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Updated: Jan 17, 2026
Simulating the Mechanics of Lens Accommodation via a Manual Lens Stretcher
Published on: February 23, 2018
A feasibility study of real-time manipulation of blur feedback to accommodation using eccentric photorefraction and a
Praveen K Bandela1,2, Arthur Ho1,2, Eric Papas1
1School of Optometry and Vision Science, UNSW, Sydney, Australia.
Significance:
This study describes a new technique that integrates an electrically tunable lens with a dynamic infrared photorefractor for real-time manipulation of blur feedback for human ocular accommodation. This technique is straightforward to implement, and it also overcomes the limitations of present paradigms used for opening the blur-feedback loop (e.g., pinholes and low spatial frequency difference of Gaussian targets).
Purpose:
To describe and validate a technique for real-time manipulation of blur feedback for ocular accommodation by integrating an electrically tunable lens with a dynamic eccentric infrared photorefractor.
Methods:
The EL-16-40-TC-VIS electrically tunable lens (Optotune, Dietikon, Switzerland AG) and the PowerRef 3 eccentric infrared photorefractor (PlusOptix, Nuremberg, Germany) were independently calibrated and integrated via a Secure Shell network protocol. The electrically tunable lens was positioned before the right eye, which accommodated multiple times to 2D step changes in optical vergence. The photorefractor captured consensual accommodative changes through the infrared filter occluded left eye at 50 fps. Blur feedback to the right eye was canceled by feeding in the sign-reversed refraction data into the electrically tunable lens in real-time at 25 fps. The feasibility of this setup to minimize robust blur-driven accommodative step responses was tested on five pre-presbyopic adults.
Results:
All subjects showed robust monocular, blur-driven accommodative responses at baseline, with a median response magnitude of 1.54 D (1.47 D to 1.54 D). The responses were reduced to only baseline fluctuations following blur-feedback manipulation. The median response magnitude following blur-feedback manipulation (-0.34 D [-0.35 D to 0.09 D]) was significantly different from baseline values (Wilcoxon Sign rank test; p=0.043).
Conclusions:
The integration of an electrically tunable lens with the photorefractor provides a real-time method for manipulating blur feedback during ocular accommodation. This technique may be a promising tool for investigating sensorimotor properties of accommodation and refractive error development. Alternate schematics for manipulating the blur feedback, expanded operating range of the electrically tunable lens, and reduced signal transmission delays may be considered in the future to enhance the efficacy of this technique.
