ROLE OF VISUAL-CORTEX IN INTER-OCULAR ALIGNMENT

  • 1 January 1979
    • journal article
    • research article
    • Vol. 18  (7) , 742-751
Abstract
The role which the visual cortex plays in the development of interocular alignment in the cat was examined by removing this structure bilaterally in 4 groups of subjects. These included kittens 10-14 days of age, 10-14 day old kittens in which one eyelid was sutured shut at the same time, normally reared adult cats, and cats dark-reared until 4 mo. of age. If the cortex is removed in young kittens, interocular alignment appears to develop normally until the kittens are 60-80 days of age. At this time, an abrupt change in alignment resulting in incyclotorsion of the optic axes is observed. If binocular vision is prevented in kittens with neonatal visual cortex lesions by suturing one eyelid shut, convergent strabismus and/or incyclotorsion are frequently observed. This characteristic incyclotorsion does not develop if similar lesions are made in adult cats; no significant alterations of eye alignment occur in these animals even after postoperative survival times of more than 6 mo. Incyclotorsion characterizes dark-reared cats when they are 1st brought into the light, but this diminishes with time and may even be replaced by excyclotorsion after the animals spend a few weeks in the light. If dark-reared cats are decorticated on being brought into the light, these changes are largely prevented. Such animals remain permanently incyclotorted relative to normal cats. The visual cortex apparently plays an important role in the development of torsional alignment of the eyes.

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