Electroretinography was performed on 14 eyes of 7 captive alligators (Alligator mississippiensis), free of ocular disease. The alligators were subjected to nine flash stimuli of increasing light intensity following dark adaptation for 30 minutes. No significant difference (p=0.12) between left and right eye responses was observed, thus allowing pooling of the results. The Naka Rushton model equation was used to describe the scotopic b wave response via mixed effects non-linear regression (R_max=166±29μV, n=0.27±0.06 and k=2.0±3.0 fL sec). No second limb of the luminance response curve occurred. At higher intensities, oscillatory potentials were present. Rod recovery time was less than 30 seconds. Implicit time did not decrease with increasing stimulus intensity. These pooled values may serve as the baseline for comparative studies.

The UPL rat is a new hereditary cataract model. The immunohistochemical localization of basic fibroblast growth factors (bFGF), acidic fibroblast growth factors (aFGF) and one FGF receptor (FGF-R1) was investigated in lenses from fetal rats with the early onset (E-type) cataract and normal UPL rat fetuses (N-type). Both FGFs and FGF-R1 were detected in lens fibers from normal and E-type rat fetuses, however, there were differences in immunohistochemical localization of bFGF and FGF-R1 in lens epithelial cells between those from lenses with the E-type cataract and from normal lenses.

Mycotic keratitis is a rare disease in dogs. A two year old, intact male Boston Terrier was presented for a corneal ulcer in the left eye. Cytological evaluation and corneal culture revealed the presence of a dematiaceous fungus, Curvularia sp and two species of gram negative bacteria. This case report documents the occurrence of mycotic keratitis in a dog and the treatment by medical and surgical means.

A trial of surgical procedure for the canine glaucoma was performed by implanting the hollow fiber for hemodialysis into the anterior chamber. Only left eyes of four healthy adult dogs were used to implant a hollow fiber (Thickness: 0.016mm, Inner diameter: 0.125mm) per eye in the anterior chamber and subconjunctival tissue. The right eyes were intact or received the no-fiber shamoperation. Animals were post-operatively treated topically with eye drop of antibiotics three times a day. Systemic antibiotics were also administered. Intraocular pressures were measured with Alcon PTGR and Tono-PenR after the surgery. As a result, intraocular pressures were decreased in the implanted eyes between day 1 and day 6 of the post-surgical period, compared with those in other eyes used as control. Turbidity in the anterior chamber was found in two of the implanted eyes about a week after the surgery, and then diminished along with the futher progression of postoperative course. Adhesion of fibrin onto the fiber was observed in the anterior chamber from one to six weeks after surgery in all cases. Fibrin can be observed not only the outer surfaces but also the inner surface of the implanted fiber as investigated using a scanning electron microcopy.

Eighteen dogs examined from April 1988 to March 1995 for complaints of total blindness or visual deficits were diagnosed with progressive rod-cone degeneration (PRCD) utilizing indirect ophthalmoscopy, tonometry, electroretinogram (ERG), and fluorescein angiography.

The animals were of the following breeds: 3 Maltese, 2 Pomeranians, 2 Toy Poodles, 2 Beagles, 2 mongrels, 1 Shetland Sheepdog, 1 Yorkshire Terrier, 1 Cavalier King Charles Spaniel, 1 Miniature Dachshund, 1 Chin, 1 Borzoi and 1 Shih Tzu.

The time owners became aware of visual abnormalities in their dogs ranged from 1 week to 2 years before the first examination. The following PRD signs were seen in all the dogs: a bilateral weakening or loss of pupillary light reflex in both eyes, mydriasis, attenuation of the retinal vessels, hyperreflectivity of the tapetal fundus, paleness of the optic disc, focal depigmentation of the nontapetal fundus, and low amplitude to non-recordable ERG. In other countries, progressive retinal degeneration is generally found in different breeds of dogs than those commonly affected in Japan. Our investigation showed that in Japan, the disease is mainly found in smaller sized dogs which are popular as pets. As PRD is thought to be a hereditary disease, systematic breeding programs and regular ophthalmologic examinations are necessary for prevention of the disease.

In order to establish a novel method for examining the electro-physiological visual functions in a toxicity test, we investigated changes in the wave patterns of the electroretinograms (ERG) and visual evoked potentials (VEP) when Ethambutol (EB), a visual toxicant, was administered to Beagle dogs. Among six male beagle dogs (about 10 months of age, body weight: 8∼11kg) used, three dogs were assigned to the EB group and three to the control group. To investigate the drug effects on visual function under the condition where no general health problems other than those relating to visual function were observed in the dogs, the dosage of EB began to be gradually reduced as soon as the remaining of the food was observed, from 1,000mg/kg/day to 200mg/kg/day. The oral administration had been continued for three months under the above-mentioned conditions. The wave patterns of ERG (a-wave, b-wave and oscillatory potentials) and VEP (flash visual evoked potential: F-VEP, and pattern reversal-visual evoked potential: P-VEP) were recorded before and after the administration. As for the post-administration, the recordings were carried out at week 1, 2, 3, 4, 8 and 13 of the administration, as well as one month after the drug withdrawal (one dog had additional test two months after withdrawal, becouse the dog showed no recovery in one month). P-VEP exhibited the following changes in wave patterns due to the EB administration; an elongation of peak latency, and obscured waves. Recoveries of both of these changes were observed after drug withdrawal. On the other hand, F-VEP exhibited no clear effects of EB administration, because the reproducibility on the changed patterns was poor. The ERG showed no effects of the EB administration.

These findings suggest that the toxic effect of EB on visual functions may be detected by recording the wave patterns of P-VEP in Beagle dogs.