Vision testing

Question 1

What is an astigmatism corrected with?

Answer 1

Cylindrical lens

Question 2

What is hypermetropia? What is it corrected with?

Answer 2

Far-sightedness - light falls behind the retina
Spherical lens - converging (convex lens)

Question 3

What is myopia? What is it corrected with?

Answer 3

Near-sightedness - light falls in front of retina
Spherical lens - diverging (concave lens)

Question 4

Where is the fovea/ macula in relation to the optic disc on a fundoscopy?

Answer 4

Fovea is lateral to the optic disc

Question 5

What does visual acuity depend on?

Answer 5

Ability of cornea to refract or bend the light
Shape of lens
Sensitivity of retina and optical neural connections
Ability of brain to interpret information

Question 6

What power do diverging and converging lens have?

Answer 6

Diverging = negative power
Converging = postitive power

Question 7

What is the snellen fraction and how is it interpreted?

Answer 7

Visual acuity = viewing distance (m) / number (distance) marked on test line

If 6/60: patient can read the line at 6m, which someone with normal vision can read at 60m

Question 8

When performing fundoscopy, what should the lens be set to initially?

Answer 8

0

Question 9

To focus on the optic disc and macula, what might you need to change the lens to?

Answer 9

-2D to -4D (weak diverging lens)

Question 10

What conditions may prevent visualisation of the red reflex?

Answer 10

Cataract, corneal scars, vitreous haemorrhage, retinal detachment

Question 11

Where should you position yourself to view the optic disc?

Answer 11

Angle of 10-15 degrees with the ophthlamoscope, slightly temporal to the patient (as optic disc = nasally), then follow the blood vessels

Question 12

A patient has right-sided homonymous hemianopia. Where is the lesion likely to be?

Answer 12

Left optic tract or left optic radiation (if affecting both inferior and superior divisions)

Question 13

Name 2 conditions that can cause right-sided homonymous hemianopia

Answer 13

Stroke
Tumour

Question 14

A patient is found to have bitemporal hemianopia. Where is the lesion likely to be? What is a likely cause?

Answer 14

Optic chiasm
Pituitary tumour

Question 15

What medical condition could cause bitemporal hemianopia?

Answer 15

Acromegaly - excessive GH production

Question 16

If your patient has an inferior retinal detachment, what visual defect are they likely to have?

Answer 16

Superior visual field loss

Question 17

If a patient has left inferior homonymous quadrantopia, where is the lesion likely to be?

Answer 17

Right superior optic radiation, i.e. via Barum’s loop in parietal lobe