anti-fungal and anti-protozoals

natacyn (5% natamycin suspension)

• MOA: binds sterols present in fungal cell membranes causing leakage and lysis

• greater effects on molds

• ocular side effects: conj hyperemia, chemosis

• dosed around the clock for 3-4 days, then 6-8 times a day for 2-3 weeks and then taper for 2 more weeks

• may need to treat for up to 8 wks

• steroids are contraindicated in fungal keratitis

Amphotericin B

• MOA: binds sterols present in fungal cell membranes causing leakage and lysis

• IV only

• better coverage against yeasts

• ocular side effects: yellowing of cornea, salmon patches on conj

nystatin

oral antifungal that binds sterols

oral antifungals that inhibit ergosterol synthesis

ketoconazole, fluconazole, voriconazole

voriconazole

DOC for systemic fungal infections

200 mg PO BID until 2 wks after resolution

signs of fungal keratitis

• large, single, central gray-white opacity with feathery borders (infiltrate beyond border of epi defect)

• satellite lesions

• also have: diffuse redness, mucopurulent discharge, anterior chamber reaction

• often misdiagnosed as bacterial on initial presentation

reasons for fungal keratitis

1. often secondary to trauma with vegetative matter

2. poor CL care hygiene (topping off)

3. systemically immunocompromised (disease or steroids)

presentation of acanthamoeba

• persistent red eye

• keratitis

• AC reaction

• photophobia

• Pain not consistent with signs

• ring infiltrate (later on in disease)

• often misdiagnosed as bacterial or herpetic

acanthamoeba

• free-living amoeba commonly found in water

• exists in two forms: trophozoite, cyst (can lie dormant and cause recurrence)

how to treat acanthamoeba

• treat concurrently with PHMB (0.02% polyhexamethylene biguanide) and 0.1% propamidine

• NSAIDS for pain, miltefosine (antiparasitic), voriconazole

• PK corneal transplant needed but will have to wait a really long time before done

what is toxoplasmosis?

a single celled parasite of cats that is transmitted to humans by ingestion or congenitally through placental blood supply

what does toxoplasmosis cause in the eye?

• retinochoroiditis (starts in retina and spreads to choroid and then vitreous causing vitritis) (headlight in the fog)

• #1 cause of posterior uveitis

• most frequent cause of infectious retinitis

• recurrence is common

when do we treat toxoplasmosis in the eye?

• any active lesion inside posterior pole

• any active lesion >1 DD in size

• significant vitritis (decrease in VA by 2 lines or more)

• no improvement in condition for 1 month

how to treat ocular toxoplasmosis?

classic triple therapy for 4-6 wks

• oral pyrimethamine and oral sulfadiazine (interupt folic acid synthesis)

• oral prednisone (at least 24 hrs after initiating antimicrobials)