Eyestrain (asthenopia) triggered by viewing 3D television may be linked with exophoria.
A new study in this month's Journal of Paediatric Ophthalmology and Strabismus has assessed 115 patients who viewed 3D high definition television for 90 minutes.
The 14 patients who reported asthenopic symptoms (ocular and non-ocular pain, dizziness or image blurring) were then compared with 22 asymptomatic patients. The only statistically significant difference between the two groups was an increased prevalence of exophoria in the symptomatic group. The exophoria is normally compensated, but extra vergence is required for 3D viewing which may lead to the symptoms.
'Although more frequent relaxation periods may be advisable for achievement of reduced symptomatology, there is no evidence to show that these 3D asthenopic symptoms are harmful to the visual system,' the study authors said.