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Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuh

Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA [email protected]

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Page 1: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Tropical

Ophthalmology. Part One of Three

Dr. Steve WallerUniformed Services

University

of Health Sciences

Bethesda, Maryland, USA

[email protected]

Page 2: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

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

Page 3: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Overview ofthree 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

Page 4: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

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

Page 5: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Global Distribution of Blindness by Cause

Cataract42 %

Trachoma15 %

Glaucoma14%

Onchocerciasis1 %

Other28 %

Macular degenerationDiabetic retinopathy

Page 6: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

State of Global Blindness

Present estimate:

– 45 million people blind

+

– 135 million visually disabled

LowVision

BlindBlind< 6/18 - 3/60 < 3/60 (or 20/400)

International classification ignores the burden of uncorrected refractive errorInternational classification ignores the burden of uncorrected refractive error

80% of blindnessis preventableor curable

Page 7: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Prevalence of Blindness

90%+ live in90%+ live inlower incomelower income

countriescountries

Page 8: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Relationship between blindness and socio-economic status

Blindness Poverty

However - the link between prosperityand health is not automatic -

Page 9: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

National cataract surgical ratesand corresponding GDP

0

5,000

10,000

15,000

20,000

25,000

30,000

0 1,000 2,000 3,000 4,000 5,000 6,000

Cataract operations per million population per year

Real GDPper capita

($)

outliersprove thecase!

Page 10: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Cataract – ‘the #1 cause’

efficient, accessible surgery = a huge impact on blindness

Page 11: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

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

Page 12: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Toxoplasma gondii

• Intracellular protozoan• Global distribution• Transmission:

– Direct ingestion of oocyst• Uncooked meat• Mucosal inoculation

– Transplacental• Cats are definitive host,

but infects all mammals

Page 13: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Ocular Manifestations

• Prominent vitritis

“headlight in the fog”

• Necrotizing

retinochoroiditis

Page 14: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

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

Page 15: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Synergistic Diseases• Sum is greater than

individual parts• Etiology often cultural

and economic• Three examples:

– Vitamin A + measles– trachoma + bacteria– HIV + many diseases

Page 16: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

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

Page 17: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

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

Page 18: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Bitot spot: early sign, foamy appearance to conjunctiva

progressionof untreated disease toblindness

Page 19: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Vitamin A and measles

Vitamin A deficiencygreatly enhances measles virulence andlethality

Page 20: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

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

Page 21: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

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 AsiaInfectious (WHO ‘TF’ stage)

Page 22: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

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

Page 23: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Conjunctivalscarring

(Arlt’s line )

Page 24: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

chronic irritationsetup for blinding bacterial keratitis

Chronic epithelial defect from misdirected lashes

Page 25: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Secondary bacterial infection

Page 26: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

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)

Page 27: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Cotton-wool spots

Page 28: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

CMV retinitis

Page 29: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Kaposi’s sarcoma

inner canthus tumor

Page 30: Tropical Ophthalmology. Part One of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA stephen.waller@usuhs.mil

Kaposi’ssarcoma of nose

see lecture parts two andthree for more TropicalOphthalmology