Ophthalmology Flashcards
(161 cards)
Define Acute closured angle glaucoma
A type of glaucoma characterised by the blockage or narrowing of the drainage angle formed by the cornea and the iris, resulting in a sudden increase intraocular pressure - primary ACAG = when the iris blocks the channel
Acute closure glaucoma risk factors
Hyperopia, age (lens grows w/ age and can push iris), Asian or Inuit ethnicity, pupillary dilatation (iatrogenic or due to being in a dark room)
Acute closure glaucoma features
- Sudden onset, acutely painful eye
- Blurred vision
- Haloes around lights
- N&V
- Red eye = ciliary flush w/ a hazy cornea
- Mid-dilated or fixed pupil
- Closed iridocorneal angle on gonioscopy
- Corneal oedema
- Raised intraocular pressure (>21) - globe may feel hard on palpation
Acute closure glaucoma investigations
- Gonioscopy to asses angle between iris and cornea
- Tonometry = measures IOP
- Examination of eye
Acute closure glaucoma management
IOP must be reduced ASAP to prevent further dmg to the ocular nerve and preserve vision:
- IOP-lowering agents = beta blockers, pilocarpine and IV acetazolamide
- IV mannitol if those don’t work (rare)
- Analgesia and antiemetics
Aim of medical management is to stabilise/reduce IOP whilst awaiting definitive surgical intervention:
- Peripheral iridotomy = laser used to make a hole in the peripheral iris to allow free flow of aqueous (contralateral eye also treated prophylactically)
- Surgical iridectomy = rarely used
Define Age-related macular degeneration
The degeneration of photoreceptors in the central retina (macula) that leads to the formation of drusen, which are visible on split-lamp biomicroscopy - can be dry or wet
Dry VS wet macular degeneration
Dry:
- 85-90% of cases
- Has drusen (yellow pigmented spots on retina) and macular thinning
- Slowly progresses over decades
Wet:
- 10-15% of cases
- Has neovascularisation, bleeding and leakage of fluid
- Rapidly progresses over months w/ poor prognosis
Age-related macular degeneration features
- Progressive loss of vision (worse for near and central vision)
- Variablitiy in visual disturbance from day to day
- Poor night vision
- Photopsia = perceived flickering of lights
- Glare
- Visual distortion (esp line perception = metamorphopsia)
Age-related macular degeneration investigations
- Slit-lamp biomicroscopy = allows identification of drusen or haemorrhages for diagnosis
- Colour fundus photography = done at each assessment to monitor progression
- Fluorescein angiography = used to identify neovascular ARMD to guide anti-VEGF therapy
- Ocular coherence tomography = allows assessment of all layers of the retina and identification of disease not visible of split-lamp
Age-related macular degeneration management
- Smocking cessation
- Dry = zinc, antioxidants, Vit A/C/E have been shown to reduce progression
- Wet = anti-VEGF injections to limit progression and even reduce vision loss (done monthly)
Define Amblyopia
AKA lazy eye - A developmental defect of cortical visual processing resulting from abnormal visual stimulation during early childhood, which leads to visual impairment - usually unilateral but can affect both eyes
Amblyopia causes
Any cause of reduced visual stimulation on 1 eye:
- Squints
- Unequal refractive error
- Congenital cataracts
- Tumours blocking the visual axis
Amblyopia features
- Blurred or cloudy vision
- Double vision
- Poor depth perception
- Eye fatigue
- Strabismus
Amblyopia management
Patch the good eye before the age of 8
Define Bacterial keratitis
A bacterial infection of the cornea, a common but sight-threatening ophthalmic emergency - often associated with minor trauma to the cornea, contact lens use or ocular surgery - most common bacteria in contact lens users = Pseudomonas
Bacterial keratitis features
- Pain
- Foreign body sensation
- Tearing/purulent discharge
- Red eye
- Corneal ulcers - may be visible w/ fluorescein staining
Bacterial keratitis investigation
- Emergency evaluation by ophthalmologist
- Corneal scrape to identify organisms = diagnostic
- Send contact lenses for culture
- Slit-lamp to assess cornea
Bacterial keratitis management
- Cessation of contact usage
- Topical (or sometimes oral) quinolones
- Cyclopentolate can be used for pain relief
Differentials for a tumour of the eyelid
- BCC = pearly sheen, rolled edges, ulcerative
- Squamous papilloma = papillary shaped w/ keratinised surface
- Seborrheic keratosis
- Sty
- Chalazion = initially painful but resolves to leave a non-tender lump
- Naevus = well-demarcated, pigmented lesion
- Xanthelasma = soft yellow lesion
- Molluscum contagiosum
- Hidrocystoma/cystadenoma = cystic lesions occurring due to blocked sweat glands
- Epidermoid cyst = inflamed/infected hair follicle
- Dacryocystitis = cystic lesion caused by blockage of the nasolacrimal gland
Define Blepharitis
A term that encompasses various conditions which cause chronic inflammation of he eyelid margin
Blepharitis causes
Staph infections, HSV or VZV infections, Meibomian gland dysfunction, seborrheic dermatitis or rosacea
Blepharitis features
Symptoms:
- Painful, gritty, itchy eyes
- Eyelids sticking together upon waking
- Dry eyes
- Symptoms associated w/ causative condition
Signs:
- Erythema of the eyelid margin
- Crusting or scaling at eyelid margin
- Visibly blocked Meibomian glands
Blepharitis management
Is a chronic condition w/ no cure - can be controlled:
- Lid hygiene at least twice a day
- Avoid contact usage during flare ups
Define Carotid cavernous fistula
An abnormal communication between the carotid artery and the cavernous sinus, leading to bleeding into the sinus - can be idiopathic or due to trauma (head injury, surgery, sinus thrombosis, aneurysm)