Acute corneal pathology - keratitis Flashcards
list 5 things that you need to consider about a patient with a corneal disease
- Symptoms
- Careful history
- Anatomy of the cornea
- External factors
- Internal factors
Don’t consider the cornea in isolation
which 2 types of keratitis are there
- Infective
- Non-infective (‘arc’ eye, dry eye, toxins)
what causes recurrent corneal erosion syndrome
The epithelium is the fastest part of the body that repairs, but if the patient had a bad abrasion then it will keep coming back as the cornea never heals properly
what role does flourescein have in assessing dryness on the cornea
it works as an indicator and grows and shows the defects on the epithelial surface
what is rose bengal used to stain
degenerate cells
what is another word for dry eye
and list 4 things that can cause it
- superficial punctate keratitis
- UV exposure
- eye lid malposition
- Bell’s palsy
- post laser refractive surgery
list 6 common ocular infections that can be transmitted by clinical contact
- viral (intracellular organisms)
- chlamydial (half way between virus and bacteria)
- bacterial
- fungal
- acanthamoebic
- parasitic
which 2 serotypes is adeno virus conjunctivitis from
8 and 19
what is it called when the cornea is involved in adenovirus
what is the key feature of an adenovirus
- adenovirus keratoconjunctivitis
key feature
- follicles in the eyelid, when pull down or evert the top eyelid as they line the conjunctiva of the lids
what is the signs and symptoms of a adenovirus keratoconjunctivitis
will be in both eyes
- red
- watery
- pain
- cornea has white fluffy infiltrates
- follicles
- pseudomembrane
in adenovirus keratoconjunctivitis, where do the epidemic outbreaks occur how long is the incubation how long is it communicable for where is its portal of entry what are it's risk factors what is it associated with what may the keratitis affect and how long can it take to resolve
- epidemic outbreaks in closed communities
(EKC) - incubation: 5-12 days
- communicable: 10-14 days
- portal of entry: conjunctiva
- risk factors: crowding, ocular trauma
- associated with cold or influenza-like illness
(PCF) - keratitis/adeno spots in cornea may affect vision and take weeks or
months to resolve
what forms the follicles in an adenovirus and what do they look like
areas of lymphocytes/white blood cells, that accumulate to try and fight off the virus
white raised round areas
what is a pseudo membrane and where is it found (seen in adenovirus)
a fibrous sheet underneath the top lid which is very painful
what is the management of adenovirus keratoconjunctivitis
- avoidance of cross-infection (separate towels etc)
- no effective anti-viral
- topical antibiotic to prevent secondary bacterial infection (to stop getting bacterial conjunctivitis on top, use a broad spectrum antibiotic)
- topical steroid - severe conjunctivitis with pseudomembrane
- topical steroid if keratitis is painful or affects vision (to help with comfort, but does not fight the infection)
in how many patients is herpes simplex virus present in and in what form
in how many people have a recurrent clinical infection
- latent in 56-90% of the world’s population
- one third of all people have recurrent clinical infection
what is the 2 types of herpes simplex virus
- HSV-1 (saliva transmission - children and adolescents)
- HSV-2 (sexual transmission or via birth canal)
• in USA this sub-type has increased by 30% in 20
years!
• likely to be the result of changed patterns of sexual
behaviour)
in the latency period, where is HSV-1 located and where is HSV-2 located
what cannot be done about them
HSV-1: trigeminal ganglion (5th cranial
nerve)
- HSV-2: sacral nerve root ganglia (S2-S5)
- cannot be eradicated
- no satisfactory vaccine exists (to prevent primary infection)
list 6 things that can cause the reactivation of a latent herpes simplex virus
- fever
- trauma
- emotional stress
- sunlight
- menstruation
- laser refractive surgery
describe how a patient with HSV-1 can get a cold sore
HSV-1 cold sores is not contagious, but is always dormant in the body
these viruses live in the ganglion and when you get a cold, the virus has a chance to attack when the body is under stress
the virus comes down the ganglia and down the nerves and ends up on the lips
what type of infection is HSV type 1 virus
and give 4 signs of HSV-1
- primary infection
- blepharo-conjunctivitis
- cold sores
- follicular conjunctivitis
- pre-auricular nodes (PAN) - swollen lymph nodes infront of the ears
what type of infection is Herpes simplex keratitis
and list 4 signs seen
- Secondary infection (from flu or stress)
- Dendritic lesions (in epithelium)
- Disciform keratitis (stroma and endothelium involved)
- Anterior stromal scars
- Geographic lesions (ulcers)
how can dendritic ulcers be see on the eye of someone with herpes simplex keratitis
flourescein
what happens if a dendritic ulcer is not managed in herpes simplex keratitis
it turns into a geographic ulcer
what is a disciform keratitis seen i herpes simplex keratitis
- wrinkles/folds seen in descents membrane
- stroma and endothelium can get involved and px can get uveitis
- when theres endothelial damage and the stroma gets swollen and damaged = tear film looks rough
what is the appearance of extensive HSV scarring and why is it difficult to treat
- new blood vessels, superficial and deep coming in (scarring from a dendritic ulcer)
- very difficult to treat due to the BVs, so can’t do corneal transplant and the surface is also rough
what is herpes zoster virus know as
what is it caused by
in how much % of the population is it present in
where is the VZV vaccination available and how does it work and how much efficacy does it have
where does it lie when its dormant
- shingles
- caused by Varicella Zoster virus (“chicken-pox”)
- present in 20% of the population
- VZV vaccination available
routine only in Germany - aim is to infect children with a live attenuated VZV to
give immunity through a sub-clinical infection - disease prevention with 85-95% efficacy
- like Herpes Simplex virus, lies dormant in nerve roots
- posterior (dorsal) spinal and cranial sensory ganglia
- chicken pox virus also lives in the ganglia, especially sensory ganglia e.g. in CN5 trigeminal nerve. pairs of ganglia down spinal chord and when supplies the thorax and abdomen is in strips and the pair of nerves supplies sensation to the skin, so the attack of HSV later in life just affects that particular nerve, so px will have a single strip of rash which is painful and sore
what is herpes zoster keratitis an involvement of and what does it produce
how many % has corneal involvement
name 2 signs
- involvement of ophthalmic division of
trigeminal nerve produces typical (unilateral)
rash over skin of face and scalp - corneal involvement in 50% (nasociliary branch of V)
- ‘pseudo-dendrites’ of mucus disciform keratitis similar to HSK vascularisation with calcium deposition chronic ulceration / melting associated with uveitis
what can happen once a patient has had shingles/herpes zoster keratitis and is recovered and what is this called
px can still get pain, even when virus has gone
called post hepatic neuralgia (serious nerve pain)
which 3 eye conditions can chlamydial infections cause
- Adult inclusion conjunctivitis
- Neonatal conjunctivitis
- Trachoma
which subgroup and serotypes is adult inclusion conjunctivitis (chlamydial infection) from
how is it caught
what 2 ocular signs is seen with this
- sub group A
- serotypes D-K
- sexually transmitted (also ophthalmia neonatorum from birth canal)
- follicular conjunctivitis (follicles in upper and lower fornix)
- punctate keratitis
what is the management of inclusion conjunctivitis of chlamydial eye disease/infection
- topical drugs of the tetracycline family (cheap antibiotic can be used in 3rd world situation)
- NB screen for genital disease:
- Chlamydial
- Other
- systemic Rx needed if genital disease present
if the follicles in adult inclusion conjunctivitis (chlamydial eye disease) is not controlled, what can happen
it can cause aggressive scarring
what sub group and serotypes is the chlamydial eye disease - Trachoma
What is trachoma
In how many countries is this endemic
What does trachoma do to the eye
Sub-group A
Serotypes A-C
it is a chronic, potentially blinding disease resulting
from repeated infection
endemic in 55 countries (N Africa and South Asia)
84 million people in those countries have active trachoma
to the eye:
- follicular conjunctivitis, scarring leading to entropion
- Pannus / corneal scarring / vascularisation
- tear deficiency
- if chlamydia is bad enough, it can cause blindness
what is the management of the chlamydial eye disease - Trachoma
systemic azithromycin (Pfizer), followed by tetracycline eye ointment in persistent cases
corneal transplant is not possible in cases of pannus due to the BV’s present
name 4 types of bacterial organisms that can cause bacterial keratitis
- Staph. Aureus
- Strep. Pyogenes
- Strep. Pneumoniae
- Pseudomonas sp. (can lose their eye in 24 hours - a week)
list 6 symptoms of a bacterial keratitis
- pain
- blurred vision
- photophobia
- redness
- watering
- discharge, stickiness (accumulation of pus, px cannot open eye in the morning)
list all the internal and external predisposing factors of a microbial keratitis
External factors:
- contact lens wear
- trauma of any type (if bacteria gets inside epithelium, cannot get washed away)
- ocular surface disease
- corneal exposure
- corneal anaesthesia
- tear deficiency
- corneal decompensation
- viral infection (HSK)
Internal factors
Immune compromise :
- chronic inflammation of the ocular surface
- trachoma, Stevens-Johnson disease, etc. (serious systemic condition)
- corneal transplantation
- immune suppression
what signs can be seen in a microbial bacterial keratitis
- Hypopyon:
not just in the cornea, but now an infection inside the eye = can lose the eye
it is an enophthalmitis from the bacterial conjunctivitis - Corneal ulcer
- Bulge in descements membrane:
stroma is gone and epithelium, bowman’s membrane right down to descements membrane which is quite tough
what is used to manage the bacterial keratitis
Topical steroid use :
- in the course of therapy for inflammation
- inadvisedly, in steroid or steroid / antibiotic combinations
Only use if 100% sure of diagnosis, so take samples of ulcer first. so that in lab they can say which antibiotic to use
can samples the patient’s contact lens case and find the organism
which type of contact lens is most susceptible to causing a microbial keratitis
extended wear soft contact lenses
what is the progression of a fungal keratitis/candititis like
which types of eyes are susceptible to this
what is a sign of fungal keratitis
- it does not happen acutely, like bacterial keratitis but is more long term and happens slower
- occurs in eyes that are compromised e.g. a corneal graft
- it has linear fluffy edges to it = fungal hyphae, which goes into the cornea and branches out into the stroma
list al signs seen in acanthamoeba keratitis
- pseudo-dendrites
- infiltrates (white cells in the cornea)
- neuroradiitis (inflammation along the corneal nerves, nerves which are normally invisible are now visible)
- ring abscess
- end stage = vascularised cornea
- Ghost vessels
The eyes are extremely painful, but when you examine the eye, it doesnt look too bad e.g. its just mildly red and has a few infiltrates, but px is it a lot of pain
what is a marginal keratitis
what are the signs
what is it related to
how is it managed
- Inflammatory response to bacterial toxins on lids (px can have blepharitis, as toxins are causing an inflammatory reaction at the edge of the lid)
- Non-infective
- Accumulation / infiltration of white cells (around the edge of the cornea, towards the limbus)
- Epithelial defect / staining
- Related to contact lens wear
- Managed with combinations of topical steroid and antibiotics +/- lid hygiene
(e. g. chloramphenicol or emoxyprolin and with steroids, as primary thing here is inflammation)
list 4 ddx of Contact lens-associated superior limbic
keratoconjunctivitis (CLASLK)
- Theodore’s superior limbic keratoconjunctivitis
• cause unknown
• inflammatory change from mechanical soft tissue
microtrauma is the final common pathway
• associated with thyroid dysfunction - phlycten
- marginal keratitis / sterile peripheral ulcer
- Bowen’s disease
list 6 causes of corneal staining in CL wearers
- Mechanical
- Exposure
- Metabolic
- Toxic
- Allergic
- Infectious
list 6 things that can cause mechanical corneal staining in CL wearers
- lens defects
- poor lens finish
- lens binding
- excessive lens bearing
- FBs beneath lens
- abrasion during insertion or removal
list 3 things that can cause exposure staining in CL wearers
- inferior arcuate staining (CL decentres superiorly)
- central stain due to dehydration of thin, high-water
CLs - ‘3 and 9 o’clock’ staining in rigid corneal CL wearers
– disruption of tear film either side of lens, resulting in
drying
– often ‘4 and 8 o’clock’
what things that can cause toxic staining in CL wearers and what type of damage can this cause to the cornea
- preservatives - toxic to the epithelium
– chlorhexidine
– thiomersal (thimerosal)
– benzalkonium chloride - may bind to the lens surface prolonging contact time with the cornea
- possibility of corneal epithelial stem cell damage
- accidental administration of toxic substances
– cleaners
– hydrogen peroxide
what types of allergic staining can be caused by CL wearers
what can this be difficult to distinguish from
what can cause this type of allergic staining and which type of hypersensitivity
- immediate (Type 1) or delayed hypersensitivity (Type 4)
- may be difficult to distinguish from toxic reactions
- traditional solutions preservatives can all cause allergic reactions
- usually of the delayed hypersensitivity type
– chlorhexidine
– thiomersal (thimerosal)
– benzalkonium chloride - similar reactions seen in the long-term users of eye drops
– tear deficiency
– glaucoma
which types of corneal infections cause corneal staining
what can all of these be related to
corneal infections of all kinds can cause corneal staining – viral – bacterial – amoebic – fungal
- all can be contact lens related
- the staining pattern may point to the aetiology, but:
all can mimic each other
