Eye Infections Flashcards
Immune privilege factors of the eye
- lack of lymph vessels and blood vessels
- No MHC 1 expression by coronal endothelial and retinal cells
- Increased expression of the FAS ligand
- Increased induction of suppressive T-cells
- Increased tolerance to antigens in the aqueous humor of the eye
- in the eye this is called anterior chamber-associated immune deviation (ACAID)
What are the most common causes of conjunctivitis (pink eye)?
- Adenovirus is most common
- HSV-1 (causes corneal lesions and ulcers)
- enterovirus/coxsackievirus (causes acute hemorrhagic conjunctivitis)
- neisseria gonorrhoeae (causes newborn pink eye a lot)
- Staph, GBS, s. Pneumoniae (causes eyelid infections in conjunction)
General rules for determining viral or bacterial causes of conjunctivitis in the world
Viral
- more common in older than 12 yrs old
- less pus (Purulent)
- more itchy, burning and watery discharge is often present
- more lymphadenopathy and chance or hemorrhages
Bacterial
- more common in younger than 12 yrs old
- more pus (Purulent)
- more redness and mucus discharge
general rules, not firm
What is to note about using corticosteroids in conjunctivitis?
Alleviates symptoms but will prolong the duration of the infection
- limit is immune response and activity
Specifics for adenovirus conjunctivitis
Can cause follicular conjunctivitis (little spots on the eyelid
Can cause pharyngoconjunctival fever (PCF)
Serotype 9/19/37 can cause epidemic keratoconjunctivis
- severe flu like symptoms with sub epithelial corneal infiltrates of lymphocytes
- can be really bad and cause blindness
What can cause subconjunctival hemorrhages
Coxsackie/enterovirus/adenovirus
- is rare but almost always viral
Acute and painful onset
Usually self-limiting (5-7 days)
- can be spread easily though
- must also monitor though, because if it doesn’t self-limit, can cause polio like illness
Highest risk in 10-15 yrs old
Ophthalmia neonaturom
Neonatal severe Purulent conjunctivitis that is caused by transmission of the the following STDs:
- neisseria gonorrhoeae
- chlamydia trachomatis
Chlamydia specific
- 5-14 days after birth (not immediate)
- can be unilateral or bilateral
- 15% chance of causes dangerous pneumonia
Gonorrhea specific
- 1-2 days after both (immediate)
- almost always bilateral
- is penicillin resist (must use ceftriaxone)
Trachoma
*globally the most important eye infection (not in US though)
Essential adult form of chlamydia specific conjunctivitis
Is dangerous because it causes scaring of the eyelid and eyelashes as well as folding of the eye lid
- this causes small scratches over time on the cornea and can lead to blindness
Is often chronic and repetitive
- is prevented by clean water face washing (hence why its rare in the US, but endemic to poor nations)
What nerve does herpes use to cause keratitis?
Trigeminal nerve and all its branches
- lies dormant until active, then travels along the nerve to the eye
Types of keratitis other than herpes/virus
Bacterial keratitis
- rare unless breach of corneal epithelium
- dangerous and can cause blindness easily
- often is pseudomonas aeruginosa especially in contact lens users who dont refresh lens cleaning fluid
Fungal keratitis
- very rare and usually in immunocompromised/HIV patients
Amoebic keratitis
- only really susceptible if all other types are ruled out or treatments aren’t working
Orbital cellulitis
Is usually caused by staph/strep and is an acute infection of tissues surrounding the eye
* 90% of all cases are preceded by sinusitis (almost all that aren’t are caused by MRSA)*
Blephartis
Infection of the eyelids and eyelids that leaves a feeling of gritty ness, burning and foreign body sensation
Eyelashes can fall out (madarosis)
Most common organisms are:
- staph
- HSV
- VZV (varicella)
- molluscum cantagiosum
- can also be caused by follicle mites and lice, but rare*
** if pubic lice on a child, this is child abuse**
Styes (hordeolums)
External = gland of Zeis
Internal = meibomian gland
Are painful except in the case of a chalazion stye.
- are granulomas within the meibomian gland not just infections
Toxoplasmosis in eye infections
Causes chorioretinitis in neonates which leads to blindness
- doesnt affect mom but does damage child
Pregnant women are not suppose to change cat litter for this
Toxocara canis eye infections
Parasitic worm that causes intense eosinophilic inflammatory response
Leads to:
- retinal detachment and granulomas
- traction bands
- posterior uveitis
- only treated via surgery or mass anti-parasitic drugs*
