Normal visual acuity requires a stationary retinal image on the fovea. If fixation instabilities cause movement of the retinal image across the fovea for a few degrees, visual acuity is diminished. Nystagmus as the fixation instability, consequently, may impair vision. Period of foveation is the area in the wave form, i.e. a brief period of time when the eye is still and is pointed at the objec...

PURPOSE To conduct a comparative study of static accommodative function between individuals with normal vision (n = 10) and patients with congenital nystagmus (n = 12). METHODS The component contribution to monocular steady-state accommodation (slope of the accommodative stimulus/response function, accommodative controller gain, tonic accommodation, and depth-of-focus) was assessed subjective...

We studied the mechanisms of oscillopsia suppression in subjects with infantile nystagmus syndrome, fusion maldevelopment nystagmus syndrome, and acquired nystagmus (AN). Hypothetical possibilities for perceptual stability were the following: (1) epochs of clear and stable vision during foveation periods of nystagmus waveforms; (2) cancellation by efference copy of motor output; (3) a combinati...

PURPOSE Although impaired color vision and ERG changes have been detected in carriers of blue-cone monochromatism (BCM), no eye movement abnormalities have been identified. Quantitative eye movements of three obligate carriers of BCM were analyzed. METHODS Horizontal and vertical eye movements of three obligate carriers of two families with BCM with visual acuity of 20/20 or better were recor...

To find an explanation of the mechanisms of central positional nystagmus in neurological patients with posterior fossa lesions, we developed a three-dimensional (3-D) mathematical model to simulate head position-dependent changes in eye position control relative to gravity. This required a model implementation of saccadic burst generation, of the neural velocity to eye position integrator, whic...

The analysis of optokinetic nystagmus (OKN) provides valuable information about the condition of human vision system. One of the phenomena that is used in the medical diagnosis is optokinetic nystagmus. Nystagmus are voluntary or involuntarily eye movements being a response to a stimuli which activate the optokinetic systems. The electronystagmography (ENG) signal corresponding to the nystagmus...

Acquired nystagmus occurs frequently in patients with multiple sclerosis and is often the cause of illusory motion of the environment (oscillopsia), and blurring of vision. Based primarily on the beneficial effect of gabapentin on acquired pendular nystagmus (APN), a GABAergic mechanism in controlling nystagmus has been hypothesised. If increasing GABA concentrations in the CNS are critical for...

Antigravitational deviation of the cupula of the lateral semicircular canal, which is also called light cupula, evokes persistent direction-changing geotropic nystagmus with a neutral point. No intractable cases of this condition have been reported. In our case, a 67-year-old man complained of positional vertigo 3 months after developing idiopathic sudden hearing loss in the right ear with vert...

A study was made of parameters of congenital nystagmus which responded to auditory biofeedback treatment. The parameters studied included foveation time, amplitude, and frequency. The patient's right retina was observed with an infrared television fundus camera, and the fundus image was recorded on video tape. The position of the eye during nystagmus, observed via the fundus camera and recorded...

OBJECTIVES/HYPOTHESIS The aim of this study was to characterize the clinical features and typical positional nystagmus in patients with persistent geotropic direction-changing positional nystagmus (DCPN) and address the possible pathophysiology of the disease. Furthermore, the proportion of light cupula among the patients showing geotropic DCPN was investigated to assume the incidence of light ...