Cataract and glaucoma case detection for Vision 2020 programs in Africa: An evaluation of 6 possible screening tests
Department of Ophthalmology, Groote Schuur Hospital, Cape Town, South Africa; School of Public Health and Family Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
PURPOSE: 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. © 2009 Lippincott Williams & Wilkins, Inc.
adult; Africa; aged; article; cataract; diagnostic accuracy; evaluation; female; glaucoma; human; intraocular pressure; lens; male; ophthalmoscope; optic disk; predictive validity; priority journal; pupil; relative; screening test; sensitivity and specificity; tonometry; validation study; visual acuity; visual field; Adult; Aged; Aged, 80 and over; Cataract; False Positive Reactions; Female; Glaucoma; Humans; Likelihood Functions; Male; Middle Aged; Ophthalmoscopy; Optic Disk; Optic Nerve Diseases; Predictive Value of Tests; Reproducibility of Results; Sensitivity and Specificity; South Africa; Vision Screening; Visual Acuity