Ophthalmology Flashcards
What are the chambers of the eye?
Anterior = cornea –> iris
Posterior = iris –> lens
Vitreous = lens –> back of eye
What is acute closed-angle glaucoma?
Angle of anterior chamber narrows acutely, causing sudden rise in IOP –> pupil becomes fixed and diated and axonal death occurs
How is aqueous humour produced and how does it normally drain?
- Produced by ciliary body into the posterior chamber, and flows through pupil into the anterior chamber
- Empties out via the drainage angle through the trabecular meshwork and through the canal of Schlemm into the aqueous veins
Predisposing factors to acute angle closure glaucoma?
- Shallow anterior chamber
- Thick lens
- Thin iris or ciliary bodies (e.g. pupil dilation at night)
- Hypermetropic eye (short axial eye length)
Primary and secondary angle closure?
Primary = occurs in patients with an anatomical predisposition
Secondary = Arises from pathological processes (e.g. traumatic haemorrhage pushing the posterior chamber forwards)
Peak incidence of acute angle closure?
40-60 years, more common in asia
What is open angle glaucoma?
Drainage system gradually becomes blocked –> outer rim atrophy of the optic nerve –> decreased peripheral vision then loss of central vision
Signs and symptoms of acute angle closure?
Symptoms
- Generally unwell; N+V
- Acute uniocular attack with headache and painful red eye,
- Blurred vision or haloes around lights at night
- Onset over hours-days
Signs
- Red eye; feels hard
Management of acute angle glaucoma?
General
- Examine visual fields, fundoscopy (nerve damage - “cupping”)
- Send IMMEDIATELY to eye unit for gonioscopy/tonometry
- Avoid eye patches or dark rooms (pupil dilation will worsen the angle closure)
Medical
- Beta-blockers (timolol) – suppresses aqueous humour production
- Acetazolamide IV (carbonic anhydrase inhibitor) – suppresses aqueous humour production
- Pilocarpine drops (cholinergic) – miosis will open up the drainage angle
- Analgesia/Antiemetics
Surgical
- Peripheral iridectomy (laser or surgery) – once IOP is controlled; a piece of iris is removed to allow aqueous to flow
What are cataracts? RIsk factors?
An opacity in the lens
- Age
- Genetic influence
- Occur early in DM
- Smoking, alcohol excess, sunlight exposure, trauma, radiotherapy, HIV
Symptoms of cataracts?
Blurred Vision
- If unilateral, often unnoticed, but loss of stereopsis affects distance judgement.
- If bilateral, gradual painless loss of vision +/- dazzle +/- monocular diplopia.
- Difficulty driving at night and haloes around street lamps.
How to diagnose a cataract?
Via retro-illumination of cataract using a handheld ophthalmoscope.
Management of cataracts?
Conservative
- Mydriatic drops or sunglasses –> if affecting lifestyle then surgery.
Surgical
- Day case using LA with small-incision surgery and pacoemulsion (breaks up the lens, then sucked out by cannula) + intraocular lens implant.
- Go home immediately, resume normal activities next day.
- Antibiotic + inflammatory drops for 3-6 weeks post-op
Risks of cataract surgery?
- 2% serious complications
- Dazzle/glare often remains
- Distance glasses often needed
Types of corneal ulcer?
- Bacterial
- Herpetic (dendritic)
- Fungal
- Protzoal
- Vasculitis (e.g. RA)
Presentation of corneal ulcer?
- Painful red eye
- Reduced visual acuity
- Photophobia
Pupil may be small due to reflexive miosis
Management of corneal ulcer?
General
- Refer to a specialist SAME DAY.
- Remove contact lenses
Medical
- Until culture results, alternate…
- Chloramphenicol drops (gram +ve)
- Ofloxacin drops (gram -ve) OR
- 0.3% cefuroxime and gentamicin drops
- Steroid drops once recovery starts.
What is this?
Hordeolum Externum (stye)
- Most common type
- Acute infection of lash follicle (in the skin) and always associated with
- Glands of Zeis (sebum-producing glands attached directly to lash follicles)
- Glands of Moll (sweat glands)
Second most common type of stye?
Hordeolum Internum
- Acute infection of a Meibomian gland situated within the tarsal plate.
- These point inwards, opening on conjunctiva.
- Causes less local reaction but leave a residual swelling (Chalazion) when they subside (treat with incision and curettage under LA
Presentation of a stye?
- Pain, redness and swelling of the lid margin. Whole of the lid may be affected.
- Swelling becomes localised, and a yellow, pus filled lesion may be seen near the lid margin (at the base of the effected eyelash) associated with an eyelid
- Localised tenderness on palpation of the eye lid
- Associated preseptal cellulites may be present
Management of a stye?
- Apply warm compress for 5-10 minutes several times each day until stye resolves.
- Topical antibiotic (fusidic acid) may prevent subsequent staphylococcal infection from a lash lower down
Types of conjunctivitis?
Non-Infectious
- Allergic (most common) - toxic, autoimmune, neoplastic
- Contact lens wearers may develop reaction
Infectious
- Non-herpetic viral (adenoviruses 80% - serous discharge)
- Bacterial (staphs, gonococcal - purulent discharge)
What is this?
Black Eye
- Result of a haematoma within the soft tissue of the eyelids. Spread may occur down over the cheek.
- It usually resolves within 14 days
What is this?
Subconjunctival Haemorrhage
- Bright red patch under the conjunctiva following rupture of a small conjunctival vessel.
- Spontaneous, slight trauma, or result of local congestion due to coughing or sneezing
- Definable margin absent if secondary to trauma since the bleeding extends backwards into the orbit.
- No discharge, painless, normal acuity.
What is this?
Hyphaema
- Haemorrhage into the anterior chamber resulting from damage to blood vessels in the iris
- Clotting does not readily occur in aqueous humour à fluid level
- Obscures vision and impairs fundosocpy
- Disperses within a few days – can cause glaucoma requiring surgical evacuation
What is this?
Corneal Abrasion
- Superficial injury to corneal epithelium à pain, lacrimation, photophobia +/- ↓acuity
- Can result from scratches from sharp objects, contact lenses, trauma, chemical injury or previous corneal disease
-
Fluorescein drops + blue light to aid diagnosis (corneal lesions stain green)
- Ask contact lens wearers if they sleep with lenses in and how they are changed
- Topical antibiotics to prevent infection
What is this?
Management?
Ectropion
- Lower lid eversion causing eye irritation, watering (drainage punctum malaligned) +/- exposure keratitis.
- Associated with old age and facial palsy.
- Management
- Plastic surgery
What is this?
Entropion
- Lid inturning; typically due to degeneration of lower lid fascial attachments and their muscles –> inturned eyelashes irritate the cornea
- Rare <40 yrs
Management
- Taping lower eyelids to cheek
- Botulinum toxin injection to lower lid
- Definitive management = surgery
What is blepharitis and how does it present?
Lid inflammation from staphs, seborrheic dermatitis or rosacea
- Eyes have burning itching red margins with scales on the lashes
Management
- Good eyelid hygeine
- Use cotton bud and baby shampoo diluted 1:10 with warm water and clean along lid margins 2x per day
Presentation of episcleritis?
- Acute onset
- Sclera look blue below a focal, cone-shaped wedge (thin edge towards pupil) or engorged vessels that can be moved over the area
- Dull ache; tender (especially over inflamed area)
- Acuity usually unaffected
Symptomatic relief - artifical tears, topical/systemic NSAIDs
What is scleritis?
- Generalised inflammation of the sclera itself with oedema of the conjuncitva, scleral thinning and vasculitic changes.
- 50% have systemic disease (RA, granulomatosis + polyangitis)
Presentation
- Constant severe dull ache which bores into the eye
- Ocular movements painful as muscles insert into sclera
- May present with headache and photophobia
- Engorged vessels can’t be moved over area as they are deeper
- Necrotising version can cause globe perforation
Differentials for red eye?
ACASES (3 serious, 3 not)
- Acute glaucoma
- Conjunctivitis
- Anterior uveitis (iritis)
- Scleritis
- Episcleritis
- Subconjunctival haemorrhage
What is injection?
Prominence of vessels
- Conjunctival
- Cilliary (iris)
Pull down eyelid to differentiate
Cover test for squint?
