Electroretinographic Changes Experimentally Induced by the Intraocular Copper

Copper fragment was introduced into the vitreous body of fourteen albino rabbits through the scleral incision at equatorial region. Both photopic and scotopic ERGs were recorded for 30 days thereafter stimulated by the electronic photoflash of 2 msec duration.The changes in scotopic b-potential were roughly classified into 3 types. The first type (5 eyes) showed acute, severe reduction, extinguishing from 6 to 24 days. The second type (3 eyes) was characterized by the absence of any remarakble changes during the whole observation period, the final b'potential being 82,4% of the original value. In the third type (6 eyes), the b-potential decreased gradually and 24.3% of the pre' operative value was attained after 30 days. The latent time and the implicit time of the b-potential increased proportionally to the reduction of the b-wave. The scotopic a-wave behaved parallel to the b-wave, and in later stage, negative (-) type of ERGs were frequently encountered. The photopic a- and b-waves changed in the similar way as the scotopic a- and b-waves, respectively. The slitlamp biomicroscopy and ophthalmoscopy revealed the fibrous tissue proliferation around the copper fragment in relatively early stage. When the proliferation progressed and extended into the vitreous body, ERG showed reduction in b-potential, and sometimes increase in b-potential was noted In cases in which connective tissue encapsulated the copper and did not extend into the vitreous body, ERG changes were much milder and slower. In histological sesctions performed 2 weeks and 3 weeks after the insertion of copper fragment, the degeneration of the retina began both in the visual cell layer and ganglion cell layer almost simultaneously. When the ERG was extinguished, the retinal tissue showed complete destruction.

The Effect of Subconjunctival Injection of Hypertonic Saline Solution

The effects of subconjunctivally injected normal saline and hypertonic saline solution on the choroidal blood flow in albino rabbits were investigated. By the injection of 0.9% saline solution, no significant changes in the choroidal blood flow took place. Subconjunctival injection of 3% saline solution produced increase in the blood flow which continued for 30 minutes. The average increase was 22%. Hot dry compress by infra-red lamp for 10 minutes increased also the blood flow by 41 % which lasted for 20 minutes after cessation of hot compress.

Changes in the Viscosity of Rabbit's Vitreous Humor Induced by Infusion of Urea

The viscosity of rabbit's vitreous filtrate was measured after intra-venous infusion of 30% urea in 10% glcuose solution and 10% glucose solution. The dosage administered was 1g per kg of body weight. As shown in table, the relative viscosity increased after infusion of urea and glucose solution and no difference was found in the extent of increase in viscosity between urea- and glucose-treated groups. The mechanism of viscosity increase and its relation to the intra-ocular pressure were discussed.