SMOOTH PURSUIT, SACCADES, AND OPTOKINETIC NYSTAGMUS IN HEALTHY ADULTS: BINOCULAR VIDEONYSTAGMOGRAPHIC ANALYSIS

Abstract

Background:
Objective assessment of oculomotor function provides valuable information for the evaluation of central and peripheral nervous system integrity. Videonystagmography (VNG) allows quantitative analysis of eye movements and facilitates the establishment of normative reference values in healthy populations.                                                                                                Methods:
Oculomotor function was assessed in 31 healthy adults (mean age: 53.6 years, range: 19–79 years) with no history of neurological disease using videonystagmography. Optokinetic nystagmus, saccadic eye movements, and smooth pursuit eye movements were recorded. Participants were divided into two age groups (<50 and ≥50 years) to investigate age-related effects. Parameters analyzed included gain, latency, velocity, accuracy, and peak velocity (velocity/amplitude ratio), depending on the type of eye movement. Results: Optokinetic nystagmus gain showed symmetrical responses between movement directions and decreased significantly with increasing stimulus velocity, while no significant association with age was observed. Saccadic eye movements demonstrated symmetrical performance in both horizontal and vertical planes. Saccadic latency increased significantly with age, whereas mean velocity, peak velocity, and accuracy were not significantly affected. Smooth pursuit gain decreased with increasing target motion frequency and age, particularly at higher frequencies, with horizontal smooth pursuit exhibiting higher gain values than vertical pursuit.                Conclusions:
The present study provides normative reference data for oculomotor parameters in a healthy Greek cohort. The findings also indicate that age-related effects on oculomotor function are parameter-specific, predominantly affecting timing-related and dynamic performance measures, while basic execution-related parameters remain relatively preserved. Ultimately, the data highlight the utility of modern binocular videonystagmography in precisely assessing oculomotor function, aiding in the differentiation between physiological aging and pathological conditions.

Key-words: saccades, smooth pursuit, optokinetic nystagmus