The Effect of 3D Visual Simulator on Children's Visual Acuity - A Pilot Study Comparing Two Different Modalities

Abstract

Purpose: To evaluate the efficacy of two non-surgical interventions of vision improvement in children.

Methods: A prospective, randomized, pilot study to compare fogging method and the use of head mounted 3D display. Subjects were children, between 5 to 15 years old, with normal best corrected visual acuity (BCVA) and up to -3D myopia. Subjects played a video game as near point work, and received one of the two methods of treatments. Measurements of uncorrected far visual acuity (UCVA), refraction with autorefractometer, and subjective accommodative amplitude were taken 3 times, at the baseline, after the near work, and after the treatment.

Results: Both methods applied after near work, improved UCVA. Head mounted 3D display group showed significant improvement in UCVA and resulted in better UCVA than baseline. Fogging group showed improvement in subjective accommodative amplitude. While 3D display group did not show change in the refraction, fogging group's myopic refraction showed significant increase indicating the eyes showed myopic change of eyes after near work and treatment.

Discussion: Despite our lack of clear knowledge in the mechanisms, both methods improved UCVA after the treatments. The improvement in UCVA was not correlated to measured refraction values.

Conclusion: UCVA after near work can be improved by repeating near and distant accommodation by fogging and 3D image viewing, although at the different degrees. Further investigation on mechanisms of improvements and their clinical significance are warranted.

Keywords: 3D; fogging; myopia; vision; visual acuity..

Fig. (1)

During the far accommodation, ciliary muscles relax, and the crystalline lens thickness decreases. On the other hand, ciliary muscles contract during near accommodation resulting in thicker lens.

Fig. (2)

The design of this study is a two-group randomized study, allocated subjects to either fogging or 3D viewing interventions.

Fig. (3)

Head mounted display system, Sky Crystal OLYMPUS POWER 3D. Manufactured by Olympus Visual Communications, Tokyo, Japan

Fig. (4)

Images used by head mounted display system.

Fig. (5a)

The mean Log MAR visual acuity measurements of both groups increased after visual burden, which means decreased vision, and patients’ eyes became more myopic. Subsequent treatment by either method improved the UCVA, but at the different degree.

Fig. (5b)

Near vision is the vision for objects 30cm form the viewer. In this normalized Diopter measurement, larger number indicates better near visual acuity. Group A subjects showed increased near vision measurements indicating the eyes were accommodated to view near objects, or became myopic, even after the treatment. Note: Diopter is the inverse of focal distance, and this is commonly used to show the degree of myopia. Normal vision, emmetropia is 0 D, meaning the image is formed on the retina. However, low myopia, which is from 0 to -3D forms image before reaching retina, indicated by negative figure. Medium myopia is between -3D to -6D, and high myopia is -6D or less. In this graph the normalized value is used that is without negative sign.

Fig. (5c)

Decreasing value in spherical equivalent means myopic change. Although the change in refraction was small, Group A showed increased myopia. Group B did not show the difference between baseline and post-treatment despite the change in UCVA.

Fig. (6a)

Group B had larger decrease in LogMAR visual acuity, meaning more improvement in UCVA. Significant difference was observed between two groups.

Fig. (6b)

No substantial difference in near point measurements.

Fig. (6c)

Refraction of the eyes changed after near work to post-treatment. The decrease in Group A shows the eyes were myopic. No significant change was observed in Group B.