Tropical ophthalmology

Question 1

Visual acuity - classification

Answer 1

Normal 6/6 - 6/12
Mild VI >6/12 - 6/18
Moderate + severe VI >6/18 - 3/60
Blind >3/60

Question 2

Blindness - global epidemiology

Answer 2

Blind 43 million
Mod/severe VI 295 million

Question 3

Trachoma

Answer 3

Chlamydia trachomatis
Person to person spread
Conjunctivitis - can be recurrent with scarring - blindness

Question 4

Glaucoma

Answer 4

Damage to optic nerve - optic disc changes
Tend to present late - loss of peripheral vision first

Question 5

Diabetic retinopathy - pathogenesis

Answer 5

BM thickening
Endothelial cell damage
RBC changes - aggregation leading to occlusions
Loss of pericytes leading to leakage
Vascular growth factors secondary to hypoxia leading to inappropriate vessel growth:
-Proliferative retinopathy
-Rubeosis iridis - fragile new vessels - increased risk of bleeding

Question 6

Blindness - global epidemiology in children

Answer 6

1.44 million blind
Mod/severe VI 22 million
Mild Vi 46 million

Question 7

Major causes of avoidable blindness in children in LMIC

Answer 7

Myopia
Corneal scarring [vit A, measles, gonococcal conjunctivitis]
Cataract
ROP
Emerging causes - Zika and Ebola

Question 8

Vitamin A deficiency - eye signs

Answer 8

Conjunctival and corneal xerosis [drying]
Bitot’s spots - accumulation of keratin, can be wiped off
Corneal ulcer

Question 9

Treatment of xerophthalmia

Answer 9

High dose vitamin A x3 doses

Question 10

Ophthalmia neonatorum

Answer 10

Gonococcal conjunctivitis of the newborn
Severe conjunctivitis with purulent discharge occurring within 28 days