Ichiro Hamasaki1, Satoshi Hasebe2, Hiroshi Ohtsuki1. 1. Department of Ophthalmology, Okayama University, Graduate School of Medicine and Dentistry, Okayama, Japan. 2. Department of Ophthalmology, Okayama University, Graduate School of Medicine and Dentistry, Okayama, Japan. shasebe@md.okayama-u.ac.jp.
Abstract
PURPOSE: To determine the validity and usefulness of a newly developed measurement method of static ocular counterrolling (s-OCR) that eliminates false-torsion factors and to test the Jampel hypothesis that s-OCR does not exist. METHODS: A lightweight measurement device, consisting of a video camera, a coaxial light source, and a laser pointer projecting a fixation target on the wall, was fixed to a subject's head by means of a mouthpiece. In 11 healthy adults (mean age: 30 +/- 15 years), digital images of the right eye were captured while the subject kept his head tilted at a randomly selected angle ranging from 0 degrees to 50 degrees . By a frame-by-frame analysis of movements of the corneal light reflex and the iris patterns, OCR was evaluated. RESULTS: Torsional eye movement in the opposite direction to head tilt was found in all subjects. The amount of torsion continuously increased until the head-tilt angle reached 40 degrees. The average (+/- SD) amplitude of a fitted sine curve was 7.6 +/- 3.2 degrees (range: 4.3 degrees-10.3 degrees), and the individual amplitude was significantly larger than the test-retest repeatability of the measurement (+/-1.7 degrees). CONCLUSIONS: The measurement method used in this study provided good test-retest repeatability and ease of application. The characteristics of torsional eye movements that we observed after minimizing the false-torsion factors agree with previous reports supporting the existence of s-OCR.
PURPOSE: To determine the validity and usefulness of a newly developed measurement method of static ocular counterrolling (s-OCR) that eliminates false-torsion factors and to test the Jampel hypothesis that s-OCR does not exist. METHODS: A lightweight measurement device, consisting of a video camera, a coaxial light source, and a laser pointer projecting a fixation target on the wall, was fixed to a subject's head by means of a mouthpiece. In 11 healthy adults (mean age: 30 +/- 15 years), digital images of the right eye were captured while the subject kept his head tilted at a randomly selected angle ranging from 0 degrees to 50 degrees . By a frame-by-frame analysis of movements of the corneal light reflex and the iris patterns, OCR was evaluated. RESULTS: Torsional eye movement in the opposite direction to head tilt was found in all subjects. The amount of torsion continuously increased until the head-tilt angle reached 40 degrees. The average (+/- SD) amplitude of a fitted sine curve was 7.6 +/- 3.2 degrees (range: 4.3 degrees-10.3 degrees), and the individual amplitude was significantly larger than the test-retest repeatability of the measurement (+/-1.7 degrees). CONCLUSIONS: The measurement method used in this study provided good test-retest repeatability and ease of application. The characteristics of torsional eye movements that we observed after minimizing the false-torsion factors agree with previous reports supporting the existence of s-OCR.
Authors: Manokaraananthan Chandrakumar; Zahra Hirji; Herbert C Goltz; Giuseppe Mirabella; Alan W Blakeman; Linda Colpa; Agnes M F Wong Journal: Arch Ophthalmol Date: 2010-04
Authors: Herbert C Goltz; Giuseppe Mirabella; Joanne C Y Leung; Alan W Blakeman; Linda Colpa; Khaled Abuhaleeqa; Agnes M F Wong Journal: Vision Res Date: 2009-05-03 Impact factor: 1.886