Visual Loss Flashcards
What does myopia mean?
Near sightedness
What does hypermetropia mean?
Long sightedness
What does presbyopia mean?
Long sightedness due to loss of elasticity in eyes
What is the presentation of macular degeneration?
Gradual worsening central visual field loss
Reduced visual acuity
Crooked or wavy appearance to straight lines
Onset is more acute in wet macular degeneration
What is the pathophysiology of wet and dry macular degeneration?
Wet: neovascularisation growing from the choroid layer into the retina. these vessels can cause oedema and quicker vision loss. VEGF stimulates this.
Dry: atrophy of the neuro-retina, gradual loss of vision, drusen are present, changes in pigmentation of retinal epithelium
What are the features that are the same in wet and dry AMD?
Atrophy of retinal pigment epithelium
Degeneration of photoreceptors
Drusen present
What are the investigations of macular degeneration?
Examination: scotoma (patch of visual loss), Amsler grid test (shows distortion of straight lines), fundoscopy
Slit lamp fundus examination
Optical coherence tomography
What is the management of dry and wet macular degeneration?
Dry: stop smoking, control BP
Wet: anti-VEGF (-mab). Injected directly into vitreous chamber once a month.
What is diplopia? What are the causes of diplopia?
Double vision
Usually due to impaired extra ocular muscles
Binocular: squint (‘strabismus’ eyes pointing in different directions)
Monocular: astigmatism, dry eyes, cataracts
What causes pupil constriction?
Parasympathetic nervous system using ACh
Oculomotor nerve
What causes pupil dilation?
Sympathetic nervous system using adrenaline
Dilator muscles
What type of pupil is seen in migraines?
Tadpole pupil can be seen
How does a third nerve palsy present?
Ptosis
Dilated non reactive pupil
Down and out position of eye
What are the causes of a third nerve palsy?
With sparing of the pupil: diabetes, HTN, ischaemia
Without sparing of pupil: tumour, trauma, cavernous sinus thrombosis, raised ICP
What is Horner syndrome?
Ptosis
Miosis
Anhidrosis (loss of sweating)
Caused by damage of the sympathetic nervous system supplying the face
What are the causes of Horner Syndrome?
Central lesions: anhidrosis of arm, trunk and face (4S's) Stroke Multiple sclerosis Swelling (tumours) Syringomelia
Pre-ganglionic lesions: anhidrosis of the face (4T's) Tumour Trauma Thyroidectomy Top rib
Post-ganglionic lesions: no anhidrosis (4 C's) Carotid aneurysm Carotid artery dissection Cavernous sinus thrombosis Cluster headache
What is the management of Horner Syndrome?
Cocaine eye drops (stop noradrenalin uptake at NMJ)
Adrenaline eye drop
What is a Holmes-Adie pupil?
Unilateral dilated pupil
Sluggish to react to light
Slow dilatation following constriction
Damage to post ganglionic parasympathetic fibres
What is a Argyll-Roberston pupil?
Found in neurosyphilis
‘Accommodates but does not react’
Constricted pupil that focuses on a near object but does not react to light
What are the DVLA requirements for vision loss?
Bilateral glaucoma, retinitis pigmentosa, bilateral retinopathy = must inform the DVLA, can drive
Diplopia = must inform the DVLA, cannot drive
Colour blindness = do not have to inform the DVLA, can drive
What are the minimum requirements for driving under the DVLA?
Snellen chart: must at least be 6/12 in each eye
Higher standards for bus and lorry drivers.
What are the signs of papilloedema?
Loss of optic cup
Loss of venous pulsation
Blurring of optic disc margin
