Long-term Visual and Refractive Outcomes of Argon Laser-treated Retinopathy of Prematurity

Purpose: In this case–control study, we measured visual acuity, objective refraction, ocular biometric parameters, and strabismus in premature cases classified according to the following categories: argon laser-treated retinopathy of prematurity (ROP), untreated spontaneously regressed ROP, no ROP, and full term controls. Methods: Cases with a history of prematurity at six years of age were categorized into the following groups: patients with a history of treated type 1 ROP using argon laser (group I), untreated spontaneously regressed ROP (group II), and no history of ROP (group III). Group IV included age-matched healthy full-term controls. Funduscopy was performed for all the cases and the control group. Results: In total, 24 eyes of 12 laser-treated ROP cases, 186 eyes of 93 spontaneously regressed ROP patients, 74 eyes of 37 premature cases with no history of ROP, and 286 eyes of 143 controls were included in the study. The mean spherical equivalent in the treated cases was not significantly different from that in the untreated cases and patients in group III. However, the average cylindrical power was significantly different among the groups (P < 0.004). Furthermore, anisometropia (≥1.5 diopter) was diagnosed with a higher rate in the treated cases (P = 0.03). The corneal curvature of the laser-treated eyes was significantly steeper and the axial length was significantly shorter than those in the other groups (P < 0.002 and P < 0.001, respectively, for multivariate analysis). Strabismus was found in three treated patients (25%). Additionally, there were three treated eyes (12.5%) diagnosed with macular dragging. Conclusion: Premature cases including those who had a history of argon laser-treated ROP and those with untreated spontaneously regressed ROP showed acceptable long-term visual and refractive outcomes along with a fairly low rate of ocular disorders

A comparative study of the impacts of unbalanced sample sizes on the four synthesized methods of meta-analytic structural equation modeling

Abstract Background In the first stage of meta-analytic structural equation modeling (MASEM), researchers synthesized studies using univariate meta-analysis (UM) and multivariate meta-analysis (MM) approaches. The MM approaches are known to be of better performance than the UM approaches in the meta-analysis with equal sized studies. However in real situations, where the studies might be of different sizes, the empirical performance of these approaches is yet to be studied in the first and second stages of MASEM. The present study aimed to evaluate the performance of the UM and MM methods, having unequal sample sizes in different primary studies. Testing the homogeneity of correlation matrices and the empirical power, estimating the pooled correlation matrix and also, estimating parameters of a path model were investigated using these approaches by simulation. Results The results of the first stage showed that Type I error rate was well under control at 0.05 level when the average sample sizes were 200 or more, irrespective of the types of the methods or the sample sizes used. Moreover, the relative percentage biases of the pooled correlation matrices were also lower than 2.5% for all methods. There was a dramatic decrease in the empirical power for all synthesis methods when the inequality of the sample sizes was increased. In fitting the path model at the second stage, MM methods provided better estimation of the parameters. Conclusions This study showed the different performance of the four methods in the statistical power, especially when the sample sizes of primary studies were highly unequal. Moreover, in fitting the path model, the MM approaches provided better estimation of the parameters

MOESM1 of A comparative study of the impacts of unbalanced sample sizes on the four synthesized methods of meta-analytic structural equation modeling

Additional file 1. Relative percentage biases of parameter estimates in the path model at stage 2. The table shows the bias values of parameter estimates for the studies with equal, moderately unequal and highly unequal samples in the path model. \bar{\varvec{n}} n ÂŻ Average sample sizes k number of studies UNIr univariate-r UNIz univariate-z MGLS modified generalized least squared TSSEM two-stage structural equation modeling

MOESM2 of A comparative study of the impacts of unbalanced sample sizes on the four synthesized methods of meta-analytic structural equation modeling

Additional file 2. Relative percentage biases of the standard error of parameter estimates in the path model at stage 2. The table shows the bias values of the standard errors of parameter estimates for the studies with equal, moderately unequal and highly unequal samples in the path model. \bar{\varvec{n}} n ÂŻ Average sample sizes k number of studies UNIr univariate-r UNIz univariate-z MGLS modified generalized least squared TSSEM two-stage structural equation modeling

Erratum to Long-term Visual and Refractive Outcomes of Argon Laser-treated Retinopathy of Prematurity

This is an Erratum to Long-term Visual and Refractive Outcomes of Argon Laser-treated Retinopathy of Prematurity. Please download the PDF or view the article HTML

Visual Impairment Prevalence, Causes, and Role of Healthcare Access: A Systematic Review and Meta-Analysis in Iran

Purpose. Healthcare access is one of the determinants of visual impairment (VI), as a public health problem. The objective of this study was to estimate VI prevalence, related causes, and its correlation with access to physicians in Iran. Methods: This systematic review and meta-analysis include observational studies published in Iran. PubMed, Web of Science, Scopus, Google Scholar, and local databases were systematically searched by using the MeSH headings. Data on the provincial distribution of physicians, as an index of access to healthcare, was retrieved. A random-effect meta-analysis was performed to assess. Results. Eight articles were included. The pooled prevalence of blindness, low vision, and VI was 0.80% (95% CI: 0.61–0.99%), 2.92% (95% CI: 2.40–3.44%), and 5.57% (95% CI: 4.71–6.43%). Refractive errors were the most common causes of VI based on PVA with the pooled prevalence of 54.6% (95% CI: 43.4–65.8%). Based on BCVA, we found that the pooled prevalence of cataracts was 37.4% (95% CI: 29.5–45.3%) as the most common cause of VI. The results of metaregression showed that the greater number of general practitioners (GPs) (P value=0.01) and pharmacists (P value=0.024) per population were associated with a lower prevalence of blindness. Conclusion. Some of the main causes of visual impairment in Iran are preventable. Access to healthcare services may lead to early diagnosis of preventable causes of VI. Further well-designed studies and national surveys should be conducted to provide accurate data from different regions of Iran