A reliable, standardized protocol that appears to differentiate mTBI from normals was developed for use in future research. This investigation represents a step toward objective identification of those with PCS. Future studies focused on increasing the specificity of eye movement differences in those with PCS are needed.

Patients: One hundred twelve patients with PD, including 18 de novo untreated patients, and 60 age-matched controls. Intervention: Modern, precise eye tracking technology was used to assess oculomotor parameters. Oculomotor function was compared between groups during fixation and while tracking a randomly displaced target on a PC monitor. Main Outcome Measures: Fixation stability and saccadic parameters. Results: All patients with PD and 2 of 60 control subjects showed oscillatory fixation instability (ocular tremor), with an average fundamental frequency of 5.7 Hz and average magnitude of 0.27°. Saccadic parameters and occurrences of square wave jerks did not differ between subjects with PD and controls. The amplitude and frequency of fixation instability did not correlate with disease duration, clinical Unified Parkinson's Disease Rating Scale scores, or dopa-equivalent dosing. No differences in oculomotor parameters were found between medicated and unmedicated patients with PD. Conclusions: All patients with PD exhibited persistent ocular tremor that prevented stability during fixation. The pervasiveness and specificity of this feature suggest that modern, precise oculomotor testing could provide a valuable early physiological biomarker for diagnosing PD.

Abstract-The effects of hyperbaric oxygen (HBO 2 ) on eye movement abnormalities in 60 military servicemembers with at least one mild traumatic brain injury (mTBI) from combat were examined in a single-center, randomized, double-blind, sham-controlled, prospective study at the Naval Medicine Operational Training Center. During the 10 wk of the study, each subject was delivered a series of 40, once a day, hyperbaric chamber compressions at a pressure of 2.0 atmospheres absolute (ATA). At each session, subjects breathed one of three preassigned oxygen fractions (10.5%, 75%, or 100%) for 1 h, resulting in an oxygen exposure equivalent to breathing either surface air, 100% oxygen at 1.5 ATA, or 100% oxygen at 2.0 ATA, respectively. Using a standardized, validated, computerized eye tracking protocol, fixation, saccades, and smooth pursuit eye movements were measured just prior to intervention and immediately postintervention. Between-and within-groups testing of pre-and postintervention means revealed no significant differences on eye movement abnormalities and no significant main effect for HBO 2 at either 1.5 ATA or 2.0 ATA equivalent compared with the sham-control. This study demonstrated that neither 1.5 nor 2.0 ATA equivalent HBO 2 had an effect on postconcussive eye movement abnormalities after mTBI when compared with a sham-control.

Background: Eye movements in essential tremor (ET) are poorly described and may present useful information on the underlying pathophysiology of the disorder.Methods: Sixty patients with ET, including 15 de novo untreated patients, and 60 age-matched controls constitute the study population. A video-based eye tracker was used to assess binocular eye position. Oculomotor function was assessed while subjects followed random horizontally and vertically step-displaced targets.Results: For all reflexive saccades, latencies were increased in ET subjects by a mean of 16.3% (p,0.01). Saccades showed reduced peak velocities with a lengthy, wavering velocity plateau, followed by slowed decelerations. For larger 30˚+ saccades, peak velocities were decreased by a mean of 25.2% (p,0.01) and durations increased by 31.8% (p,0.01). The frequency of square wave jerks (SWJs) in patients was more than triple that of controls (p,0.0001). Despite frequent interruptions by SWJs, fixations were otherwise stable and indistinguishable from controls (root mean square [RMS] velocity, p50.324). The abnormal eye movement parameters were independent of disease duration, tremor severity, and medication therapy.Discussion: In contrast to normally swift onset and efficient acceleration/deceleration movements, saccades in ET are characterized by abnormally prolonged latencies and slowed velocity profiles. Although ET subjects maintain highly stable fixations, they are interrupted by increased numbers of SWJs. This study reveals novel oculomotor deficits in ET, which are distinct from the eye movement dysfunction of other movement disorders, supporting a role for eye tracking to assist in the differential diagnoses of not only atypical, but also more common movement disorders.