Spontaneous ophthalmic lesions in 2,382 male and 2,370 female Crj: CD (SD) (CD) rats, 1,032 male and 1,062 female Slc: Wistar (Wistar) rats, and 1,146 male and 1,132 female F344/DuCrj (F344) rats, which had been used in toxicity tests performed in our institute, were examined and characteristics of the lesions were compared among these 3 strains. The incidences of ophthalmic lesions were 2.35% in male and 1.14% in female CD rats, 6.40% in male and 4.33% in female Wistar rats, and 4.36% in male and 3.71% in female F344 rats. In comparison of the incidences of ophthalmic lesions among the 3 strains, the incidences of the anterior segment and optic media lesions in Wistar rats and the incidence of the posterior segment lesions in F344 rats were higher than those in the other strains. The incidences of retinal atrophy in the 3 strains of rats tended to increase with age.

Age-related changes in the retina of pigmented rats were examined functionally and histopathologically using 5 and 28-month-old male Long-Evans rats.

Corneal opacity, cataract and change of color in the fundus were observed in the 28-month-old rats, though there were no changes in the 5-month-old rats. As compared with the 5-month old rats, amplitudes of a- and b-waves in the electroretinogram (ERG) were significantly depressed and latency of b-wave was prolonged in the 28-month-old rats. Histopathologically, in the 28-month-old rats, atrophy of the retina was observed, and inflammation in the cornea and degeneration of the lens were sporadically seen. Thickness (number of nuclei) of the inner and outer nuclear layers were significantly decreased.

From these results, it is suggested that the retinal function in aged pigmented rats is depressed by agerelated decrease of photoreceptor cells, however the depression was relatively slight as compared to that in aged albino rats.

Corneal epithelial abrasion model in rabbit is an important technique for evaluation of effect on corneal healing. In published studies, the corneal epithelium is usually abraded using a trephine and a spatula or scalpel blade operating under a microscope. In the present study, the technique was simplified to remove the corneal epithelium.

Oxybuprocaine hydrochloride was used for surface anesthesia of the cornea under general anesthesia. A circular incision of 5.5 mm in diameter and 50 μm in depth was made in the center of the cornea by sterile trephine. With the aid of fluorescien dyeing to ascertain the site of the circular incision, fine forceps and a sterile wet cotton swab were used to remove the corneal epithelium with rubbing the area surrounded by the circular imprint. The extent of abrasion was confirmed by the further staining with fluorescein dye. The abrasion site was washed with saline solution to remove debris and residual topical anesthetic.

The availability of the present model was assessed by evaluating the effect of benzalkonium chloride (BAC) on healing of mechanically produced corneal abrasion as mentioned above. BAC solution of 0.015% or 0.050% was instilled three times a day for 2 days after abrasion, and saline was used as a negative control. The abrasion site of the corneal epithelium stained with fluorescein was examined twice a day. Observation was terminated when the abrasion site was not detected by staining with fluorescein. The area of the abrasion site was calculated by multiplying the minimal span and the maximal span of the stained site. A area under the time response curve (AUC; a percentage of the abrasion area compared to the initial one) was calculated using the trapezoidal rule to characterize the time response pattern.

The abrasion sites of the corneal epithelium were completely healed within 72 hours not only in the animals of the control group, but also in those of the BAC treatment groups. Following BAC treatment, the AUC of the abrasion area in the 0.050% BAC group became statistically significantly (P<0.05) greater than that of controls.

In summary, this model for the corneal epithelial abrasion healing studies in rabbit is applicable for routine use in testing of effects of ophthalmic solution on corneal healing.

Twenty-one apparently healthy newborn squirrel monkeys were examined for the persistence and disappearance of the hyaloid artery using an opthalmoscope. On the day of birth, the hyaloid artery could be detected in all the newborn animals. At the ages between 17 and 24 days, the hyaloid artery disappeared without exception. The persistence of the hyaloid artery in the newborns and its disappearance during the early period of the lifetime can, therefore, be regarded as a normal phenomenon in the developmental process of infant squirrel monkeys.

We applied conventional scattering-type Raman spectroscopy to the fish corneas. With the corneas of the following fishes; bluegill, Japanese catfish, ayu and Japanese char, the spectra of collagen proteins but not proteoglycans could observed. Three Raman bands specific for carotenoid compound like β-carotene were detected with the corneas of carp and gold fish, indicating that these fishes contain a kind of carotenoid. No carotenoids were detected in the corneas of bluegill, Japanese catfish, ayu or Japanese cher.

The changes of the ocular fundus in a colony-born cynomolgus monkey with chronic renal retinopathy were examined for a long period including before and after the onset of lesions. A series of examinations such as fluorescein angiography, indocyanine green angiography, and electroretinogram was conducted after the onset of the lesions. With ophthalmoscopy, cotton-wool spots and retinal hemorrhages throughout the fundus, and also macular star figures were observed in both eyes. By fluorescein angiography, retinal arterial stenosis was detected concomitant with chronic nephropathy. Fluorescein leaking spots were found to be consistent with cotton-wool spots, and the regions of hypofluorescence were detected coinciding with those of retinal hemorrhages. Moreover, indocyanine green leaking spots were corresponded to the parts of fluorescein leaking spots in the fluorescein angiograph. The responses of both corn and rod systems seemed to be within normal levels on electroretinogram.