in each pupil, caused by light reflecting back from the vascularised retina.

Causes of an absent red reflex

Absence of the red reflex in adults is often due to cataracts in the patient’s lens blocking the light. Other causes include vitreous haemorrhage and retinal detachment.

Absence of the red reflex in children can be due to congenital cataracts, retinal detachment, vitreous haemorrhage and retinoblastoma.

The presence of a white reflex (leukocoria), regardless of whether the red reflex is partly visible suggests the presence of one of the pathologies mentioned previously.

  • Assess for the red light reflex
    Assess for the red light reflex

Assess the anterior segment of the eye

Ophthalmoscope settings

To set up the ophthalmoscope for assessing the anterior surface of the eye adjust the diopter dial to a high green number (e.g. 10 or 15) which changes the ophthalmoscope into a magnifying glass.

How to assess the anterior segment of the eye

1. Stand to the side of the patient and place your hand on the patient’s forehead to prevent an accidental collision.

2. Approach the eye and assess the anterior segment using the ophthalmoscope:

  • Fluorescein dye can be applied as an eye drop which will stain and fluoresce yellow under the blue cobalt light filter of the ophthalmoscope if there is damage to the corneal or conjunctival epithelium (e.g. an abrasion).
  • Look for white opacities on the cornea which may be suggestive of a corneal ulcer.
  • Assess the anterior segment of the eye
    Assess the anterior segment of the eye

Assess the fundus

Ophthalmoscope settings

To set up the ophthalmoscope for assessing the fundus, adjust the diopter dial so that it is the net result of yours and the patient’s refractive error:

  • If you and the patient have normal visual acuity, set the dial to 0 (e.g. 0 + 0 = 0).
  • If you have a refractive error but are planning to wear glasses/contact lenses that correct this, assume you have a refractive error of 0 and add the patient’s refractive error to this (e.g. 0 + -2 = -2).
  • If the patient has a refractive error and you have normal visual acuity set the dial to the net refractive error. An example of this would be (your refractive error of 0) + (patient’s refractive error of -2) = a setting of -2.
  • If the patient has a refractive error and you have a refractive error set the dial to the net refractive error. An example of this would be (your refractive error of +3) + (patient’s refractive error of -2) = a setting of +1.
  • If things appear out of focus during the assessment, simply adjust the diopter dial until things look sharper.

Assess the optic disc

1. If you are assessing the patient’s right eye, you should hold the ophthalmoscope in your right hand and vice versa. Place the hand not holding the ophthalmoscope onto the patient’s forehead to prevent accidental collision between yours and the patient’s face.

2. Approaching from a 45-degree angle slightly temporal to the patient, move closer whilst maintaining the red reflex.

3. Begin by identifying a blood vessel and then follow the branching of this blood vessel towards the optic disc (the branches point like arrows towards the optic disc).

4. Once you identify the optic disc assess its characteristics including the contour, colour and the cup (“3Cs”):

  • Contour: the borders of the optic disc should be clear and well defined. If the borders appear blurred it may suggest the presence of optic disc swelling (papilloedema) secondary to raised intracranial pressure.
  • Colour: a healthy optic disc should look like an orange-pink doughnut with a pale centre. The orange-pink colour represents well-perfused neuro-retinal tissue. A pale optic disc suggests the presence of optic atrophy which can occur as a result of optic neuritis, advanced glaucoma and ischaemic vascular events.
  • Cup: the cup is the pale centre of the orange-pink doughnut mentioned previously. The pale colour of the cup is due to the absence of neuroretinal tissue. The vertical size of the cup can be estimated in relation to the optic disc as a whole, known as the “cup-to-disc ratio“. A cup-to-disc ratio of 0.3 (i.e. the cup occupies one-third of the height of the optic disc) is generally considered normal. An increased cup-to-disc ratio suggests a reduced volume of healthy neuro-retinal tissue, which can occur in glaucoma.
  • Perform fundoscopy
    Perform fundoscopy

Assess the retina

5. Methodically assess each quadrant of the retina and the associated vascular arcades in a clockwise or anticlockwise fashion looking for evidence of pathology:

  • Superior temporal (ST)
  • Superior nasal (SN)
  • Inferior nasal (IN)
  • Inferior temporal (IT)
  • Assess each quadrant of the retina
    Assess each quadrant of the retina
Types of retinal pathology
  • Arteriolar narrowing: subtle, with generalised arteriolar narrowing with typical copper or silver wire appearance. Most commonly associated with the early stages of hypertensive retinopathy.
  • Arteriovenous nipping/nicking: areas of focal narrowing, and compression of venules at sites of arteriovenous crossing. The typical appearance involves bulging of retinal veins on either side of the area where the retinal artery is crossing. Most commonly associated with grade 2 hypertensive retinopathy.
  • Dot and blot haemorrhages: arise from bleeding capillaries in the middle layers of the retina and may look like microaneurysms if small enough. They are most commonly associated with diabetic retinopathy.
  • Flame haemorrhages: larger haemorrhages with a flame-like appearance caused by rupture of pre-capillary arterioles or small veins in the retinal nerve fibre layer. Most commonly associated with grade 3 hypertensive retinopathy, thrombocytopaenia, retinal vein occlusion and trauma.
  • Cotton wool spots: appear as small, fluffy, whitish superficial lesions and represent infarcts of the neuro-retinal layer. They are most commonly associated with diabetic retinopathy and grade 3 hypertensive retinopathy.
  • Hard exudates: waxy yellow lesions with relatively distinct margins arranged in clumps or rings, often surrounding leaking microaneurysms. They are most commonly associated with diabetic retinopathy and grade 3 hypertensive retinopathy.
  • Neovascularisation: formation of new blood vessels that appear as a net of small curly vessels, with or without associated haemorrhages. They may be located on the optic disc or elsewhere on the retina. They are most commonly associated with advanced proliferative diabetic retinopathy.
  • Pan-retinal photocoagulation: the primary treatment for proliferative diabetic retinopathy. Clinically it is seen as clusters of pale burn marks on the retina which have been created by the laser used in the treatment process.
  • Branch retinal vein occlusion: blockage of one of the four retinal veins, each of which drains about a quarter of the retina. Typical signs include flame haemorrhages, dot and blot haemorrhages, cotton wool spots, hard exudates, retinal oedema, and dilated tortuous veins.

Assess the macula

6. Finally, inspect the macula by asking the patient to briefly look directly into the light of the ophthalmoscope. The macula is found lateral (temporal) to the optic nerve head and is yellow in colour. The central part of the macula, the “fovea” is about the same diameter as the optic disc and appears darker than the rest of the macula due to the presence of an additional pigment.

  • Assess the macula
    Assess the macula
Types of macula pathology
  • Hard exudates: waxy yellow lesions with relatively distinct margins arranged in clumps or rings, often surrounding leaking microaneurysms. They are most commonly associated with diabetic retinopathy, grade 3 hypertensive retinopathy and retinal vein occlusions.
  • Drusen: yellow-white flecks scattered around the macular region representing remnants of dead retinal pigment epithelium. Most commonly caused by age-related macular degeneration.
  • Cherry-red spot: associated with central retinal artery occlusion which typically presents with sudden profound visual loss.

Assess the other eye

Repeat assessment of the anterior segment, red reflex and fundus on the other eye. You will need to approach the patient from the opposite side and hold the ophthalmoscope in your other hand.


To complete the examination

Explain to the patient that the examination is now finished.

Thank the patient for their time.

If mydriatic drops were instilled, remind the patient they cannot drive for the next 3-4 hours until their vision has returned to normal.

Wash your hands.

Summarise your findings

Suggest further assessment and investigations

All of the following further assessments and investigations are dependent on the patient’s presenting complaint and in most cases, none of them would need to be performed:

  • Amsler chart: to assess for central visual loss and distortion which is commonly associated with macular degeneration.
  • Cranial nerve examination: to further assess for evidence of cranial nerve pathology (e.g oculomotor nerve).
  • Blood pressure: if there are concerns about hypertensive retinopathy.
  • Capillary blood glucose: if there are concerns about diabetic retinopathy.
  • Retinal photography: to better visualise any abnormalities noted on fundoscopy.

References

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