ObjectiveTo evaluate the repeatability and reproducibility of macular ganglion cell-inner plexiform layer (GCIPL) thickness measurement using spectral-domain optical coherence tomography (Cirrus HD-OCT).
MethodOne hundred and eight eyes of 54 normal subjects (26 males and 28 females) between 19 and 75 years of age were included. Each eye underwent macular scanning using Cirrus HD-OCT Macular Cube 512×128 protocol by two operators. Three scans of each eye were obtained by each operator. For the right eye of each subject, three extra scans were obtained using Macular Cube 200×200 protocol by one operator. The average, minimum, superotemporal, superior, superonasal, inferonasal, inferior, and inferotemporal GCIPL thickness was analyzed and the repeatability of GCIPL thickness measurement was evaluated with intra-operator, inter-operator, intra-protocol, and inter-protocol intraclass correlation coefficients (ICC). Ten extra scans were obtained from the left eyes of 10 randomly selected subjects for reproducibility assessment with coefficients of variation (CV).
ResultsThe intra-operator ICC of macular GCIPL measurement using Macular Cube 512×128 protocol by two operators were 0.959-0.995 and 0.954-0.997, respectively; and the inter-operator ICC were 0.944-0.993. All intra-and inter-operator ICC were > 0.800 with the highest and lowest records of the average and minimum GCIPL thickness, respectively. The intra-protocol ICC of Macular Cube 512×128 protocol and Macular Cube 200×200 protocol were 0.986-0.996 and 0.927-0.997, respectively; and the inter-protocol ICC were 0.966-0.994. All intra-and inter-protocol ICC were > 0.800. CV of GCIPL thickness measurement using Macular Cube 512×128 protocol were (0.70±0.31)%-(1.35±0.86)%.
ConclusionCirrus HD-OCT can measure macular GCIPL thickness in normal eyes with excellent repeatability and reproducibility.
ObejctiveTo investigate the consistency and reproducibility of macular perfusion parameters in early diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA).MethodsA prospective cross-sectional observational study. Forty-six patients (46 eyes) diagnosed with mild nonproliferative DR were included in this study. There were 24 males and 22 females, with the mean age of 59.16±10.32 years. Two macular scan sizes of 3 mm×3 mm and 6 mm×6 mm were performed by the same operator, and the same test was performed by another operator. The superficial retinal layer (SRL) and deep retinal layer (DRL) in the foveal avascular zone (FAZ) and vessel density (VD) were quantified. The consistency of the two scan sizes and the reproducibility of the same scan size were also evaluated. The consistency was determined by the intraclass correlation coefficient (ICC). If the intraclass correlation coefficient (ICC)＞0.80, consistency was good; if 0.4≤ICC＜0.8, consistency was general; if ICC＜0.40, consistency was poor.ResultsIn the 3 mm×3 mm and 6 mm×6 mm scanning sizes, the mean results of the two examiners were calculated. The FAZ of SRL were 0.39±0.13 mm2 and 0.42±0.15 mm2, FAZ of DRL were 0.74±0.22 mm2 and 0.89±0.23 mm2. The VD of SRL were (32.23±2.86)% and (31.91±3.01)%, VD of DRL were (43.73±4.64)% and (45.12±5.49)%. The consistency analysis showed that the ICC of SRL-FAZ and DRL-FAZ were 0.920 and 0.812, respectively; the ICC of VD were 0.833 and 0.830, respectively. The consistency was good. The reproducibility analysis of different examiners in the same scan size was better in the consistency of SRL FAZ and VD.ConclusionOCTA in two scanning sizes to measure FAZ and VD of early DR has good consistency and reproducibility.
As the highest level of evidence in evidence-based medicine, systematic reviews have a profound impact on clinical practice and policy-making. However, challenges remain regarding the methodological rigor and reproducibility of their results. In recent years, replication research on systematic reviews has emerged as a critical approach to ensuring evidence quality, rational allocation of research resources and advancing evidence-based medicine. This article systematically reviews the theoretical foundations and research value of replication studies in systematic reviews, with a focus on their core design principles and implementation process. Key methodological steps are discussed, including assessing the necessity of replication, determining the type of replication, pre-registration, obtaining data and code, conducting independent re-analyses, and evaluating result consistency. Meanwhile, using the childhood deworming program as an illustrative case, we further outline the practical workflow of conducting replication research and demonstrate its importance in confirming the robustness of evidence and strengthening confidence in decision-making. In addition, this study synthesizes the methodological challenges encountered throughout the entire replication process, from literature searching to data analysis, and discusses future directions involving the integration of artificial intelligence, the development of reporting standards such as PRITERS, and the establishment of supportive research infrastructures. Overall, this work aims to provide methodological guidance for the standardized conduct of replication studies and to support the high-quality development of evidence-informed practice.
