The repeatability of the Goldmann-Weekers adaptometer for measuring cone adaptation

Abstract

To assess the inter-session repeatability of the Goldmann-Weekers adaptometer for the measurement of cone dark adaptation in a population of healthy subjects. Data were obtained from 31 healthy adults (mean age 21.5 ± 2.5) on 2 days. At each visit, pupils were dilated and a 96% bleach of cone photopigment was administered to the test eye before threshold was monitored continuously for 5 min in the dark using the Goldmann-Weekers adaptometer. A single exponential function was fitted to the threshold recovery data on a least squares basis. The coefficient of repeatability (CoR) was calculated to assess the repeatability of the time constant of recovery (τ), initial threshold and final threshold. Cone dark adaptation functions were successfully recorded from all subjects on both visits. The CoR was 79.48 s for τ, 0.71 log cdm(-2) for the initial threshold, and 0.58 log cdm(-2) for the final threshold. Paired samples t-tests showed that there were no significant differences between visits for any of the parameters assesed. Although the Goldmann-Weekers adaptometer was capable of monitoring the rapid changes in threshold that occur during cone dark adaptation, the CoR for τ was relatively large compared to the mean recovery time constants (126.48 ± 40.33 and 119.94 ± 33.25 s at the first and second visits, respectively). This indicates that the Goldmann-Weekers adaptometer is unlikely to be a useful instrument to chart changes in an individual's vision over time.

Measurement of cone dark adaptation: a comparison of four psychophysical methods

“…The CoR obtained for cone τ measured using the Goldmann-Weekers adaptometer in this study (1.18 +/-0.22 minutes) is consistent with previous reports [44]. Contrary to expectations, the repeatability of the Goldmann-Weekers adaptometer was similar to that of the computer based methods, despite the fact that, unlike the computer based methods, the stimuli presented by the Goldmann-Weekers adaptometer are controlled by an operator i.e.…”

Assessment of age changes and repeatability for computer-based rod dark adaptation

“…The general problem with the GWA is its poor repeatability for cone recovery. Gaffney et al [31] have shown a clinically unacceptable CoR for cone recovery time constant, and concluded that the GWA would not be a useful instrument for documenting visual changes in future clinical trials. Christoforidis and Zhang [32] also used GWA in a test–retest paradigm.…”