Abstract
Purpose :
Binocular adaptive optics visual simulators (B-AOVS) are useful instruments for combined optical and visual evaluation. However, most existing systems cannot properly manage eye convergence. The aim of this work was to develop a version of the B-VAOS incorporating automatic vergence control, allowing testing through controlled wavefront profiles under more realistic visual conditions.
Methods :
The instrument was adapted from a commercial monocular version of AOVS (VAO, Voptica SL, Murcia, Spain). Two screens are used for eye-independent stimulus presentation, while the optical paths are conjoined to use a single phase modulator for wavefront control, a Hartmann-Shack (HS) sensor for wavefront aberrations measurement, and a pupil camera for subject positioning. Additional modifications include an intensity modulator for artificial pupil control, an electrically tunable lens to increase measurement and correction ranges, and a periscope incorporating a stepper motor to control inter-pupillary distance and two servo motors to automatically set the vergence angle. As an example of application, visual acuity was measured under different convergence conditions with fixed focus at infinity for different amounts of induced high-order aberrations (HOA).
Results :
The instrument presents a measurement range of +/-15D in defocus and 1µm individual HOA (4.5-mm pupil). GPU processing allows real-time measurements in both eyes up to 7-mm pupils. A Full HD phase modulator allows for an even larger correction range. Together with a pupil tracking system, the periscope can automatically set any convergence up to 25 cm with an angular precision of 0.09 degrees. Preliminary results on the accommodation-convergence conflict show the expected drop in visual acuity for larger values of induced convergence. Adding spherical aberration seems to reverse this trend and to reduce visual fatigue, and coma produces smaller improvements while reducing overall visual acuity.
Conclusions :
A new version of B-VAOS simulator with automatic control of convergence has been developed. The performance of the device has been tested to further study the accommodation-convergence interaction under conflicting conditions, finding a reduction on visual fatigue with added aberrations. With the addition of convergence control, this device allows more realistic testing to better understand the impact of different optical profiles on depth of focus.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.