Change In Ocular Alignment Research Articles

Disconjugate ocular motor adaptation in rhesus monkey

We report a model for inducing disconjugate, orbital-position dependent, ocular motor adaptation in the rhesus monkey. Animals wore a combination of laterally-displacing prisms placed in front of one eye calling for a discrete change in ocular alignment when the eyes reached particular orbital positions. After wearing the prism combination the animals developed adaptive changes both in static alignment during fixation and in dynamic alignment during eye movements. These changes persisted with only one eye viewing and so became independent of the immediate presence of disparity cues. There were, however, imperfections in the adaptive responses; the changes in the innervation were gradual across the prism edge, not abrupt as required. This finding may reflect inherent limitations in the capability for disconjugate adaptation.

Changes in Retinal Correspondence after Changes in Ocular Alignment

We studied the changes in retinal correspondence for 32 constant strabismic patients whose ocular alignment was altered either surgically or spontaneously over a period of time. Patients having normal retinal correspondence (N = 10) generally maintained normal correspondence after the change in ocular alignment. Patients with anomalous retinal correspondence (N = 20) behaved differently. Thirteen of these patients maintained anomalous correspondence and seven patients developed normal correspondence after the change in ocular alignment. For the patients who developed normal correspondence, the direction of the strabismus also changed. We conclude that normalization of retinal correspondence is more likely to occur in strabismic deviations that are overcorrected.

The prism bar--Prentice and frontal positions.

The prism cover test has been in use for many years for measuring ocular alignment. The measurements obtained are used for both calculating the amount of correction needed in strabismus surgery, and monitoring any change in ocular alignment with recovery from muscle imbalance. Variability may arise from its use in either the frontal position or the Prentice position. Most prism bars used in the United Kingdom are calibrated for use in the Prentice position. Inaccurate results arise when a prism bar is used in a position for which it is not calibrated. The theoretical calculation for adjusting measurements obtained in the frontal position with prisms calibrated for use in the Prentice position was assessed clinically. A new modified equation is proposed incorporating practical aspects of performing the prism cover test. A table of values is included to assist in determining the necessary adjustment, so allowing for a more reliable assessment.

The Change in Ocular Alignment between the First Day and Six Weeks following Eye Muscle Surgery

The Change in Ocular Alignment between the First Day and Six Weeks following Eye Muscle Surgery

Graphic Analysis of Paralytic Strabismus with the Lancaster Red-Green Test

We used the Lancaster red-green test to monitor changes in ocular alignment in patients with paralytic strabismus. By inferring the position of the right eye and that of the left eye at many different positions of gaze and then plotting the data on a graph, one can derive a static eye position curve. The location of the curve relative to the line depicting normal ocular alignment ( orthophoria ) indicates whether there is an esodeviation or an exodeviation . The slope of a line drawn tangent to the curve indicates, for that particular point, whether the deviation is concomitant or not and which eye is relatively weak or restricted and by how much. This graphic technique provides a simple, sensitive, and quantitative measure of ocular alignment that may be especially useful for detecting subtle changes in the relative positions of the two eyes. This method may be a useful adjunct in the planning and evaluation of therapy for patients with paralytic strabismus.