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

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.

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.

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

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

Prevalence of Blindness 90%+ live in lower income countries

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

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

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

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. 2004 Dec;169(12):952-7.

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

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

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.

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

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

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

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

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

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

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)

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

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 

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

Secondary bacterial infection

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)

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

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

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

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