Does the dynamic cross cylinder test measure the accommodative response accurately?

BackgroundThe dynamic cross cylinder (DCC) test is a standard clinical procedure used to assess the accommodative response (AR) subjectively. However, because of potential problems arising from the ambiguous stimulus conditions, it is unclear whether this test provides an accurate measure of the AR. The aim of this study was to compare clinical subjective findings with objective measurements of the AR.MethodsSubjective findings to a 2.50-diopter (D) accommodative stimulus obtained with the DCC test (without fogging lenses) were compared with objective measurements of the AR obtained with a Grand Seiko WAM 5500 optometer (RyuSyo Industrial Co. Ltd., Kagawa, Japan) in 25 young subjects. As spherical lenses were introduced to quantify the subjective finding, objective measures of the AR were also recorded through these lenses.ResultsThe mean AR recorded subjectively and objectively was 2.35 and 1.68 D, respectively (P < 0.0001). Of the 10 subjects who demonstrated a lead of accommodation subjectively, only 1 had a lead objectively. For the 8 subjects who showed a lag of accommodation subjectively, all had a lag objectively. Introducing lenses produced a significant change in the mean AR.ConclusionThe subjective DCC test as performed here does not provide an accurate measurement of the AR to a near target in a young population. We recommend that alternative techniques such as using an objective, open-field optometer or Cross-Nott retinoscopy be adopted for determining the within-task AR.