"Handbook of biomedical optics", edited by David A. Boas, Constantinos Pitris, and Nimmi Ramanujam

David A. Boas, Constantinos Pitris, and Nimmi Ramanujam, Eds.

A special section on the system and technology on health informative

Abstract is not available in fulltext

Disconjugacy Of Eye Alignment Is Greater With Near Fixation During Binocular Viewing In Amblyopia

"Binocular eye movements were recorded at 500 Hz using the EyeLink 1000 eye tracker (SR Research Ltd., Ontario, Canada). Twenty subjects (nine normal and eleven amblyopic; age: 8-45 years) were asked to fixate on a blue cross subtending 0.5° at a near distance of 57 cm or at a far distance of 4 m for 20-second epochs of binocular or monocular viewing. Disconjugacy of eye alignment was estimated by the area of the 68% bivariate contour ellipse (BCEA) for the difference between right and left eye positions, by the percentage of fixation time within a 0.1°x 0.1° range, and microsaccade characteristics. Mean ± standard error of the mean were shown, log(BCEA) was used to normalize the distribution, and significance testing was performed with the Student's t-test.

A device for continuous monitoring of true central fixation based on foveal birefringence

A device for continuous monitoring of central fixation utilizes birefringence, the property of the Henle fibers surrounding the human fovea, to change the polarization state of light. A circular scan of retinal birefringence, where the scanning circle encompasses the fovea, allows identification of true central fixation—an assessment much needed in various applications in ophthalmology, psychology, and psychiatry. The device allows continuous monitoring for central fixation over an extended period of time in the presence of fixation targets and distracting stimuli, which may be helpful in detecting attention deficit hyperactivity disorder, autism spectrum disorders, and other disorders characterized by changes in the subject’s ability to maintain fixation. A proof-of-concept has been obtained in a small study of ADHD patients and normal control subjects