Ocular Motility Patterns in Intellectual Disability: Insights from the Developmental Eye Movement Test

Area of Science:

• Ophthalmology
• Neuroscience
• Developmental Psychology

Background:

• The Developmental Eye Movement (DEM) test assesses visual-motor skills.
• Objective measurement of ocular motility in individuals with intellectual disability (ID) is crucial for understanding their visual-motor processing.
• Existing DEM test norms may not be applicable to individuals with ID.

Purpose of the Study:

• To objectively measure ocular motility parameters of the DEM test using an eye tracker in subjects with intellectual disability (ID).
• To compare ocular motility in subjects with and without ID during the DEM test.

Main Methods:

• The DEM test was administered to 45 subjects with ID.
• Eye movements were recorded using an eye tracker during the DEM test.
• Objective ocular motility parameters were extracted from DEM subtests A, B, and C.

Main Results:

• Significant positive correlations were found between saccadic speed and length in both eyes of subjects with ID.
• Subjects with a higher percentage of ID showed more fixations, saccades, errors, and longer test completion times.
• Individuals without ID exhibited faster saccades with greater amplitude compared to those with ID.

Conclusions:

• Eye tracking provides objective quantification of DEM test ocular motility parameters in subjects with ID.
• Ocular movements were conjugated in subjects with ID, with consistent saccade length and speed.
• Significant differences in ocular motility parameters between subjects with and without ID highlight the need for ID-specific normative data.