Transcript Tropical Ophthalmology. Part II.

Tropical Ophthalmology
Part Two of Three
Dr. Steve Waller
Uniformed Services
University
of Health Sciences
Bethesda, Maryland, USA
[email protected]
Overview of part 2
• Epidemic keratoconjunctivitis
• onchocerciasis
• fungal keratitis
• pterygium
Epidemic Keratoconjunctivitis:
a lesson in disease control
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Periodic pandemics (“Apollo 11 disease”)
adenovirus 5,8,19,37 – “Shipyard fever”
adeno 3,4,7 and enterovirus 70 = AHC
Hands, swim pools, eye examinations
Acute pink eye, preauricular lymph node
Sunglasses, tears, handwashing
Quarantine, soap, gloves
large occupational impact
sign directing patients away from hospital
toward tent clinic during epidemic at US
military base in the Philippines in 1987
• the EKC tent =‘no-touch’ exam (Q-tips)
• double-masked, controlled trial of
medications done
Quarantine
dorm and
chow hall
provided to
all military
patients
conjunctival
follicles
• Sub-epithelial
infiltrates
limit return to duty
decisions
– grounded
navigator story
Onchocerciasis:
“River Blindness”
• 90% in Africa,
foci in W. Hemisphere
• Infectious for 10-15 years
• Simulium fly blood meal
• Subcutaneous nodules
• Skin snips, slit lamp
• Prevention best - same as malaria
• Ivermectin reduces larval load for 6 mos
Onchocerciasis
• Filarial nematode disease of the tropics:
34 countries in Africa and Latin America
• 18 million infected, 2 million blind
• Blindness >15% in hyperendemic areas
of Africa in ages >40
• Prophylaxis: avoid vector, dawn/dusk
• Migrations to/from fertile riverside in
West Africa for generations
• Ivermectin vs. DDT failure in Kenya
endemic areas in Latin America
River Blindness
Black fly (Simulium)
vector eggs
require fast-flowing
(oxygenated) stream,
often found near base
of mountains; can range
up to 1 mile (farther if
blown by a storm). Ingests
immature (L1) larvae
when it bites human,
transmits mature (L3)
larvae on later bite.
Adults form the nodule.
Lifecycle
Subcutaneous
nodule
Lymphatic
obstruction,
“Lizard skin”
nodules
and
contents
Diagnosis by skin snip
taking skin
specimen
does not
draw blood
microscopic view
of unsheathed
microfilariae in skin
Diagnosis by eye exam
Head down for 2 min
before slit lamp exam
scars in
cornea leads
to blindness
Chorioretinal disease
- can resemble diabetic retinopathy
or retinitis pigmentosa
Onchocerciasis
• A success story!
• Ivermectin given
free to WHO for
distribution
Oncho Control Program
declared victory in 11
West African countries
in Dec 02; 19 remaining
endemic countries
Fungal Keratitis
• Rural tropics, work-related
• “Vegetable matter” trauma
• Natamycin (only FDA
approved drug for years)
• Itraconazole 200 mg pill
into 5 cc saline*
• Betadine 2½%*
• Recent contact lens solution
‘epidemic’ (Fusarium)
* Off label use
“satellite”
lesions
are common
traits of
presenting
fungal
corneal
infections
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Perforation may
speed up
healing!
Glue applied
- can graft later
Eye usually lost if
abscess reaches sclera
Pterygium
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Etiology: sun (direct/reflected), wind, dryness
Geography: tropical, seaside, desert
Aggressive in young adult patients
Management key: ‘do no harm’
– sunglasses/hats, surgery, cab for tractors!
Relative
risks
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Never wear a hat – 2x
No sunglasses or spectacles – 9x
Sandy, outdoor work – 11x
Lives within 30 degrees of equator – 44x
Treatment can
be worse than
disease: upper
photo shows
aggressive
recurrence; lower
photo shows melt
of sclera after
use of mitomycin