Related Experiment Video
Updated: Feb 3, 2026
08:27
Quantification of Oculomotor Responses and Accommodation Through Instrumentation and Analysis Toolboxes
Published on: March 3, 2023
1.5K
The Normal Accommodative Convergence/Accommodation (AC/A) Ratio.
1a Orthoptics and Vision Science , University of Liverpool , Brownlow Hill , United Kingdom.
Journal of Binocular Vision and Ocular Motility
|October 26, 2018
Summary
The Accommodative Convergence (PD)/Accommodation ratio (AC/A) was measured in visually normal individuals. Clinical methods yielded significantly different AC/A ratios, suggesting methods are not interchangeable.
Area of Science:
- Ophthalmology
- Optometry
- Vision Science
Background:
- The Accommodative Convergence (PD)/Accommodation ratio (AC/A) is a critical clinical measure.
- Standardized AC/A ratio values are widely accepted in clinical practice.
Purpose of the Study:
- To measure the AC/A ratio in a cohort of visually normal participants.
- To compare AC/A ratios obtained using common clinical methods.
Main Methods:
- Fifty visually normal subjects participated in the study.
- AC/A ratios were measured using four methods: distance gradient (DG), near gradient (NG), synoptophore gradient (SG), and heterophoria (H).
Main Results:
- Median AC/A ratios varied significantly across methods: NG (2.0), DG (1.0), SG (1.0), and H (5.0).
- Statistically significant differences were found between most method pairs (p < 0.05), except DG vs. SG.
- Lens power toleration and latent deviation influenced AC/A ratios in specific methods.
Conclusions:
- AC/A ratios in this cohort were lower than historical norms for gradient methods.
- Different clinical methods yield non-interchangeable AC/A values.
- A universal normal range for AC/A ratios should not be applied across all measurement techniques.
Related Concept Videos
01:54Convergent Evolution
32.9K
Evolution shapes the features of organisms over time, ensuring that they are suited for the environments in which they live. Sometimes, selection pressure leads to the rise of similar but unrelated adaptations in organisms with no recent common ancestors, a process known as convergent evolution.
32.9K
01:20AC Sources
4.1K
Direct current is a flow of electric charge in only one direction and has a steady state of constant voltage in the circuit. Rectifiers, batteries, commutator-equipped generators, and fuel cells are some examples of devices that generate direct current. Nowadays, most applications use a time-varying voltage source. Alternating current is a flow of electric charge that periodically reverses direction. An alternating current is produced by an alternating emf that is generated in a power plant. If...
4.1K
01:17Region of Convergence
925
The z-transform is a powerful mathematical tool used in the analysis of discrete-time signals and systems. It is a crucial tool in the analysis of discrete-time systems, but its convergence is limited to specific values of the complex variable z. This range of values, known as the Region of Convergence (ROC), is fundamental in determining the behavior and stability of a system or signal. The ROC defines the region in the complex plane where the z-transform converges, which can take various...
925
01:31Resistor in an AC Circuit
3.2K
An alternating emf or voltage source is needed to supply an alternating current (AC) to a circuit. A coil of wire rotating in a magnetic field at a constant angular speed represents such a source. It also generates a sinusoidal alternating emf and serves as an industrial alternator.
One-way current through the meter is measured using diodes. A diode is a device with better conductivity in one direction compared to the other; in its ideal state, it has zero resistance in one direction and allows...
One-way current through the meter is measured using diodes. A diode is a device with better conductivity in one direction compared to the other; in its ideal state, it has zero resistance in one direction and allows...
3.2K
01:26Power in an AC Circuit
2.3K
In a DC circuit, the power consumed is simply the product of the DC voltage times the DC current, given in watts. However, the power consumed for AC circuits with reactive components is calculated differently. Since electrical power is the "rate" at which energy is used in a circuit, all electrical and electronic components and devices have a safe operating range for electrical power.
In a DC circuit, there is no sinusoidal waveform associated with the supply; the voltages and currents are...
In a DC circuit, there is no sinusoidal waveform associated with the supply; the voltages and currents are...
2.3K
01:21Convergence of Fourier Series
401
The Fourier series is a powerful mathematical tool for representing periodic signals as an infinite sum of complex exponentials. In practice, this infinite series is truncated to a finite number of terms, yielding a partial sum. This truncation makes the approximation of the signal feasible but introduces certain challenges, particularly near discontinuities, known as the Gibbs phenomenon.
The Gibbs phenomenon refers to the persistent oscillations and overshoots that occur near discontinuities...
The Gibbs phenomenon refers to the persistent oscillations and overshoots that occur near discontinuities...
401