Applied Sciences (Jul 2021)
Accommodative Relaxation by Extending the Viewing Distance through the Simple Optical Design of a Double-Mirror System
Abstract
Purpose: This paper discusses the accommodative relaxation of myopic adults using a simple double-mirror design. This optical design can extend the viewing distance to 2.285 m and can magnify the image up to 3.386 times, and it results in the accommodative relaxation of a single human eye. By using this optical design, accommodative relaxation may improve eye fatigue and, furthermore, it may delay the progression of myopia. Method: This study recruited 32 subjects with an average age of 20.8 ± 0.95 years old. After an examination of their refractive status, disposable contact lenses with a corresponding refractive error were fitted, and the dynamic accommodative response and change in pupil size were measured by using an open-field autorefractor. The subjects gazed at two different viewing distances. First, they gazed at a real object, which was placed 0.4 m in front of them. Second, the subjects gazed at a virtual image through a double-mirror system at a distance of 2.285 m. The dynamic accommodative responses and pupil size data were collected under these two viewing distance conditions. Results: When the subjects gazed at a real object that was 0.4 m away, or a virtual image that was 2.285 m away, the mean value of the accommodative response was 1.69 ± 0.31 D or 0.11 ± 0.05 D, and the pupil size was 3.79 ± 0.49 mm or 4.09 ± 0.72 mm, respectively. The accommodative response decreased, and the pupil size increased when using the double-mirror system, and therefore, accommodative relaxation can be achieved by using this new optical design. Conclusions: In the present study, we first successfully proposed a simple optical design to relax the accommodation, and the fluctuations of the accommodation response were stable, with an extended viewing distance of 2.285 m. This design may be applied for the improvement of visual function in applications such as the reduction of asthenopia and the control of myopia.
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