1. It has been hypothesized, but not verified empirically, that the control of human ocular accommodation is mediated by either the red‐green or yellow‐blue colour channels. Our goal was to determine experimentally whether the red‐green channel by itself could influence the accommodative response. 2. To find out, we isolated the red‐green channel through chromatic bandpass filtering and measured accommodation under dynamic and static conditions. The effect of this filtering was to modulate the red‐green channel without disturbing either the yellow‐blue or luminance channels. 3. Accommodative gain (ratio of response to stimulus amplitude) declined monotonically with decreasing bandwidth under dynamic conditions. Because the outputs of both the luminance and yellow‐blue colour channels did not vary with bandwidth, the only explanation is that the red‐green opponent process was responsible for the effect. 4. Under static conditions, however, accommodation was independent of bandwidth. This may be attributable to the decreased sensitivity to chromatic contrast that occurs at low temporal frequencies.

In order to elucidate the role of optical defocus in the development of late-onset myopia (LOM), we employed both theoretical and experimental approaches. In the theoretical study, which has been reported previously, we suggested a model in which an accommodative sensory operator was added to simulate the sensory part of the accommodation system. Results derived from the model showed that the sensory part might increase the system's threshold to the accommodative error (or defocus) signal. In this study, we measured the perceptual depth-of-focus and the system's threshold to the defocus signal for three refractive error groups: emmetropic (Emm), stable myopic (S.M.), and progressing myopic (P.M.). Results show that there are no significant differences in the perceptual depth-of-focus among the three groups. However, the defocus threshold values of the P.M. group are significantly higher than the values of the other two groups. This result in combination with our previous findings, leads us to suggest that individuals susceptible of developing myopia from sustained near-work have a specific oculomotor risk profile. Although we are still trying to determine the specific sequence of changes among dark-focus, AC/A ratio, the accommodative system's defocus threshold, and refractive error, we are convinced that the changes of oculomotor parameters underlie the type of myopia associated with near-work.

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Students with low vision, including those with multiple disabilities, are entitled to a comprehensive educational program that includes services from professionals in the field of visual impairment. This program should encompass a range of specialists and services that enable the students to complete current and future tasks in school, at home, in the workplace, and in the community. In particular, students with low vision require appropriate assessment, instruction, and adaptations to facilitate visual efficiency.Although students with low vision represent the largest subgroup of students with visual impairments (Kirchner & Diamant, 1999), their intensive instructional needs have not been clearly understood. As a consequence, comprehensive instructional strategies that are geared toward this specific population are only now emerging (Corn,

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