Test-retest variability in visual field testing using frequency doubling technology

Area of Science:

• Ophthalmology
• Neuroscience
• Medical Technology

Background:

• Visual field (VF) testing is crucial for detecting and monitoring various ocular and neurological conditions.
• Frequency Doubling Technology (FDT) offers a unique method for assessing VF sensitivity.
• Understanding test-retest variability (TRV) is essential for accurate interpretation of VF results.

Purpose of the Study:

• To quantify the test-retest variability (TRV) in normal subjects using serial visual fields (VF) with the Frequency Doubling Technology (FDT) instrument.
• To assess the uniformity of TRV across different regions of the visual field.
• To compare FDT VF variability with other perimetric methods.

Main Methods:

• Twenty-one healthy adults (aged 23-60) underwent four serial FDT VF tests (Zeiss-Humphrey FDT analyzer, C-20 program) on one eye.
• Tests were spaced 2-4 days apart, with two preliminary tests to minimize learning effects.
• TRV was calculated as the standard deviation of sensitivity values at each location across the four tests.

Main Results:

• The mean TRV for the entire visual field was 2.44 ± 1.32 dB.
• Mean TRV was relatively uniform across superior, inferior, nasal, and temporal hemifields (ranging from 2.40 to 2.48 dB).
• TRV was also consistent across foveal, central, and peripheral locations (ranging from 2.16 to 2.54 dB).

Conclusions:

• Test-retest variability in FDT visual fields is uniform across the tested visual field.
• FDT VF variability is more consistent than standard and short-wavelength automated perimetry.
• A strong inverse correlation exists between mean sensitivity and TRV in normal subjects.