The accommodative response is more affected by the type of refractive error than the method of stimulation, field of view (FOV), or stimulus depth.
This study aims to analyze the effect of stimulation method, stimulus depth, and FOV on the accommodation response (AR) for emmetropes (EMM), late-onset myopes (LOM), and early-onset myopes (EOM).
Monocular AR was measured in 26 young observers (n = 9 EMM, n = 8 LOM, n = 9 EOM) under 60 different viewing conditions that were the result of permuting the following factors: (1) stimulation method (free space or Badal lens viewing), (2) stimulus depth (flat or volumetric), (3) FOV (2.5, 4, 8, 10, and 30°), and (4) accommodative stimulus (AS: 0.17, 2.50, and 5.00 diopters [D]).
Mixed analysis of variance for 2.50 D of AS resulted in a significant effect of refractive group (F = 6.77, P < .01) and FOV (F = 1.26, P = .04). There was also a significant interaction between stimulus depth and FOV (F = 2.73, P = .03) and among stimulation method, FOV, and refractive group (F = 2.42, P = .02). For AS of 5.00 D, there was a significant effect of refractive group (F = 13.88, P < .01) and stimulation method (F = 5.16, P = .03). There was also a significant interaction of stimulation method, stimulus depth, and refractive group (F = 4.08, P = .03). When controlling for all interactions, LOM showed larger lags than EMM and EOM; the AR did not significantly change for fields of 8, 10, and 30°, and it did not significantly differ for different stimulation methods or stimulus depth.
Previously reported differences in AR when using lens-based methods compared with free space viewing may be explained by the effect of other factors such as the FOV or the depth of the stimulus. Targets with an FOV of 8 or 10° may be optimal for accurate ARs.
1Davalor Research Center, Universitat Politècnica de Catalunya, Terrassa, Spain
2Center for Sensors, Instruments and Systems Development, Universitat Politècnica de Catalunya, Terrassa, Spain
3New England College of Optometry, Boston, Massachusetts *email@example.com
Submitted: November 14, 2016
Accepted: July 15, 2017
Funding/Support: This research was supported by the Spanish Ministry of Economy and Competitiveness under grant DPI2014-56850-R, the European Union, and by Davalor Salud, S.L. None of the institutions had a role in the realization of this article.
Conflict of Interest Disclosure: None of the authors have reported a conflict of interest.
Author Contributions and Acknowledgments: Conceptualization, Data Curation, Formal Analysis, Investigation, Methodology, Software, Supervision, Validation, Visualization, Writing – Original Draft, Writing – Review & Editing: CO; Conceptualization, Methodology, Supervision, Validation, Visualization, Writing – Review & Editing: MA; Conceptualization, Formal Analysis, Investigation, Methodology, Supervision, Visualization, Writing – Original Draft, Writing – Review & Editing: FAVD; Funding Acquisition, Project Administration, Resources, Supervision, Writing – Review & Editing: JP.
CO thanks the Generalitat de Catalunya for his awarded PhD studentship.