Visual Defects Flashcards
Patients may find it difficult to articulate their symptoms of visual loss, so need to ask direct questions. What 3 questions can you start with?
- Do things look distorted/crooked?
- Is there a shadow?
- Does the shadow move?
How would ‘blurred vision/fuzziness’ present?
- Out of focus/not sharp
- No distortion or shadowed (no bent/nothing missing)
What are 2 potential causes of blurred vision?
- a refractive problem (cornea, lens, shape of eye)
- a macular problem
How would ‘glare’ typically present?
- Difficulty seeing in bright light
- Low sun
- Driving at night
- Fluorescent light in supermarkets
- Similar effect produced by having dusty car windscreen
- Vision good otherwise
What is ‘glare’ often due to?
Cataract
How would ‘distorted vision’ typically present?
- Things look wavy, jumbled up. Lines not straight/ bent. Kink in lines
- Effect could be produced by having crumpled film in camera (or crumpled photo)
Typical causes of distorted vision?
- Condition affecting retina:
- Wet macular degeneration
- Macular hole
- Macular pucker
- Retinal detachment
What could cause a patient’s vision to be described as ‘pale’?
-
Optic nerve disease:
- Optic neuritis e.g. MS
- Compressive optic nerve disease e.g. pituitary tumour
-
Condition affecting retina:
- Wet macular degeneration
- Central serous retinopathy (fluid beneath the retina)
What is a ‘floater’?
Floaters are tiny pieces of debris in the eye’s fluid, known as the vitreous humour –> important feature is movement
What is a ‘floater’ caused by?
Degeneration in vitreous humour:
- Vitreous syneresis
- Posterior vitreous detachment
- Vitreous haemorrhage
A visual field defect (e.g. part of vision missing/ missing things/ shadow/ thumb print) is always a sign of what?
A serious problem
If the visual field is homonymous, what does this indicate?
same visual field both eyes –> a defect of visual pathways
If the visual field is not homonymous, what does this indicate?
Retinal or optic nerve problem
What is confrontation testing?
Confrontation visual field testing involves having the patient looking directly at your eye or nose and testing each quadrant in the patient’s visual field by having them count the number of fingers that you are showing. This is a test of one eye at a time
Label the types of visual defects:
A. Central B. Cecocentral C. Nasal
D. Arcuate E. Nasal wedge F. Quadrantic
G. Altitudinal H. Hemianopia
I. Paracentral + enlarged blind spot
What is a Glaucoma?
A common eye condition where the optic nerve becomes damaged. Usually caused by abnormally high pressure in eye e.g. due to blocked or restricted drainage in your eye or high blood pressure.
What is ‘cataract’?
- WHAT: Opacity of the lens
- Common aging change
Symptoms of cataract?
- Gradual onset
- Blurred vision, glare, change in refraction
Treatment of cataract?
phacoextraction with lens implant –> great improvement of symptoms
There are 2 blood supplies to the retina. What are they?
1) Choroid – underneath the sclera, supplies the outer 2/3 of retina
2) Vascular supply – supplies inner 1/3 of retina
A lot of supply to the retina therefore requires diffusion from the choroid.
How does retinal pigment epithelium maintain the environment of photoreceptors?
RPE removes waste product from cones and rods
What can reduced function of retinal pigment epithelium lead to?
Drusen
What are drusen?
Drusen are small yellow deposits of lipids that accumulate under the retina
What are the signs of dry age related macular degeneration (ARMD)?
- Drusen
- RPE pigmentation
- RPE atrophy
- Gradual deterioration
- Particularly affects reading vision
- Loss of small area leads to severe visual loss as it is central vision that is impaired, not peripheral
- Early stages often symptomatic
Treatment of dry ARMD?
- No effective medical treatment but lifestyle changes can help:
- Stop smoking
- Dietary changes/supplement
- Wear glasses in the light to prevent further damage
- Low visual aids
What type of ARMD would a sudden deterioration of vision indicate?
Wet ARMD
What is central retinal artery occlusion (CRAO)?
Obstruction of vasculature of retina on that side, leading to sudden vision loss
What can be seen in ophthalmoscope in CRAO?
Pallor and cherry red spot
Does vision recover in CRAO?
No
What are 2 major causes of CRAO?
- Embolic
- Carotid artery disease that throws emboli upwards –> most common cause
- Heart disease –> valve disease that throws off clots/emboli/fibrin
- Giant cell arthritis
What does CRAO require?
Urgent steroid therapy
What is giant cell arteritis? How does it present?
An inflammatory disease of unknown cause affecting the large blood vessels of the scalp, neck and arms. Inflammation causes a narrowing or blockage of the blood vessels, which interrupts blood flow. Typically affects elderly.
- Headache
- Malaise
- Visual loss
Needs urgent treatment!
What is the most common cause of CRAO?
Carotid artery disease
What are the risk factors for carotid artery disease?
Hypertension, Smoking, Diabetes, High Cholesterol
What is a carotid endarterectomy? When would it be performed?
Carotid endarterectomy is a surgical procedure to remove a build-up of fatty deposits, which cause narrowing of a carotid artery. Done if greater than 70% stenosis.
Why is urgent treatment in CRAO required even though vision loss is irreversible?
High risk to fellow eye
What is Metamorphosia?
Metamorphopsia is a visual defect that causes linear objects, such as lines on a grid, to look curvy or rounded. It’s caused by problems with the eye’s retina, and, in particular, the macula
Differential diagnoses for distorted vision?
- Wet macular degeneration
- Macular hole
- Macular pucker
- Retinal detachment
Effective treatment is now available for ARMD. What is it?
- VEGF (vascular endothelial growth factor) which stimulates growth of the choroidal neovascular membrane.
- antiVEGF stops this from happening and so is the treatment à reverses visual loss.
What is a macular hole?
A small break in the macula that can cause blurred and distorted vision
