Static and dynamic accommodation measured using the WAM-5500 Autorefractor.

PURPOSE

This study was undertaken to compare static and dynamic accommodation measurements using the Grand Seiko WR-5500 (WAM) in young, phakic subjects.

METHODS

Fifteen subjects, aged 20 to 28 years (23.8 ± 0.58 years; mean ± SD years) participated. Accommodation was stimulated with printed text presented at various distances. In static mode, three measurements were taken for each stimulus amplitude. In dynamic mode, 5-Hz recordings were started, and subjects alternately looked through a transparent near chart and focused on a letter chart at 6 m for 5 seconds and then focused on the near letter chart for 5 seconds for a total of 30 seconds. After smoothing the raw data, the highest three individual values recorded in each 5-s interval of focusing at near were averaged for each stimulus amplitude. Analysis of variance and Bland-Altman analysis were used to compare the static and dynamic measurements. A calibration was performed with +3.00 to -10.00 D trial lenses behind an infrared filter, in 1.00 D steps in 5 of the 15 subjects.

RESULTS

Stimulus-response graphs from static and dynamic modes were not significantly different in the lower stimulus range (<5.00 D, p = 0.93), but differed significantly for the higher stimulus amplitudes (p = 0.0027). One of the 15 subjects showed a significant difference between the static and dynamic modes. Corresponding pupil diameter could be recorded along with the accommodation responses for the subjects, and pupil diameter decreased with increasing stimulus demand. Calibration curves for static and dynamic measurements were not significantly different from the 1:1 line or from each other (p = 0.32).

CONCLUSIONS

Slight differences between the dynamically and statically recorded response amplitudes were identified. This is attributed to differences in the accommodative responses in this population and not to the instrument performance. Dynamic measurement of accommodation and pupil constriction potentially provides additional useful information on the accommodative response other than simply the response amplitude.