Related Experiment Video
Updated: May 29, 2026
11:26
Ratiometric Calcium Imaging of Individual Neurons in Behaving Caenorhabditis Elegans
Published on: February 7, 2018
The rise and fall of caecanometry
Gregory L Stephens1, David Perrigin
1College of Optometry, University of Houston, 505 J. Davis Armistead Bldg., Houston, TX 77204-2020, USA. gstephens@uh.edu
Hindsight (Saint Louis, Mo.)
|September 23, 2011
Summary
Caecanometry was a visual fields exam technique from 1949 that linked blind spot size to infections. This method, mainly used in the southern US, became obsolete by the mid-1970s.
Area of Science:
- Ophthalmology
- Medical History
Background:
- Caecanometry was a visual fields examination technique introduced in 1949 by Ingwold Davidsen, O.D.
- It was based on the premise that blind spot size changes with specific infections.
Observation:
- The technique focused on the constriction of the blind spot.
- This constriction was hypothesized to correlate with infections located above the shoulder blades.
Findings:
- The Davidsen-Wottring caecanometer was patented to measure blind spot size and shape.
- Caecanometry was primarily practiced in the southern United States.
Implications:
- The technique represented an early, albeit short-lived, attempt to correlate visual field parameters with systemic health indicators.
- Its decline by the mid-1970s highlights the evolution of diagnostic methods in ophthalmology.
More Related Videos
08:09Measuring and Mapping Patterns of Soil Erosion and Deposition Related to Soil Carbonate Concentrations Under Agricultural Management
Published on: September 12, 2017
08:32PARbars: Cheap, Easy to Build Ceptometers for Continuous Measurement of Light Interception in Plant Canopies
Published on: May 9, 2019
Related Concept Videos
02:41Constant Volume Calorimetry
Calorimeters are useful to determine the heat released or absorbed by a chemical reaction. Coffee cup calorimeters are designed to operate at constant (atmospheric) pressure and are convenient to measure heat flow (or enthalpy change) accompanying processes that occur in solution at constant pressure. A different type of calorimeter that operates at constant volume, colloquially known as a bomb calorimeter, is used to measure the energy produced by reactions that yield large amounts of heat and...
01:05Gravimetry: Overview
Gravimetric analysis is a quantitative method where the analyte is isolated and weighed directly or after conversion into a substance of known composition. Gravimetric analysis can be classified as precipitation, electrogravimetry, volatilization, and particulate gravimetry, based on the method used to isolate the analyte.
In precipitation gravimetry, the analyte is converted into a precipitate and weighed. For example, the silver content in a sample can be estimated by precipitating and...
In precipitation gravimetry, the analyte is converted into a precipitate and weighed. For example, the silver content in a sample can be estimated by precipitating and...
01:03Precipitation Gravimetry
Precipitation gravimetry is based on converting an analyte into a sparingly soluble precipitate, which is separated by filtration and weighed. An ideal precipitate should be pure, insoluble, of known composition, and easily filtered from the reaction mixture.
In determining nickel by gravimetric analysis, a precipitant of ethanolic dimethylglyoxime is added to a hot nickel salt solution. This is quickly followed by the dropwise addition of dilute ammonia solution until precipitation occurs. A...
In determining nickel by gravimetric analysis, a precipitant of ethanolic dimethylglyoxime is added to a hot nickel salt solution. This is quickly followed by the dropwise addition of dilute ammonia solution until precipitation occurs. A...
01:12Instrument Calibration
Instrument calibration is essential for ensuring that instruments produce accurate and consistent results. It is vital in manufacturing, healthcare, testing laboratories, and scientific research. Calibration processes are specific to each instrument and help enhance data accuracy. Each instrument has a unique calibration process tailored to its design and function to improve data accuracy.
Analytical Balance Calibration
An analytical balance measures mass and requires regular calibration to...
Analytical Balance Calibration
An analytical balance measures mass and requires regular calibration to...
01:18Errors in Taping
Errors in taping arise from multiple factors that can significantly impact measurement accuracy in surveying. Misalignment of the tape, often due to human error, is one primary source. A skilled rear tapeman, using a telescope, can help correct alignment by guiding the head tapeman; however, human limitations still lead to small inaccuracies. These errors may include misplacement of pins or inaccurate tape readings due to common visual confusions, such as mistaking a six for a nine. Such...
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,...