The anatomical basis of eye examinations

Question 1

snellen chart for visual acuity

if you fail on two letter on that line then the line before that is how you mark it
measures the global function of the eye

let them have glasses on

6metres away
If the patient reads the 6/6 line but gets more than 2 letters wrong, the previous line should be recorded as their acuity
If the patient cannot see the top line, reduce the distance to 3 and then 1 metres (record as 3/denominator or 1/denominator)
Then ask if they can count how many fingers you are holding up
Then ask if they can see gross hand movements
Then ask if they can detect light with a pen torch

Answer 1

Each line is labelled with the distance in metres it should be seen by a normally sighted eye
Acuity is recorded as a fraction – the distance from the chart is the numerator (number on top) and the furthest line seen as the denominator e.g. at 6 metres the patient can read to the 9 metre line = 6/9
Ask the patient to cover one eye and read the lowest line they are able to
Test acuity first with spectacles and then a pinhole if available

Question 2

causes of decreased visual acuity

Answer 2

Visual acuity is a test of the optic nerve (cranial nerve II). Causes of decreased visual acuity include:
Optic neuritis
Lesions higher in the visual pathways
Cataracts/corneal scarring
Age-related macular degeneration

Question 3

When you shine a light in one eye, both pupils constrict.

How does this happen?

Answer 3

Afferent (sensory) = Optic nerve (II) – projects to pretectal nucleus
Efferent (motor) = Oculomotor nerve (III) – projects from Edinger-Westphal nucleus to ciliary ganglion

Question 4

funduscopy inspect what - whispering in ear

Answer 4

retina

gives indications about ICP - twiddle until you can see the retina
Assess for fundal reflex/red refex: look through the scope and shine the light at the patients eye about one arms length away. Look for a reddish reflection in the pupil = light reflecting back from the vascularised retina
Right eye of patient – hold ophthalmoscope in right hand
‘Whisper not kiss’ – be slightly to the patients side
Identify a blood vessel and follow this to the optic disc. Assess the four retina quadrants
Assess the macula – ask patient to look briefly directing into the light

Question 5

what is a papilloedema

Answer 5

Papilloedema refers to optic disc swelling secondary to raised intracranial pressure. Optic disc margins appear blurred and small haemorrhages may be seen.

disc becomes indistinct and white

Question 6

what might you see on hypertensive retinopathy

Answer 6

flame haemorrhage
hard exudates
papilloedema
cotton wool spots

Question 7

absence of red reflex in children

Answer 7

congenital cataracts, retinoblastoma

Question 8

absence of red reflex in adults

Answer 8

cataracts, vitreous haemorrhage, retinal detachment

Question 9

Retinoscopy
Hand held instrument (retinoscope) projects a beam of light into the eye
The light is then moved around the back of the eye, which gives the examiner information about whether the patient has a refractive error and what type (short sightedness, long sightedness or astigmatism)

who is it useful for

Answer 9

Performed by optometrist

Useful for people who can’t communicate e.g. children or people with dementia

Question 10

refraction test

what does this help test for

Answer 10

Helps to determine whether short/long-sighted or whether has astigmatism

Question 11

Long-sightedness (hypermetropia/hyperopia) causes the light from distant objects to focus

how to correct

happens when older

Answer 11

behind the eye

requires convex lens

Question 12

Short-sightedness (myopia) causes light from distant objects to focus

how to correct it

Answer 12

in front of the retina.

concave lens

Objects close to the eye can be focussed onto the retina.

Question 13

what is astigmatism

Answer 13

In astigmatism, the eye is shaped more like a rugby ball than a football. This makes the light focus in more than one place in the eye. This can lead to headaches and vision. Astigmatism can often be associated with long or short-sightedness. This can be corrected with a lens.

Question 14

what test measures the shape and curve of the cornea

Answer 14

Keratometry test

Question 15

kernatoconus

Answer 15

cornea protrudes out looks like eye is a pyramid falling out

afrocaribbean people - corrected with glasses

Question 16

bulls keratopthy

Answer 16

cysts in cornea
side effects of surgery to the eye

corneal scarring - viral infection like herpes

Question 17

peripheral field vision test

what is normal

Answer 17

Peripheral vision is vision as it occurs outside the point of fixation, i.e. away from the centre of gaze.

Normal is 90-95 degrees temporal to central vision.
60-65 nasal

Several types of test:
Automated perimetry/tangent screen exam – occur at optometrist, use machinery/computers
Confrontational exam – sit opposite the patient and move hand in and out of peripheral vision – patient will tell you when they are able to see your fingers

Question 18

for bipolar hemianopia, nasal hemianopia, homonymous hemianopia and left homonymous hemainopai with macula sparing

what test for this

Answer 18

peripheral field test

total one eye blinds is via a VA test

Question 19

Intraocular pressure measurement

Answer 19

Measures the pressure created by the fluid in your eyes
Can be measured using a tonometer. Sends a puff of air into the eyes, causes reflex closure
Pressure measured by reaction and resistance to pressure from the puff of air
Can also use applanation tonometry (manual) instrument placed on eye – done with anaesthetic drops

Question 20

slit lamp gives 3D view of eye - assess depth

keratitis
corneal abrasion
cataracts feature

Answer 20

Binocular microscope the provides a 3D view of the eye
Slit beam allows the anterior segment of the eye to be examined
Can use in ED to look for and remove foreign bodies or assess abrasions

Question 21

keratitis

cause

Answer 21

ifnalmtion of cornea - herpes simplex dendritic ulcer

Question 22

corneal abrasion

Answer 22

blue trauma pain redness and photophobia and lacrimiantion

Question 23

cataracts feature

Answer 23

cloudy lens

Question 24

corneal reflex

Answer 24

Protective reflex – stimulation of one cornea causes both eyes to blink. Sensory input  trigeminal nerve (ophthalmic division, Va), motor response  facial nerve

Question 25

You are testing a 42-year-old female patient’s visual acuity using a Snellen Chart. On examination you deem her left eye normally sighted, but she only able to read at 6 metres what a normally sighted person would be able to read at 18 metres with her right eye. What level of visual acuity should this be recorded as?

Left eye 6/6, right eye 6/12
Left eye 6/6, right eye 6/18
Left eye 6/6, right eye 18/6
Left eye 6/12, right eye 6/6
Left eye 6/12, right eye 12/6

Answer 25

left eye 6/6 right eye 6/18

Acuity is recorded as a fraction – the distance from the chart is the numerator (number on top) and the furthest line seen as the denominator e.g. at 6 metres the patient can read to the 9 metre line = 6/9

Question 26

You are testing a the pupillary reflexes of a patient you suspect has multiple sclerosis. When you shine a light into their left eye, both pupils constrict. You then move the light source to their right eye and both pupils dilate. When you move the light source back to the left eye, both pupils constrict again. Which of the following have you observed?

A normal response
Left-sided relative afferent pupillary defect
Left-sided relative efferent pupillary defect
Right-sided relative afferent pupillary defect
Right-sided relative efferent pupillary defect

Answer 26

right sided relative afferent pupillary defect

Afferent = sensory arm of the reflex (A = Arrives)
The normal response to light should be constriction. When the light is shone in the abnormal right eye, the pupils dilate instead of constrict, as if the light is not ther

Question 27

You are spending the day shadowing the optometrist. You watch them carry out a retinoscopy test on 10-year-old girl who is non-verbal due to a learning disability. She has been referred from her school due to concerns about her eyesight. The optometrist shines the light at the back of the eye and moves it from side to side. They note that the red reflex moves along the back of the eye AGAINST movement.
Which refractive error is the optometrist now suspecting?

Astigmatism
Hypermetropia
Myopia 
No refractive error
Presbyopia

Answer 27

myopia

The retinal reflex at the back of the eye should not move if there is no refractive error.
The retinal reflex will move IN THE DIRECTION OF MOTION if there is hypermetropia or presbyopia and will CHANGE ANGLE if there is astigmatism.
It will move AGAINST motion in myopia (short-sightedness).

Astigmatism (uh-STIG-muh-tiz-um) is a common and generally treatable imperfection in the curvature of the eye that causes blurred distance and near vision. - cornea

Presbyopia is the gradual loss of your eyes’ ability to focus on nearby objects- ageing

Question 28

Question 4: You are examining a patient with a history of idiopathic intracranial hypertension who has come in with a severe headache. In the Emergency Department. Using a fundoscope, you look into the back of their eyes. You note blurring of the optic disc margins.

Which of the following conditions are you now concerned about?

Astigmatism
Diabetic retinopathy
Hypermetropia
Myopia
Raised intracranial pressure

Answer 28

RAISED ICP

Blurred optic disc margins demonstrates papilloedema, which is a sign of raised intracranial pressure.

Question 29

Whilst shadowing an ophthalmologist for the day, they ask you if you know of any tests which might be helpful to measure intra-ocular pressure in glaucoma. You say…

Fundoscopy
Keratometry
Ocular tonometry
Retinoscopy
Slit lamp examination

Answer 29

ocular tonometry

Fundoscopy: used to look at the retina at the back of the eye. Useful in concerns about raised ICP and monitoring diabetic and hypertensive retinopathy
Keratometry: measurement of the shape of the cornea
Retinoscopy: used to assess for refractive error
Slit lamp examination: can look for corneal damage and/or foreign body in the eye.

Question 30

driving standard sneellen chart

Answer 30

6/12