Tear α-synuclein as a biomarker for Parkinson's disease: A systematic review and meta-analysis.

BACKGROUND: Parkinson's disease symptoms mostly manifest after significant and irreversible neuropathology. Hence, there is a need to identify biomarkers that can provide indications of disease before significant neuronal degeneration occurs. OBJECTIVE: To estimate the difference in the concentration of α-synuclein protein in tears between individuals with Parkinson's disease and healthy controls. DATA SOURCES: PubMed, Scopus, and Web of Science. The last database search was on December 20, 2023. STUDY ELIGIBILITY CRITERIA: Primary prospective studies in humans measuring the level of α-synuclein in tears and clinical outcomes reported using mean or median. PARTICIPANTS AND INTERVENTIONS: Individuals with Parkinson's disease and healthy controls. STUDY APPRAISAL AND SYNTHESIS METHODS: The risk of bias was assessed using the Newcastle-Ottawa Scale. The I2 statistic was used to estimate heterogeneity. The outcome measure was the difference in tear total and oligomeric α-synuclein. Mean difference (MD) was used to assess the outcome. The certainty of evidence was rated following the Grading of Recommendations Assessment and Development and Evaluation (GRADE) system. RESULTS: Three hundred twenty-seven Parkinson's disease and 312 healthy control subjects from five studies and 177 Parkinson's disease and 166 healthy control subjects from two studies were included in total α-synuclein levels and oligomeric α-synuclein levels analysis, respectively. Total α-synuclein level was not different between Parkinson's disease and healthy controls (MD = 0.02 ng/mL [95% confidence interval {CI}: 0.00 to 0.05 ng/mL; I2 = 90%; Z = 1.79; p=0.07; number of studies = 5; GRADE rating = very low]). Stratifying the data based on disease duration, total α-synuclein was higher in subjects with Parkinson's disease duration ≥7 years compared with healthy controls (MD = 0.04 ng/mL [95% CI: 0.03 to 0.05 ng/mL; I2 = 0%; Z = 8.24, p<0.00001; number of studies = 2; GRADE rating = low]) but not different between the two groups (MD = -0.12 ng/mL (95% CI: -0.38 to 0.15 ng/mL; I2 = 93%; Z = 0.84, p=0.40; number of studies = 3; GRADE rating = very low]). Oligomeric α-synuclein level was higher in Parkinson's disease compared with controls (MD = 6.50 ng/mL [95% CI: 2.79 to 10.20 ng/mL; I2 = 94%; Z = 3.44; p=0.0006; number of studies = 2; GRADE rating = very low]). LIMITATIONS: High heterogeneity between studies. Potential sources of heterogeneity could not be explored due to the limited number of studies. CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS: Tear α-synuclein has the potential to be a noninvasive biomarker for Parkinson's disease. Studies are, however, needed to increase certainty in the biomarker and establish how the protein's changes in tears correlate with Parkinson's disease progression and severity.

Efficacy comparison of combining cross-linking and refractive laser ablation in progressive keratoconus: systematic review and meta-analysis.

OBJECTIVE: This study assessed the effect of combining corneal collagen cross-linking (CXL) with refractive laser ablation techniques for the treatment of keratoconus, a progressive corneal disorder. METHODS: We performed a systematic review and meta-analysis to assess the effect of combined CXL and refractive techniques. We included all published clinical trials or observational studies published by September 1, 2023. We calculated and compared the standardized mean difference (SMD) between CXL alone and CXL plus laser ablation for uncorrected distance visual acuity, best-corrected distance visual acuity, spherical equivalent manifest refraction, sphere and cylinder, flat keratometry (K1), steep keratometry (K2), and central corneal thickness. RESULTS: We identified 13 studies that fulfilled our inclusion and exclusion criteria. The average follow-up was 21.3 ± 11.8 months. The CXL plus laser ablation group showed improvement in uncorrected distance visual acuity logMAR (SMD, -0.35; 95% CI, -0.67 to -0.04; p = 0.029), best-corrected distance visual acuity logMAR (SMD, -0.17; 95% CI, -0.30 to -0.03; p = 0.014), spherical equivalent manifest refraction (SMD, -0.28; 95% CI, 0.06-0.50; p = 0.013), and change in maximal corneal curvature (Kmax; SMD, -0.41; 95% CI, -0.69 to -0.13; p = 0.004) compared with CXL alone. However, central corneal thickness decreased further among patients who underwent CXL plus laser ablation (SMD, -0.37; 95% CI, -0.66 to -0.07; p = 0.016). No effect was observed in terms of sphere (p = 0.878), cylinder (p = 0.859), K1 (p = 0.907), or K2 (p = 0.169). Ectasia was not observed as an adverse effect resulting from the additional corneal ablation performed during the CXL treatments. CONCLUSIONS: This study showed that combining refractive laser ablation techniques with standard or accelerated CXL treatment improved visual and refractive outcomes and anterior corneal curvature values.

Association between Dyslipidemia and Meibomian Gland Dysfunction: A Systematic Review and Meta-Analysis.

PURPOSE: This study aimed to use meta-analysis to estimate the association between dyslipidemia and meibomian gland dysfunction. METHODS: The following databases were searched: PubMed, Google Scholar, and Scopus. Case-control and cohort studies assessing the association between dyslipidemia and meibomian gland dysfunction were included. The association was assessed using odds ratios. Heterogeneity between studies was assessed with the χ2 statistic and degree of inconsistency. The quality of studies was assessed using the Newcastle-Ottawa Scale. The systematic review was registered on PROSPERO (ID: CRD42022347982). RESULTS: The systematic review included three case-control and two cohort studies. The odds of hypercholesterolemia and hypertriglyceridemia in meibomian gland dysfunction were 5.45 (95% confidence interval [CI], 1.65 to 17.95) and 3.28 (95% CI, 1.25 to 8.62), respectively. The odds of elevated serum low-density lipoprotein and reduced high-density lipoprotein in meibomian gland dysfunction were 2.72 (95% CI, 1.24 to 5.98) and 1.15 (95% CI, 0.74 to 1.79), respectively. The current study's limitation is that the effects of sex, age, and meibomian gland dysfunction severity on the association between dyslipidemia and meibomian gland dysfunction were not assessed. CONCLUSIONS: The current study suggests a significant association between dyslipidemia and meibomian gland dysfunction. This finding suggests that meibomian gland dysfunction diagnosis may call for dyslipidemia screening.

Strabismus and amblyopia in Africa - a systematic review and meta-analysis.

The objective of this review was to estimate the prevalence of strabismus and amblyopia in Africa. A systematic online literature search was conducted for articles on strabismus and amblyopia in Africa. Meta-analysis was performed, using the Freeman-Tukey double arcsine transformation, to estimate the prevalence of strabismus and amblyopia in Africa. Subgroup analyses were conducted according to age, gender, study year, and type of amblyopia. Meta-regression was used to evaluate the influence of predetermined factors on the prevalence of amblyopia. 8 (1 population-based & 7 school-based) and 21 (3 population-based & 18 school-based) studies on strabismus and amblyopia with sample sizes of 22,355 and 46,841, respectively, were included in the review. Overall prevalence of strabismus in Africa was estimated to be 0.8% (95% CI: 0.4% - 1.4%); exotropia was 0.2% (95% CI: 0.1% - 0.5%) and esotropia was 0.5% (95% CI: 0.1% - 1.2%). Overall prevalence of amblyopia was estimated to be 0.6% (95% CI: 0.3% - 0.9%); refractive and strabismic amblyopia were 1.1% (95% CI: 0.2% - 2.5%) and 0.4% (95% CI: 0.2% - 0.6%), respectively. Prevalence estimate of amblyopia in males was 1.8% (95% CI: 0.7% - 3.3%) and in females was 1.3% (95% CI: 0.4% - 2.6%). There was a significant association between the prevalence of amblyopia and the type of amblyopia (p = .007) and the study year (p = .006). Although there appears to be a relatively low prevalence of strabismus and amblyopia in Africa, there is a dearth of well-designed population-based studies on strabismus and amblyopia in Africa, resulting in the lack of epidemiological information on strabismus and amblyopia within the general African population. Information about the prevalence of strabismus and amblyopia across Africa can inform policy making and design and implementation of public health intervention program.

Regional variations and temporal trends of childhood myopia prevalence in Africa: A systematic review and meta-analysis.

PURPOSE: To provide contemporary and future estimates of childhood myopia prevalence in Africa. METHODS: A systematic online literature search was conducted for articles on childhood (≤18 years) myopia (spherical equivalent [SE] ≤ -0.50D; high myopia: SE ≤ -6.00D) in Africa. Population- or school-based cross-sectional studies published from 1 Jan 2000 to 30 May 2021 were included. Meta-analysis using Freeman-Tukey double arcsine transformation was performed to estimate the prevalence of childhood myopia and high myopia. Myopia prevalence from subgroup analyses for age groups and settings were used as baseline for generating a prediction model using linear regression. RESULTS: Forty-two studies from 19 (of 54) African countries were included in the meta-analysis (N = 737,859). Overall prevalence of childhood myopia and high myopia were 4.7% (95% CI: 3.3%-6.5%) and 0.6% (95% CI: 0.2%-1.1%), respectively. Estimated prevalence across the African regions was highest in the North (6.8% [95% CI: 4.0%-10.2%]), followed by Southern (6.3% [95% CI: 3.9%-9.1%]), East (4.7% [95% CI: 3.1%-6.7%]) and West (3.5% [95% CI: 1.9%-6.3%]) Africa. Prevalence from 2011 to 2021 was approximately double that from 2000 to 2010 for all studies combined, and between 1.5 and 2.5 times higher for ages 5-11 and 12-18 years, for boys and girls and for urban and rural settings, separately. Childhood myopia prevalence is projected to increase in urban settings and older children to 11.1% and 10.8% by 2030, 14.4% and 14.1% by 2040 and 17.7% and 17.4% by 2050, respectively; marginally higher than projected in the overall population (16.4% by 2050). CONCLUSIONS: Childhood myopia prevalence has approximately doubled since 2010, with a further threefold increase predicted by 2050. Given this trajectory and the specific public health challenges in Africa, it is imperative to implement basic myopia prevention programmes, enhance spectacle coverage and ophthalmic services and generate more data to understand the changing myopia epidemiology to mitigate the expanding risk of the African population.

PREVALENCE OF MEIBOMIAN GLAND DYSFUNCTION IN AFRICA: A SYSTEMATIC REVIEW AND META-ANALYSIS OF OBSERVATIONAL STUDIES.

PURPOSE: To review and summarize information on meibomian gland dysfunction (MGD) epidemiology in Africa. METHODS: A systematic search of online databases was conducted for literature/studies on MGD in Africa. Meta-analysis was conducted to estimate the prevalence of MGD in Africa. Meta-regression was used to explore sources of heterogeneity. RESULTS: Twelve studies conducted in five countries were included in the review. All studies were hospital-based studies. Nine studies were included in the meta-analysis; the total sample size was 4963 and participants' age range was 17-96 years. The overall prevalence estimate of MGD in Africa was 45.9% (95% CI: 27.6-64.1%). Prevalence of MGD among males and females were each pooled from three studies and in urban and rural setting from 6 and 3 studies, respectively. Prevalence of MGD among males and females were 56.0% (95% CI: 22.4-89.5%) and 58.9% (95% CI: 28.5-89.4%) respectively; in urban and rural settings were 42.8% (95% CI: 21.1-64.5%) and 65.7% (95% CI: 25.7-95.7%), respectively. There was no association of MGD with sex (p = .872) and with study setting (p = .231). CONCLUSION: There is a paucity of evidence on MGD prevalence in Africa, emphasizing the need for epidemiological studies to enhance our understanding of region-specific differences in MGD in Africa. The pooled estimate from hospital-based studies, however, suggests a substantial MGD burden in Africa. Epidemiological studies are needed to assess if this translates to a high disease burden within the general African population.

Comparison of the performance of the dry eye questionnaire (DEQ-5) to the ocular surface disease index in a non-clinical population.

OBJECTIVE: To compare the performance of the dry eye questionnaire (DEQ-5) with the Ocular Surface Disease Index (OSDI) and further validate the DEQ-5 questionnaire. METHODS: A population-based cross-sectional study conducted in Ghana. OSDI and DEQ-5 questionnaires were administered to participants. Cronbach's alpha was used to evaluate the reliability of the OSDI and DEQ-5 questionnaires. Analysis of variance was used to evaluate the discriminant validity of DEQ-5. Concurrent validity was evaluated using the Spearman correlation analysis. A receiver operating characteristic (ROC) curve was generated to describe the sensitivity and specificity of the DEQ-5 questionnaire for diagnosis of dry eye symptoms. Cohen Kappa was used to evaluate agreement between the two questionnaires. RESULTS: The reliability of the overall OSDI and DEQ-5 scores were 0.919 and 0.819 respectively. The mean (SD) DEQ-5 scores for asymptomatic, mild, moderate and severe dry eye symptoms as defined by the OSDI grading were 3.05 (2.73), 5.13 (3.69), 7.65 (3.30) and 9.77 (4.16) respectively. There was a statistically significant correlation between total OSDI and total DEQ-5 scores (rs = 0.649, p < 0.0001). The area under the curve (AUC) of the ROC curve for DEQ-5 was 0.835 (95 % CI: 0.796 - 0.875). A DEQ-5 threshold of 5.5 yielded maximum sensitivity (0.712) and specificity (0.827). The Cohen kappa using a the DEQ-5 total score threshold of 5.5 was K = 0.539 (p < 0.0001). CONCLUSION: In conclusion, performance of the DEQ-5 questionnaire in discriminating symptoms of dry eye is comparable to the OSDI questionnaire. The DEQ-5 questionnaire is a valid measure of dry eye symptoms and can be used as a dry eye symptoms assessment tool in both clinical and epidemiological studies.

Keratoconus in Africa: A systematic review and meta-analysis.

PURPOSE: The aim of this review is to evaluate the prevalence of and factors associated with keratoconus in Africa. METHOD: A systematic online literature search was conducted for articles on keratoconus in Africa. Meta-analysis was performed to estimate the prevalence of keratoconus in Africa. The Freeman-Tukey double arcsine transformation was used to minimize the effects of studies with extremely high or low prevalence estimates on the overall pooled estimates. Leave-one-out sensitivity analysis was used to assess the robustness of the pooled effects and potential outliers. Meta-regression was performed to explore associations between keratoconus, gender and age. RESULTS: Twelve studies were included in the review; 5 from Egypt, 2 from South Africa, 2 from Kenya, 1 from Sudan, 1 from Ghana and 1 from Nigeria. Two studies were conducted in allergic conjunctivitis patients, 4 in keratoconus patients, 1 in contact lens service seekers, 1 in pre-LASIK patients, 1 in refractive patients and 1 in a student population. Eight studies were included in the meta-analysis. The overall prevalence estimate of keratoconus in Africa was 7.9% (95% CI: 2.5%-16.0%). The prevalence of keratoconus among males and females in Africa was estimated to be 9.3% (95% CI: 2.5%-19.5%) and 5.8% (95% CI: 1.5%-12.7%) respectively. The estimated prevalence of unilateral and bilateral keratoconus was 2.6% (95% CI: 0.4%-6.5%) and 5.8% (95% CI: 1.6%-12.3%), respectively. The estimated prevalence of mild keratoconus was 2.2% (95% CI: 0.7%-4.7%), moderate keratoconus was 3.5% (95% CI: 0.0%-11.8%) and severe keratoconus was 4.0% (95% CI: 0.0%-19.6%). There was no significant association between gender and the prevalence of keratoconus in Africa (p = 0.63), and age and the prevalence of keratoconus in Africa (p = 0.78). CONCLUSION: The estimated prevalence of keratoconus reported here is higher than prevalence values reported in other meta-analyses or different geographical locations. This is mainly because studies included in this meta-analysis were either conducted on a cohort at high risk of keratoconus or a population with high possibility of finding keratoconus patients. There is a dearth of well-designed population-based studies on keratoconus in Africa, resulting in a lack of epidemiological information. This highlights the urgent need for research on keratoconus in Africa.

Prevalence and associated risk factors of symptomatic dry eye in Ghana: A cross-sectional population-based study.

PURPOSE: This study sought to estimate the prevalence and associated risk factors of symptomatic dry eye in the general non-clinical Ghanaian population. METHODS: This was a cross-sectional population-based study conducted from November 2019 to February 2020. A stratified, multistage, random sampling technique was used to select participants aged 18 years and above from the capital cities of eight administrative regions in Ghana. Symptomatic dry eye was assessed using the Ocular Surface Disease Index questionnaire (OSDI). A study specific structured questionnaire was administered to collect information on participants' demographics and self-reported risk factors of dry eye disease such as smoking, diabetes, hypertension, arthritis, ocular allergies, pregnancy, contact lens wear, use of topical glaucoma medication and multivitamin supplement. Multiple linear regression analysis was used to explore associations between symptomatic dry eye and participant characteristics. A p-value of 0.05 was considered statistically significant. RESULTS: A total of 1316 individuals participated in the study [mean (SD) age 37.0 (15.72) years; range 18-90 years; 50.2 % males]. The prevalence of symptomatic dry eye was 69.3 % [95 % CI: 66.7 % - 71.7 %; mean (SD) OSDI score of 26.97 (21.52)]: 19.8 %, 16.6 % and 32.9 % mild, moderate and severe symptoms respectively. The most common ocular symptom was sensitivity to light (experienced at least some of the time), reported by 67.1 % of participants; most affected vision-related activity was reading (49.3 %); most common environmental trigger of dry eye symptoms was windy conditions (61.3 %). There was a significant positive association between symptomatic dry eye and age (p < .0001), female sex (p = .026), arthritis (p = .031), ocular surface allergy (p = .036) and regional zone (p = .043). CONCLUSION: There is a high prevalence of dry eye symptoms in Ghana. This represents a high dry eye disease burden and a significant public health problem that needs immediate attention.

Contact lens complications among wearers in Ghana.

PURPOSE: Contact lens (CL) practice is relatively new in Ghana; a country where the geographical location (warm climate) lends itself to harsh environmental conditions (high humidity) known to influence CL wear. Recent studies suggest an increase in CL wear (corrective and cosmetic), yet, there are no studies about CL-related complications. This study sought to determine the complications associated with CL wear in Ghana. METHODS: This was a retrospective cohort study. The medical records of contact lens wearers from five CL clinics in the two largest metropolises in Ghana, Accra and Kumasi, were reviewed. Included in the study were records of individuals who visited the clinics within the period of 2013-2016. Data on patients with contact lens-related complications were analyzed. RESULTS: The prevalence of CL complications was 29.06 %. The mean ±â€¯SD age of patients with CL complications was 35 ±â€¯15 years. Contact lens complications were more common in females (52.90 %). The majority of complications were in soft contact lens wearers (82.35 %). Refractive error correction was the most common indication for CL wear (61.76 %) among those with complications, followed by keratoconus (14.71 %), scarred blind eye (14.71 %), corneal ulcer (5.88 %) and anterior staphyloma (2.94 %). Contact lens complications reported were giant papillary conjunctivitis (41.18 %), corneal infiltrates (23.53 %), bacterial keratitis (14.71 %), corneal abrasion (11.76 %), dry eye (5.88 %) and corneal oedema (2.94 %). The causes of CL complication were inappropriate lens cleaning (29.41 %), poor hygiene (23.53 %), overnight contact lens wear (17.64 %), poor lens fit (14.71 %) and reaction to contact lens solution (14.71 %). CONCLUSION: Contact lens complications were more common in soft contact lens wearers in Ghana. Giant papillary conjunctivitis was the most common contact lens complication reported. Adherence to CL wear care regimen and good personal hygiene may prevent the majority of CL complications observed in Ghana.

Childhood Obesity and Overweight in Ghana: A Systematic Review and Meta-Analysis.

The increasing prevalence of childhood obesity and overweight is considered a public health issue in both developed and developing countries. This systematic review and meta-analysis estimates the prevalence of childhood obesity and overweight in Ghana. A multiple database search was conducted for articles published between January 1, 2001, and October 31, 2019, reporting the prevalence of childhood obesity and overweight in Ghana. Databases searched include PubMed, Google Scholar, Scopus, Cochrane Library, World Health Organization (WHO) Library Information System, and Africa Journals Online. Data were pooled from the articles to calculate an overall estimate of childhood obesity and overweight using a random-effects model after variance stabilization with Freeman-Tukey double arcsine transformation. This review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Sixteen studies with a combined sample size of 29,160 were included in the review. Analysis indicates that approximately 19% of children in Ghana either have obesity or are overweight. The prevalence of childhood obesity and overweight was 8.6% (95% CI: 4.8%-13.4%) and 10.7% (95% CI: 5.9%-16.6%), respectively. Although not significant, higher obesity (4.6% vs. 2.6%) and overweight (11.0% vs. 7.2%) prevalence were estimated for females than for males. There was a significantly higher obesity prevalence estimate (17.4% vs. 8.9%) in rural settings than in urban settings (p=0.0255). The high prevalence of childhood obesity and overweight estimated in this review is of worrying concern. It is a significant public health problem that has implications on the health of present and future generations in Ghana and as such calls for proactive measures to be put in place. Also, the driving forces behind the increasing prevalence of childhood obesity in Ghana need to be investigated.

Comparison of the clinical estimation of cup-to-disk ratio by direct ophthalmoscopy and optical coherence tomography.

OBJECTIVE: To compare the clinical estimation of cup-to-disk ratio determined by direct ophthalmoscopy and optical coherence tomography in glaucoma diagnosis and monitoring. METHODS: A retrospective, cross-sectional study involving a review of 71 optical coherence tomography scans dating from June 2011 to January 2012 at a private imaging lab in Ghana. At the respective referring facilities, only 31 out of the 71 corresponding patient records were successfully reviewed. RESULTS: Majority (54.84%) of the 31 patient records successfully reviewed were women. The mean age was 44.54 ± 16.15 years. Cup-to-disk ratio was grouped into ⩽0.4, >0.4-0.6, >0.6-0.8, and >0.8-1.0 based on direct ophthalmoscopy values. The overall mean cup-to-disk ratio estimated by the optical coherence tomography and direct ophthalmoscopy were 0.72 ± 0.21 and 0.60 ± 0.26, respectively. Overall, there was no statistically significant difference in the mean cup-to-disk ratio estimation by direct ophthalmoscopy and optical coherence tomography [right eye (p = 0.0629); left eye (p = 0.0766)]. There was a statistically significant difference between direct ophthalmoscopy and optical coherence tomography cup-to-disk ratio estimation for values ⩽0.4 [right eye (p = 0.0061); left eye (p = 0.0063)] and values >0.4-0.6 [right eye (p = 0.0243); left eye (p = 0.0498)]. There was no statistically significant difference between conventional direct ophthalmoscopy and optical coherence tomography cup-to-disk ratio estimation for cup-to-disk ratio >0.6. CONCLUSION: We recommend clinicians document which method they use in evaluating optic nerve head parameters. This is to ensure that subsequent clinical decisions are not influenced by an apparent change in these parameters, especially cup-to-disk ratio as different methods might give different values.