Assessment of binocular alignment using the three-dimensional Strabismus Photo Analyzer

Abstract

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.

Automated Analysis of Binocular Alignment Using an Infrared Camera and Selective Wavelength Filter

“…18 Secondly, the resolution and quality of the infrared images were not much affected by spectacle wear, and this is another major improvement from the previous version, which could not measure subjects wearing spectacles. 10 Finally, this method is simple and noninvasive. It requires minimal interpretation and can be implemented easily in normal clinical practice compared to eye tracking methods, such as scleral search coils or spectacle-mounted liquid crystal shutters.…”

“…10 This software shows excellent agreement with the Krimsky test, but cannot measure the latent component of strabismus, resulting in less correlation with the PCT. 10 To overcome this limitation, we developed an occluder made with a unique filter that blocks the subject's view and all visible light, but selectively transmits infrared light with wavelengths above 720 nm. Thus, photographs taken under infrared light with the selective wavelength filter in front of the eye visualize the details of the eye completely behind the occluder, while blocking the subject's view.…”

“…These images were preprocessed, registered, and analyzed automatically with the 3D Strabismus Photo Analyzer, of which the detailed mechanisms and procedures were introduced in our previous study. 10 The algorithms of the software were modified slightly from its prototype, and the angle kappa of each eye was estimated semiautomatically during fixation while the opposite eye was occluded. Measurements were taken with the selective wavelength filter in front of either eye and the mean value was noted.…”

“…While the recently reported software can detect only manifest strabismus, the inclusion of the selective wavelength filter allows automatic quantification of these dynamic properties of strabismus. 10 In our study, we evaluated the efficacy of automated image analysis using images acquired with a selective wavelength filter and an infrared video camera to estimate binocular alignment, and compared the results with the standard PCT.…”

“…There have been a few trials to interpret the Hirschberg test or Krimsky test objectively using photographic and videographic methods by estimating the displacement of the corneal light reflex to obtain the angle of ocular misalignment. [1][2][3][4][5][6][7][8][9][10] Few attempts have been made to measure and quantify automatically the dynamic and latent properties of strabismus associated with disruption of fusion. 11,12 Techniques that can analyze the PCT automatically require minimal operator interpretation, and this can improve the reliability of manual measurements, as well as being efficient and more applicable in clinical practice.…”