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Amblyopia is a common visual disorder that results in a spatial acuity deficit in the affected eye. Orthodox treatment is to occlude the unaffected eye for lengthy periods, largely determined by the severity of the visual deficit at diagnosis. Although this treatment is not without its problems (poor compliance, potential to reduce binocular function, etc) it is effective in many children with moderate to severe amblyopia. Diagnosis and initiation of treatment early in life are thought to be critical to the success of this form of therapy. Occlusion is rarely undertaken in older children (more than 10 years old) as the visual benefits are considered to be marginal. Therefore, in subjects where occlusion is not effective or those missed by mass screening programs, there is no alternative therapy available later in life. More recently, burgeoning evidence has begun to reveal previously unrecognized levels of residual neural plasticity in the adult brain and scientists have developed new genetic, pharmacological, and behavioral interventions to activate these latent mechanisms in order to harness their potential for visual recovery. Prominent amongst these is the concept of perceptual learning-the fact that repeatedly practicing a challenging visual task leads to substantial and enduring improvements in visual performance over time. In the normal visual system the improvements are highly specific to the attributes of the trained stimulus. However, in the amblyopic visual system, learned improvements have been shown to generalize to novel tasks. In this paper we ask whether amblyopic deficits can be reduced in adulthood and explore the pattern of transfer of learned improvements. We also show that developing training protocols that target the deficit in stereo acuity allows the recovery of normal stereo function even in adulthood. This information will help guide further development of learning-based interventions in this clinical group. [ABSTRACT FROM AUTHOR]

Vision screening was performed on 268 pre-school children: 170 from a private pre-school, 33 from a Caribbean-American parochial pre-school and 65 pre-school children from a clinic serving indigent Spanish farm-workers. Using a multi-station format, a stereoacuity test and two visual acuity tests were performed during a single screening session. The time it took to complete a test was recorded. To pass the screening, children were required to pass one visual acuity test and the stereoacuity test. Children who could not complete the protocol were retested at a later date. Children who failed the screening and every fourth child who passed the screening were referred for a full eye examination. The parents and teachers were masked to the results of the screening as well as the optometrists who performed the eye examination. Sensitivity, specificity and accuracy scores were 100%, 79% and 80%, respectively. Three-year-old children completed the Lea Symbol Chart more often than the HOTV. No differences in time required to complete a visual acuity test were found. The Lea Symbol chart is more likely to be completed by young children. Testability changes significantly with age rather than with the instrument when socio-ethnic factors are held constant. Differences among groups and the sensitivity of the screening are discussed. [ABSTRACT FROM AUTHOR]