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R.G. Bosworth, Y.–Z. Wang, E.E. Birch; Local and Global Motion Sensitivity in Infantile Esotropia and Normal Subjects From 3 Months to 5 Years of Age . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3151.
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© ARVO (1962-2015); The Authors (2016-present)
The development of global motion sensitivity remains poorly understood. The age at which motion sensitivity reaches maturity is still unknown, as many studies focus on young infants who show very poor global motion sensitivity. Moreover, global motion has been suggested to be a vulnerable aspect of development (Braddick et al, 2003). Here we report local and global motion coherence thresholds over a wide age range, in normal subjects and in subjects with infantile esotropia (ET).
Spatial two–alternative forced–choice preferential looking was used in three motion tasks, in which random–dot patterns were presented on the left and right sides of the monitor (after Wattam–Bell, 1996). Global motion detection task: the central third segment of one random–dot pattern had a variable percent of coherently moving dots and the flanks contained randomly moving dots, while the other side contained only randomly moving dots. Global motion discrimination task: the central third segment of one random–dot pattern contained coherently moving dots flanked by opposing motion, while the other side contained a uniform coherent motion. Local motion detection task: one side contained a variable proportion of coherently moving dots amid a background of static dots while the other side contained only static dots. Coherence thresholds were obtained in a staircase procedure. Sixteen infantile ET patients (5–64 months of age; onset by 6 months; post–treatment alignment within 8 pd), and 55 normals (3–46 months of age) were tested.
From 3 months to 8 months of age, performance on the local motion detection, global motion detection and global motion discrimination tasks improved 15x, 2.5x and 1.4x, respectively. Local motion detection reached adultlike levels at 8 months of age; while global motion detection and discrimination remained 6.2x and 5.4x worse than adult in the 2–4 year old age group. Infantile ET patients’ local and global motion performance was similar to that of age–matched normals (t tests; p > 0.20).
Local motion detection improves most rapidly reaching adultlike levels by 8 months while global motion sensitivity develops more slowly, still not reaching adultlike levels by 4 years of age. Although it is known that directional asymmetries may be present in children with infantile ET, both local and global motion sensitivity is normal.
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