Purpose
To study the accommodative dynamics when the accommodative demand (AD) is changed in an unpredictable manner during an accommodative facility test.
Methods
Seventeen young healthy subjects (mean age ± standard deviation (SD) of 23 ± 2) were measured monocularly 2 consecutive times with 5 different tests. The first two were the conventional monocular accommodative facility tests for far and near distance performed with a manual flipper held by a clinician. The remaining 3 were automated and conducted using the electro-optical system with and open-field autorefractor. Two out of the 3 automated tests replicated the conventional accommodative facility tests for far and near distances. The last automated test was a hybrid approach where both far and near accommodative facility tests were automated and integrated into only one test that randomized among the 4 accommodative demands.
Results
The within-subject standard deviations for far and near distance obtained with the manual flipper accommodative facility test were: ±1 and ±1 cpm. Analogously for the automated test: ±3 and ±4 cpm. The 95% limits of agreement between the manual and the automated test for far and near distance were: (-18, 12) and (-15, 3). In regards to accommodation dynamics of the hybrid test: the response time and accommodative response were significantly (p<0.05) larger for accommodation than disaccommodation for high accommodative demands only. The response times during the transitions 0.17/2.17 D and 0.50/4.50 D were not significantly different between the hybrid and the conventional automated tests.
Conclusions
The automated accommodative facility test does not agree well with the manual flipper test for both far and near distances. It is likely that the operator delay when flipping the lens account for the differences. The hybrid test is able to provide a more comprehensive examination of the accommodative capability to change focus over time than the conventional accommodative facility test. Unexpectedly, the unpredictability of the stimulus did not to affect accommodation dynamics.
