Investigative Ophthalmology & Visual Science, Vol. 32, No. 5. April 1991 Copyright © Associaiion for Research in Vision and Ophthalmology Disconjugate Adaptation to Long-Standing, Large- Amplitude, Spectacle-Corrected Anisometropia Akihiko Oohira,*j- Dovid 5. Zee,*f and David L. Guyron* A 12-yr-old anisometropic patient had worn corrective eyeglasses (right eye, -0.50 +1.50 X 125; LE, -9.75 +2.50 X 60) for 7 yr, and then changed to contact lenses. Eye movements were recorded before and after the change to contact lenses using binocular search coils. In habitual spectacle viewing, the patient showed disconjugate adaptation. During monocular viewing, for example, ocular alignment changed by as much as 4° during a 20° saccade. Also, during monocular viewing, with cither eye, placing the spectacle lens in front of the eye caused an increase in the disconjugate adaptive response compared with viewing without lenses. This finding emphasizes the context specificity of adaptive responses. After switching to contact lenses, the patient still wore his spectacles for 20-40 min each day. Although there was little residual disconjugate adaptation for vertical saccades, he showed consid- erable adaptation for horizontal saccades, especially for gaze changes that required divergence. The persistence of a partial state of disconjugate adaptation allowed the patient to use immediate, disparity- induced, horizontal vergence to aid ocular alignment in either the contact-lens-viewing or the spectacle- viewing condition. A more complete reversion to conjugacy occurred after nine days of exclusive use of his contact lenses. Then, in a short-term experiment, two minutes of binocular viewing through the eyeglasses induced a considerable reversion toward the previous state of disconjugate adaptation (up to 1.25°of vergence change during monocular viewing). Finally, the waveform of the adapted (to specta- cles) intrasaccadic vergence change with monocular viewing was similar to the waveform of the una- dapted intrasaccadic vergence change during binocular relaxations between targets that required a combined saccade and vergence. This finding suggests a common mechanism for adaptation to specta- cle-corrected anisometropia and for normal binocular vergcncc-saccade interactions. Invest Ophthal- mol Vis Sci 32:1693-1703, 1991 Much research has focused on the mechanisms by which the central nervous system calibrates eye move- ments for optimal visual-oculomotor performance. Most studies were concerned with adaptive control of conjugate ocular motor mechanisms, ie, simulta- neous, identical adjustments of the innervation to both eyes, to assure that saccades, pursuit, and vestibu- lar eye movements are accurate. 1 Other studies have investigated mechanisms of disconjugate ocular mo- tor adaptation, ie, adjustments of the relative innerva- tion to the two eyes to ensure optimal binocular vi- sual-oculomotor performance. 2 ' 3 From the *Dcpartment of Ophthalmology and the tDcpartmcnt of Neurology, School of Medicine. The Johns Hopkins University. Baltimore. Maryland. Supported by research grant #EYOI849 and core grant #EY0l765 from the National Eye Institute, the National Institutes of Health, Bethesda, Maryland, a postdoctoral fellowship from the Fight for Sight Research Division of the National Society to Prevent Blindness, and a fellowship from the Dana Foundation. Submitted for publication: May 24. 1990: accepted October 24, 1990. Reprint requests: David S. Zee. MD. Meyer 2-147, The Johns Hopkins Hospital, Baltimore. Maryland 21205 One model for the investigation of disconjugate oc- ular motor adaptation is spectacle-corrected anisome- tropia. 4 Because of the prismatic effects (rotational magnification) of the corrective lenses away from their optical centers, a retinal disparity occurs for most of the targets in the visual periphery. Accord- ingly, if binocular fixation is to be immediate when the eyes reach the new location of the target, the cen- tral nervous system must readjust ocular alignment during every conjugate change in gaze. Erkelens et al 5 showed this in subjects with small degrees of specta- cle-corrected anisometropia. Zee and Levi 6 showed this in myopic subjects in whom spectacle-corrected anisometropia was simulated by having them wear a contact lens in one eye and a spectacle lens in front of the other (contact lenses are not associated with a ro- tational magnification effect). We studied a 12-yr-old boy who had worn eye- glasses for 7 yr to correct a large, almost 10-diopter anisometropia, and then changed to contact lenses. By recording his eye movements before and after he switched to contact lenses, we studied his capability for disconjugate adaptation. 1693