1. Tropical Ophthalmology. Part One of Three
Dr. Steve Waller
Uniformed Services University
of Health Sciences
Bethesda, Maryland, USA

2. Author
ophthalmologist and global health faculty at Uniformed Services University of the Health Sciences, a US government school
US Air Force officer for over 30 years
taught and performed eye surgery in 16 countries
dedicated to reducing preventable blindness throughout the world

3. Overview of three lectures
Tropical Ophthalmology in
three parts: topically divided
Epidemiology of blindness: cataract (toxoplasmosis)
Synergy of diseases: vitamin A + measles, trachoma + bacterial keratitis, HIV + many diseases
Disease Control: EKC, oncho
Environmental: fungal keratitis, pterygium
Exotics: atypical TB, leprosy, beach apple, loa loa, tarantula
Zoonotics: toxocara, myiasis
Iatrogenic: rabies, acanthamoeba
Working together for a better world
Part one (first 30 slides) will be epidemiology (illustrated by cataract and by toxoplasmosis, which is often masked by cataract),
and diseases whose disability is sometimes worsened by synergy with a second disease.
Part two will be diseases that are gradually being controlled and diseases associated with environmental causes.
Part three will conclude with some ‘exotic’ diseases most often seen in the tropics, zoonotic diseases, and iatrogenic diseases more common in tropical conditions.

4. Epidemiology of Blindness
Blindness is a tropical disease!
Poor vision is #3 cause* of disability worldwide
Approximately 75% of global blindness is curable or preventable (US National Eye Institute, Nov 2006)
Top worldwide cause is cataract
India, China, Africa
Solution is efficient, accessible surgery
* Uncorrected refractive error big issue
Accessible cataract surgery and customized spectacles would both be huge steps forward in reducing needless visual disability worldwide.

5. Global Distribution of Blindness by Cause
Macular degeneration
Other
28 %
Diabetic retinopathy
Onchocerciasis
1 %
Glaucoma
14%
Cataract
42 %
Trachoma
15 %

6. State of Global Blindness
80% of blindness
is preventable
or curable
Present estimate:
45 million people blind +
135 million visually disabled
Low
Vision
Blind
< 6/18 - 3/60
< 3/60 (or 20/400)
6/18 is 20/60 equivalent vision. Note that screening does not attribute cause, which is often absence of glasses!
International classification ignores the burden of uncorrected refractive error

7. Prevalence of Blindness
90%+ live in
lower income
countries

8. Relationship between blindness and socio-economic status
Poverty
However - the link between prosperity
and health is not automatic -

9. National cataract surgical rates and corresponding GDP
Real GDP
per capita
($)
outliers
prove the
case! 
Most countries lie on the diagonal line, showing greater wealth leads to greater access to cataract surgery. However, the
data with arrows show that paradigm is imperfect! High volume surgery in low income India (lower arrow)
contrasts with low volume surgery in relatively better-off Russia. (upper arrow)
These differences are not due to differences in incidence of cataract. 
Cataract operations per million population per year

10. Cataract – ‘the #1 cause’
efficient, accessible surgery =
a huge impact on blindness

11. Toxoplasmosis Chrorioretinal scars hidden by cataract
Very common in developing world
Significant cause of strabismus (evil eye)
#1 cause (20%) of
reduced vision after
successful cataract
surgery in Central
American country in
our study, 2004
U.S. Air Force Mobile Ophthalmic Surgery Team.
Reilly CD, Waller SG, Flynn WJ, Montalvo MA, Ward JB. Mil Med Dec;169(12):952-7.

12. Toxoplasma gondii Intracellular protozoan Global distribution
Transmission:
Direct ingestion of oocyst
Uncooked meat
Mucosal inoculation
Transplacental
Cats are definitive host,
but infects all mammals
chart shows life cycle of parasite

13. Ocular Manifestations
Prominent vitritis
“headlight in the fog”
Necrotizing
retinochoroiditis
vitritis is inflammation of vitreous gel in posterior part of the eye

14. Toxoplasmosis
Clinical diagnosis with help from ELISA, Western blot, PCR
Negative serology argues against infection, but positive serology does not prove disease
Tx: sulfadiazine, pyrimethamine, Septra (off label), cryotherapy
Cover sandbox; don’t shake litter box
Freezing temperatures are not adequate – cysts survive in sand up to one year
No recommendation in FDA product insert for use of Septra in toxoplasmosis. Both sulfadiazine and pyrimethamine are recommended for treatment of toxo encephalitis.

15. Synergistic Diseases Sum is greater than individual parts
Etiology often cultural
and economic
Three examples:
Vitamin A + measles
trachoma + bacteria
HIV + many diseases

16. Vitamin A deficiency
a leading cause of preventable childhood blindness
associated with other deficiencies
first symptom - night blindness
scaly skin, dry eye, prone to ulcer
prompt response to 200,000 unit pill x 3
WHO classification on next slide

17. WHO classification XN – night blindness (easy to screen)
X1A – conjunctival xerosis
X1B – Bitot’s spot
X2 – corneal xerosis
X3A – keratomalacia and small ulcer
X3B – large ulcer
XS – corneal scar
XF – xerophthalmic fundus
Screening of villages can be done by visiting at dusk – children who have inadequate night vision will stop playing outdoors and go to hut early

18. Bitot spot: early sign, foamy appearance to conjunctiva
progression
of untreated
disease to
blindness
Upper photos: Bitot spot on conjunctiva, nasal and temporal exposed areas. Also note poor photo flash light reflection on right photo, due to poor tear film.
Lower series of photos show (clockwise from upper left): Bitot spot; exposure ulcer (with fluorescein stain); larger sterile ulcer from poor tear film and chronic dryness; end-stage central scar from healed infection

19. Vitamin A and measles
Vitamin A deficiency
greatly enhances measles virulence and
lethality

20. Trachoma
Chlamydia trachomatis, eye disease same strains as genital disease
Multiple infections, poor hygiene
Direct contact, children worst
Passed on hands and by flies
Upper lid scarring, lashes in-turned
Soap/water, TCN or erythro ung
Zithromycin helpful, temporarily
ung is ointment

21. Trachoma epidemiology
500 million people infected
Most common preventable blindness
2 million blind in endemic areas
North and sub-Sahara Africa
Middle East
North India
Southeast Asia
Infectious
(WHO ‘TF’ stage)

22. Clinical diagnosis of trachoma
at least two of the following:
lymphoid follicles on upper tarsal conjunctiva
typical conjunctival scarring (Arlt’s line)
limbal follicles or Herbert’s pits
vascular pannus

23. Conjunctival scarring (Arlt’s line )
Linear white scar across upper lid conjunctiva is called “Arlt’s line”
Upper photo shows more injection and active disease; lower photo shows chronic scarring 

24. chronic irritation setup for blinding bacterial keratitis
Chronic epithelial
defect from
misdirected
lashes
chronic irritation setup for blinding bacterial keratitis

25. Secondary bacterial infection

26. HIV eye disease
Most blinding opportunistic infections are chorio-retinal
cytomegalovirus (beta Herpes 5) - most common
toxoplasmosis, others
Kaposi’s sarcoma of conjunctiva
Corneal microsporidiosis (no photo)

27. Cotton wool spots of early HIV retinopathy; young patients with these findings in absence of diabetes, hypertension, or recent compressive event should be tested for HIV.
Cotton-wool spots

28. CMV “pizza pie” lesion involving macula and disc of right eye
CMV retinitis

29. Kaposi’s sarcoma inner canthus tumor
Conjunctival lesion at medial aspect of right eye
inner canthus tumor

30. see lecture parts two and three for more Tropical Ophthalmology
Kaposi’s
sarcoma
of nose
see lecture
parts two and
three for
more Tropical
Ophthalmology
Kaposi’s sarcoma in AIDS
Go to Part II of this lecture
Go to Part III of this lecture