Keratoconus in Africa: A systematic review and meta‐analysis

Abstract

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.

Retracted: The association between keratoconus and allergic eye diseases: A systematic review and meta‐analysis

“…A recent systematic review of 7 million participants found that KC incidence was 1.38 per 1000 population, 20 while another meta-analysis estimated KC rates in Africa to be 7.9%. 21 There may have been inherent bias in the selection criteria for the subjects within these studies, with many participants possessing predisposing factors that may have resulted in an increased incidence of KC among the studied population. These factors included the presence of allergic conjunctivitis, contact lens seekers, pre-LASIK patients, refractive patients, and students.…”

Childhood vision impairment and refractive error in Zimbabwe: A hospital-based retrospective study

“…In Africa, however, there is a paucity of knowledge on keratoconus. As stated by Akowuah et al ( 19 ) in a systematic review, the prevalence of keratoconus in Africa is 7.9 per cent, with limitations including studies conducted in highrisk populations. Masiwa and Moodley ( 20 ) observed in their review study that early diagnosis of keratoconus is critical for prompt intervention and a favourable prognosis, nevertheless, the patients in this study had a relatively high mean age (10.63) at presentation.…”

Evaluating the association between MPDZ-NF1B rs1324183 and keratoconus in an independent northwestern Chinese population

“…Results concerning gender and age preponderance on keratoconus vary between previous studies. Most of them demonstrated that gender and age both associated with high prevalence of KC [ 34 – 40 ], but some people reported that there was no gender preponderance in KC and also no significant association between age and the prevalence of KC [ 11 , 41 ]. In our study, no difference in gender and age between KC cases and controls could be because of the small number of subjects.…”