Related Experiment Video
Updated: Jul 12, 2026
09:57
How to Measure Cortical Folding from MR Images: a Step-by-Step Tutorial to Compute Local Gyrification Index
Published on: January 2, 2012
27.8K
Comparison of Multiple Techniques for Measuring Geographic Atrophy: A Systematic Review and Network Meta-Analysis.
Ophthalmic Surgery, Lasers & Imaging Retina
|March 31, 2025
Summary
This study evaluated various geographic atrophy (GA) measurement techniques against standard autofluorescence blue (AF-Blue). Most methods showed fair agreement with AF-Blue, though some underestimated or overestimated GA.
Area of Science:
- Ophthalmology
- Medical Imaging
- Retinal Diseases
Background:
- Geographic atrophy (GA) is a leading cause of vision loss.
- Accurate measurement of GA progression is crucial for clinical trials and patient management.
- Standard autofluorescence blue (AF-Blue) is a common method for GA assessment.
Purpose of the Study:
- To compare the accuracy of various imaging techniques for measuring geographic atrophy (GA) against the standard autofluorescence blue (AF-Blue) method.
- To identify which GA measurement techniques demonstrate the best agreement with AF-Blue.
Main Methods:
- Bayesian network meta-analysis of studies comparing GA imaging techniques.
- Searched PubMed, Scopus, and Cochrane databases.
- Included 18 studies with 2,001 eyes, analyzing techniques such as color fundus photography (CFP), OCT angiography (OCTA), and optical coherence tomography fundus image (OFI).
Main Results:
- No significant differences were found among most GA measurement techniques compared to AF-Blue.
- Color fundus photography (CFP), OCT angiography (OCTA), en face sub-retinal pigment epithelium (SubRPE) slab, optical coherence tomography fundus image (OFI), and near-infrared reflectance (NIR) showed good agreement with AF-Blue.
- Autofluorescence green (AF-Green), fluorescein angiography (FA), and multicolor autofluorescence (MC-AF) underestimated GA, while autofluorescence infrared (AF-IR) overestimated it.
Conclusions:
- There is fair agreement between AF-Blue and several current techniques for measuring geographic atrophy (GA).
- CFP, OCTA, SubRPE slab, OFI, and NIR reflectance are reliable alternatives for GA measurement.
- Care should be taken when interpreting results from AF-Green, FA, MC-AF, and AF-IR due to under- or overestimation of GA.
Related Concept Videos
01:30Electronic Distance Measuring Instruments
Electronic Distance Measuring Instruments (EDMs) are essential tools in modern surveying, offering precise distance measurements by emitting electromagnetic signals and calculating the time required for these signals to travel to a target and return. Two primary types of signals are used in EDMs — light waves and microwaves — each suited to specific environmental and distance requirements. Light-wave-based EDMs utilize either infrared or laser light, providing high accuracy over short distances...
01:25Methods of Obtaining Topography
Topography involves measuring and mapping land elevations, natural features, and artificial structures to create accurate representations of the terrain. Topographic surveying relies on traditional and modern methods, each with distinct advantages and limitations.Traditional Surveying Methods:Transit stadia surveys and plane table surveys were widely used traditional surveying methods. These techniques relied on instruments like theodolites and stadia rods for measuring distances and angles,...
01:30Types of Global Positioning System Surveys
GPS surveying methods vary in application, accuracy, and data collection techniques, catering to diverse surveying and mapping needs. Static GPS, kinematic GPS, and real-time kinematic (RTK) surveying are widely used. Each technique offers distinct advantages.Static GPS involves placing one receiver at a known reference point and another at the target point. It collects exact positional data by observing multiple satellite ranges over an extended period, achieving centimeter-level accuracy for...
01:29Levels of Use of a GIS
Geographic Information Systems (GIS) operate across three levels of application, each representing an increasing degree of complexity: data management, analysis, and prediction. These levels reflect the expanding functionality and versatility of GIS technology in handling spatial data for diverse purposes.Data ManagementAt its foundational level, GIS serves as a tool for data management, enabling the input, storage, retrieval, and organization of spatial data. This level is often employed in...
01:23GIS Software, Hardware, and Sources of GIS Data
A Geographic Information System (GIS) combines specialized software and hardware to effectively manage, analyze, and present spatial and related data. GIS software includes critical functionalities such as a user interface for easy navigation, database management tools for handling spatial and attribute data, and data retrieval features for efficient access. Analytical tools transform raw data into insights, while display functions produce maps and reports in various formats for effective...
01:21Manipulation and Analysis
GIS manipulation and analysis functions are vital for decision-making and planning. These activities range from data retrieval tasks, such as selecting information based on specific criteria, to advanced analytical techniques that address complex spatial problems.One critical GIS analysis method is overlaying, which combines multiple data layers to examine impacts. For example, overlaying a river-dammed lake boundary with road networks can identify affected infrastructure. Another common...