Visual discomfort while watching stereoscopic three-dimensional movies at the cinema Fabrizio Zeri 1 and Stefano Livi 2 1 Optics and Optometry, Department of Sciences, Roma Tre University, Rome, and 2 Department of Social and Developmental Psychology, University of Rome “Sapienza”, Rome, Italy Citation information: Zeri F, Livi S. Visual discomfort while watching stereoscopic three-dimensional movies at the cinema. Ophthalmic Physiol Opt 2015; 35: 271–282. doi: 10.1111/opo.12194 Keywords: 2D movie, stereoscopic three- dimensional movie, visual discomfort, visual symptoms Correspondence: Fabrizio Zeri E-mail address: fabrizio.zeri@uniroma1.it Received: 22 September 2014; Accepted: 13 December 2014; Published Online: 13 February 2015 Abstract Purpose: This study investigates discomfort symptoms while watching Stereo- scopic three-dimensional (S3D) movies in the ‘real’ condition of a cinema. In par- ticular, it had two main objectives: to evaluate the presence and nature of visual discomfort while watching S3D movies, and to compare visual symptoms during S3D and 2D viewing. Method: Cinema spectators of S3D or 2D films were interviewed by questionnaire at the theatre exit of different multiplex cinemas immediately after viewing a movie. Results: A total of 854 subjects were interviewed (mean age 23.7 Æ 10.9 years; range 8–81 years; 392 females and 462 males). Five hundred and ninety-nine of them viewed different S3D movies, and 255 subjects viewed a 2D version of a film seen in S3D by 251 subjects from the S3D group for a between-subjects design for that comparison. Exploratory factor analysis revealed two factors underlying symptoms: External Symptoms Factors (ESF) with a mean Æ S.D. symptom score of 1.51 Æ 0.58 comprised of eye burning, eye ache, eye strain, eye irritation and tearing; and Internal Symptoms Factors (ISF) with a mean Æ S.D. symptom score of 1.38 Æ 0.51 comprised of blur, double vision, headache, dizziness and nausea. ISF and ESF were significantly correlated (Spearman r = 0.55; p = 0.001) but with external symptoms significantly higher than internal ones (Wilcoxon Signed- ranks test; p = 0.001). The age of participants did not significantly affect symp- toms. However, females had higher scores than males for both ESF and ISF, and myopes had higher ISF scores than hyperopes. Newly released movies provided lower ESF scores than older movies, while the seat position of spectators had min- imal effect. Symptoms while viewing S3D movies were significantly and negatively correlated to the duration of wearing S3D glasses. Kruskal–Wallis results showed that symptoms were significantly greater for S3D compared to those of 2D mov- ies, both for ISF (p = 0.001) and for ESF (p = 0.001). Conclusions: In short, the analysis of the symptoms experienced by S3D movie spectators based on retrospective visual comfort assessments, showed a higher level of external symptoms (eye burning, eye ache, tearing, etc.) when compared to the internal ones that are typically more perceptual (blurred vision, double vision, headache, etc.). Furthermore, spectators of S3D movies reported statisti- cally higher symptoms when compared to 2D spectators. Introduction Since the beginning of the first decade of the twenty-first century, the world of cinematography has witnessed a sudden renaissance of stereoscopic three-dimensional (S3D) cinema. In this period, the number of S3D movies produced and distributed, as well as the number of theatres equipped with the available digital S3D screens, has steadily increased. © 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists Ophthalmic & Physiological Optics 35 (2015) 271–282 271 Ophthalmic & Physiological Optics ISSN 0275-5408