1) The previous results obtained from ophthalmoscopic studies on the ocular fundus of fish were reviewed.

2) The results of histopathological investigations of carp, in which fundi were diagnosed to be in various pathological conditions by ophthalmoscopic observations, were reported. From the results of these investigations, it was inferred that fundus abnormalities in carp such as dilatation and tortuosity of vitreal vessels and retinal pigment degeneration might be caused by renal insufficiency.

3) Funduscopic photography of specimens of bigeye (Priacanthus macracanthus) which have a very high falciform process, and of specimens of red sea bream (Pagrus major) which have a low falciform process, were shown.

As an animal model of drug-induced retinopathy, beagle dogs were orally treated with zinc pyridinethione (ZPT) and subjected to time-lapse ophthalmological, electrophysiological, and histopathological examinations.

Administration of 40mg/kg ZPT 3 days a week for 1 to 3 weeks resulted in typical ocular disorders: abnormal pupillary response to light, edema and hemorrhage in the fundus (tapetum lucidum), and retinal detachment. Histopathological observation revealed degeneration of the tapetum lucidum and pigment epithelium, and intense neutrophil infiltration. Three weeks after the last dosing, the pigment epithelium and tapetum lucidum disappeard, the retina atrophied and the optic fibers degenerated.

Administrition of 20mg/kg ZPT 3 to 5 days a week for 2 months produced decrease in amplitude of ERG and VEP waves and decrease in ocular tension from the 2nd dosing week on. Reflection of light from the tapetum lucidum also became weaker with the progress of successive administration. Histologically, mild disarrangement of laminal structure in the tapetum lucidum was the only detectable morphological change in these mildly involved dogs. In a follow-up study, the dogs recovered in a week after drug withdrawal from the slight functional disorder induced by ZPT.

We have been conducting ophthalmic examinations in rats and accumulating back ground data during the past 6 years. Approximately 1000 SD rats have been examined with a fundus camera or binocular indirect ophthalmoscope. Slight tortuosity of retinal vessels, prominant choroidal vessels and persistent hyaloid remnant were not uncommon findings in our laboratory control animals. Preretinal arteriolar loop, focal sacculation of retinal arterioles, preretinal hemorrhage, focal retinal atrophy, retinal detachment, and coloboma were also observed.

Ocular toxicity can result from topical or systemic administration of various chemicals and is evaluated histologically on a routine basis in safety assessment studies. As a result of its peculiar architecture, the eye is one of the more difficult tissues to process and artifacts are difficult to avoid with formalin-fixed specimens. We have adopted a procedure which was presented at a meeting of the Japan Association of Histotechnology which provides superior fixation and has significantly increased the quality of our routine eye sections from rodent and non-rodent species. This presentation will review our technique and variations resulting from different fixatives on hematoxylin and eosin stained eye specimens of rats.

This study was made to establish the methods of measurement, recording and evaluation of the a, b wave and oscillatory potentials of electroretinogram (ERG) in rabbits and other experimental animals.

The appropriate selections of electrodes, photostimulators, amplifiers and fixation of animals to record the ERG were discussed. The amplitude versus stimulus intensity curve was used to decide the condition of the photostimulation intervals and intensity. To obtain reproducible data, the following statistical methods were introduced: experimental design, nonlinear least square method, transformations of data, analysis of variance test, coefficient of variation (C. V.), and signal-to-noise ratio (S/N), etc. Moreover, we emphasized that it was necessary to study the isolated ERG and neurotransmitters for further understanding of the retinal functions.

A screw electrode was implanted on the intracranial dura mater of guinea pigs, and after dark adaptation, 50 photic stimuli at the interval of 10 sec were given with a xenon lamp intensity of 2.0 joule, and the ERG and VEP were recorded. The ERG showed no change after 3 months and 24 applications of ethylacetate in the control group, but in the TDI-treated group α and β waves showed prolonged latency and decreases in amplitude. The VEP showed no remarkable change in the control group, but in the TDI-treated animals some changes were seen in P1-N1 amplitude. These changes suggested that repeated exposure to TDI causes a decline in the retinal function.

ヤギの新生仔期眼底像の変化について，9頭，計18眼球を用いて観察した。うち6頭は，出生時に初乳を飲用した個体で，他の3頭は，出生から3日間代用乳を飲用した動物であった。Tapetum lucidum, 視束円板，Tapetum nigrumおよび網膜血管における色調の変化は，初乳飲用例では出生からその後もほぼ同様の色調を示した。初乳非飲用群では，Tapetum lucidumは，生後72時間目まで，初乳飲用個体に比べ黄色調を呈した。網膜出血は，初乳飲用個体の観察眼球の約75%で観察されたが，初乳非飲用群では観察されなかった。硝子体動脈は調査期間中を通じ，両群の全個体で遺残した。