Ophthalmology Flashcards
Open angle glaucome Tx
MoA
1st line = latanoprost
2nd line = timolol
brinzolamide
Briminodine
1st line = latanoprost
- PG analogue
- increases uveoscleral outflow
2nd line = timolol
- avoid in asthmatics
- reduces aqueous production
- beta-blocker
brinzolamide
Briminodine
- reduces production and increases clearance
What investigation should you do in suspected orbital cellulitis?
The presence of signs indicating the possible involvement of extraocular muscles and fatty tissues within the orbit (proptosis and limited ocular movement) suggests that orbital cellulitis is more likely to be the diagnosis rather than preorbital cellulitis.
Where orbital cellulitis is suspected, a contrast enhanced-CT scan of the orbits, sinuses and brain should be considered to support the diagnosis and to search for possible complications such as abscess which may require surgical drainage.*
What does an OCT look at?
retina
What should you think of in:
- central field loss
- peripheral field loss
Macular degeneration is associated with central field loss
Primary open-angle glaucoma is associated with peripheral field loss
Age-related macular degeneration
most common cause of blindness in the UK.
Degeneration of the central retina (macula)
usually bilateral
degeneration of retinal photoreceptors that results in the formation of drusen - seen on fundoscopy and retinal photography.
Two forms:
Dry (90% of cases, geographic atrophy) macular degeneration: characterised by drusen - yellow round spots in Bruch’s membrane
Wet (10% of cases, exudative, neovascular) macular degeneration: characterised by choroidal neovascularisation. Leakage of serous fluid and blood can subsequently result in a rapid loss of vision. Carries worst prognosis
Recently there has been a move to a more updated classification:
early age-related macular degeneration (non-exudative, age-related maculopathy): drusen and alterations to the retinal pigment epithelium (RPE)
late age-related macular degeneration (neovascularisation, exudative)
Age-related macular degeneration (ARMD) is the commonest cause of visual loss in elderly persons in the developed world. It affects 30-50 million people worldwide.
Epidemiology
male to female ratio = 1:2
Average age of presentation = > 70 years of age
Risk factors
Advancing age - risk increases 3 fold for > 75 years, versus those aged 65-74.
Smoking - current smokers 2x as likely as non-smokers to have ARMD related visual loss, and ex-smokers have a slightly increased risk of developing the condition
Family history
First degree relatives of a sufferer of ARMD are thought to be four times more likely to inherit the condition.
Other: those associated with increased risk of ischaemic cardiovascular disease, such as hypertension, dyslipidaemia and diabetes mellitus.
Patients typically present with a subacute onset of visual loss with:
a reduction in visual acuity, particularly for near field objects
difficulties in dark adaptation with an overall deterioration in vision at night
fluctuations in visual disturbance which may vary significantly from day to day
they may also suffer from photopsia, (a perception of flickering or flashing lights), and glare around objects
Signs:
distortion of line perception may be noted on Amsler grid testing
fundoscopy reveals the presence of drusen, yellow areas of pigment deposition in the macular area, which may become confluent in late disease to form a macular scar.
in wet ARMD well demarcated red patches may be seen which represent intra-retinal or sub-retinal fluid leakage or haemorrhage.
Investigations:
slit-lamp microscopy is the initial investigation of choice, to identify any pigmentary, exudative or haemorrhagic changes affecting the retina which may identify the presence of ARMD. This is usually accompanied by colour fundus photography to provide a baseline against which changes can be identified over time.
fluorescein angiography is utilised if neovascular ARMD is suspected, as this can guide intervention with anti-VEGF therapy. This may be complemented with indocyanine green angiography to visualise any changes in the choroidal circulation.
ocular coherence tomography is used to visualise the retina in three dimensions, because it can reveal areas of disease which aren’t visible using microscopy alone.
Treatment:
the AREDS trial examined the treatment of dry ARMD in 3640 subjects. It showed that a combination of zinc with anti-oxidant vitamins A,C and E reduced progression of the disease by around one third. Patients with more extensive drusen seemed to benefit most from the intervention. Treatment is therefore recommended in patients with at least moderate category dry ARMD.
Vascular endothelial growth factor, (VEGF) is a potent mitogen and drives increased vascular permeability in patients with wet ARMD. A number of trials have shown that use of anti-VEGF agents can limit progression of wet ARMD and stabilise or reverse visual loss. Evidence suggests that they should be instituted within the first two months of diagnosis of wet ARMD if possible. Examples of anti-VEGF agents include ranibizumab, bevacizumab and pegaptanib,. The agents are usually administered by 4 weekly injection.
Laser photocoagulation does slow progression of ARMD where there is new vessel formation, although there is a risk of acute visual loss after treatment, which may be increased in patients with sub-foveal ARMD. For this reason anti-VEGF therapies are usually preferred.
Treatment of macular degeneration
what should you be aware of for supplements?
what supplements should be prescribed?
smokers take supplements without beta-carotene as this increases risk of lung cancer
High dose antioxidant and mineral supplementation Vitamin C 500mg Vitamine E 400U beta-carotene 15mg Zinc 80mg as zinc oxide Copper 2mg as cupric oxide
Which stage of diabetic retinopathy is neovascularisation seen in?
proliferative
Which is associated with which?
Acute angle closure glaucoma
Primary open angle glaucoma
hypermetropia
myopia
Acute angle closure glaucoma is associated with hypermetropia, where as primary open-angle glaucoma is associated with myopia
What are some causes of tunnel vision?
papilloedema glaucoma retinitis pigmentosa choroidoretinitis optic atrophy secondary to tabes dorsalis hysteria
A young man presents with an acute, painful red eye associated with photophobia and blurred vision. On examination the pupil is small and irregular
- anterior uveitis
Holmes-Adie pupil
Holmes-Adie pupil is a benign condition most commonly seen in women. It is one of the differentials of a dilated pupil.
Overview
unilateral in 80% of cases
dilated pupil
once the pupil has constricted it remains small for an abnormally long time
slowly reactive to accommodation but very poorly (if at all) to light
Holmes-Adie syndrome
association of Holmes-Adie pupil with absent ankle/knee reflexes
A man who has a history of syphilis presents with bilateral small, irregular pupils which respond to accomodation but not to light
Argyll-Robertson pupil
MoA of pilocarpine
muscarinic receptor agonist
Block blobs that moves with eye movement
vitreous haemorrhage
what should you consider in someone with flashes and floaters?
vitreous degeneration
