Eye infections Flashcards
Why do pharmacists need to know about eye infections
They are a common presenting problem in primary care
Prompt diagnosis is essential with appropriate treatment
What happens in infectious conjunctivitis
Conjunctival (the barrier between the cornea and the environment) blood vessels dilate and lead to inflammation
Describe the structures of the eye
AT the front there is the conjunctiva which protects the cornea. Behind this is the iris, lens and cilliary muscle.
At the back of the eye there is a vitrious body (the globby bit) behind which is the retina and the sclera
Can a patient presenting with blurred vision, pain, photophobia or hyperpurulent discharge be treated in the pharmacy
No, they must be refered to an opthamologist urgently as these symptoms require specialist treatment
What sort of eye complaints can be treated in the pharmacy and what is the likely cause of each
- Mucopurulent discharge - bacterial conjunctivitis (non-gonococcal)
- Serous discharge without itching - viral conjunctivitis
- Serous discharge with itching/ just itching - allergic conjunctivitis
What is the most common cause of conjunctivitis
The most common cause is a virus (60-90%)
Adenovirus is the most common, herpes simplex or zoster can also cause it
Self limiting - the adaptive immune response will resolve it within 7-14 days
Adenovirus conjunctivitis is very contagious. Can be transmitted via fomites and can evade disinfection mechanisms
The virus can remain infectious whilst dessicated (dried)
How do we classify viruses
Using their nucleic acid
Adenovirus has a double stranded DNA nuclec acid structure
How can we treat adenovirus conjunctivitis
Nothing approved for adenovirus infection
Cidofivir inhibits DNA virus replication
Ribavirin is a broad spectrum anti-viral - these drugs may be used in immunocompromised patients
Supportive care and advice - this is usually a self limiting illness. Talk about hygiene
Which three types of bacteria cause bacterial conjunctivitis
Haemophilus influenzae (has nothing to do with flu!) gram neg
Streptococcus pneumoniae gram pos
Staphylococcus aureus gram pos
How do we treat bacterial conjunctivitis
Antibiotic eye-drops associated with improved remission
Broad-spectrum agent is recommended because gram pos and gram neg can be the causative agent
Chloramphenicol 0.5% drops for 7 days (for over 12s)
1% ointment for use at bedtime
Who is affected by gonococcal conjunctivitis
Neonates and sexually active young adults
It is, however, uncommon
This is a very serious infection. It can spread easily and if it makes its way to the brain it can cause bacterial meningitis
How do we treat gonococcal conjunctivitis
We would ideally obtain swabs and refer to ophthalmologist
We treat it with ceftriaxone therapy.
Who is at risk of developing chlamydial conjunctivitis
People who also have a genital chlamydial infection
What are the symptoms of chlamydial conjunctivitis
Conjunctival hyperaemia, discharge and lymphoid follicle formation
How do we treat chlamydial conjunctivitis
Immediate referral required as it can cause blindness
Azithromycin or Doxycycline treatment
What is infectious keratitis
An infection of the cornea (has surpassed the conjunctiva)
Its an emergency as it is a significant cause of blindness
What are the risk factors for infectious keratisis
Contact lenses (poor hygiene associated) Corneal abrasions/injury Chemical/physical trauma Diabetes Immunosuppressive disease Topical steroid use (can compromise the conjunctiva)
What are the causative agents of bacterial keratitis
- Staphylococcus aureus
- Coag. Negative Staphs
- Pseudomonas aeruginosa (contact lenses) Green colour and characteristic smell
What are the viruolence factors associated with the pseudomonas aeruginosa
- Resistant to disinfectants and antimicrobial agents (contact lense solution)
- Very good at adhering to plastic and itself (forms biofilms)
Virulence factors:
Pili (allows for adhesion)
Flagella (motile)
Protease production (break down proteins allowing them to aquire nutrients)
What are the signs and symptoms of bacterial keratitis
Pain Photophobia Decreased/Blurred vision Redness Discharge Corneal Infiltrates History of trauma/contact lense use/immunocompromised
How do we treat bacterial keratitis
Topical Antibiotics
Monotherapy with a fluoroquinolone eg. Ciprofloxacin. Stops bacterial dna from coiling - inhibits topoisomerase
Corneal grafting?
If suspect BK do not provide chloramphenicol (only works against minor infections)
What are some key points around herpes simplex keratitis
Important cause of infectious blindness
Can be recurrent
Check history regarding cold sores
What are some adverse effects of topical antibiotics
Systemic adverse effect - must be used accurately
Large volume of liquid drains out of the eye
Some adverse effects include skin irritation, itching or rash with sulfonamide, sulfacetamide and neomycin
Fluoroquinolones can cause local irritation, stinging, chemosis, conjunctival hyperaemia, corneal precipitations and alteration of taste
What are the formulation considerations for eyedrops
Must be approximate to tears to avoid irritation
Preservative if multi-dose is required (benzyl type)
Isotonicity
pH
Viscosity - needs to be failry viscous to ensure its absorbed and not run down the face
