Norra MacReady

April 11, 2011

April 11, 2011 (San Diego, California) — Poor coordination might be added to the list of woes experienced by children with deficient stereopsis or amblyopia, according to findings presented here at the American Society of Pediatric Ophthalmology and Strabismus 37th Annual Meeting.

"As well as dealing with squint and amblyopia, these children have to deal with being clumsy," John J. Sloper, PhD, said in an oral presentation of the data.

Usually, stereoscopic feedback is incorporated into the visual control of reaching and grasping movements by the time a child reaches 9 years of age; this is impaired in children with poor stereopsis or amblyopia, explained Dr. Sloper, from Moorfields Eye Hospital, London, United Kingdom.

To examine the effect of this impairment on eye–hand coordination, Dr. Sloper and colleagues compared the speed and accuracy of reaching and grasping under binocular and monocular conditions in 21 children with amblyopia and deficient stereopsis and 15 normal children. All of the children ranged from 4 to 8 years of age.

The investigators used a 3-dimensional motion-capture vision system, consisting of 3 infrared cameras, to record hand movements involved in reaching and grasping 2 different-sized objects in 3 locations. The system had a spatial resolution of less than 0.5 mm and a temporal resolution of 16.67 ms. The movement parameters measured included speed (movement time, peak velocity, and time to peak deceleration) and accuracy (velocity corrections, path adjustments, and collisions). Grasp parameters included precontact components (such as width of peak grip and grip closure time) and grip errors (such as precontact adjustments and postcontact corrections).

The children with amblyopia had significantly slower movement times in all 3 conditions tested (with binocular vision and with monocular vision with both the dominant and nondominant eye). Specifically, they required almost double the time using feedback in the final approach as the normal children did (< .01) and made 1.5 to 3.0 times more errors in the reach path (< .01) and grip positioning (< .05). Patients with the poorest stereoacuity showed the greatest impairments, prompting Dr. Sloper to comment that "some stereoacuity is better than no stereoacuity."

This study "confirms that hand–eye coordination skills are impaired in children with amblyopia, compared to controls," said R. Michael Siatkowski, MD, professor of ophthalmology at the Dean McGee Eye Institute in Oklahoma City, Oklahoma, who was not involved in this research. "What is surprising is that even when amblyopic children were doing the tasks monocularly with their normal eye, they still performed more poorly than normal children using only 1 eye. This tells us that amblyopia affects the visual system in more ways than we once thought, and perhaps the concept of having '1 good eye' is not sound."

Dr. Sloper and Dr. Siatkowski have disclosed no relevant financial relationships.

American Society of Pediatric Ophthalmology and Strabismus (AAPOS) 37th Annual Meeting: Paper 5. Presented March 31, 2011.

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