Eye Investigations + Visual Defects Flashcards
What are investigations for the eye
Fluorescein Angiography Optical Coherence tomography ERG EOG VEP Open slit lamp Fundoscopy
What is fluorescein angiography
Retina impermeable to fluorescein
Choroid vessels are so look white
If there is leak in the retina will be able to detect
When do you use
Neovascular macular degeneration suspected
GCA
What does optical coherence tamography do
Scans the macula
See different layers of retina
Useful for macular and disc pathology
What is your blind spot
Optic nerve
No photoreceptor cells
What does ERG do
Measures AP’s in retina and function
What does EOG
Measures function of retinal pigment epithelium and photoreceptors
What does VEP do
Records optic nerve function
When is it useful
MS
What does reduced amplitude suggest
Ischaemia
Neuropathy
What does latency suggest
Optic neuritis
How do you investigate retinal pathology
Visual acuity / field Fundoscopy Fluorescein angiography Optic coherence tomography Electrophysiology - EOG / ERG
What is myopia
Short sightedness
How does this occur
Light focuses in front of retina in VH as eye is too long
What do you want to stop this happening
Bend rays of light less so focus on retina (use concave lens)
No accommodation
What are the symptoms of short sightedness
Close objects are clear but distant = hazy
May have headache
Divergent squint
How do you Rx
Biconcave lenses (minus lens)
Glasses
Laser eye surgery
What should you do if presents with divergent squint
Test for refractive error
What is long sightedness
Hypermetropia
What happens
Light focuses past retina as eye is too short
Distant objects will focus past but can accommodate
Can focus on far away objects as accommodate but as move closes the power is used up
Symptoms
Close up = hazy
Eye strain
Convergent squint
How do you Rx
Biconvex lens
Laser eye
What does convergent squint require
Immediate treatment to preserve vision and prevent a lazy eye
Wha is astigmatism
Non spherical curvature of cornea or lens so everything is hazy
How do you treat
Special glasses
Laser eye surgery
What is presbyopia
Long sightedness of old age as lens less mobile so can’t change shape
How do you treat
Biconvex glasses
What are causes of squint (strabismus) and what happens
Concomitant - imbalance of extra-ocular muscles = most common and occur in childhood
Paralytic = rare
Leads to diplopia
Brain copes by reducing signal from less dominant eye leading to a lazy eye
How do you Dx
Examination Refer ophthalmology Eye movement Fundoscopy to rule out retinoblastoma Visual acuity Corneal light reflexion test Cover test
How do you Rx
Eye patches over good eye to prevent ambylopia and encourage use of the squint eye
Refer 2 for surgery
What are risk of surgery
Diplopia
Slipped muscle
Over-correction
What are underlying issues
Usually idiopathic Cerebral palsy SOL - retinoblastoma Hydrocephalus Trauma
