Cataract incidence in sub-Saharan Africa: what does mathematical modeling tell us about geographic variations and surgical needs?
OBJECTIVE
To apply a previously described mathematical model, designed to estimate cataract incidence from age-specific prevalence, to Rapid Assess of Avoidable Blindness survey data from Sub-Saharan Africa in order to estimate the incidence of cataract and therefore surgical needs.


METHODS
All Rapid Assessment of Avoidable Blindness surveys from Sub-Saharan Africa were identified. A previously developed mathematical model, designed to estimate the incidence of operable cataract was applied to those (27/32) meeting the inclusion criteria.


RESULTS
Incidence varied significantly across the continent with the result that cataract surgery rate targets required to eliminate cataract vary too. When variation in age structure is also taken into account, the cataract surgery rate needed to eliminate cataract visual impairment at the level of 6/18 ranges from 1200-4500 surgeries per year per million population.


CONCLUSIONS
This is important evidence of significant variation in the incidence of cataract within Sub-Saharan Africa. The variation may be related to genetic or cultural variations on the continent and has important implications for planning services.
Kilimanjaro Centre for Community Ophthalmology International, Groote Schuur Hospital , Observatory , South Africa .
Susan
S
Lewallen
Paul
P
Courtright
Daniel
D
Etya'ale
Wanjiku
W
Mathenge
Elena
E
Schmidt
Joseph
J
Oye
Anne
A
Clark
Talithia
T
Williams
D017954:Africa South of the Sahara / Q000453:epidemiology; D001766:Blindness / Q000517:prevention & control; D002386:Cataract / Q000453:epidemiology*; D002387:Cataract Extraction / Q000706:statistics & numerical data*; D005843:Geography; D006301:Health Services Needs and Demand / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D008962:Models, Theoretical; D015995:Prevalence