Characteristics of accommodation toward apparent depth

Abstract

This paper deals with characteristics of accommodation evoked by perceived depth sensation and the dynamic relationship between accommodation and vergence, applying newly developed optical measurement apparatuses. A total of five subjects looked at three different two-dimensional stimuli and two different three-dimensional stimuli; namely a real image and a stereoscopic image. With regard to the two-dimensional stimuli, a manifest accommodation without any accompanying vergence was found because of an apparent depth sensation even though the target distance was kept constant. With regard to the three-dimensional stimuli, larger accommodation and clear vergence were evoked because of binocular parallax and a stronger depth sensation. As for the stereoscopic image, a manifest overshoot (the accommodation peaked first and receded considerably) was found while the vergence remained constant. On the other hand, the overshoot of accommodation was smaller when subjects were watching the real image. These results reveal that brain depth perception has a higher effect on accommodation than expected. The relationship of accommodation and vergence toward the stereoscopic image suggests a reason why severe visual fatigue is commonly experienced by many viewers using stereoscopic displays. It has also paved the way for the numerical analysis of the oculomotor triad system.

Visual Discomfort and Visual Fatigue of Stereoscopic Displays: A Review

“…6 Ocular Near Triad Accommodation, vergence, and pupillary dynamics, i.e., the ocular near triad, continuously interact to control the functioning of the eyes. 7 To obtain clear, binocular single vision, our eyes are accommodated and converged by an amount that depends on the distance between us and the object of interest. Vergence can be defined as movement of our eyes in opposite directions to locate the area of interest on the fovea and accommodation as alteration of the lens to obtain and maintain the area of interest focused on the fovea.…”

Predicting Visual Discomfort Using Object Size and Disparity Information in Stereoscopic Images

“…The vergenceaccommodation conflict is indeed an old issue that has been investigated by numerous studies [7], [10]- [13]. In the 90's, the research groups in [10], [11] reported that, in stereoscopic 3-D viewing, the vergence-accommodation conflict was one of the factors in determining visual discomfort and fatigue. Recent studies have provided empirical evidence that the vergence-accommodation conflict can cause visual discomfort and fatigue [4], [14], [15].…”

Binocular retinal scanning laser display with integrated focus cues for ocular accommodation

“…While changing vergence, the viewer is forced to maintain accommodation at a static level to keep the screens in focus. Takeda et al (1999) found significant amounts of accommodation to stereoscopic images in a simulated virtual display. In keeping with the findings by Takeda and colleagues, Inoue and Ohzu (1997) found that pronounced accommodation responses occur when viewing stereo pairs.…”