Restorative visual rehabilitation is frequently used to enhance the visual development and function of children with low vision. An important strategy within this field is visual stimulation, which is particularly used for infants and toddlers with low vision, as well as for children who have both developmental disabilities and low vision.This study has two primary objectives.The first objective is to examine the effect of using intensive, specific, and flickering black-and-white checkerboard patterns to enhance visual function in children with mild to moderate low vision. The second objective is to develop a visual stimulation program tailored for children with severe or profound multiple disabilities and visual impairments, and to evaluate its effectiveness.

Investigators will recruit 200 children with various types and severities of visual disorders. Additionally, investigators will collect eye movement assessment data using an eye-tracking system from 30 typically developing infants under two years old to validate the oculomotor assessment newly designed for this study. For this component, the reliability of our oculomotor assessment will be validated through test-retest reliability in both typically developing children and children with multiple disabilities and visual impairments who are enrolled in visual rehabilitation.

The intervention programs include two types:

1. One program provides extensive passive visual stimulation, incorporating attentional modulation during the process to facilitate training. Passive visual stimulation is delivered continuously using appropriate visual materials tailored to the participants' visual abilities, such as illuminated toys or high-contrast patterns. These stimuli are positioned around infants or children, or repeatedly presented by caregivers. This approach allows young children or those with lower cognitive abilities and visual impairments to receive visual stimulation even without active participation. Through this passive intervention model, visual function can be improved.

   Although this model is flexible and suitable for infants or children with low compliance, it poses challenges in quantifying the amount of visual training provided. This limitation affects the ability to verify the efficacy of interventions in clinical trials.

   This version incorporates technical terms and ensures clarity for academic or clinical documentation, while emphasizing the model's flexibility and its limitations.

2. Another program provide checkerboard pattern, a fundamental visual element processed by the early vision system, is used widely in vision science research, visual function assessment, and training. This program incorporates perceptual learning theories that emphasize attentional modulation and the oddball design concept. Salient oddball patterns appear randomly within the ongoing checkerboard reversal stimuli. Participants are required to press a special button when these patterns appear, with engaging auditory feedback provided to reinforce correct responses. This design aims to sustain the visual attention of visually impaired infants and children on the checkerboard reversal patterns for longer durations. Neurologically, the program strengthens top-down modulation mechanisms in the brain through random salient stimuli, enhancing bottom-up processing of early visual information.

Researchers adjusted square sizes through trial-and-error and clinical experience, often enlarging the squares to engage the children effectively. However, this strategy may not fully accommodate children with low vision combined with developmental disabilities. Behavioral observations suggest that integrating sVEP to identify occipital response thresholds and utilizing eye-tracking systems could refine square size adjustments and improve intervention strategies and outcome evaluations.

Additionally, this program may not be suitable for children with severe or profound low vision. The need for quick physical or verbal responses to transient oddball stimuli and the requirement to recognize checkerboard patterns demand a certain level of visual acuity and sustained attention. These factors pose challenges for children with severe multiple disabilities (MDVI), who often require longer response times, have shorter attention spans, and struggle with repetitive tasks. Despite these challenges, MDVI children exhibit visual plasticity, making visual stimulation interventions valuable. Developing alternative visual stimulation programs tailored to the needs of children with severe or profound MDVI is essential for maximizing their potential benefits.

Passive visual stimulation group

Inclusion Criteria:

1. Children aged less than or equal to 12 years old.
2. The causes of visual disorder in children are unlimited.
3. The acuity of children's better eye ranges between hand move and 0.2.
4. Children with multiple disabilities and visual disorders typically exhibit developmental levels ranging from moderate to severe or below.
5. The parents of these children exhibit a positive attitude and are willing to cooperate with visual learning programs.
6. Infants under 1 year old with low vision without other developmental issues , under or equal to moderate developmental issues.

Exclusion Criteria:

1. Significant refractive errors that affect acuity but are unable to cooperate with wearing corrective glasses in two training sessions.
2. Requires patching for monocular vision rehabilitation but is unable to cooperate with patching in two training sessions.
3. The individual is unable to adapt to the training environment and cooperate with visual learning in two sessions due to unstable emotions or difficulty adapting to the environment.

Perceptual learning group Inclusion Criteria

1. Children aged less than or equal to 12 years old.
2. No restrictions on the causes of visual impairment in children.
3. Best-corrected visual acuity (BCVA) in the better eye is equal to or better than 0.02.
4. If children have additional developmental issues, their disability severity should primarily be mild or moderate.
5. The primary caregiver demonstrates a positive attitude and is willing to cooperate with the visual training program.
6. The child is capable of completing calibration with an eye-tracking device. Exclusion Criteria

(1)Significant refractive errors that severely affect vision, where the child cannot adapt to wearing corrective glasses within two training sessions.

(2)Requires occlusion therapy for monocular visual rehabilitation but cannot cooperate with occlusion within two training sessions.

(3)Inability to adapt to the training environment or cooperate with visual training due to emotional instability or difficulty adjusting within two training sessions.

(4)Unstable physiological conditions (e.g., epilepsy, sleep disturbances) that prevent consistent participation in visual training.