Ophthalmology - Other Flashcards
What is the function of eyelids?
Prevent the eye from drying out.
Protect the eye from foreign bodies and excessive light.
What is the function of meibomian glands?
Modified sebaceous glands that produce the lipid outer layer of tear film.
What is blepharitis?
Inflammation of the eyelid, causing dry eye disease.
Aetiology of blepharitis.
Congestion and inflammation of eyelash follicles and meibomian glands.
Presentation of blepharitis.
Bilateral symptoms:
- ocular irritation
- foreign body sensation
- burning
- redness
- crusting
- watering of the eye
Treatment and prevention of blepharitis.
Lid hygiene:
- warm compression of eyelids
- eyelid massage
- cleaning eyelids with cotton wool
Topical antibiotic ointment can be applied to reduce bacterial colonisation.
Aetiology of a stye.
Staphylococcal infection of an eyelash follicle.
Presentation of a stye.
Tender, red eyelash follicle swelling.
Management of stye.
Often resolves spontaneously; encourage lid hygiene:
- warm compression of eyelids
- eyelid massage
- cleaning eyelids with cotton wool
Other treatments may include:
- removal of eyelash
- incisional drainage
- topical antibiotics
What is chalazion?
Granulomatous inflammatory lesion forming in an obstructed meibomian gland.
NOT infective.
Presentation of chalazion.
PAINLESS red eyelid cysts, in the internal eyelid.
Management of chalazion.
Often resolves spontaneously; encourage lid hygiene:
- warm compression of eyelids
- eyelid massage
- cleaning eyelids with cotton wool
What is entropion?
Age-related inward turning of the eyelid.
Inward-turning eyelashes may irritate the cornea, causing ulceration and risking sight loss.
Management of entropion.
- examination for corneal abrasion / keratitis
- frequent lubrication eyedrops
- referral to ophthalmology for surgical correction
What is ectropion?
Age-related outward turning of the eyelid*.
This causes a disruptive tear drainage, resulting in a sore and watery red eye.
*associated with CNVII palsy (Bell’s palsy)
Management of ectropion.
- lubricating eye drops
- taping the eyes shut
What is trichiasis?
Eyelashes grow inwards due to damage eyelash follicles, irritating the cornea:
- corneal ulceration (keratitis)
- sight loss
Management of trichiasis.
Often resolves spontaneously; encourage lid hygiene:
- warm compression of eyelids
- eyelid massage
- cleaning eyelids with cotton wool
Electrolysis or laser ablation can destroy the lash follicle and may provide a permanent solution.
What is the purpose of topical mydriatics?
Dilating eye drops to facilitate examination of the eye with an ophthalmoscope or slit lamp.
Which topical mydriatics are used most commonly?
Tropicamide and phenylephrine - dilatory effects wear off sooner.
What is the purpose of fluoresceine sodium 1% eyedrop?
Fluorescent dye applied in slit-lamp examination to allow visualisation of corneal defects.
What is the purpose of anaesthetic eyedrops?
- ophthalmic surgery
- intraocular pressure measurement (Goldmann applanation tonometer)
- examination of eye
What classes of medications are used to reduce intra-ocular pressure in the context of glaucoma?
- alpha agonists
- beta-blockers
- carbonic anhydrase inhibitors
- prostaglandin analogues
- cholinergics
Alpha agonist eye drops.
a) examples
b) MOA
c) side effects
a) iodipine
b) decrease production of aqueous humour in anterior chamber, reducing IOP.
c) headache; dry mouth; dry nose
Beta-blocker eye drops.
a) examples
b) MOA
c) side effects
a) timolol maleate
b) decrease production of aqueous humour in anterior chamber, reducing IOP.
c) hypotension; bradycardia; bronchospasm; reduced libido; depression
Contraindications to beta blocker eyedrops.
Bronchospasm: asthma; COPD
Bradycardia: heart failure
Carbonic anhydrase eye drops.
a) examples
b) MOA
c) side effects
a) acetazolamide
b) decrease production of aqueous humour in anterior chamber, reducing IOP.
c) paraesthesia
Prostaglandin analogue eye drops.
a) examples
b) MOA
c) side effects
a) latanoprost; bimatoprost
b) increase aqueous outflow of the eye, reducing IOP.
c) long eyelashes; hyperpigmentation
Cholinergic eye drops.
a) examples
b) MOA
c) side effects
a) pilocarpine
b) miosis stops crowding of trabecular meshwrok, opening the angle (used in AACG)
c) blurred vision; flushing
What is the role of artificial tear eyedrops?
Sooth burning, gritty sensation of the eye and associated blurring of vision.
Helps to keep the eye hydrated.
What is strabismus?
AKA squint.
Eyes do not properly align with each other when focusing to look at an object.
Causes of strabismus.
Primary:
- idiopathic
- congenital
Secondary:
- CN palsy
- intracranial infection
- space occupying lesion
- myopathies
- orbital fracture
Risk factors for strabismus.
- family history
- low birth weight
- prematurity
- maternal smoking
Red flags of strabismus.
- recent trauma
- symptoms of raised intracranial pressure
- new strabismus in school-age child
What is anisocoria?
Unequal size of pupils.
Causes of a constricted pupil.
- RAPD
- trauma
- Horner’s syndrome
- anterior uveitis
- pharmacological (opioids)
Causes of Horner’s syndrome.
- stroke
- MS
- Pancoast tumour
- thyroid mass
- cervical rib
- carotid artery dissection
- cavernous sinus thrombosis
- cluster headache
Patient presenting with an acute history of Horner’s syndrome, neck pain and dysphagia.
Urgent MRI to investigate for carotid artery dissection.
Causes of a dilated pupil.
- Aide’s pupil
- oculomotor nerve palsy
- pharmacological (atropine, MDMA, ecstacy, beta blockers)
What is Aide’s pupil?
A benign condition secondary to infection of the ciliary ganglion.
Results in a poor light reflex, and a slow accommodation reflex.
Features of thyroid eye disease.
NO SPECS
No signs or symptoms
Occular irritation (dryness, gritty)
Soft tissue involvement (conjunctival oedema, injection)
Proptosis
Extraocular muscle involvement
Corneal exposure
Sight loss
Laboratory investigations for thyroid eye disease.
- TFTs
- antibody testing (TSH-receptor antibodies, anti-TPO antibodies)
Imaging for thyroid eye disease.
- ultrasound scan (?extraocular muscle enlargement)
- CT orbit (?optic nerve involvement)
Management of thyroid eye disease.
In severe cases, steroids given to reduce inflammation and swelling.
Complications of thyroid eye disease.
-loss of sight
- eye popping out
- gaze abnormalities
- raised IOP
What is amblyopia?
Lazy eye - a reduction in visual acuity due to an insult in the visual pathway during the critical period of visual development.
What period is considered to be critical for visual development?
Birth to three months of age.
Visual development continues in some capacity until the age of 7.
Causes of amblyopia.
Ocular pathology (e.g. squint, high refractive error) interferes with normal cortical visual development.
This results in reduced visual acuity with no structural eye problem.
Management of amblyopia.
- eliminating obstacle to vision (e.g. cataracts)
- correcting refractive error
- forcing the use of the poorer eye (patching)
Complications of amblyopia.
Permanent reduced visual acuity.
Poor co-operation with patching is common; can give atropine eyedrops to weaken good eye.
