Optics and psychophysics in a clinical setting: success of a screening battery for assessing visual functioning in human infants

MacNeil, Doreen Elizabeth (2009) Optics and psychophysics in a clinical setting: success of a screening battery for assessing visual functioning in human infants. Masters thesis, Memorial University of Newfoundland.

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Abstract

Compared to preschool screening, infant vision screening has typically been regarded as much less feasible as infants require more expensive equipment, highly trained personnel, and/or much longer screening times for individual patients. However, early infancy to 3 years marks a critical period of plasticity during which time synaptic connections within the brain are capable of rearranging based on experience. This critical period extends for a variable period of time, but the extent of the plasticity diminishes with age, thus, responsiveness to treatment lessens with age and the depth of impairment is influenced by the duration of the visual abnormality. The evidence for early sensitive, or critical periods, suggests that the best opportunity for prevention and treatment can be expected if screening takes place as early in life as possible. -- The primary objective of the present study was to develop and assess a suitable vision screening battery for infants, namely those within the initial stages of the period of visual plasticity. Infants and toddlers (N=189) were assessed with a battery of the latest optical and psychological tests. Within a single session, we attempted to measure, for each eye, optical refractive error, visual acuity, contrast sensitivity, and conducted a full ocular alignment/motility examination. -- The battery was relatively successful with all age groups. Notably, all children completed at least one test, 95% completed 2 tests and nearly half (48%) completed 4 tests. Furthermore, the average completion time of the test battery for all age groups was 12.8 minutes with a range across age groups of 9.2 to 13.8 minutes. Thus, the present study was successful in demonstrating that children between the ages of 6-months and 3 years can be tested on several aspects of visual functioning in a fairly effective and efficient manner using a relatively comprehensive battery of tests. The promising results of the present study highlight the potential to screen children at a much younger age than is currently standard and represents an important step in the assessment and further development of childhood screening programs.

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