Background: Vision loss is a major public health concern that significantly affects developing countries, including South Africa. Although existing literature have reported on the prevalence, causes, and impact of vision loss on the quality of life of affected individuals (children and adults) in parts of South Africa, there is no evidence of the prevalence and associated factors of vision loss in the general population. Hence, this study aimed to determine the prevalence of vision loss and its associated factors in South Africa using a population-based survey. Methods: Secondary analyses were conducted using data from the South African National Health and Nutrition Examination Survey (SANHANES-1), a population-based national health survey conducted from 2011 to 2012. Vision loss was defined as presenting visual acuity (PVA) worse than Snellen 6/12 in the better eye. Visual acuity was assessed by clinicians and participants’ subjective response to vision-related questions. Univariate and multiple logistic regression models were used to examine the association of the independent variables with vision loss. Results: The analytic sample comprised 4346 individuals with a mean age of 39.1 years. Female sex accounted for 55.6% of the participants. The prevalence of vision loss among participants was 9.2% (95% CI: 7.7–10.9). Older age (45–54 years, OR = 2.99, p < 0.001; 55–64 years, OR = 5.78, p < 0.001 and ≥ 65 years, OR = 5.12, p < 0.001), female sex (OR = 1.50, p = 0.016), and previous diabetes diagnosis (OR = 2.28, p = 0.001) were significantly associated with increased odds of vision loss. Further, secondary school education (OR = 0.71, p = 0.031), white ethnicity (OR = 0.11, p = 0.007), residing in Mpumalanga province (OR = 0.12, p < 0.001) and having never had an eye examination (OR = 0.56, p = 0.003) were significantly associated with reduced odds of vision loss. Conclusion: Almost one in ten participants had vision loss. Adopting strategies targeted at reducing barriers to the utilization of eye care services will promote early detection and management of blinding conditions, and thereby, decrease the burden of vision loss in South Africa.

Purpose: The high-performance visual function associated with central vision is mediated by the macula (the central retina), which accumulates three diet-derived pigments (the carotenoids lutein [L], zeaxanthin [Z], and meso-zeaxanthin [MZ]). Our study sought to investigate the impact on visual function, including contrast sensitivity (CS), of supplementation with these naturally occurring carotenoids, in individuals with low retinal concentrations. Methods: Subjects consumed daily a formulation containing 10 mg L, 2 mg Z, and 10 mg MZ (active group; n = 53) or placebo (n = 52) for a period of 12 months. Study visits were at baseline, 3, 6, and 12 months. Contrast sensitivity at 6 cycles per degree (cpd) was the primary outcome measure (POM). Secondary outcome measures included CS at other spatial frequencies, best-corrected visual acuity (BCVA), glare disability, photostress recovery, and light scatter. Macular pigment optical density (MPOD) was measured using dual-wavelength autofluorescence, and serum carotenoid concentrations were analyzed using high performance liquid chromatography (HPLC). Results: Compared to placebo, statistically significant improvements from baseline CS were detected at 6 (P = 0.002) and 1.2 (P = 0.004) cpd in the active group. Additionally, improvements in CS were commensurate with the observed increases in retinal concentrations of these carotenoids (r = 0.342, P = 0.002 at 6 cpd). Conclusions: These results indicate that dietary fortification with the macular carotenoids can have meaningful effects on visual function.

Background: The macula (central retina) contains a yellow pigment, comprising the dietary carotenoids lutein (L), zeaxanthin (Z), and meso-zeaxanthin, known as macular pigment (MP). The concentrations of MP’s constituent carotenoids in retina and brain tissue correlate, and there is a biologically-plausible rationale, supported by emerging evidence, that MP’s constituent carotenoids are also important for cognitive function. Objective: To investigate if patients with Alzheimer’s disease (AD) are comparable to controls in terms of MP and visual function. Methods: 36 patients with moderate AD and 33 controls with the same age range participated. MP was measured using dual-wavelength autofluorescence (Heidelberg Spectralis ^® ); cognitive function was assessed using a battery of cognition tests (including Cambridge Neuropsychological Test Automated Battery). Visual function was recorded by measuring best corrected visual acuity (BCVA) and contrast sensitivity (CS). Serum L and Z concentrations (by HPLC) and age-related macular degeneration (AMD, by retinal examination) status were also assessed. Results: In the AD group, central MP (i.e., at 0.23°) and MP volume were significantly lower than the control group (p < 0.001 for both), as were measures of BCVA, CS, and serum L and Z concentrations (p < 0.05, for all). Conclusion: AD patients were observed to exhibit significantly less MP, lower serum concentrations of L and Z, poorer vision, and a higher occurrence of AMD when compared to control subjects. A clinical trial in AD patients designed to investigate the impact of macular carotenoid supplementation with respect to MP, visual function, and cognitive function is merited.

Background: Patients with Alzheimer's disease (AD) exhibit significantly less macular pigment (MP) and poorer vision when compared to control subjects. Objective: To investigate supplementation with the macular carotenoids on MP, vision, and cognitive function in patients with AD versus controls. Methods: A randomized, double-blind clinical trial with placebo and active arms. 31 AD patients and 31 age-similar control subjects were supplemented for six months with either Macushield (10 mg meso-zeaxanthin [MZ]; 10 mg lutein [L]; 2 mg zeaxanthin [Z]) or placebo (sunflower oil). MP was measured using dual-wavelength autofluorescence (Heidelberg Spectralis ^® ). Serum L, Z, and MZ were quantified by high performance liquid chromatography. Visual function was assessed by best corrected visual acuity and contrast sensitivity (CS). Cognitive function was assessed using a battery of cognition tests, including the Cambridge Neuropsychological Test Automated Battery (CANTAB)). Results: Subjects on the active supplement (for both AD and non-AD controls) exhibited statistically significant improvement in serum concentrations of L, Z, MZ, and MP (p < 0.001, for all) and also CS at (p = 0.039). Also, for subjects on the active supplement, paired samples t-tests exhibited four significant results (from five spatial frequencies tested) in the AD group, and two for the non-AD group, and all indicating improvements in CS. We found no significant changes in any of the cognitive function outcome variables measured (p > 0.05, for all). Conclusion: Supplementation with the macular carotenoids (MZ, Z, and L) benefits patients with AD, in terms of clinically meaningful improvements in visual function and in terms of MP augmentation.

Purpose To compare the impact of sustained supplementation using different macular carotenoid formulations on macular pigment (MP) and visual function in early age-related macular degeneration (AMD). Patients and methods Sixty-seven subjects with early AMD were randomly assigned to: Group 1 (20 mg per day lutein (L), 0.86 mg per day zeaxanthin (Z); Ultra Lutein), Group 2 (10 mg per day meso-zeaxanthin (MZ), 10 mg per day L, 2 mg per day Z; Macushield; Macuhealth), Group 3 (17 mg per day MZ, 3 mg per day L, 2 mg per day Z). MP was measured using customised heterochromatic flicker photometry and visual function was assessed by measuring contrast sensitivity (CS) and best-corrected visual acuity (BCVA). AMD was graded using the Wisconsin Age-Related Maculopathy Grading System (AREDS 11-step severity scale). Results At 3 years, a significant increase in MP from baseline was observed in all groups at each eccentricity (P<0.05), except at 1.75° in Group 1 (P=0.160). Between 24 and 36 months, significant increases in MP at each eccentricity were seen in Group 3 (P<0.05 for all), and at 0.50° in Group 2 (P0.05 for all). At 36 months, compared with baseline, the following significant improvements (P<0.05) in CS were observed: Group 2—1.2, 6, and 9.6 cycles per degree (c.p.d.); Group 1—15.15 c.p.d.; and Group 3—6, 9.6, and 15.15 c.p.d. No significant changes in BCVA, or progression to advanced AMD, were observed. Conclusion In early AMD, MP can be augmented with a variety of supplements, although the inclusion of MZ may confer benefits in terms of panprofile augmentation and in terms of CS enhancement.

Background: Macular pigment (MP) levels correlate with brain concentrations of lutein (L) and zeaxanthin (Z), and have also been shown to correlate with cognitive performance in the young and elderly. Objective: To investigate the relationship between MP, serum concentrations of L and Z, and cognitive function in subjects free of retinal disease with low MP (Group 1, n = 105) and in subjects with AMD (Group 2, n = 121). Methods: MP was measured using customized heterochromatic flicker photometry and dual-wavelength autofluorescence; cognitive function was assessed using a battery of validated cognition tests; serum L and Z concentrations were determined by HPLC. Results: Significant correlations were evident between MP and various measures of cognitive function in both groups ( r = –0.273 to 0.261, p ≤0.05, for all). Both serum L and Z concentrations correlated significantly ( r = 0.187, p ≤0.05 and r = 0.197, p ≤0.05, respectively) with semantic (animal) fluency cognitive scores in Group 2 (the AMD study group), while serum L concentrations also correlated significantly with Verbal Recognition Memory learning slope scores in the AMD study group ( r = 0.200, p = 0.031). Most of the correlations with MP, but not serum L or Z, remained significant after controlling for age, gender, diet, and education level. Conclusion: MP offers potential as a non-invasive clinical biomarker of cognitive health, and appears more successful in this role than serum concentrations of L or Z.