Cataract and glaucoma case detection for Vision 2020 programs in Africa: an evaluation of 6 possible screening tests.
OBJECTIVE
To determine if there is a screening test or a combination of screening tests that may be suitable for cataract and glaucoma case detection in Vision 2020 programs in Africa.


METHODS
Design-Screening methods validation study. Setting-Groote Schuur Hospital, Cape Town, South Africa. Subjects-African patients aged 40 years and older with known cataract or with known glaucoma, and accompanying relatives aged 40 years and older with no known eye pathology. Outcome measures-Sensitivity, specificity, positive and negative likelihood ratios, and accuracy of 6 screening tests, used alone and in various combinations.


RESULTS
Testing the pinhole visual acuity using a cut point of 6/18 in 1 or both eyes has a sensitivity and specificity greater than 90%, a positive likelihood ratio greater than 10.0, a negative likelihood ratio less than 0.1, and an accuracy greater than 90% for case detection of cataract or glaucoma. Examination of the optic disk with a lens free direct ophthalmoscope using a cut point of 0.7 for the vertical cup:disk ratio combined with testing for an afferent pupil defect has similar values for case detection of glaucoma.


CONCLUSIONS
These tests may be suitable for use in Vision 2020 programs in Africa.
Cook
Colin
C
Department of Ophthalmology, Groote Schuur Hospital, Observatory, Cape Town, South Africa. colin.cook@uct.ac.za
Cockburn
Nicole
N
van der Merwe
Junet
J
Ehrlich
Rodney
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000175:diagnosis* / Q000453:epidemiology; D005189:False Positive Reactions; D005260:Female; D005901:Glaucoma / Q000175:diagnosis* / Q000453:epidemiology; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D009887:Ophthalmoscopy; D009898:Optic Disk / Q000473:pathology; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000453:epidemiology; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013019:South Africa / Q000453:epidemiology; D015351:Vision Screening / Q000295:instrumentation*; D014792:Visual Acuity / Q000502:physiology