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Original article
Assessment of binocular alignment using the three-dimensional Strabismus Photo Analyzer
  1. Hee Kyung Yang1,
  2. Sang Beom Han1,
  3. Jeong-Min Hwang1,
  4. Young Jae Kim2,
  5. Chang Bu Jeong2,
  6. Kwang Gi Kim2
  1. 1Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
  2. 2Biomedical Engineering Branch, Division of Convergence Technology, National Cancer Center, Goyang, Korea
  1. Correspondence to Dr Jeong-Min Hwang, Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, 166 Gumiro, Bundang-gu, Seongnam, Gyeonggi-do 463-707, Korea; hjm{at}


Aim To evaluate the efficacy of the three-dimensional (3D) Strabismus Photo Analyzer for estimating binocular alignment using photographs.

Methods Thirty-two subjects with exotropia, 30 subjects with esotropia and 38 orthotropic subjects were included. Two independent ophthalmologists examined the angle of deviation using the Krimsky test and prism and alternate cover test (PCT). Full-face photographs were obtained using an 8.2-megapixel digital single-lens reflex camera, and the images were analysed using the 3D Strabismus Photo Analyzer. The images were adjusted for age-dependent ophthalmic biometry and angle κ. The main outcome measures were inter-observer variability, test‐retest reliability and correlation between the angles of deviation measured by different methods.

Results The 95% limit of agreement of inter-observer variability was ±3.5° (6.1 prism dioptres (PD)), ±3.1° (5.4 PD) and ±1.5° (2.6 PD) for the Krimsky test, PCT and the 3D Strabismus Photo Analyzer, respectively. The test‐retest reliability was ±2.8° (4.9 PD) for the 3D Strabismus Photo Analyzer versus the Krimsky test. The results of the Krimsky test and 3D Strabismus Photo Analyzer showed a strong positive correlation.

Conclusions The 3D Strabismus Photo Analyzer is a simple and reliable tool for measuring ocular deviation. It has excellent agreement with the Krimsky test and substantially improved reproducibility.

  • Hirschberg
  • Krimsky
  • image analysis
  • strabismus
  • eye (globe)
  • field of vision
  • imaging
  • optic nerve
  • public health
  • child health (paediatrics)
  • diagnostic tests/investigation
  • glaucoma
  • retina
  • degeneration

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  • Funding This study was supported by a grant from the Seoul R&BD Program (ST090841).

  • Competing interests None.

  • Ethics approval Ethics approval was provided by the Institutional Review Board of Seoul National University Bundang Hospital. All aspects of the research protocol were in compliance with the Declarations of Helsinki.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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