An exploration of the initial effects of stereoscopic displays on optometric parameters

Autostereoscopic 3D viewing can change the dimensions of the crystalline lens in myopes

PURPOSE

Autostereoscopic displays have become increasingly common, but their impact on ocular dimensions remains unknown. We sought to identify changes in the crystalline lens dimensions induced by autostereoscopic three-dimensional (3D) viewing.

METHODS

Forty young adults (age: 22.6 ± 2.0 years, male/female: 15/25) were consecutively enrolled and randomly divided into two groups (3D and two-dimensional [2D] viewing groups) to watch a 30-min movie clip displayed in 3D or 2D mode on a tablet computer. The lens thickness (LT), diameter, curvature, decentration and tilt were measured with anterior segment optical coherence tomography under both non-accommodating (static) and accommodating conditions.

RESULTS

In the static condition, the LT decreased by 0.03 ± 0.03 mm (p < 0.001) and the anterior radius of curvature (ARC) increased by 0.49 ± 0.59 mm (p = 0.001) post-3D viewing. In contrast, following 2D viewing, the ARC decreased by 0.23 ± 0.25 mm (p = 0.001). Additionally, the increase in the steep ARC post-3D viewing was greater in high-myopic eyes than low to moderate myopic eyes (p = 0.04). When comparing the accommodative with the static (non-accommodative) condition, for 3D viewing the lens decentration decreased (-0.03 ± 0.05 mm, p = 0.02); while for 2D viewing, the posterior curvature radius (-0.14 ± 0.20 mm, p = 0.006) and diameter (-0.13 ± 0.20 mm, p = 0.01) decreased.

CONCLUSIONS

Viewing with the autostereoscopic 3D tablet could temporally decrease the thickness and curvature of the lens under non-accommodating conditions. However, its long-term effect requires further exploration.

Study of the Immediate Effects of Autostereoscopic 3D Visual Training on the Accommodative Functions of Myopes

Purpose

Stereoscopic viewing has an impact on ocular dynamics, but its effects on accommodative functions are not fully understood, especially for autostereoscopic viewing. This study aimed to investigate the changes in dynamic accommodative response, accommodative amplitude, and accommodative facility of myopes after autostereoscopic visual training.

Methods

We enrolled 46 adults (men = 22 and women = 24; age = 21.5 ± 2.5 [range = 18–25] years, spherical equivalent: −4.52 ± 1.89 [−8.88 to −1.75] diopters [D]) who visited the Eye & ENT Hospital of Fudan University. The study population was randomly divided into three-dimensional (3D) and two-dimensional (2D) viewing groups to watch an 11-minute training video displayed in 3D or 2D mode. Dynamic accommodative response, accommodative facility, and accommodative amplitude were measured before, during, and immediately after the training. Accommodative lag and the variability of accommodation were also analyzed. Visual fatigue was evaluated subjectively using a questionnaire.

Results

Accommodative lag decreased from 0.54 ± 0.29 D to 0.42 ± 0.32 D (P = 0.004), whereas accommodative facility increased from 10.83 ± 4.55 cycles per minute (cpm) to 13.15 ± 5.25 cpm (P < 0.001) in the 3D group. In the 2D group, there was no significant change in the accommodative lag (P = 0.163) or facility (P = 0.975), but a decrease in accommodative amplitude was observed (from 13.88 ± 3.17 D to 12.71 ± 2.23 D, P = 0.013). In the 3D group, the accommodative response changed with the simulated target distance. Visual fatigue was relatively mild in both groups.

Conclusions

The immediate impact of autostereoscopic training included a decrease in the accommodative lag and an increase in the accommodative facility. However, the long-term effects of autostereoscopic training require further exploration.

Unexpectedly high prevalence of asthenopia in Australian school children identified by the CISS survey tool

Background

To date there have been few systematic attempts to establish the general prevalence of asthenopia in unselected populations of school-aged children. Thus, the aim of this study was to determine whether the incorporation of Borsting et al’s 2003 Revised Convergence-Insufficiency Symptom Survey (CISS) into a general school vision screening could aid in the identification of children with visual discomfort and indicate the need for further investigation.

Methods

Vision screening of an unselected middle school population investigated and analysed the incidence of self-reported nearwork-related visual discomfort via the CISS along with distance and near visual acuities plus non-cycloplegic autorefraction using a Shin-Nippon NVision-K 5001.

Results

Of the 384 unselected students approached in Grades 6–9, 353 participated (92.2%, mean 13.2 ± 1.4 years). The mean CISS score for the population without amblyopia and/or strabismus (96.0% of all students) was 16.8 ± 0.6, i.e., 45% of students in this cohort had CISS scores greater than one standard deviation above the mean found by Borsting et al. in 2003 during their validation study of the CISS on 9 to 18 year old children without binocular anomalies. Regression analyses indicated significantly higher (p < 0.001) mean CISS scores for the 3.2% who were hyperopes ≥ + 2.00D by non-cycloplegic autorefraction (27.7 ± 14.7) and for those who were amblyopic (24.3 ± 6.6) or strabismic (34.0 ± 9.8). The mean CISS score of 31.6 ± 9.0 for non-amblyopic/strabismic students having near vision poorer than 0.1 LogMAR was significantly higher (p < 0.001) than for those with good acuity.

Conclusion

The most important finding of this study was the high incidence of asthenopia in an unselected population and that refractive status per se was not a major contributor to CISS scores. The results highlight the usefulness of the CISS questionnaire for assessment of visual discomfort in school vision screenings and the need for future exploration of near binocular vision status as a potential driver of asthenopia in school students, especially given current trends for frequent daily use of computers and handheld devices and necessarily prolonged accommodative-convergence effort at near, both at school and at home.

Visual fatigue and discomfort after stereoscopic display viewing

PURPOSE

Different types of stereoscopic video displays have recently been introduced. We measured and compared visual fatigue and visual discomfort induced by viewing two different stereoscopic displays that either used the pattern retarder-spatial domain technology with linearly polarized three-dimensional technology or the circularly polarized three-dimensional technology using shutter glasses.

METHODS

During this observational cross-over study performed at two subsequent days, a video was watched by 30 subjects (age: 20-30 years). Half of the participants watched the screen with a pattern retard three-dimensional display at the first day and a shutter glasses three-dimensional display at the second day, and reverse. The study participants underwent a standardized interview on visual discomfort and fatigue, and a series of functional examinations prior to, and shortly after viewing the movie. Additionally, a subjective score for visual fatigue was given.

RESULTS

Accommodative magnitude (right eye: p < 0.001; left eye: p = 0.01), accommodative facility (p = 0.008), near-point convergence break-up point (p = 0.007), near-point convergence recover point (p = 0.001), negative (p = 0.03) and positive (p = 0.001) relative accommodation were significantly smaller, and the visual fatigue score was significantly higher (1.65 ± 1.18 versus 1.20 ± 1.03; p = 0.02) after viewing the shutter glasses three-dimensional display than after viewing the pattern retard three-dimensional display.

CONCLUSIONS

Stereoscopic viewing using pattern retard (polarized) three-dimensional displays as compared with stereoscopic viewing using shutter glasses three-dimensional displays resulted in significantly less visual fatigue as assessed subjectively, parallel to significantly better values of accommodation and convergence as measured objectively.

Stereoscopic 3D entertainment and its effect on viewing comfort: comparison of children and adults

Children's and adults' viewing comfort during stereoscopic three-dimensional film viewing and computer game playing was studied. Certain mild changes in visual function, heterophoria and near point of accommodation values, as well as eyestrain and visually induced motion sickness levels were found when single setups were compared. The viewing system had an influence on viewing comfort, in particular for eyestrain levels, but no clear difference between two- and three-dimensional systems was found. Additionally, certain mild changes in visual functions and visually induced motion sickness levels between adults and children were found. In general, all of the system-task combinations caused mild eyestrain and possible changes in visual functions, but these changes in magnitude were small. According to subjective opinions that further support these measurements, using a stereoscopic three-dimensional system for up to 2 h was acceptable for most of the users regardless of their age.