Contact lens wearer case Flashcards
A 25-year old female chinese student presents with a painful red eye to the eye casualty. What are 6 important questions to ask?
- When did the pain start?
- Has your vision been affected?
- Have you had any problems with your eyes in the past?
- Do you wear contact lenses?
- Have you showered or swam in your contact lenses?
What are 4 key things to examine in a patient who is 25, a contact lens wearer with a few days history of pain, blurred vision and wears contact lenses in the shower most mornings?
using slit lamp:
- Conjunctiva
- Cornea
- Anterior chamber
- Fluorescein staining of cornea
Examination of the 25 year old contact lens wearer shows a red and inflamed conjunctiva, a fluffy central opacity in the cornea, a collection of pus in the anterior chamber (hypopyon), and the central portion of the opacity stains with fluorescein (indicating overlying corneal epithelial defect). What is the likely diagnosis?
Microbial keratitis/ corneal ulcer
What are 4 organisms that can be responsible for microbial keratitis/ corneal ulcer?
- Bacteria
- Viruses
- Fungi
- Protozoa (especially acanthamoeba)
What is the differential diagnosis of a painful red eye? 4 things.
- Microbial keratitis (most likely due to central opacity, young patient, wears contact lenses)
- Uveitis
- Angle closure glaucoma
- Scleritis
What are 4 urgent investigations that would be performed in a patient with suspected microbial keratitis and corneal ulcer?
- Corneal scrape
- Gram stain
- Culture and sensitivity
- Question about contact lenses: do you wear them, what type (soft/ hard, monthly/ daily)
What does a corneal scrape involve?
Sterile scalpel blade used to scrape away some of infected corneal epithelim, then placed on microscope slides for gram staining and agar plates for culture
What are the three most common bacterial corneal pathogens?
- Pseudomonas species - gram negative
- Staphylococcus species - gram positive
- Streptococcus species - gram positive
Which type of bacteria do severe contact lens-related infections of the cornea tend to be
Gram negative, particularly pseudomonas species
What are the 3 most common fungal corneal pathogens (despite being rare in the UK)?
- Candida species (yeast like)
- Fusarium species (filamentous)
- Aspergillus species (filamentous)
What are 6 factors that predispose to bacterial keratitis?
- Contact lens wear (especially soft lenses worn over night, increased days of wear, poor hand/lens/storage hygiene)
- Ocular surface disease
- Ocular trauma or surgery
- Immune compromise
- Topical steroid se
- Lid margin infection (usually staphylococcal)
What are 7 symptoms of microbial keratitis?
- Pain, moderate to severe, acute onset, rapid progression
- Redness
- Photophoia
- Discharge
- Blurred vision (especially if lesion on visual axis)
- Awareness of white or yellow spot on cornea
- Usually unilateral
What are 6 signs of microbial keratitis?
- Lid oedema
- Epihpora
- Discharge (mucopurulent or purulent)
- Conjunctival hyperaemia and infiltration
- Corneal lesion usually single (central or mid-peripheral)
- Anterior chamber activity: flare, cells, hypopyon or coagulum if severe
What is the treatment for bacterial keratitis?
- Ophthalmic emergency & sight threatening: admit patient for intensive drop administration and regular examination by ophthalmologist every 12-24 hours
- Topical antibiotics: broad spectrum, usually dual therapy, although monotherapy used by some units
What type of broad spectrum antibiotic should be used for bacterial keratitis with gram positive organisms?
Cefuroxime
What type of broad spectrum antibiotic should be used for bacterial keratitis with gram negative organisms?
Ofloxacin
What regimen of antibiotics should be used to treat bacterial keratitis?
Intensive regimen to maintain high concentration: give drops intensively, usually every 30-60 minutes during the day and night for at least 48 hours
Why aren’t systemic antibiotics usually used for bacterial keratitis?
Poor bioavailability of systemic antibiotics in eye, high local concentration possible with intensive drops. Some oral antibiotics do penetrate the eye (e.g. ciprofloxacin) and may be useful if there is a risk of corneal perforation to prevent endophthalmitis
Should topical steroids be used in bacterial keratitis and why?
No - risk of immunosuppression initially; if used when there is active infection, will worsen condition and may even cause perforation of the cornea
What are 4 complications of a corneal ulcer?
- Loss of vision - even if appropriate antibiotics given and settles quickly
- Corneal perforation - if infection can’t be abated; can lead to endophthalmitis
- Endophthalmitis - if infection gets into globe
- Loss of eye - if there is endophthalmitis that fails to respond to treatment - scoop out contents of globe but leave sclera, aka evisceration of the globe
Why is endophthalmitis such as devastating complication of bacterial keratitis?
once microbe gains access to vitreous caivty, can continue unabated. Vitreous humour is clear and hence not vascularised so no blood vessels to recruit an immune response.
What is the treatment for endophthalmitis secondary to bacterial keratitis?
Urgent intravitreal antibiotics
Why can loss of the eye occur as a complication fo bacterial keratitis?
if infection progresses and there is endophthalmitis that fails to respond to treatment, eye may need to be removed. Usually done evisceration of the globe: scooping out the contents of the globe but leaving behind the sclera
Why could a patient’s vision still be poor even after successful treatment of bacterial keratitis?
Corneal scarring
What is the definitive treatment for corneal scarring following bacterial keratitis?
Corneal transplant: either full or partial thickness depending on level of scarring
