opthalmology Flashcards
Acute angle closure glaucoma:
1. Features
2. Investigations (2)
- Features of acute angle closure glaucoma:
- severe pain: may be ocular or headache
- decreased visual acuity
- symptoms worse with mydriasis (e.g. watching TV in a dark room)
- hard, red-eye
- haloes around lights
- semi-dilated non-reacting pupil
- corneal oedema results in dull or hazy cornea
- systemic upset may be seen, such as nausea and vomiting and even abdominal pain - Investigations:
1- tonometry to assess for elevated IOP
2- gonioscopy (literally looking, oscopy, at the angle, gonio): a special lens for the slit lamp that allows visualisation of the angle
Acute angle closure glaucoma- initial management
combination of eye drops, for example:
- a direct parasympathomimetic (e.g. pilocarpine, causes contraction of the ciliary muscle → opening the trabecular meshwork → increased outflow of the aqueous humour)
- a beta-blocker (e.g. timolol, decreases aqueous humour production)
- an alpha-2 agonist (e.g. apraclonidine, dual mechanism, decreasing aqueous humour production and increasing uveoscleral outflow)
- intravenous acetazolamide- reduces aqueous secretions
acute angle closure glaucoma- definitive management
the definitive management for this condition is a peripheral iridotomy to relief the intraocular pressure.
What is blepharitis?
1. causal mechanisms? (2)
2. Associated condition?
inflammation of the eyelid margins
- causal mechanisms:
- Posterior blepharitis (most common)- is due to meibomian gland dysfunction
- Anterior blepharitis - less common, is due to staph infection or seborrheic dermatitis - Associated with rosacea
Blepharitis
1. Features
2. Management (3)
- Features:
- usually bilateral
- grittiness and discomfort around eyelid margins
- eyelids may be sticky in the morning
- Swollen eyelids may be seen in staphylococcal blepharitis
- styes and chalazions are more common in patients with blepharitis
- there can be secondary conjunctivitis - Management:
1- softening of the lid margin using hot compresses twice a day
2- ‘lid hygiene’ - mechanical removal of the debris from lid margins
- cotton wool buds dipped in a mixture of cooled boiled water and baby shampoo is often used
- an alternative is sodium bicarbonate, a teaspoonful in a cup of cooled water that has recently been boiled
3- artificial tears may be given for symptom relief in people with dry eyes or an abnormal tear film
What is a cataract? what is the biggest risk factor?
A cataract is a common eye condition where the lens of the eye gradually opacifies i.e. becomes cloudy. This cloudiness makes it more difficult for light to reach the back of the eye (retina), thus causing reduced/blurred vision. Cataracts are the leading cause of curable blindness worldwide.
Ageing is the biggest risk factor- One study found that 30% of individuals aged 65 and over had a visually-impairing cataract in either one or both eyes
Cataracts:
1. Symptoms (4)
2. Sign
3. Investigations (2)
- Symptoms of a cataract:
1 - Reduced vision
2- Faded colour vision: making it more difficult to distinguish different colours
3- Glare: lights appear brighter than usual
4- Halos around lights - Sign: Defect in the red reflex: the red reflex is essentially the reddish-orange reflection seen through an ophthalmoscope when a light is shone on the retina. Cataracts will prevent light from getting to the retina, hence you see a defect in the red reflex.
- Investigations:
1- Ophthalmoscopy: done after pupil dilation. Findings: normal fundus and optic nerve
2- Slit-lamp examination. Findings: visible cataract
classification of cataracts (4)
1- Nuclear: change lens refractive index, common in old age
2- Polar: localized, commonly inherited, lie in the visual axis
3- Subcapsular: due to steroid use, just deep to the lens capsule, in the visual axis
4- Dot opacities: common in normal lenses, also seen in diabetes and myotonic dystrophy
management of cataracts:
1. Early disease
2. Definitive management
- Non-surgical: In the early stages, age-related cataracts can be managed conservatively by prescribing stronger glasses/contact lens, or by encouraging the use of brighter lighting. These options help optimise vision but do not actually slow down the progression of cataracts, therefore surgery will eventually be needed
- Surgery is the only definitive management of cataracts. This involves removing the cloudy lens and replacing this with an artificial one. Cataract surgery has a high success rate with 85-90% of patients achieving 6/12 corrected vision (on a Snellen chart) postoperatively.
central retinal vein occlusion- presentation
Fundoscopy signs? (2)
- sudden, painless reduction or loss of visual acuity, usually unilaterally
- fundoscopy shows (1) widespread hyperaemia and (2) severe retinal haemorrhages - ‘stormy sunset’
central retinal vein occlusion- management
- the majority of patients are managed conservatively
- indications for treatment in patients with CRVO include:
1. macular oedema - intravitreal anti-vascular endothelial growth factor (VEGF) agents
2. retinal neovascularization - laser photocoagulation
central retinal artery occlusion:
1. Causes
2. features (3)
3. Management/prognosis?
- Thromboembolism (e.g. from atherosclerosis) or arteritis (e.g. temporal arteritis)
- Features:
1- sudden, painless unilateral visual loss
2- relative afferent pupillary defect
3- ‘cherry red’ spot on a pale retina - Management is difficult and the prognosis is poor
any underlying conditions should be identified and treated (e.g. intravenous steroids for temporal arteritis)
if a patient presents acutely then Intraarterial thrombolysis may be attempted but currently, trials show mixed results.
What is chronic open angle glaucoma?
Chronic open angle glaucoma refers to optic neuropathy with the death of optic nerve fibres, with or without raised intraocular pressure (IOP). Glaucoma leads to characteristic visual field changes over time.
what is the difference between open angle glaucoma and angle closure glaucoma?
In open-angle, eye pressure builds gradually, but in closed-angle, it’s far more sudden. Open-angle glaucoma is not a medical emergency, but can cause vision issues over time; closed-angle is a medical emergency requiring immediate medical attention.9
fundoscopy signs of chronic open angle glaucoma (4) and finding on tonometry?
- Optic disc cupping - cup-to-disc ratio >0.7 (normal = 0.4-0.7), occurs as loss of disc substance makes optic cup widen and deepen
- Optic disc pallor - indicating optic atrophy
- Bayonetting of vessels - vessels have breaks as they disappear into the deep cup and re-appear at the base
- Additional features - Cup notching (usually inferior where vessels enter disc), Disc haemorrhages
- IOP > 24 mmHg as measured by Goldmann-type applanation tonometry
