This article explored the perspectives of 25 patients regarding virtual reality (VR)-based rehabilitation following knee surgery and identified the important factors that allowed patients to immerse themselves in rehabilitation. Qualitative analysis of data collected via open-ended questionnaire and quantitative analysis of data from physical assessments and surveys were conducted. In the open-ended questionnaire, the majority of participants mentioned level of difficulty as the most common reason for selecting both the most and the least immersive exercise programs. Quantitative analysis showed that participants experienced a high level of flow (3.9 +/- 0.3 out of 5.0) and a high rate of expectation of therapeutic effect (96%) and intention of exercise adherence (96%). Further, participants with more severe pain or physical dysfunction tended to have more positive experiences (e.g., Difficulty-Skill Balance, Clear Goals, and Transformation of Time), leading to high levels of flow during VR-based rehabilitation. In conclusion, VR-based games are potentially acceptable as a motivational rehabilitation tool for patients following knee surgery. However, to best meet patients' needs, it might be useful to equip a VR program with varied levels of difficulty, taking into account the severity of the individual's knee injury. Additionally, severe pain or physical dysfunction might act as an indication rather than a contraindication for VR-based rehabilitation.

Purpose: Watching three-dimensional (3D) images is known to induce ocular and non-ocular symptoms, such as eye discomfort, fatigue, headache, and nausea, which can be referred to as “3D asthenopia”. This study investigated ophthalmic factors associated with 3D asthenopia. Methods: One hundred fifteen volunteers, aged 18 to 55 years, were enrolled in this study. 3D images were shown to all volunteers with 3D high-definition television for 90 minutes. Subjects who felt eyestrain were assigned to the asthenopia group (14 subjects) and subjects without symptoms were assigned to the control group (22 subjects). Ophthalmic factors including visual acuity, refractive errors, interpupillary distance, intraocular pressure, tear break-up time, near point of accommodation, presence of strabismus, stereoacuity, and retinal abnormalities were evaluated and compared between the two groups. Results: Six subjects in the asthenopia group had exophoria and 1 subject in the control group had constant exotropia. None of these participants had previously noticed symptoms of strabismus. Only the presence of strabismus was significantly different between the groups ( P = .008). Conclusion: The presence of exophoria may be a risk factor for 3D asthenopia, and 3D television may induce asthenopia by exacerbating this latent problem.