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Objective To determine the prevalence, etiologies, and risk factors of blindness and visual impairment among persons age 40 years and older residing in an urban West African location. Design Population-based cross-sectional study. Participants Five thousand six hundred and three participants residing in Tema, Ghana. Methods Proportionate random cluster sampling was used to select participants age 40 and over living in the city of Tema. Presenting distance visual acuity was measured at 4 and 1 meters using a reduced Logarithm of the Minimum Angle of Resolution (logMAR) tumbling E chart and then with trial frame based on autorefraction. A screening examination was performed in the field on all participants. Complete clinical examination by an ophthalmologist was performed on participants with best corrected visual acuity < 20/40 or failure of any screening test. Main Outcome Measures Age- and gender-specific prevalence, causes, and risk factors for blindness (visual acuity in the better eye of < 20/400, World Health Organization definition) and visual impairment (visual acuity in the better eye of < 20/40). Results Six thousand eight hundred and six eligible participants were identified of which 5603 (82.3%) participated in the study. The mean age (±standard deviation) of participants was 52.7±10.9. The prevalence of visual impairment was 17.1% and blindness was 1.2%. After refraction and spectacle correction, the prevalence of visual impairment and blindness decreased to 6.7% and 0.75% respectively, suggesting that refractive error is the major correctable etiology of visual impairment and blindness in this population. Of 65 subjects having visual acuity < 20/400, 22 (34%) were correctable with refraction, 21 to the level of visual impairment, and one to normal. The remaining 43 (66%) had underlying pathology (19 cataract, 9 glaucoma, 3 non-glaucomatous optic neuropathy, 3 corneal opacities, 3 retinal disease, 5 undetermined) that prevented refractive correction. Increased age was a significant risk factor for blindness and visual impairment. Conclusions There is a high prevalence of blindness and visual impairment among those aged ≥40 years in Tema, Ghana, West Africa. Refractive error is a major cause of blindness and visual impairment in this population, followed by cataract, glaucoma, and corneal disease.

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Purpose To compare the results of Glaucoma Progression Analysis (GPA, Carl Zeiss Meditec, Dublin, CA) to subjective expert consensus in the detection of glaucomatous visual field progression. Design Retrospective, observational case series. Participants 100 eyes of 83 glaucoma patients. Methods Five serial Humphrey visual fields from 100 eyes of 83 glaucoma patients were evaluated by five masked glaucoma subspecialists for determination of progression. Four months later, with a randomly reordered patient sequence, the same visual field series were re-evaluated by the same graders, at which time they had access to the Glaucoma Progression Analysis (GPA) printout. Main Outcome Measures The level of agreement between majority expert consensus and GPA, both before and after access to GPA data, was assessed using kappa statistics. Results On initial review and on re-evaluation with access to the GPA printout, the level of agreement between majority expert consensus and GPA was fair (kappa = 0.52, 95% confidence interval [CI] = 0.35 – 0.69 and 0.62, 95% CI = 0.46 – 0.78, respectively). Expert consensus was more likely to classify a series of fields as showing progression than was GPA (p ≤ 0.002). There was good agreement between expert consensus on initial review and reevaluation 4 months later (kappa = 0.77, 95% CI = 0.65 – 0.90). Conclusions The level of agreement between majority expert consensus of subjective determination of visual field progression and GPA is fair. In cases of disagreement with GPA, the expert consensus classification was usually progression. Access to the results of GPA did not significantly change the level of agreement between expert consensus and the GPA result; however, expert consensus did change in 11 of 100 cases.

PurposeTo determine if there are systematic differences in cup-to-disc ratio (CDR) grading using fundus biomicroscopy compared to stereoscopic disc photograph reading.MethodsThe vertical cup-to-disc ratio (VCDR) and horizontal cup-to-disc ratio (HCDR) of 2200 eyes (testing set) were graded by glaucoma subspecialists through fundus biomicroscopy and by a reading center using stereoscopic disc photos. For validation, the glaucoma experts also estimated VCDR and HCDR using stereoscopic disc photos in a subset of 505 eyes that they had assessed biomicroscopically. Agreement between grading methods was assessed with Bland-Altman plots.ResultsIn both sets, photo reading tended to yield small CDRs marginally larger, but read large CDRs marginally smaller than fundus biomicroscopy. The mean differences in VCDR and HCDR were 0.006±0.18 and 0.05±0.18 (testing set), and -0.053±0.23 and -0.028±0.21 (validation set), respectively. The limits of agreement were ~0.4, which is twice as large as the cutoff of clinically significant CDR difference between methods. CDR estimates differed by 0.2 or more in 33.8-48.7% between methods.ConclusionsThe differences in CDR estimates between fundus biomicroscopy and stereoscopic optic disc photo reading showed a wide variation, and reached clinically significance threshold in a large proportion of patients, suggesting a poor agreement. Thus, glaucoma should be monitored by comparing baseline and subsequent CDR estimates using the same method rather than comparing photographs to fundus biomicroscopy.