RETINA - INFECTIOUS RETINOPATHIES Flashcards
what is histoplasmosis? what is the name of the species involved?
fungal infection caused by histoplasma capsulatum.
how does someone become infected w/ histoplasmosis?
typically infected by inhaling the fungus from bat or bird poop.
where is histoplasmosis most common?
Ohio & mississippi river valleys
symptoms of histoplasmosis?
- asymptomatic
- metamorphopsia if CNVM
signs of histoplasmosis (triad)?
- histo spots - multiple, small, yellow-white, punched out lesions.
- peripapillary atrophy (PPA)
- maculopathy (CNVM) - appears green/gray.
*** no vitritis or anterior uveitis!
w/u for histoplasmosis?
- Amsler grid to evaluate central vision.
- look for signs of CNV - IVFA confirms CNVM.
- DO FA/OCT.
tx for histoplasmosis?
- Anti-fungal tx is not helpful!
Tx aimed to control CNVM:
* Anti-VEGF – for subfoveal CNVM
* Focal laser photocoagulation – for extrafoveal CNVM
- F/U in pts w/out CNVM but macular changes – every 6 months.
- F/U in pts w/ no macular Dz – every 1 year
what is toxoplasmosis? what species causes it?
it a (protozoan) prasitic infetion caused by toxoplasma gondii.
how does someone become infected with toxoplasmosis?
caused by eating raw meat, exposure to cat feces or can be acquired or passed along in utero.
what are the 2 ways that toxoplasmosis can be acquired?
- congenital - exposure to cat feces by pregnant woman leads to fetal infection.
- acquired - most common in immunocompromised pt and most likely due to eating raw meat or unwashed produced.
Toxoplasma gondii can only complete its reproductive cyle in what organism?
cats
toxoplasmosis is the most common cause of what eye condition?
posterior uveitis
(it is necrotizing)!
symptoms of toxoplasmosis?
- active infection - unilateral: blurry vision + red eye + floaters + uveitis + vitritis
- inactive infection - asymptomatic
signs of toxoplasmosis?
Active/acquired case:
* present with fluffy yellow-white lesions with an overlying vitritis (headlights in the fog) - with no underlying chorioretinal scar b/c there hasn’t been enough time to scar.
Inactive/congenital:
* Sharply delineated singular macular chorioretinal scar.
* strabismic amblyopia
* nystagmus
Other ocular signs:
* cataracts
* anterior uveitis
* RD
* CNVM
* CME
can toxoplasmosis reacvtivate? how does it appear?
yes, appears as an active case: with fluffy white lesion next to past chorioretinal scar.
tx/managment for toxoplasmosis?
- active case - pyrimethamine, sulfadiazine, folinic acid, abx; azithromycin, clindamycin, bactrim, steroids; prednisone.
- refer to neurology to r/o encephalitis.
- no sub-conj or sub-tenon’s injections.
what is toxocariasis? what species is involved?
it is a parasitic infection causes by the roundworm Toxocara canis.
how can someone get toxocariasis?
Children typically infected by transfer of worm eggs via contact w/ dog feces or unwashed produce or undercooked meat.
symptoms of toxocariasis?
blurry vision
signs of toxocariasis?
white signs:
* endophthalmitis
* leukocoria - 2/2 macular dragging due to posterior pole granuloma.
other signs:
* chorioretinal scar
* RD
* vitritis or papilitis
w/u for toxocariasis?
Most helpful to confirm diagnosis:Toxocara (Enzyme-Linked Immunosorbent Assay) ELISA testing
tx for toxocariasis?
- inflammation - topical/oral/ sub-tenon steroid.
- RD - repaired with surgery
what is lyme dz? what species is involved?
bacterial infection caused by borrelia burgdorferi
how does someone get lyme dz?
organism is transmitted to humans through the bite of a tick that has fed on an infected animal, particularly a deer or rodent.
s/s of lyme dz
Signs and symptoms occur in 3 stages following the infectious event:
Stage 1: Early signs include a pathognomonic “bull’s eye” skin rash (typically within 3 to 30 days),
Stage 2: typically follows weeks to months after Stage 1, if left untreated. Significant ophthalmic signs usually first appear (late Stage 2 or early Stage 3), which include;
* unilateral or bilateral posterior uveitis
* papilledema,
* optic atrophy,
* optic neuritis.
* CN 7 palsy
Stage 3: The late stage of Lyme disease most commonly includes chronic Lyme arthritis of large joints
wha cranial nerve palsy is lyme dz associated with?
CN 7 palsy
w/u for lyme dz?
Do ELISA and western blot to confirm
tx for lyme dz?
- Lyme dz w/out neurological issues: Oral ABx – doxy 100mg po bid for 10-21 days.
- In children, pregnant woman, and others who cant take doxy –> amoxicillin 500mg po tid or azithromycin 500mg po daily.
- Lyme dz w/ neuro manifestations: IV ABx – ceftriaxone 2g IV daily for 2-3 wks.
- Some symptoms may go away w/ tx but some stay.
- F/U –> 1-3 days until improvement then weekly.
what is CMV? what species is involved?
- It is an opportunistic infection in those who are immunosuppressed (HIV).
- herpes virus
who gets cytomegalovirus?
those with CD4 counts of <50cell/mm3
signs of CMV?
- CMV retinitis - with overlying vitritis
tx for CMV?
- antiviral intravenous & intravitreal injections should be considered.
- oral antivirals if dz improves - ganciclovir / foscarnet / cidofovir
what is acute retinal necrosis (ARN) and progressive outer retinal necrosis sysmdrome (PORN)?
viral STD (herpes zoster) infection & only occur in immunocompromised pts.
ARN & PORN occur in patients with __?
HIV or other immunocompromised pts
symptoms of ARN & PORN?
- unilateral blurry vision
- floaters
signs of ARN?
will start unilateral –> 30% spread to other eye.
* peripheral areas of well-demarcated white necrosis –> will spread circumferentially around the peripheral retina (spares posterior pole until late dz).
* anterior granulomatous uveitis & vasculitis
* RD - in late stage
signs of PORN?
- 1st sign - minimal anterior uveitis & vitritis followed by yellow-white retinal infiltrates.
- 2nd sign - rapid full thickness necrosis w/ early involvment of the macula.
- 3rd sign (late) - RD
tx for ARN?
tx is aimed at sparing the other eye:
* IV antivirals + oral steroids to control inflammation.
* if unresponsive - intravitreal antiviral injections.
* for anterior uveitis - tx with topical steroid + cycloplegic
* for RD - surgically repair.
tx for PORN?
- Oral - valacyclovir & famciclovir.
- Intravenous - acyclovir, valacyclovir, famciclovir.
- Intravitreal - foscarnet, ganciclovir.
- inflammation - topical steroids
- retinal detachment - surgically
what is cysticercosis? what species is involved?
- it is a parasitic infection caused by cysticerus cellulosae.
how do you get cysticercosis?
by ingesting undercooked pork
symptoms of cysticercosis?
- progressive blurry vision
- VF defects
signs of cysticercosis?
- inflammatory retinal cysts - caused by larva in vitreous, sub-retina, anterior chamber, eyelids.
tx for cysticercosis?
- systemic (IV or oral) steroids.
- larva should be surgically removed (vitrectomy) or lasered
what is diffused unilateral subacute neuroretinitis? what species is involved?
- infection caused by 2 worms; ancylostoma cainum (dog hook worm) or baylisascaris procyonis (raccoon intestinal worm)
symptoms of unilateral subacute neuroretinitis?
- unilateral blurry vision
signs of unilateral subacute neuroretinitis
- PR outer segment destruction –> VF defects
- when the worm dies - retinal inflammation and scarring
- CR atrophy
- optic nerve pallor
tx for unilateral subacute neuroretinitis
- PRP against the worm
- systemic steroids for retinal inflammation.
