Understanding EOG Eye Velocity
Electrooculography records the voltage difference around the eye. The eye behaves like a small dipole. The cornea is usually positive. The retina is usually negative. When the eye rotates, the electrode voltage changes. A calibrated voltage change can therefore estimate angular movement.
Why Velocity Matters
Eye movement velocity describes how fast gaze changes. It is useful in physics labs, visual research, vestibular tests, interface studies, and biomedical signal projects. Slow values may show pursuit or drift. Larger values may indicate a saccade. The number is not a medical diagnosis. It is an estimate based on signal quality.
Calibration and Timing
Calibration is the most important input. It links voltage to degrees of eye rotation. A subject may look between known targets. The measured voltage difference is divided by the target angle. That gives microvolts per degree. Timing is also critical. A short interval can create a large velocity. A wrong sampling rate can distort the result. Use the same units for each trial.
Noise and Uncertainty
EOG signals contain baseline shifts, blink artifacts, electrode movement, and amplifier noise. The calculator lets you enter a noise floor and calibration error. These values build a practical uncertainty range. A strong signal compared with noise gives better confidence. A weak signal should be repeated or filtered.
Interpreting Results
Positive velocity means the ending voltage is greater than the starting voltage. Depending on electrode placement, that may represent rightward or upward motion. Negative velocity means the opposite direction. Always confirm polarity during calibration. The radian value is included for physics formulas. The degree value is easier for most eye movement reports.
Good Practice
Clean the skin before attaching electrodes. Keep leads still. Record a baseline. Ask the subject to avoid blinking during short trials. Use several repetitions. Compare results with known target movements. Export the result when you need lab records. The example table shows common input patterns. It helps you check whether your values are reasonable before running new measurements.
Limits of the Method
The calculation assumes a linear relationship across the measured range. Very large rotations may not stay linear. Electrode placement changes sensitivity. Treat outputs as engineering estimates. Confirm important findings with controlled calibration data whenever possible.