Presentation on theme: "Tropical Ophthalmology. Part Three of Three"— Presentation transcript:
1 Tropical Ophthalmology. Part Three of Three Dr. Steve WallerUniformed Services Universityof Health SciencesBethesda, Maryland, USA
2 Unusual tropical eye diseases Not commonly found in U.S., even in teaching hospitalsFive examples:atypical tuberculosis (TB)leprosymanzanillo keratopathyloa loa conjunctivitistarantula keratopathy
3 Atypical TB after LASIK or transplant, steroid gtts incidence resurgingLarge bacterial corneal ulcer with anterior chamber purulent hypopyongtts = eyedrops
4 Leprosy neurotrophic cornea entropion can have uveitis in lepromatous diseaseUpper left: inturned lashes (entropion) causing corneal scarringMiddle: classic ‘leonine facies’ with lid and facial droop from neuromuscular atrophyUpper right: insensate (neurotrophic) cornea with sterile ulcer from absence of blink reflex.Lower right: infection in neurotrophic eyeLepromatous is multi-bacillary form; tuberculoid is pauci-bacillary
5 Manzanillo tree sap keratopathy Manzanillo or “beach apple” treecommon to Caribbean, east coast of FloridaSap is milky latex vesicant known for delayeddermal effects; folk medicine for conjunctivitisAcute ocular effects first described in UStroops during WWIIOther natural blistering agents:cantharidine (beetle) – no known antidotepoison ivy/oakpodophyllum (mandrake root)
6 case seen in military hospital in San Antonio Scarring and fine vessels around peripheral cornea due to past manzanillo sap exposure. Not likely to progress or disable patient in future.
7 Vesicant toxicity to cornea Mustard gas: alkylationcrosslinks DNA and denatures proteinclinical effect:cornea edemaischemiasecondary meltor ulcerWorld War I scene, FranceMain toxicity in WWI France was pulmonary, with secondary pneumonia often fatal in pre-antibiotic era. Small number of English soldiers were blinded; vast majority recovered with no disability. Some rural areas of France were quarantined for decades after mustard exposure.
8 Loa loa: the “eye worm” Filarial nematode of West and Central Africa mango fly (Chrysops), bites at dawn/dusk20 million infected, >30% in hyperendemic areasadult worms live for 20 years, up to 60 mm longsubcutaneous orsubconjunctivalmigration“Calabar swelling”from allergicangioedema(named for easternNigeria seaport)Another reason to cover your arms and legs at dawn and dusk in the tropics!Photo shows sub-conjunctival adult worm in west African patient. Worm is active and movement is painful.Calabar is port in eastern Nigeria, ancient and tied to slave trade
9 Manifestations and life cycle pruritis, skin tracksfevermeningitislarvae travel invesselsmango fly stages1-4 years to mature
10 Prevention, Diagnosis, Treatment Prevention: avoid vector contact, apply insecticide to mango grovesDiagnosis: clinical or find microfilariae on Wright or Giemsa stains of daytime bloodTreatment: surgery, ivermectin*, albendazole*, mebendazole** off label useAll three medications are broad-spectrum antihelminthics, but there is no FDA recommendation in their product inserts for use in cases of loa loa opthalmic or systemic disease.
11 Excision of subconjunctival loa loa worm Left photo: adult excised from under conjunctiva under local anestesiaWorm is about 5 cm (2”) long
12 Tarantula keratopathy Uriticating hairs - dorsal abdomen‘Cloud’ of hairs easily rubbed off
13 diagnose by history of exposure and pain without inflammation fine barbedhairs in cornea,can migrate to retinaBarbed hairs make one-way trip into eye, can cause local inflammation in posterior segment of eye
14 Zoonotic eye diseases Preferred host is non-human Paratenic (dead-end) visit by parasite, but damage still done!Two examples:Toxocara vitreoretinopathyorbital myiasis
15 Ocular larva migrans (Toxocara canis or cati) Worldwide distributionRisk factor: exposure to canine/feline fecessandbox is infective up to one year after feces deposited
16 Toxocara life cycle adults in canine intestine fecal contact by human eggs hatch in GI tractmigrate in blood vesselsexits at end organbrain, eyeliverlungs
18 Myiasis Infestation of tissue or cavities by maggot (Diptera) Internal: subretinal migratory tracksExternal: lids or conjunctivaOrbital: debilitated patient, abscessTreatment is excision
19 Photo essay: anterior orbital myiasis caused by human botfly (Dermatobia hominis). Goodman RL, Montalvo MA, Reed JB, Scribbick FW, McHugh CP, Beatty RL, Aviles R.Arch Ophthalmol Jul;118(7):
20 Dermatobia hominisAKA human botfly, torsalo (Central America), ‘beef worm’ (Belize), ‘mosquito worm’Habitat: forests and river valleys in Latin America, imported to USAcase in Dallas County, TX, 2003Hosts: man, cattle, dogs, birds
21 Dermatobia hominis Life cycle of 3-4 months Female attaches eggs to a fly, mosquito, or (rarely) tick, who then transmit to egg to human host1mm ‘bot’ hatch, enter host at bitegrows over 6-12 weeks to 20 mmMature larvae exit furuncle opening, drops to ground, pupates for daysAdult does not eat, mates within one day, and lives only one week
22 Larva Furuncular myiasis: movement often observed within opening Two oral hooks at distal end, two dark respiratory ‘spiracles’near skin breakAdult fly: ½”, yellow,resembles a bee
23 Ophthalmomyiasis externa Treatment:Occlude breathing tube with beeswax, gum, ointment, fat, drop of nicotineExcisionSubretinal larva: argon laserReal Texas cowboys just spit a little chewin’ twobacky on the breathin’ hole….
24 Iatrogenic Diseases Rabies in corneal transplant Most recent case - Iran, 19968 reported cases (one US case in 1979)implications for regulation and eye banking in developed and developing worldIn November 2011, I could only find 8 reported cases of transplanted rabies in literature. Oregon case from 1979, France 1980, Thailand 1981, India 1990’s and Iran 1996.
25 Acanthamoeba Keratitis Ubiquitous, warm waterHomemade contact lens solutions and hot tubsChronic pain and ulcerMedications (all off label use): Brolene (0.1% propamidine), PHBG 0.02% , neomycin, miconazole, othersPhoto: Esmeraldas province, EcuadorBrolene not available in US, except from CDC on humanitarian need basis. PHBG (polyhexabiguanide) is a swimming pool cleaning chemical, both though an appropriate pool store and filtered/diluted for ophthalmic use. Neomycin and miconazole are diluted forms of IV solutions. None of these medications has FDA product insert recommendation for use in amoebic keratitis.
26 trophozoiteand cystUpper left is schematic of active form (trophozoite) and cysts; lower left is electron microscope photo of cysts.Right hand photo shows trophozoites migrating across microbiology plate of non-nutrient agar and E. coli, the classic positive lab finding.
27 clinical appearanceUpper photo shows stromal infiltate in upper 2/3rds of cornea and adjacent scleral inflammationLower left photo shows classic ring infiltrate but no scleral involvementLower right photo shows post-op corneal transplant, enlarged nearly to sclera in effort to capture entire infection. Sutures and incision near sclera and its vascular supply greatly increase risk of transplant rejection.
28 Signs and symptoms radial keratoneuritis: infiltrate along radial cornealnervesAmoeba use nerves as ‘highway’ to migrate within stroma – apparent cause of pain and inflammatory neuritispain out of proportion to findingsparacentral ring infiltrateprior medical failure or diagnosis of HSV
29 Working Together International partnerships are key! Address the cultural gap in researchCommon understanding of diseaseCommon understanding of ‘science’
30 The good news Increasing access to eye surgery Inexpensive intraocular lenses now available worldwideIvermectin and the UN’s Onchocerciasis Control ProgramImproving nutritionIncreasing opportunities for service
31 Summary Epidemiology: still much needless suffering around the world Synergy: culture and diseaseEnvironment: protection is affordableExotics: rare but importantIatrogenics: preventableThe future is brightTaj Mahal from downriver
32 Questions? Sandanista monument in Managua Go to Part I of this lecture Go to Part I of this lectureGo to Part II of this lecture