Ophthalmology Flashcards
What is a cataract?
A common eye condition where the lens of the eye gradually opacifies (becomes cloudy)
What is the leading cause of curable blindness worldwide?
Cataracts
What is the main feature of cataracts?
Reduced/ blurred vision
This is due to the cloudiness which makes it more difficult for light to reach the back of the eye
What is the epidemiology of cataracts?
- More common in women
- Incidence increases with age
What is the most common cause of cataracts?
Normal ageing process
What are some of the other causes of cataracts?
- Smoking
- Increased alcohol consumption
- Trauma
- DM
- Long-term corticosteroids
- Radiation exposure
- Myotonic dystrophy
- Metabolic disorders: hypocalcaemia
What are the features of cataracts?
- Reduced vision
- Faded colour vision: more difficult to distinguish colours
- Glare: lights appear brighter than usual
- Halos around lights
What is the sign of cataracts on examination?
Defect in red reflex:
1. Red-reflex is the reddish-orange reflection when a light is shone on the retina by an ophthalmoscope
2. Cataracts prevent light from reaching the retina
3. Therefore there will be a defect in the red reflex
What are the investigations of cataracts?
- Ophthalmoscopy: (after pupil dilation) shows a normal fundus and optic nerve, defect in red reflex
- Slit-lamp examination: shows a visible cataract
What is the classification for cataracts?
- Nuclear: change lens refractive index, common in old age
- Polar: localized, commonly inherited, lie in the visual axis
- Subcapsular: due to steroid use, just deep to the lens capsule, in the visual axis
- Dot opacities: common in normal lenses, also seen in diabetes and myotonic dystrophy
What is the general management for cataracts?
- Conservative
- Surgical
What is the conservative management of cataracts?
- Prescribing stronger glasses/contact lens
- Encourage the use of brighter lighting
(these only help optimise vision rather than slow down progression, surgery will eventually be needed)
What is the surgical management of cataracts?
- Only effective treatment
- Removing the cloudy lens and replacing with an artificial one
- Patients should be advised on the use of eye drops and eyewear
What is the success rate of surgical management of cataracts?
High success rate with 85-90% of patients achieving 6/12 corrected vision (on a Snellen chart) postoperatively
What should the referral for surgical management for cataracts be dependent on?
- Whether a visual impairment is present
- Impact on quality of life
- Patient choice
What are some of the complications following surgical management of cataracts?
- Posterior capsule opacification: thickening of the lens capsule
- Retinal detachment
- Posterior capsule rupture
- Endophthalmitis: inflammation of aqueous and/or vitreous humour
What is central retinal artery occlusion?
A relatively rare cause of sudden unilateral visual loss
What are the two causes of central retinal artery occlusion?
- Thromboembolism: from atherosclerosis
- Arteritis e.g. temporal arteritis
What are the features of central retinal artery occlusion?
- Sudden, painless unilateral visual loss
- Relative afferent pupillary defect
- ‘cherry red’ spot on pale retina
What are the investigations for central retinal artery occlusion?
*ESR for temporal arteritis
1. Identification of classic symptoms: sudden painless visual loss on one side
2. Relative afferent pupillary defect on examination
3. Fundoscopy: ‘cherry red’ spot on the background of a pale retina which is indicative of retinal hypo perfusion
4. Imaging if suspecting thromboembolism? MR?
What is the management of central retinal artery occlusion?
- Identify and treat any underlying condition e.g. IV prednisolone for temporal arteritis
- If acute presentation, intra-arterial thrombolysis may be attempted
What is the main concern with managing central retinal artery occlusion?
Management is difficult and prognosis is poor
What is central retinal vein occlusion?
A cause for sudden painless loss of vision, usually unilaterally
What are the risk factors for central retinal vein occlusion?
- Increasing age
- Hypertension
- Cardiovascular disease
- Glaucoma
- Polycythaemia
What are the features of central retinal vein occlusion?
- Sudden painless reduction or loss of vision, usually unilaterally
- Fundoscopy findings: widespread hyperaemia, severe retinal haemorrhages - ‘stormy sunset’
What are the main differences in fundoscopy between central retinal vein and artery occlusion?
Artery occlusion: ‘cherry red’ spot on a pale (hypoxic) retina
Vein occlusion: widespread hyperaemia, severe retinal haemorrhages, ‘stormy sunset’
What is branch retinal vein occlusion (as opposed to central)?
- Occurs when a vein in the retinal venous system is occluded
- Thought to be due to a blockage of retinal veins at arteriovenous crossings
- Results in a more limited area of the funds being affected
What is the management of central retinal vein occlusion?
- Majority of patients managed conservatively
- Management includes intravitreal anti-vascular endothelial growth factor (VEGF) agents and laser photocoagulation
What is the indication for intravitreal anti-vascular endothelial growth factor management in central retinal vein occlusion?
Macular oedema
What is the indication for laser photocoagulation in the management of central retinal vein occlusion?
Retinal neovascularization
What are the most common causes of sudden, painless loss of vision?
- Ischaemic/ vascular (referred to as ‘amaurosis fugax’) e.g. TIA, central retinal artery/ vein occlusion
- Vitreous haemorrhage
- Retinal detachment
- Retinal migraine
Which is more common, central retinal artery occlusion or central retinal vein occlusion?
Central retinal vein occlusion
What is conjunctivitis?
Inflammation of the lining of the eyelids and eyeball
The most common eye problem presenting to primary care
What is conjunctivitis characterised by?
Sore, red eyes associated with a sticky discharge
What are the two types of conjunctivitis?
- Infective (bacterial and viral)
- Allergic
1What are the features of bacterial conjunctivitis?
- Purulent discharge
- Eyes may be ‘stuck together’ in the morning
What are the features of viral conjunctivitis?
- Serous discharge
- Recent URTI
- Preauricular lymph nodes
What are the investigations for infective conjunctivitis?
Usually clinical
Can consider:
1. Rapid adenovirus immunoassay- 2 visible lines equal positive
2. Cell culture/ Gram stain/ PCR- isolate viral or bacterial strains, amplify DNA
What is the management for infective conjunctivitis?
- Normally a self-limiting condition, should settle without treatment within 1-2 weeks
- Can offer chloramphenicol (topical antibiotics), given 2-3 hours initially
- Topical fusidic acid is an alternative, used for pregnancy women, BD
- For contact lens users:
a. Do not wear during the infection
b. Topical fluoresceins should be used to identify any corneal staining
c. Offer topical antibiotics e.g. chloramphenicol - Give advice to not share towels
- School exclusion is not necessary
What is allergic conjunctivitis?
Inflammation of the lining of the eyelids and eyeball in response to an irritant
Usually seen in the context of hayfever
What are the features of allergic conjunctivitis?
- Bilateral symptoms: conjunctival erythema, conjunctival swelling (chemosis)
- Itch is prominent
- Eyelids may be swollen
- PH of atopy
- May be seasonal (due to pollen) or perennial (due to dust mite, washing powder or other allergens)
What is the management of allergic conjunctivitis?
- First line = topical or systemic anti-histamines
- Topical mast-cell stabilisers e.g. Sodium cromoglicate and nedocromil
What is atopy?
IgE mediated atopic conditions:
1. Asthma
2. Allergic dermatitis e.g. eczema
3. Allergic rhinitis e.g. hay fever
What is glaucoma?
A group of disorders characterised by optic neuropathy due to raised intraocular pressure
What are the different types of glaucoma?
- Acute closed-angle glaucoma
- Primary opened-angle glaucoma
- Chronic closed-angle glaucoma
What are some of the secondary causes of glaucoma?
- Trauma
- Uveitis
- Steroid use
- Rubeosis iridis: DM, central retinal vein occlusion
- Congenital e.g. Buphthalmos: enlargement of the eyelid
What is the uvea?
- The vascular coat of the eyeball
- Lies between the sclera and retina
- Composed of 3 parts:
a. Iris
b. Ciliary body
c. Choroid
What is the anterior chamber?
The area between the cornea and lens, filled with clear aqueous fluid which is nutrient-rich
What is the role of the ciliary body?
To secrete aqueous fluid into the anterior chamber
What structure drains the aqueous fluid out of the eye?
Trabecular meshwork through the canal of Schlemm
What is the normal intraocular pressure?
12-21 mmHg
What is acute angle-closure glaucoma (AACG)?
A type of glaucoma where there is a rise in IOP secondary due to an impairment in the aqueous fluid outflow (trabecular meshwork dysfunction)
What are the factors that predisposed to acute angle-closure glaucoma (AACG)?
- Hypermetropia (long-sightedness)
- Pupillary dilatation
- Lens growth associated with age
What are the features of acute angle-closure glaucoma (AACG)?
- Severe pain: either 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 leads to dull or hazy cornea
- Systemic upset e.g. nausea, vomiting, abdominal pain
What is the management for acute angle-closure glaucoma (AACG)?
EMERGENCY - urgent referral to ophthalmology
Emergency medical treatment is required to lower the IOP with more definitive surgical treatment once the acute attack has settled
What is the initial medical treatment used in the management of acute angle closure glaucoma (AACG)?
- Combination of eyedrops:
a. Direct parasympathomimetic e.g. pilocarpine, opens the trabecular meshwork therefore allowing drainage of the aqueous humour
b. Beta-blocker e.g. timolol, decreases aqueous humour production
c. alpha-2- agonist e.g. apraclonidine, decreases aqueous humour production and increases outflow - IV acetazolamide: reduces aqueous secretions
What is the definitive surgical management for acute angle-closure glaucoma (AACG)?
Laser peripheral irirdotomy
Creates a tiny hole in the peripheral iris which drains the aqueous humour (alternative drainage pathway)
What is the cause of acute angle-closure glaucoma?
Rise in IOP due to an impairment in the aqueous humour outflow/ drainage
What is primary open-angle glaucoma (POAG)?
An insidious onset of optic neuropathy due to raised IOP, usually detected on routine optometry
What are the risk factors for primary open-angle glaucoma (POAG)?
- Increasing age
- Genetics
- Afro-Carribean ethnicity
- Myopia
- Hypertension
- DM
- Corticosteroids
What are the features of primary open angle glaucoma (POAG)?
Often symptomatic and detected during routine optometry appointments:
1. Peripheral visual field loss: nasal scotomas progressing to ‘tunnel vision’
2. Decreased visual acuity
3. Optic disc cupping
What are the signs of primary open-angle glaucoma (POAG) on fundoscopy?
- Optic disc cupping (due to loss of disc substance), cup: disc ratio > 0.7
- Optic disc pallor: due to atrophy
- Bayonetting of vessels: disappear into the deep optic disc cup and re-appear at the base
- Additional features: cup notching (where vessels enter disc inferiorly), disc haemorrhages
How is the diagnosis of primary open-angle glaucoma (POAG) made?
- Found and provisionally made by optometrist
- Referred to ophthalmology via GP who carry out a set of investigations
What are the investigations for primary open-angle glaucoma (POAG)?
- Automated perimetry: assess visual fields
- Slit lamp examination with pupil dilation: assess optic nerve and fundus
- Application tonometry: measure IOP
- Central corneal thickness measurement
- Gonioscopy: assess peripheral anterior chamber configuration and depth
Using this and risk factors, assess risk of future visual impairment
What is are the two main differences between acute angle-closure and primary open-angle glaucoma (AACG vs POAG)?
- Trabecular meshwork dysfunction: in AACG there is an impairment in aqueous outflow due to this leading to rise in IOP
- Features: AACG is an acute presentation of painful red eye, impaired vision and haloes around eyes. In POAG, often asymptomatic with a slow rise in IOP causing peripheral visual field loss and optic disc cupping
What is the management of primary open-angle glaucoma (POAG)?
- First line: prostaglandin analogue eyedrops
- Second: beta blocker, carbonic anhydrase inhibitor or sympathomimetic eyedrop
- If more advanced, surgery or laser treatment can be tried
What is the aim of eyedrops in the management of primary open-angle glaucoma (POAG)?
Aim to lower the IOP which in turn prevents progressive loss of visual fields
What is the surgical management of primary open-angle glaucoma (POAG)?
Trabeculectomy- similar surgery to AACG to create a new pathway for aqueous humour drainage
What is an important consideration in the management of primary open-angle glaucoma?
Reassessment:
1. To exclude progression and visual field loss
2. Needs to be more frequent if IOP uncontrolled or if the patient is high risk
What is a raised IOP?
> 24 mmHG