Age related change of optokinetic nystagmus in healthy subjects: a study from infancy to senescence

Abstract

Background: Optokinetic nystagmus (OKN) gain is asymmetrical between temporal to nasal (TN) and nasal to temporal (NT) stimulation in infancy and decreases at older ages. The age at which OKN gain becomes symmetrical and decreases is debated. The aim was to investigate OKN over the whole lifespan in a large sample of healthy subjects. Methods: In a prospective, cross sectional study OKN was tested monocularly using TN and NT small field stimulation. Stimulation velocity was 15˚/s and 30˚/s for children aged under 1 year (n = 97), and 15˚/s, 30˚/s, 45˚/s, and 60˚/s for older subjects (1-9 years, n = 66; 10-89 years, n = 86). Gain was measured using infrared oculography. Results: Significant OKN gain asymmetry in favour of TN versus NT stimulation was found during the first 5 months of life (p,0.05). Only at 11 months of age was OKN symmetrical in 100% of the subjects. The percentage of children with symmetrical OKN decreased with increasing stimulus velocity. OKN gain increased in the second and third years (p,0.05 for 15˚/s), remained stable until 50 years of age, and showed a small but significant decrease afterwards for the tested velocities (between 6% and 18%, p,0.05). Conclusions: Infrared oculography is an accurate method to assess OKN, especially in children. Knowledge about change of OKN in healthy subjects could be helpful to interpret OKN in patients with abnormal binocular vision or lesions of the central nervous system.

Smooth pursuit in infants: maturation and the influence of stimulation

“…Since FEF and SEF are known to be involved in SPEM gain,18 19 the intensive development between 2 and 6 months old may reflect profound maturation of the frontal cortex during this period. This is consistent with the maturation of other oculomotor parameters including saccadic accuracy and optokinetic symmetry 20 21. In contrast the sensory system, in particular the fovea, matures up to 11–15 months of age 22…”

The Effect of Aging on Torsional Optokinetic Nystagmus

“…2 This is in agreement with other studies comparing younger subjects with older subjects; superior horizontal OKN gains were always observed in the younger subjects. [3][4][5] Similarly, vertical OKN was also reduced in healthy elderly subjects (mean age, 70 Ϯ 8 years), who had lower tracking gain and greater phase lag than healthy young subjects (mean age, 30 Ϯ 6 years).…”

“…[2][3][4][5] This has been attributed to age-related degeneration in cortical areas responsible for motion perception and in the retinogeniculate pathway, 6 though degeneration of ocular motor areas cannot be ruled out. The effect of vertical OKN has also been investigated.…”

Psychophysical testing in rodent models of glaucomatous optic neuropathy

“…tracking motion following the stimulus, and an accompanying eye movement of opposite direction resetting the image (Valmaggia et al, 2004) in the rodent. The head of the rodent is immobilized during testing by surgically embedding a headpost to the skull and subsequently clamping it to a restrainer that holds the animal.…”

“…Determining the ratio of the slow speed eye movement and the stimulus speed identifies the quality of the OKN, also called the optokinetic gain (Valmaggia et al, 2004). This technique has its disadvantages, since surgical intervention demands a high level of technical ability and an increased risk of animal loss.…”