The purpose of this research study is to see how well the treatment of a participant's eye coordination and/or focusing problems improves eye muscle responses and symptoms of eyestrain. We will use an entertainment device called a virtual reality headset to play a custom-designed video game to find out how well the treatment of binocular vision improves a participant's coordination and/or focusing problem. The virtual reality headset uses eye-trackers to monitor progress in a totally objective manner. Objective testing allows the doctor to determine the results without relying on a participant's ability to answer questions or respond verbally in any way. We will compare the results of a participant before and after playing the video game.

Inclusion Criteria:

• Age 9 years and older
• CISS score ≥ 16
• Best-corrected distance visual acuity of 20/25 or better in each eye
• Random dot stereopsis appreciation of 500 seconds of arc or better
• Parent or subject understands the protocol and is willing to enroll in the study

Exclusion Criteria:

• Constant strabismus at distance or near
• Vertical heterophoria ≥ 2 ∆ at distance or near
• ≥ 2 line interocular difference in best-corrected visual acuity
• Near point of accommodation > 20 cm in either eye as measured by push-up method
• Manifest or latent nystagmus
• Non-strabismic binocular vision and accommodative disorders associated with known disease of the brain
• Diseases known to affect accommodation, vergence, or ocular motility such as multiple sclerosis, Graves orbitopathy, myasthenia gravis, diabetes mellitus, Parkinson disease
• Any ocular or systemic medication known to affect accommodation or vergence such as anti-anxiety agents (e.g., Librium or Valium), anti-arrhythmic agents (e.g., Cifenline, Cibenzoline), anti-cholinergics, bladder spasmolytic drugs (e.g., Propiverine), hydroxychloroquine, chloroquine, phenothiazines (e.g., Compazine, Mellaril, Thorazine), tricyclic antidepressants (e.g., Elavil, Nortriptyline, Tofranil)
• Inability to comprehend and/or perform any study-related test or procedure

Examiner (Outcomes Assessor) will be masked by pooling participants from another study.