The Florida comparative ophthalmology programs excel in professional teaching, clinical service, research, postdoctoral training, and public service. The combination of veterinary ophthalmologists and visual scientists, first developed at Florida, has served as a model for other veterinary college ophthalmology programs. The senior faculty members with diverse professional and research expertise and programs worked as a team to create a unique comparative ophthalmology academic program.

N-Methyl-N-Nitrosourea (MNU), a potent carcinogen, has been known to have retinotoxic action in rats. MNU was intraperitonealy administered once to rats at doses of 0, 40 and 60 mg/Kg. The rats were examined before and at 1, 2, 3, 7, 28, and 35 days after administration of MNU. Generally changes in electroretinography preceded those in morphology. Initial histochemical changes were detected in the retinal photoreceptor cells. The nuclei of photoreceptor cells showed disorder 3 days after treatment with 40 mg/Kg and piknosis 1 day after 60 mg/Kg. In the 40 mg/Kg group, photoreceptor cells showed a normal arrangement at 35 days, though the photoreceptor layer and outer nuclear layer were extensively disrupted 7 days after treatment with 60 mg/Kg. ERG revealed lowered amplitude in the a-wave and b-wave 1 day after the 40 and 60 mg/Kg treatment. In fundoscopy, narrowed retinal veins, increased fundal reflection and clear optic disks were observed 21 days after treatment with 40 mg/Kg and 7 days after 60 mg/Kg. In the 40 mg/Kg group, the damaged part of the retina disappeared and normal structure was restored by 35 days. The retinal lesion around the optic nerve head was severer than in the other retinal regions.

Effects of argon laser coagulation (Coherent Ultima 2000) were compared on the tapetal and non-tapetal zones of the ocular fundus in dogs by observing photographs of the ocular fundus and the fluorescein angiograms. The left eyes of five healthy adult mixed-breed dogs, weighing 11 to 14 Kg, and two 2-month-old native Japanese Shiba dog weighing 4 Kg each were used. The dogs were restrained under general anesthesia with xylasine and hydrochloride ketamine for the laser coagulation. The conditions were as follows, spot size: 100 μm; powere level: 100 mW; and exposure duration: 0.2 seconds.

Bleeding on the tapetal and non-tapetal zones was observed by ocular fundus angiography immediately after coagulation. The lesions were seen as dark spots on the tapetal zone and remained at least 4 weeks after coagulation. On the non-tapetal zone the lesions were bright spots immediately after coagulation and became unclear 4 weeks later. The light reflection on the peripheral tapetal zone had changed more than that of the non-tapetal zone. There was no difference between adult and young animals in the influence of the coagulation on the fundus.

Therefore, in dogs and other animals which have a tapetum lucidum in the choroid, the effects of laser coagulation seemed to be different between tapetal and non-tapetal zones.

A method was established for measuring intraocular pressure (IOP) in anesthetized rats using a clinical hand aplanation tonometer. In order to determine whether this procedure could be used to assess an increase in IOP, an attempt was made to measure the increase in IOP induced experimentally by loading 5% glucose solution and administering dexamethazone eye drops. with this method we were able to measure an increase in IOP induced by either dexamethazone or glucose loading over a time course. IOP data in non-treated rats obtained earlier in our laboratory were used for background data as well. The deviation in the IOP background data was comparatively small, and the mean IOP was 18.9 mmHg in males and 18.3 mmHg in females. We concluded that this is an easy measurement method that provides a precise and useful index for the increase in IOP for drug safety research by comparing the control data.

The retina of suckling beagles up to 6 weeks of age was observed morphologically and the relationship between functional and morphological developments in the posterior portion of eye was discussed. As early as 1 week after the birth, the nerve fiber, ganglion cell, inner plexiform and outer neuroblastic layers were histologically identified. The rods and cones layer was found near the external limiting membrane. Tapetal cells exhibited spindle-shaped contour and irregularly arranged. Electron microscopically, synapses were hardly found in the inner plexiform layer at 1 week of age. At 2 weeks of age, the neuroblastic layer which had been identified between the inner plexiform layer and the external limiting membrane at 1 week of age differentiated into 3 layers to form the inner granular, outer plexiform and outer granular layers. At this time point, numerous synapses with abundant synaptic vesicles were seen in the neurons of inner plexiform layer. At 3 weeks of age, the inner and outer segments were distinguished in the rods and cones layer. The axons of photoreceptor cells extended into the outer plexiform layer. At 6 weeks of age, the overall structure of the retina was almost same with that of the adult, and tapetal cells have developed well and regularly arranged like as pavement. Above mentioned morphological sequence of retinal differentiation, concentrated during 3 weeks from 2 weeks of age, was closely related to the functional development as revealed electrophysiological examination.

The scale readings of Schiotz tonometer were compared to anterior chamber manometric recordings in normal and glaucomatous dog eyes. This in vivo studies compared the tonometer scale readings with 5.0, 7.5 and 10.0 weights to manometric pressures recorded from the anterior chamber in dogs under general anesthesia. The tonometric scale readings from both open and closed systems were compared to the actual manometric pressures.

There were no significant differences between the normal and glaucomatous eyes comparing the 5.5, 7.5 and 10 g weights in both the open and closed systems. Ocular rigidity for the normal canine eye at 10 to 20 mm Hg intraocular pressure was 0.0263. The dog has less displacement of aqueous humor than man when the Schiotz instrument is placed on the cornea with the 5.5 g, 7.5 g and 10 g weights.