Unoperated Eyes Research Articles

Effects of extraocular muscle section on receptive fields in cat superior colliculus

In order to find out whether changes in the ocular dominance histograms of the visual cortex are mirrored in the superior colliculus, we sectioned cats' right medial and right lateral reclus muscles during the second week of life. We found that most cells in the superior colliculus contralateral to the unoperated eye become dominated by the unoperated eye, while most cells in the superior colliculus contralateral to the operated eye remain binocularly driven. In contrast, most cells in each visual cortex become monocularly driven, some by the operated eye, others by the unoperated eye. Squint surgery does not change the proportion of directionally selective cells in the superior colliculus, but does change the distribution of preferred directions, increasing the proportion of cells preferring approximately vertical simulus movement. These results suggest that the ability to move the eyes normally is important for the maintenance of normal receptive fields in the superior colliculus.

Patterning of neuronal locus specificities in retinal ganglion cells after partial extirpation of the embryonic eye

AbstractA variety of transplantation procedures were used to analyze the determinants of locus specificity pattern in eye fragments prepared at stage 31/32. When right eye fragments were rotated through 0–360° in situ, or grafted to a stage 31/32 or stage 27/28 host, or grown in vitro 48 hours prior to reimplantation, the orientation of the retinotectal map always matched the anatomical orientation of the rounded‐up fragment, while the internal organization of the map was characteristic for the original fragment type: normal or double‐nasal in NF eye grafts, normal or double‐temporal in TF eye grafts, normal or double‐ventral in VF eye grafts. Fragments from stage 31/32 left eyes showed similar behavior, but mapped from the right orbit with one axis inverted as occurs after contralateral transplantation of whole left eyes. When one rounded‐up fragment and one normal eye (or one rounded‐up nasal fragment and one rounded‐up temporal fragment) were placed side‐by‐side in the same orbit and allowed to “superinnervate” the same tectum, both retinae mapped across the entire tectum with no unshared tectal regions. Finally, in fragments prepared from previously‐rotated (at stage 25/26) eyes, the organization and orientation of the map conformed to the new retinal axes, often in direct conflict with the anatomical polarity of the eye. The results are considered in terms of (1) the histogenesis of the retina in eye fragments; (2) the stability of the program for patterning of locus specificities, which is set down when the optic cup undergoes axial specification at stages 28–31; (3) the factors controlling selective modification of this program and their localization in eye fragments; and (4) the extent to which the range of locus specificities, deployed across the ganglion cell population of rounded‐up fragments, approximates that found in the normal unoperated eye.

The effect of blockade of the arteriae ciliares posteriores longae on the transparence and on the transport of 45Ca into the rabbit's cornea.

At 120 Angora-albino rabbits both Aa. ciliares post. longae were cut through the sclera on the right eye in a distance of 3–4 mm from the limbus. The left unoperated eye served as a control. The rabbits, divided into 12 groups, were observed for 30 minutes, 3 hrs, 5 hrs, 1 day, 2 days, 3 days, 1 week, 2 weeks, 3 weeks, 1 month, 2 mths and 3 mths. In the case of 106 rabbits the cornea remained clear. The transport of the isotope45Ca, given intravenously, into the cornea was not limited by the blockade of these arteries.

Combined Medical and Surgical Therapy for Complicated Cases of Peripheral Uveitis

Trapdoor diathermy beneath the exudative mounds of peripheral uveitis reduced the inflammation. Five eyes were operated on because of secondary glaucoma and were controlled by diathermy and medical therapy. One eye with detachment was reattached, and the exudative mass regressed. The exudative masses may disappear for years following the diathermy. No surgical complications were encountered. Unilateral operations of the most severely involved eye, in cases of bilateral disease, resulted in the operated eye being quieter than the unoperated eye. Posterior pole edema and glaucoma frequently occurred in these cases. Applanation pressures were significantly higher than Schiotz. Peripheral uveitis is common and should be suspected in cases of cyclitis without a posterior chorioretinal scar. When steroids produce side effects or fail to control the inflammation of peripheral uveitis, antimetabolites (ie, cyclophosphamide) have proven effective.

Visual acuity as a reinforcement in learning to control pupil size

Cervical sympathectomy was performed unilaterally on twenty-three cats and bilaterally on five cats. In one experiment we measured the size of the normal pupil which is known to dilate consensually after unilateral sympathectomy. The change in size of the normal pupils of eight cats housed together in a large, well-lighted room was compared with that of seven cats housed separately in dimly lighted cages. One week postoperatively the return to normal size from postoperative dilation was further advanced in the free-ranging animals than in the caged ones. In another experiment, where the interest was in the changes in size of the sympathectomized pupil, five cats with bilateral cervical sympathectomy had more nearly recovered normal pupil size 2 weeks after surgery than had fifteen cats with unilateral sympathectomy, although the treatment of the two groups was identical in other respects. We interpret the differences between the groups in both experiments as being results of learning in the autonomic nervous system, the reinforcement being the improvement in visual acuity resulting from random fluctuations in the size of the pupil. In the first experiment these fluctuations were produced more frequently in the free-ranging animals than in the caged ones. In the second experiment increased visual acuity was more reinforcing for the animals with bilateral sympathectomy than for the unilateral ones, for the former could not rely upon almost normal vision in an unoperated eye.

Role of the sympathetic and parasympathetic systems in the consensual pupillary darkness reflex

In a previous experiment it was shown that unilateral sympathectomy of the pupil produces a dilation of the contralateral pupil. This effect was interpreted as a consensual pupillary dilation; it was suggested that the constricted sympathectomized pupil allowed less light to impinge upon the ipsilateral retina. The present experiment was performed to verify this finding without recourse to any surgical procedure and to assess the role of the sympathetic and parasympathetic innervations in this consensual pupillary dilation. In normal unoperated cats (Group I) opaque black plstic contact lenses were placed over one eye. Three days later the opposite pupil had significantly increased in diameter. This observation rules out the possibility that the results of the previous experiment were a specific effect of the surgical procedure. Other cats were unilaterally sympathectomized (Group II). Three days after placement of the contact lens over the unoperated eye, the sympathectomized pupil had significantly increased in diameter. Evidently the parasympathetic contributes to this consensual pupillary dilation response. However, the pupillary dilation of Group I was significantly greater than that of Group II, which is evidence that the sympathetic innervation is also important in consensual pupillary dilation.

Experimental data on local immunity of the operated and unoperated rabbit eye

Numerous studies have proven the undoubted participation of the normal, not irritated eye in the general immunity of the body. However, the antibody content in the tissues and fluids of the eye appeared to be extremely low. Under conditions of eye irritation, especially during punctures of the anterior chamber and vitreous body, the number of antibodies increases greatly, and some of them appear in the chamber humor and vitreous body only for the first time under these conditions.