Prevalence, Causes and Socio-Economic Determinants of Vision Loss in Cape Town, South Africa

PURPOSE: To estimate the prevalence and causes of blindness and visual impairment in Cape Town, South Africa and to explore socio-economic and demographic predictors of vision loss in this setting. METHODS: A cross sectional population-based survey was conducted in Cape Town. Eighty-two clusters were selected using probability proportionate to size sampling. Within each cluster 35 or 40 people aged 50 years and above were selected using compact segment sampling. Visual acuity of participants was assessed and eyes with a visual acuity less than 6/18 were examined by an ophthalmologist to determine the cause of vision loss. Demographic data (age, gender and education) were collected and a socio-economic status (SES) index was created using principal components analysis. RESULTS: Out of 3100 eligible people, 2750 (89%) were examined. The sample prevalence of bilateral blindness (presenting visual acuity <3/60) was 1.4% (95% CI 0.9-1.8). Posterior segment diseases accounted for 65% of blindness and cataract was responsible for 27%. The prevalence of vision loss was highest among people over 80 years (odds ratio (OR) 6.9 95% CI 4.6-10.6), those in the poorest SES group (OR 3.9 95% CI 2.2-6.7) and people with no formal education (OR 5.4 95% CI 1.7-16.6). Cataract surgical coverage was 68% in the poorest SES tertile (68%) compared to 93% in the medium and 100% in the highest tertile. CONCLUSIONS: The prevalence of blindness among people ≥50 years in Cape Town was lower than expected and the contribution of posterior segment diseases higher than previously reported in South Africa and Sub Saharan Africa. There were clear socio-economic disparities in prevalence of vision loss and cataract surgical coverage in this setting which need to be addressed in blindness prevention programs

Consensus generation of a minimum set of outcome measures for auditing glaucoma surgery outcomes—a Delphi exercise

Purpose: To identify the key set of glaucoma surgery outcome measures considered most important and practical to collect by glaucoma specialists. Methods: One hundred two glaucoma specialists (57 members of the UK and Eire Glaucoma Society (UKEGS) and 45 members of the European Glaucoma society (EGS)) took part in an Online Delphi exercise. The RAND/UCLA appropriateness method was used analyse data from each round and generate a disagreement index. Results: Participants agreed on 13 baseline data points and 12 outcomes that were considered important and practical to collect. For intraocular pressure (IOP) percentage reduction in IOP from baseline (last three IOP readings pre-op) and reduction below a specified target were considered important. For visual fields, change in a global visual field index, e.g. MD, and development of progression as assessed by linear regression were considered important. From a safety perspective, any visual loss resulting in a doubling of the minimal angle of resolution, loss of 5 dB or more of visual field or development of advanced field loss (Hodapp Parrish Anderson Stage 4) was considered important. The importance of routinely using patient reported outcome measures (PROMs) was highlighted. Consensus suggested that outcomes of glaucoma treatments should be reported at 1, 5 and 10 years. Conclusions: There was broad consensus on a minimum dataset for reporting the outcomes of glaucoma surgery and outcome measurement intervals

Number of People Blind or Visually Impaired by Glaucoma Worldwide and in World Regions 1990 – 2010: A Meta-Analysis

Objective: To assess the number of individuals visually impaired or blind due to glaucoma and to examine regional differences and temporal changes in this parameter for the period from 1990 to 2012. Methods: As part of the Global Burden of Diseases (GBD) Study 2010, we performed a systematic literature review for the period from 1980 to 2012. We primarily identified 14,908 relevant manuscripts, out of which 243 high-quality, population-based studies remained after review by an expert panel that involved application of selection criteria that dwelt on population representativeness and clarity of visual acuity methods used. Sixty-six specified the proportion attributable to glaucoma. The software tool DisMod-MR (Disease Modeling–Metaregression) of the GBD was used to calculate fraction of vision impairment due to glaucoma. Results: In 2010, 2.1 million (95% Uncertainty Interval (UI):1.9,2.6) people were blind, and 4.2 (95% UI:3.7,5.8) million were visually impaired due to glaucoma. Glaucoma caused worldwide 6.6% (95% UI:5.9,7.9) of all blindness in 2010 and 2.2% (95% UI:2.0,2.8) of all moderate and severe visual impairment (MSVI). These figures were lower in regions with younger populations (10%). From 1990 to 2010, the number of blind or visually impaired due to glaucoma increased by 0.8 million (95%UI:0.7, 1.1) or 62% and by 2.3 million (95%UI:2.1,3.5) or 83%, respectively. Percentage of global blindness caused by glaucoma increased between 1990 and 2010 from 4.4% (4.0,5.1) to 6.6%. Age-standardized prevalence of glaucoma related blindness and MSVI did not differ markedly between world regions nor between women. Significance: By 2010, one out of 15 blind people was blind due to glaucoma, and one of 45 visually impaired people was visually impaired, highlighting the increasing global burden of glaucoma

Assessing diabetic control - reliability of methods available in resource poor settings

Aims and methods To examine the reliability of random venous or capillary blood glucose testing, random urine glucose testing, and a current symptom history in predicting a high HbA(1c) in Type 2 diabetic patients taking oral hypoglycaemic agents in a poorly controlled rural African population. Results For a cut-off point for HbA(1c) of greater than or equal to 8%, for random venous plasma glucose of greater than or equal to 14 mmol/L (present in 47.2% of subjects), specificity was 97.1% (95% CI 85.1-99.9), sensitivity 56.8% (48.8-64.5) and positive predictive value (PPV) 98.9% (94.2-99.9). HbA(1c) greater than or equal to 8% is predicted by a random capillary blood glucose of 17 mmol/L (present in 28.4% of subjects) with specificity 100% (90.0-100.0), PPV 100% (93.7-100.0) and sensitivity of 34.3% (27.2-42.1). HbA(1c) greater than or equal to 8% is predicted by the presence of heavy glycosuria (greater than or equal to 55 mmol/L) (present in 35.6%) with specificity 94.1% (80.3-99.3), sensitivity of 41.9% (34.1-49.9) and PPV 97.1% (89.9-99.6). Polyuria/nocturia (present in 31.3%) was the only symptom found to be associated with poor control, with a specificity for predicting HbA(1c) of greater than or equal to 8% of 81.5% (61.9-93.7), PPV 89.1% (76.4-96.4) and sensitivity 30.6% (22.9-39.1). Conclusions Where resources are short, random glucose testing can be used to detect a significant proportion of those with the worst control with a high degree of specificity enabling primary care staff to modify treatment safely. Where facilities are limited capillary blood or urine testing with reagent strips, may be substituted for venous plasma testing in the laboratory. A symptom history was insufficient to replace biochemical testing, but where this is unavailable, urinary symptoms may be helpful

Continued explosive rise in HIV prevalence among pregnant women in rural South Africa

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Follow-up survey of cataract surgical coverage and barriers to cataract surgery at Nkhoma, Malawi.

PURPOSE: Nkhoma Eye Hospital, Malawi provides high volume, high quality free cataract surgery to people in its catchment region of Central-Malawi. However, a previous survey in 2000 indicated that only 1 in 7 people with bilateral blindness from cataract had received surgery in a 10-mile radius of Nkhoma. METHODS: We conducted a population-based survey in 2006 in the 32 villages within a 10-mile radius of Nkhoma Hospital in people aged ≥ 40 years in order to investigate the cataract surgical coverage (CSC) and barriers to cataract surgery. RESULTS: The prevalence of blindness (visual acuity [VA] <3/60 in better eye) in 835 people aged ≥ 40 was 1.3% (95% CI 0.5-2.1), of which 36.4% was due to cataract. Overall, the CSC was 83.3%, and for eyes (VA<3/60) was 66.0%. The CSC was lower in females compared to males (73.3% vs. 100.0%. P < 0.001). The most common barrier to surgery was cost (58%). CONCLUSION: Our results demonstrate a 5-fold increase in coverage in the 6 years, primarily by increasing efficiency of the service provider and providing a community screening and referral service. Supporting the ophthalmic personnel with appropriate infrastructure and management has been central to this shift. Implementing an active case finding and referral mechanism has enabled this unit to provide regular high volume cataract surgery. There is a need to understand the factors influencing perceptions about cost as a barrier in this community and the disparity between need and access to services for women

Impact of on-site testing for maternal syphilis on treatment delays, treatment rates, and perinatal mortality in rural South Africa: a randomised controlled trial

Background: Syphilis remains a significant cause of preventable perinatal death in developing countries, with many women remaining untested and thus untreated. Syphilis testing in the clinic (on-site testing) may be a useful strategy to overcome this. We studied the impact of on-site syphilis testing on treatment delays and rates, and perinatal mortality. Methods: We conducted a cluster randomised controlled trial among seven pairs of primary healthcare clinics in rural South Africa, comparing on-site testing complemented by laboratory confirmation versus laboratory testing alone. Intervention clinics used the on-site test conducted by primary care nurses, with results and treatment available within an hour. Control clinics sent blood samples to the provincial laboratory, with results returned 2 weeks later. Results: Of 7134 women seeking antenatal care with available test results, 793 (11.1%) tested positive for syphilis. Women at intervention clinics completed treatment 16 days sooner on average (95% confidence interval: 11 to 21), though there was no significant difference in the proportion receiving adequate treatment at intervention (64%) and control (69%) clinics. There was also no significant difference in the proportion experiencing perinatal loss (3.3% v 5.1%; adjusted risk difference: -0.9%; 95% CI -4.4 to 2.7). Conclusions: Despite reducing treatment delays, the addition of on-site syphilis testing to existing laboratory testing services did not lead to higher treatment rates or reduce perinatal mortality. However on-site testing for syphilis may remain an important option for improving antenatal care in settings where laboratory facilities are not available

Impact of on-site testing for maternal syphilis on treatment delays, treatment rates and perinatal mortality in rural South Africa: a randomised controlled trial

Syphilis remains a significant cause of preventable perinatal death in developing countries, with many women remaining untested and thus untreated. Syphilis testing in the clinic (on-site testing) may be a useful strategy to overcome this. We studied the impact of on-site syphilis testing on treatment delays and rates, and perinatal mortality. We conducted a cluster randomised controlled trial among seven pairs of primary healthcare clinics in rural South Africa, comparing on-site testing complemented by laboratory confirmation versus laboratory testing alone. Intervention clinics used the on-site test conducted by primary care nurses, with results and treatment available within an hour. Control clinics sent blood samples to the provincial laboratory, with results returned 2 weeks later. Of 7134 women seeking antenatal care with available test results, 793 (11.1%) tested positive for syphilis. Women at intervention clinics completed treatment 16 days sooner on average (95% confidence interval: 11 to 21), though there was no significant difference in the proportion receiving adequate treatment at intervention (64%) and control (69%) clinics. There was also no significant difference in the proportion experiencing perinatal loss (3.3% v 5.1%; adjusted risk difference: -0.9%; 95% CI -4.4 to 2.7). Despite reducing treatment delays, the addition of on-site syphilis testing to existing laboratory testing services did not lead to higher treatment rates or reduce perinatal mortality. However on-site testing for syphilis may remain an important option for improving antenatal care in settings where laboratory facilities are not available.