Abstract
Purpose :
To describe a novel LED-based instrument for chromatic visual field perimetry and perform comparisons to a commercially-available field perimeter.
Methods :
An LED perimeter was developed using a black ganzfeld dome integrated with 15 LEDs. The LEDs were separated by 10 deg along the horizontal axis (70 deg nasal to 70 deg temporal). Chromaticity at each field location could be set by altering the luminance of 4 independent narrow-band LEDs (red, green, blue, amber). The stimulus size was equivalent to the Goldmann V (1.72 deg). During the test, all 15 locations were illuminated with achromatic light (0.5 cd/m2) and a red or blue luminance increment was presented at a randomly selected location for 100 ms. The subject indicated whether the stimulus increment was perceived and luminance sensitivity was measured using a 4-2-1-0.5 staircase procedure. Sensitivity for red and blue stimuli were measured for 5 healthy subjects, which were compared to their sensitivities measured with a commercially-available Octopus 900 perimeter (Haag-Streit). Stimulus and test characteristics of the Octopus perimeter approximated those of the LED perimeter. The correlation between sensitivity measured with the two perimeters was determined by Pearson correlation. In addition, Bland-Altman analyses were performed to compare sensitivities for the two tests.
Results :
Log sensitivity measured with the Octopus and LED perimeters were correlated for the red (r=0.89, p < 0.001) and blue (r=0.52, p = 0.003) stimuli. Bland-Altman analyses indicated that sensitivity for the red stimulus was 0.58 log units lower for the LED measurements than for the Octopus measurements, with the limits of agreement spanning ±0.52 log units. Sensitivity for the blue stimulus was 1.1 log units lower for the LED measurements than for the Octopus measurements, with the limits of agreement spanning approximately ±0.55 log units.
Conclusions :
The data indicate approximate agreement in sensitivity for the LED and Octopus perimeters. The explanation for the overall lower LED sensitivity remains to be determined, but differences in adapting field size and stimulus wavelength may play a role. The novel LED perimeter allows flexible control over stimulus chromatic and temporal characteristics, not possible with commercially-available field perimeters, which may be of use in future clinical studies.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.