Examination of the Eye & Vision – OSCE Guide

Introduction

Wash hands

Introduce yourself

Confirm patient details

Explain examination

Gain consent

Appropriately position the patient

Visual Acuity

Snellen chart

• Stand the patient at 6 metres from the Snellen chart
• If patient is long-sighted (hyperopia) ensure they wear glasses
• Ask the patient to cover one eye & read to the lowest line they can manage
• Visual acuity is recorded as the distance from the chart (numerator) over the number of the lowest line read (denominator)
• Record the lowest line the patient was able to read (e.g. 6/6 which is equivalent to 20/20 – patient can read at 6 metres what a healthy person could read at 6 metres)
• If patient reads the 6/6 line, but gets 2 letters incorrect, you would record as 6/6 (-2)
• If patient gets more than 2 letters wrong, then the previous line should be recorded as their acuity
• 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 element to their poor vision
• Repeat above with the other eye

Fine print reading

Ask patient to cover one eye

Ask patient to read a paragraph of small print in a book/newspaper

Repeat with the other eye

If they normally wear glasses for reading, ensure these are worn for the assessment

 Visual Fields

1. Sit directly opposite the patient, at a distance of around 1 metre
2. Ask patient to cover one eye with their hand
3. If the patient covers their right eye, you should cover your left eye (just mirror the patient)
4. Ask patient to focus on your face & not move their head or eyes during the assessment, you should do the same and focus your gaze on the patients face
5. Ask the patient to tell you when they can see your fingertip wiggling
6. Position your fingertip at the border of one of the quadrants of your visual field
7. Slowly bring your fingertip inwards, towards the centre of your visual field until the patient sees it
8. If you are able to see your fingertip, but the patient cannot, this would suggest a reduced visual field
9. Repeat this process for each quadrant, then repeat the entire process for the other eye
10. Document your findings

Visual neglect / inattention

1. Sit directly opposite the patient, at a distance of around 1 metre
2. Ask patient to focus on your face & not move their head or eyes during the assessment
3. Hold both arms out, with your fingers in the periphery of both yours & the patients field of vision
4. Remind the patient to keep their head still & their eyes fixed on your face
5. Ask patient to point at which fingers are moving
6. Move the fingers of left & right hand in whichever order you choose
7. Then move the fingers of both hands simultaneously
8. If the patient only points to one of the hands, when fingers are moving on both hands, this would be suggestive of visual neglect

Visual neglect can suggest damage to the frontal or parietal lobes of the brain - stroke, trauma, etc

 Pupils

Inspection

Size
Shape
Symmetry

Reflexes

Too best see pupillary reflexes, the room should be dimly lit

Direct pupillary reflex

Shine light into the pupil & observe constriction of that pupil
Sluggish or lack of constriction may suggest pathology – optic nerve / brain stem pathology, drugs

Consensual pupillary reflex

Again shine a light into the pupil
This time observe the contralateral pupil
A normal consensual response involves the contralateral pupil constricting
Lack of a normal  consensual response may suggest:

• Damage to one or both optic nerves.
• Damage to the Edinger Westphal Nucleus

Swinging light test

• Move the pen torch rapidly between the 2 pupils
• This test may detect a  relative afferent pupillary defect (RAPD) - caused by damage of the tract between the optic nerve & optic chiasm, such as optic neuritis in multiple sclerosis. It is also known as a “Marcus-Gunn” pupil.)
• A RAPD can be detected by paradoxical dilatation of the affected pupil when light is shining into it (it should normally constrict)

Accommodation reflex

• Ask the patient to focus on a distant object
• Then ask them to focus on a much closer object (often a finger or pen torch)
• A normal accommodation reflex involving constriction & convergence of the pupils should be observed

Cover / Uncover Test

Firstly inspect for a squint (strabismus) whilst the patient is at rest looking straight ahead

Then perform the cover / uncover test to detect if a manifest strabismus (heterotropias) or a latent strabismus (heterophorias) are present:

• Alternating Cover Test
• Unilateral Cover Test

Eye Movements

Ask the patient to keep their head still & follow your finger with their eyes

Move your finger through the various axis of eye movement (“H“ shape)

Observe for restriction of eye movements – e.g. inability to abduct eye in affected eye in abducens (VI) nerve palsy

Observe for any obvious nystagmus and saccades:

Physiological Nystagmus is often observed at the extremes of gaze (end point nystagmus)

The rapid, jerky movement that corrects the gaze after the slower deviation is called a saccade

Fundoscopy

Preparation

Darken the room

Ideally the patient should have their pupils dilated with short-acting  mydriatic eye drops (e.g. 0.5% tropicamide)

Ask the patient to fixate on a distant object

Assess for red reflex

Ideally this should be assessed at a distance of around 30cm
Looking through the ophthalmoscope observe for a reddish / orange reflection in the pupil
The red reflex is caused by light reflecting back from the vascularised retina
Absence of the red reflex in adults often is due to cataracts in the patients lens, blocking the light, but it can also be associated with retinoblastoma

Move in closer & examine the eye with the fundoscope

Begin medially & assess the optic disc - colour / contour / cupping
Assess the retinal vessels – cotton wool spots / AV nipping / neovascularisation
Finally assess the macula – ask to look directly into the light – Drusen seen in macular degeneration

To complete the examination

Thank patient

Wash hands

Summarise findings

Mention further investigations you would like to perform:

• Ishihara colour testing plates
• Retinal photography
• Full cranial nerve examination