Akihiro Sugiura

Effect of strategic accommodation training by wide stereoscopic movie presentation on myopic young people of visual acuity and asthenopia

The abnormal contraction of ciliary muscles due to the performance of a near visual task for several hours causes various vision problems such as asthenopia and visual loss. However, these problems can be resolved by activating the muscles by alternately repeating negative and positive accommodation. In this study, we have verified the effect of accommodation training that uses the strategy of presenting a stereoscopic movie to myopic youth and measuring the uncorrected distant visual acuity, spherical diopter (SPH), a flicker test and subjective index of asthenopia obtained using a visual analog scale (VAS). Stereoscopic movies are prepared by using the POWER 3D method (Olympus Visual Communications Co., Ltd.), which reduces the inconsistency between the experienced and the actual senses. Thirty-two myopic students aged 20 ± 1 years (16 males and 16 females) were chosen as the subjects. One group performed the accommodation training for 6 min, and the other group underwent a near visual task during the same period as the control group. We concluded that the accommodation training using a stereoscopic movie had temporarily improved visual acuity. This training seemed to lead to a decrease in asthenopia.

Effect of an Eyesight Recovering Stereoscopic Movie System on Visual Acuity of middle-aged and Myopic Young People

By relaxing the contracted focus-adjustment muscles around the eyeball, such as the ciliary and extraocular muscles, improvement of the pseudo-myopia is expected. This understanding has led to the development of an eyesight recovering apparatus called Dr.REX, which uses stereoscopic video. In this study, we verify effects of the apparatus on eyesight of myopic young persons (16M & 16F) and 12 middle-aged persons. In the Measurement 1, the young were examined in the medium-range (>10 days) effect. Moreover, the middle-aged were investigated on several trials of the eyesight recovering apparatus in the Measurement 2. As a result, the visual acuity was statistically improved by continuous DR.REX treatment. We considered that the effect of the visual acuity recovery device is temporary, but the findings suggested that the continuous use of DR.REX will promote a ciliary muscle-stretching effect, leading to the improvement of visual acuity.

A Temporal Analysis of Body Sway Caused by Self-Motion During Stereoscopic Viewing

While continuously viewing objects in motion, humans may develop an illusionary sense of moving in the opposite direction as the objects, despite being quiescent. This phenomenon is termed as vection. In this study, we investigated the effect of long-duration viewing through binocular stereopsis on vection by measuring the body sway. Subjects watched a static movie for a minute, sinusoidal-motion movie at 0.3 Hz for 3 min, and the initial static movie for a minute, in sequence. We had three observations from the results of this study. First, the longer the viewing time, the higher the synchrony with direction of motion in the movie. Stoppage of the motion-movie and returning to viewing a static movie decreases the synchrony gradually. Second, synchrony is higher while viewing a 3D- than a 2D-movie. Third, the body sways in the anteroposterior direction in a cyclical manner by sensing self-motion in the horizontal direction.

Effects of Two-Minute Stereoscopic Viewing on Human Balance Function

Recently, with the rapid progress in image processing and three-dimensional (3D) technologies, stereoscopic images are not only available on television but also in theaters, on game machines, and elsewhere. In contrast to two-dimensional (2D) films that project flat images, stereoscopic films elicit the feeling of being at a live performance. However, asthenopia and visually-induced motion sickness (VIMS) can result from the exposure to these films. Even though various hypotheses exist, the pathogenesis of VIMS is still unclear. There is not enough knowledge on the effects of stereoscopic images on the living body, and the accumulation of basic research is thus important. The aim of this paper is to accumulate information relevant to VIMS and to examine whether the exposure to 3D video clips affects the human equilibrium functions. We evaluated body sway by conducting stabilometry studies. As a result, we verified that 3D viewing effects on our equilibrium function depends on exposure time.

Temporal Analysis of Body Sway during Reciprocator Motion Movie Viewing

OBJECTIVES We aimed to investigate the effect of stereoscopic viewing and the degree of awareness of motion sickness on posture by measuring body sway during motion movie viewing. METHODS Nineteen students (12 men and 7 women; age range, 21-24 years) participated in this study. The movie, which showed several balls randomly positioned, was projected on a white wall 2 m in front of the subjects through a two-dimensional (2-D)/three-dimensional (3-D) convertible projector. To measure body sway during movie viewing, the subjects stood statically erect on a Wii balance board, with the toe opening at 18 degrees. The study protocol was as follows: The subjects watched (1) a nonmoving movie for 1 minute as the pretest and then (2) a round-trip sinusoidally moving-in-depth-direction movie for 3 minutes. (3) The initial static movie was shown again for 1 minute. Steps (2) and (3) were treated as one trial, after which two trials (2-D and 3-D movies) were performed in a random sequence. RESULTS In this study, we found that posture changed according to the motion in the movie and that the longer the viewing time, the higher the synchronization accuracy. These tendencies depended on the level of awareness of motion sickness or the 3-D movie viewed. CONCLUSIONS The mechanism of postural change in movie viewing was not vection but self-defense to resolve sensory conflict between visual information (spatial swing) and equilibrium sense (motionlessness).

Experimental study on control of visually evoked postural responses by galvanic vestibular stimulation

Visually evoked postural responses (VEPRs) are physiological responses to perceived motion that are related to visually induced motion sickness (VIMS). We considered that VEPRs are just a conflict correction response aimed at matching information from the senses of vision and equilibrium. We also believe that understanding the consequences of suppression or acceleration of VEPRs may elucidate the pathogenic mechanism of VIMS and help establish methods for preventing VIMS. Our group has developed a system combining digital imagery and galvanic vestibular stimulation (GVS) to manipulate VEPRs. In this study, we attempted to verify a method of extrinsically controlling VEPRs. We determined the GVS current values that induced loss of motion sensation in subjects watching moving objects, measured body sway under different movie speed and GVS-off or on conditions, and tested whether GVS could counteract VEPRs. The results clearly showed that 1) the GVS current value increased along with increased motion speed observed in a video, and 2) it was possible to control VEPRs by GVS. However, it was difficult to completely control VEPRs by GVS, possibly because characteristics of posture can change based on the allocation of consciousness.

A Study on Within-Subject Factors for Visually Induced Motion Sickness by Using 8K Display

Visually induced self-motion perception (vection) is one of the phenomena related to human vision. It often emerges as a precursory symptom of motion sickness while viewing moving images. Employing a large number of subjects in a wide range of age groups and using a large-scale 8 K display, we investigated within-subject factors which can influence a sense of vection. We report some results of statistical analyses of vection-induced body sway which occurred when the subjects viewed rotating images on the display. Then we find that our fundamental study may provide useful information in order to set safety guidelines for large-scale ultra-high-definition displays such as 4K and 8K which are becoming popular in public use.

Effect of Controlled Consciousness on Sense of Presence and Visually Induced Motion Sickness While Viewing Stereoscopic Movies

In our previous study, we found it is possible to have an effect of change in the condition of consciousness (allocation of consciousness) on visually evoked postural response (VEPRs) Then, in this study, we verified effect of controlling consciousness on VEPRs, visually induced motion sickness (VIMS), a sense of presence while viewing 3D movies. Participants watched 3D movie consisted of several colored balls sinusoidal moving at 0.25 Hz in the depth direction for 3 min each under condition following pre-instruction. The detail of the pre-instruction were “sway body in a parallel/opposite direction”. The position of the body sway center of pressure was continuously recorded. As subjective evaluation, participants completed a simulator sickness questionnaire and reported three feelings (the sense of presence, motion and interactive) by using a visual analog scale. The results clearly showed that (1) The influence of pre-instruction appeared much stronger than that of VEPRs, and (2) The relationship between change in body sway and degree of VIMS or the feeling of presence do not always match under the situation included multi factors related to sense information or the condition of consciousness.

Effect of Reading a Book on a Tablet Computer on Cerebral Blood Flow in the Prefrontal Cortex

OBJECTIVES By measuring cerebral blood flow in the prefrontal cortex, we aimed to determine how reading a book on a tablet computer affects sleep. METHODS Seven students (7 men age range, 21-32 years) participated in this study. In a controlled illuminance environment, the subjects read a novel in printed form or on a tablet computer from any distance. As the subjects were reading, the cerebral blood flow in their prefrontal cortex was measured by near-infrared spectroscopy. The study protocol was as follows. 1) Subjects mentally counted a sequence of numbers for 30 s as a pretest to standardized thinking and then 2) read the novel for 10 min, using the printed book or tablet computer. In step 2), the use of the book or tablet computer was in a random sequence. Subjects rested between the two tasks. RESULTS Significantly increased brain activity (increase in regional cerebral blood flow) was observed following reading a novel on a tablet computer compared with that after reading a printed book. Furthermore, the region around Brocas area was more active when reading on a tablet computer than when reading a printed book. CONCLUSIONS Considering the results of this study and previous studies on physiological characteristics during nonrapid eye movement sleep, we concluded that reading a book on a tablet computer before the onset of sleep leads to the potential inhibition of sound sleep through mechanisms other than the suppression of melatonin secretion.

Temporal Evolution in Potential Functions While Peripheral Viewing Video Clips with/without Backgrounds

In daily life, stereoscopic image technology, such as 3D TV and movies, has become used in various places. Images, not limited to stereoscopic images, may exhibit unfavorable biological effects depending on the viewing and physical conditions, age, and individual differences. In our previous study, an increase was indicated in the sway values that were observed while/after peripheral viewing a stereoscopic video clip. Backgrounds are considered to affect our balance function. We examine the effect of the exposure to stereoscopic video clips without the background on our equilibrium function paper, and fifteen healthy young males voluntarily participated in the present study. Their stabilograms were recorded during monocular vision or binocular parallax vision using semipermeable smart glasses, where the subjects maintained the Romberg posture in stabilometry. We also measured the body sway with the subjects’ eyes closed 0–3 min after the exposure to the video clips. We herein compare the temporal averaged potential functions to control the standing posture during the exposure to 2D/3D video clips with those after the exposure.