Static accommodation in congenital nystagmus.

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 subjectively using a Hartinger coincidence-optometer, except for depth-of-focus, which was determined psychophysically. RESULTS: The group mean slope for the patients with nystagmus was not significantly different from that found in the normal subjects. However, their variability was markedly increased. Therefore, the patients with nystagmus were divided into three subgroups with regard to the normal accommodative stimulus/response function slope criterion. The majority of patients with nystagmus (n = 10) exhibited slopes that were outside of normal limits, being greater than (n = 4) or less than (n = 6) the normal range. Depth-of-focus was the only parameter found to be significantly different between the normal and the nystagmus groups. When the nystagmus group was divided with respect to etiology--ie, albinotic (n = 4) versus idiopathic (n = 8)--there were no significant differences found for the various accommodative parameters. CONCLUSIONS: We speculate that the primary component contributing to the anomalous accommodative behavior was the increased depth-of-focus, with this perhaps being related to abnormal fixational eye movements and eccentric fixation, and more generally related to overall reduced sensitivity resulting from the early abnormal visual experience.

Stability of tonic vergence.

Tonic vergence was monitored at 30 min intervals over a 10 hr period of a single day and at intervals of approximately 14 days over a period of 19 weeks. Measurements were also made during a continuous 112 min period in total darkness. Tonic vergence showed neither significant systematic variation nor large random fluctuations during the course of either a day or weeks, demonstrating stability under naturally occurring viewing conditions. During the period in total darkness, however, tonic vergence exhibited a significant decreasing trend, ie, eye position became less convergent with time. Stability was therefore poorer in the absence of visual stimuli.

Wallenberg's syndrome: a first-person account.

As clinicians, we may be faced with the patient who has had a stroke with resultant visual and ocular manifestations. Often it is difficult to appreciate the implications of the symptoms and their effects on the quality of life. In this article the first author describes his experiences as a patient, with the hope that this account will assist others to understand this condition better, thus resulting in both enhanced care and sensitivity.

A case of Wallenberg's syndrome: ocular motor abnormalities.

Eye movements were measured objectively in a patient with Wallenberg's syndrome during the course of his 2-year recovery period. The patient exhibited a change in fixational and reading eye movement patterns consistent with concurrent reduction in symptoms. The results demonstrate the importance of clinical eye movement recordings in such patients to understand more fully the relationship between the visually related symptoms and the objective oculomotor correlates.

Relation between distance heterophoria and tonic vergence.

The distance heterophoria was measured using both the von Graefe and Maddox rod clinic procedures under standard reduced illumination conditions and in total darkness. Tonic vergence was measured in total darkness. The phoria measures were more divergent than tonic vergence, with the von Graefe being the more divergent of the two measures. The difference between the phoria and tonic vergence position is believed to be due to accommodative divergence derived from the decrease of accommodation, relative to the tonic level, required to focus the distance phoria target. Equations were derived to predict tonic vergence from the phoria value.