Eye Movement Parameters and Cognitive Functions in Older Adults

Eye movement behavior will be assessed as an objective measure of cognitive control in older adults. Eye-tracking data will be collected using the J7EF Gaze Smart Glasses (Jorjin Technologies), a non-invasive wearable eye-tracking system with a sampling frequency of 30 Hz. Participants will perform standardized visual tasks while eye movement behavior is recorded.

Outcome measures will include task-related eye movement patterns, such as gaze behavior and saccadic performance, which reflect attentional control and higher-order cognitive processing. Alterations in these eye movement parameters have been associated with cognitive impairment. Eye movement measures will be used to characterize differences in cognitive function across participant groups.

The Mini-Mental State Examination (MMSE) is a widely used cognitive screening tool originally developed by Folstein and McHugh in 1975 (Folstein et al., 1975). It consists of 30 items assessing six domains of cognitive function: orientation, attention, memory, language, verbal comprehension, praxis, and constructional ability. Higher scores indicate better cognitive function. A total score between 24 and 30 suggests intact cognitive function; scores between 18 and 23 are indicative of mild cognitive impairment; and scores from 0 to 17 reflect moderate to severe cognitive impairment.

In the present study, the MMSE is used to classify adults aged 65 years and older into cognitive status groups, including a cognitively healthy group, a mild cognitive impairment (MCI) group, and a dementia group, based on established score thresholds.

The FXS task is designed to measure fixation stability. Participants are instructed to fixate on a white dot, that appears sequentially at different screen locations: initially in the center, then alternately to the left and right sides of the screen.Each position is maintained for 5 seconds, during which participants are instructed to maintain their gaze on the white dot. The sequence proceeds as follows: Center (5 seconds), right side (5 seconds), left side (5 seconds), and return to center (5 seconds). The task duration is approximately 20 seconds.

The Vertical Fixation Task is designed to assess vertical saccadic eye movements and fixation stability. A white fixation dot is sequentially displayed on a black background at specific vertical locations. The target is presented at the center of the screen and then alternates between upper and lower positions at 5-second intervals (center-upper-lower-center), with a total task duration of approximately 20 seconds.

The HPT is designed to evaluate participants' ability to perform smooth horizontal pursuit eye movements. A white dot then appears at the center of a black screen, prompting participants to fixate and track the dot continuously as it begins moving horizontally. The stimulus moves smoothly and repeatedly from left to right and back across the screen. Participants are instructed to visually follow the moving dot toward to left and right side without shifting their head position. The task duration is approximately 30 seconds.

The VPT is designed to evaluate participants' ability to perform smooth horizontal pursuit eye movements. A white dot then appears at the center of a black screen, prompting participants to fixate and track the dot continuously as it begins moving vertically. The stimulus moves smoothly and repeatedly from up to down across the screen. Participants are instructed to visually follow the moving dot toward to up and down side without shifting their head position. The task duration is approximately 30 seconds.

The HST is designed to evaluate rapid, reflexive saccadic eye movements in response to abrupt horizontal target shifts. A white fixation dot appears at the center of the screen and then jumps alternately between the far left and far right positions. Participants are instructed to track the dot continuously from left to right for the entire duration of the task (approximately 30 seconds). Each positional shift is abrupt, requiring quick and accurate horizontal saccades.

The VST is designed to evaluate rapid, reflexive saccadic eye movements in response to abrupt horizontal target shifts. A white fixation dot appears at the center of the screen and then jumps alternately between the far up and far down positions. Participants are instructed to track the dot continuously from up to down for the entire duration of the task (approximately 30 seconds). Each positional shift is abrupt, requiring quick and accurate horizontal saccades.