Reproducibility of corneal, macular and retinal nerve fiber layer thickness measurements using the iVue-100 optical coherence tomography

Purpose: To determine the intra-session and inter-session reproducibility of corneal, macular and retinal nerve fiber layer thickness (RNFL) measurements with the iVue-100 optical coherence tomography in normal eyes.Methods: These parameters were measured in the right eyes of 50 healthy participants with normal vision. Six scans each for corneal thickness, macular and optic nerve head were taken on one day (intra-session), followed by similar repeated measures on five separate days (inter-session). Reproducibility was computed using intra-class correlation coefficient (ICC), coefficient of variation (COV), and test-retest variability (TRV).Results: For intra-session reproducibility, the ICC, COV and TRV values for mean corneal thickness were 0.924, 2.82%, and 3.06 μm respectively. For the mean macular thickness, they were 0.978, 4.64% and 4.51 μm respectively, while for mean RNFL thickness they were 0.946, 3.19%, and 5.66 μm respectively. Inter-session values for mean corneal thickness were 0.926, 2.65% and 3.48 μm, and 0.916, 2.24% and 2.03 μm for mean macular thickness. For mean RNFL thickness, they were 0.962, 2.21%, and 4.72 μm respectively.Conclusion: There was good reproducibility of all measured parameters. However, mean RNFL thickness measurements were the most reproducible, suggesting that this may be the best parameter to use to determine measured changes over time.Keywords: Corneal thickness, macular thickness, retinal nerve fiber layer thickness, iVue-100, reproducibilit

Effects of spectacles and telescopes on visual function in students with oculocutaneous albinism

Purpose: To investigate the effects of spectacle and telescope corrections on visual acuity (VA), contrast sensitivity (CS) and reading rates (RR) in students with oculocutaneous albinism (OCA). Methods: An observational study design was conducted on 81 students with OCA. Distance and near VA, CS and RR were measured without correction, with spectacle correction and with a combination of spectacle correction and telescopes. Results: The mean distance and near VA values with a combination of spectacle correction and telescopes were significantly better than those without correction and with spectacle correction alone (p = 0.01). Mean CS values achieved with spectacles alone were significantly better than those obtained with a combination of spectacles and telescopes (p = 0.01). There was no significant difference between logCS values obtained without correction compared to those obtained with a combination of spectacle correction and telescopes. There were no significant differences between RR values obtained with a combination of spectacles and telescopes and those without and with spectacle correction alone (all p > 0.05). Conclusion: This article provides valuable information to eye care practitioners on the effects of spectacles and telescopes on visual acuity, contrast sensitivity and reading rate in students with OCA

Colour vision deficiency among students in Lagos State, Nigeria

Background: Congenital colour vision defects are x-linked inherited, non-progressive and untreatable disorders that describe poor colour discrimination.Objective: To determine the prevalence of congenital colour vision deficiency among students in Lagos, Nigeria.Methods: A school-based cross-sectional, cluster sample study was conducted to test the colour vision of 2326 primary and high school students. Inclusion criteria were Snellen VA 20/20 or better and absence of known ocular pathologies. Colour vision deficiency (CVD) was evaluated with the Richmond-HRR colour vision test plates.Results: There were 1014 (43.6%) males and 1312 (56.4%) females with a mean age of 13.40 ± 2.40 years (range = 7−22 years). The prevalence of CVD was 58 (2.5%), which was higher in males 49 (4.8%) than females 9 (0.7%). The prevalence of congenitalCVD was significantly associated with males (p = 0.00), but not with females (p = 0.22). Of the 58 cases of CVD, 17 (0.7%) had protan deficiency, 38 (1.6%) had deutan deficiency and three (0.1%) were unclassified.Conclusion: The prevalence of congenital CVD among students in Lagos is comparable to findings in other parts of Nigeria but differs from other parts of the country. These results strengthen the need to establish school vision screening.Keywords: Colour vision deficiency, Richmond-HRR, prevalence, red-green defects, Nigeria

Retinal nerve fibre layer thickness values and their associations with ocular and systemic parameters in Black South Africans.

Purpose: To measure the retinal nerve fibre layer (RNFL) thickness values and investigate their associations with other parameters in healthy eyes of Black South Africans. Methods: 600 participants with healthy eyes, of whom 305 (50.83%) were males and 295 (49.17%) were females, with a mean age of 28.15 \ub1 13.09 years, underwent a detailed ophthalmic examination. RNFL thickness was measured by iVue SD-OCT. Results: The mean global RNFL thickness was 110.01 \ub1 7.39 \u3bcm. The RNFL was thickest inferiorly (135.06 \ub1 9.66 \u3bcm) and superiorly (131.72 \ub1 10.46 \u3bcm), thinner nasally (87.24 \ub1 13.22 \u3bcm), and thinnest temporally (73.63 \ub1 15.66 \u3bcm). Multivariate analysis showed that thicker mean global RNFL thickness was significantly associated with younger age, shorter axial length (AL) and hyperopia (p < 0.001). Mean RNFL thickness decreased by approximately 0.11 \u3bcm per year of aging life, and by 1.02 \u3bcm for each 1-mm of axial elongation. There was a 0.62 \u3bcm RNFL thickness increase for every dioptre change in spherical power towards more hyperopia. Conclusion: Mean RNFL thickness values and their associations established in this population may be of clinical value when assessing factors that influence this parameter and diagnosing diseases affecting it

Colour vision deficiency among students in Lagos State, Nigeria

Background: Congenital colour vision defects are x-linked inherited, non-progressive and untreatable disorders that describe poor colour discrimination. Objective: To determine the prevalence of congenital colour vision deficiency among students in Lagos, Nigeria. Methods: A school-based cross-sectional, cluster sample study was conducted to test the colour vision of 2326 primary and high school students. Inclusion criteria were Snellen VA 20/20 or better and absence of known ocular pathologies. Colour vision deficiency (CVD) was evaluated with the Richmond-HRR colour vision test plates. Results: There were 1014 (43.6%) males and 1312 (56.4%) females with a mean age of 13.40 \ub1 2.40 years (range = 7 1222 years). The prevalence of CVD was 58 (2.5%), which was higher in males 49 (4.8%) than females 9 (0.7%). The prevalence of congenital CVD was significantly associated with males (p = 0.00), but not with females (p = 0.22). Of the 58 cases of CVD, 17 (0.7%) had protan deficiency, 38 (1.6%) had deutan deficiency and three (0.1%) were unclassified. Conclusion: The prevalence of congenital CVD among students in Lagos is comparable to findings in other parts of Nigeria but differs from other parts of the country. These results strengthen the need to establish school vision screening. DOI: https://dx.doi.org/10.4314/ahs.v19i2.48 Cite as: Oduntan OA, Mashige KP, Kio FE. Colour vision deficiency among students in Lagos State, Nigeria. Afri Health Sci.2019;19(2): 2230-2236. https://dx.doi.org/10.4314/ahs.v19i2.4

Knowledge and practices of parents about child eye health care in the public sector in Swaziland

Background: Swaziland, like many other developing countries, lacks appropriate eye health services, particularly for children. Aim: To determine the knowledge and practices of parents about child eye health care in the public sector in Swaziland. Setting: The setting for this study was Swaziland. Methods: A descriptive study involving cross-sectional sampling methodology and quantitative analysis was employed with 173 randomly selected parents whose children attended public schools in Swaziland. Results: Out of 173 participants, 104 (60.1%) parents reported that they have never taken their children for an eye test and 69 (31.7%) felt that their children’s vision was fine. Ninety-seven (53.1%) parents indicated having no knowledge about child eye conditions and no significant association was found between level of education and knowledge of eye conditions affecting children (p = 0.112). Having an immediate family member who wore spectacles increased the likelihood of a child being taken for eye testing (p = 0.001), but decreased the likelihood of being well informed about eye health (p = 0.218). Of those parents who reported taking their children for eye tests, 34 (49.3%) reported that they were given eye drops and 31 (44.9%) stated that their children were prescribed spectacles. Eighty-seven (50.3%) parents accepted the idea of their children wearing spectacles. Conclusion: The findings of the study suggest the need for parents to be informed about basic child eye health care and the importance of their children having regular eye examinations

Relationship between biometry, fovea, and choroidal thickness in Nigerian children with myopia

Background: Understanding the relationship between biometric and structural changes in childhood myopia is necessary to effectively manage myopia progression. Aim: To determine the relationship between ocular biometry, fovea and sub-fovea choroidal thickness in school-aged children with myopia of Nigerian descent. Setting: Abuja, Nigeria. Methods: This study involved 189 children (117 girls and 72 boys), and myopia was defined as cycloplegic spherical equivalent refraction (SER) of ≤ −0.50 D. Keratometry values, biometry data, fovea and sub-foveal choroidal thickness (SFChT) values were obtained from medical records retrospectively and analysed. Results: The median age was 13 years (interquartile range [IQR]: 5). The median SER, fovea and SFChTs were −2.63 D (IQR: 3.38), 249 μm (IQR: 118) and 225 μm (IQR: 341), respectively. Male children had flatter corneas, thicker fovea and thinner SFChT compared to female children. The vitreous chamber and axial length were longer and sub-fovea choroid was thinner in children with high myopia. There was a weak but significant positive correlation between myopia and sub-fovea choroidal thickness (r = 0.270 respectively, P  0.01). A moderate negative correlation was found between myopia and vitreous chamber depth (r = −0.536, P  0.001), and a strong negative correlation was found between myopia and axial length (r = −0.706, P  0.001). Conclusion: Myopia in school-aged Nigerian children is associated with sub-fovea choroidal thinning, increased vitreous chamber depth and axial elongation. Contribution: This study provides data on the relationship between ocular biometry, fovea and sub-foveal choroidal thickness in school-aged Nigerian children with myopia

Systematic review and meta-analysis of myopia prevalence in African school children

PURPOSE: Increased prevalence of myopia is a major public health challenge worldwide, including in Africa. While previous studies have shown an increasing prevalence in Africa, there is no collective review of evidence on the magnitude of myopia in African school children. Hence, this study reviews the evidence and provides a meta-analysis of the prevalence of myopia in African school children. METHODS: This review was conducted using the 2020 Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Five computerized bibliographic databases, PUBMED, Scopus, Web of Science, ProQuest, and Africa Index Medicus were searched for published studies on the prevalence of myopia in Africa from 1 January 2000 to 18 August 2021. Studies were assessed for methodological quality. Data were gathered by gender, age and refraction technique and standardized to the definition of myopia as refractive error ≥ 0.50 diopter. A meta-analysis was conducted to estimate the prevalence. Significant heterogeneity was detected among the various studies (I2 >50%), hence a random effect model was used, and sensitivity analysis was performed to examine the effects of outliers. RESULTS: We included data from 24 quality assessed studies, covering 36,395 African children. The overall crude prevalence of myopia over the last two decades is 4.7% (95% CI, 3.9-5.7) in African children. Although the prevalence of myopia was slightly higher in females (5.3%, 95%CI: 4.1, 6.5) than in males (3.7%, 95% CI, 2.6-4.7; p = 0.297) and higher in older [12-18 years 5.1% (95% CI, 3.8-6.3) than younger children (aged 5-11 years, 3.4%, 95% CI, 2.5-4.4; p = 0.091), the differences were not significant. There was a significantly lower prevalence of myopia with cycloplegic compared with non-cycloplegic refraction [4.2%, 95%CI: 3.3, 5.1 versus 6.4%, 95%CI: 4.4, 8.4; p = 0.046]. CONCLUSIONS: Our results showed that myopia affects about one in twenty African schoolchildren, and it is overestimated in non-cycloplegic refraction. Clinical interventions to reduce the prevalence of myopia in the region should target females, and school children who are aged 12-18 years

A comparison of postural and diurnal variations in intraocular pressure using the iCare rebound tonometer and Perkins applanation tonometer in admitted adults in Kenya

Background: Elevated intraocular pressure (IOP) remained the most important known risk factor for glaucoma. Aim: To compare the postural and diurnal IOP variations using the iCare rebound tonometer (RT) and Perkins applanation tonometer (PAT). Setting: Kakamega County Hospital, Kenya. Methods: Elevated intraocular pressure measurements were taken by two (masked) examiners with two devices in the morning (06:00–09:00), midday (12:00–15:00) and evening (18:00–21:00), in the sitting followed by supine positions in one randomly selected eye of 24 oculo-visual healthy hospital-admitted patients. Effects of the time of the day and position of the body within and between devices were analysed with the Statistical Package for Social Sciences. Results: The mean IOP measured by the RT ranged from 6 mmHg to 24 millimetres of mercury (mmHg) in the sitting position and from 10 mmHg to 26 mmHg in the supine position. The mean IOP measured using PAT ranged from 6 mmHg to 21 mmHg in the sitting position and from 8 mmHg to 24 mmHg in the supine position. The IOP measured by both devices significantly varied with position (p < 0.05). Perkins applanation tonometer on average gave a significantly higher IOP (1.7 mmHg [p = 0.003] and 1.3 mmHg [p = 0.034]) at 06:00 compared to that at 12:00 and 18:00, respectively. The IOP readings with the RT were on average 2.2 mmHg and 3.0 mmHg higher at 06:00 compared to that at 12:00 and 18:00, respectively (p < 0.0005). Conclusion: Significant reductions were observed in postural and diurnal IOPs in the sitting positions and in the afternoon, respectively. Diurnal IOP variations were slightly higher when measured by RT compared to when measured by PAT

Public awareness and perception towards COVID-19 in sub-saharan African countries during the lockdown

Background: The coronavirus disease (COVID-19) outbreak has caused a universal health crisis resulting in significant morbidities and mortalities particularly among high-risk groups. This study sought to determine regional factors associated with knowledge and attitude towards COVID-19 mitigation practices and risk perception of contracting the disease in Sub-Saharan African (SSA) countries. Methods: A cross-sectional anonymous online study was conducted among 1970 participants between April and May 2020, during the lockdown in many SSA countries. Recruitment of participants was via WhatsApp, Facebook and emails using authors’ networks. The outcome variables were KAP (knowledge, attitudes and practice) of COVID-19 and analysis of variance (ANOVA) with post hoc test was run to assess the level of KAP by four regions in SSA. Simple and multiple linear regression (MLR) analyses were performed to examine factors associated with the outcome measures in the four SSA regions. Results: Mean knowledge (P=0.707) and risk perception (P=0.904) scores by four regions in SSA did not differ significantly. However, the mean attitude score was higher among West Africans compared with Southern (P=0.019) and Central Africans (P=0.003). MLR analysis revealed that among those living in West (adjusted coefficient β=-0.83 95% CI: -1.19, -0.48) and Southern Africa (β=-0.91 95% CI: -1.42, -0.40), having a primary or secondary education was associated with a decrease in knowledge scores while not being worried about COVID-19 decreased risk perception scores across the four SSA regions(West [β=-6.57, 95% CI: -7.53, -5.62], East [β=-6.24: 95% CI: -8.34,-4.15], Central [β=-6.51, 95% CI: -8.70, -4.31], and Southern Africa [β=-6.06: 95% CI: -7.51, -4.60]). Except among Southern Africans, participants who practiced self-isolation had positive attitude towards COVID-19. Conclusion: Future research on health education regarding COVID-19 or a future related pandemic in SSA should target people with lower education, those who do not self-isolate, those living in Southern and Western Africa and not worried about contracting COVID-19