Histopathologic Examination Of Eyes Research Articles

OCULAR ANATOMY AND PATHOLOGY IN LUMHOLTZ'S TREE-KANGAROO (DENDROLAGUS LUMHOLTZI).

Lumholtz's tree-kangaroo (Dendrolagus lumholtzi) is one of two species of tree-kangaroos found in Queensland, Australia. There is little information about ocular anatomy and pathology in any species of tree-kangaroo, and there are claims of blindness from unknown causes in free-ranging Lumholtz's tree-kangaroos. This study investigated ocular anatomy and pathology in 80 individuals, using examination of 31 live animals and histopathologic examination of eyes from 49 carcasses. Tree-kangaroos were found to have a typical vertebrate eye with immuno-histochemical evidence for dichromatic color vision. Only 5.4% of animals had evidence of pathology from traumatic injury, infection, or a variety of nonspecific lesions. Toxoplasmosis was implicated in ocular lesions in three animals. This study did not find evidence of widespread blindness in free-ranging animals nor evidence of toxic optic neuropathy. Examinations of live animals highlighted the need to establish normal ocular examination parameters and vision testing protocols suitable for use in tree-kangaroos and the need for more comprehensive examination and testing of animals thought to have vision loss of unknown origin.

Clinicopathological report of cerebroocular myopathy syndrome

PURPOSE: To report a case of cerebroocular myopathy syndrome with a focal absence of the Descemet membrane. DESIGN: Clinicopathological case report. METHODS: A clinical and histopathologic examination of eye, brain, and viscera of a white male newborn of normal term, who died at 11 days of age with the diagnosis of cerebroocular myopathy syndrome. RESULTS: The autopsy revealed hazy left cornea, hypoplasia of the cerebellum, and corpus collusum with mild microcephaly. Microscopy of the left eye showed the additional findings of a central focal defect of the Descemet membrane with an absence of the posterior third of central corneal stroma and delicate fibrous strands connected to the iris. CONCLUSION: The absence of the Descemet membrane and the missing posterior corneal keratocytes as well as the fibrous strands connecting the iris are findings to be added to the previously reported signs of cerebro-ocular myopathy.

An Intravitreal Sustained-Release Triamcinolone and 5-Fluorouracil Codrug in the Treatment of Experimental Proliferative Vitreoretinopathy

To determine the efficacy and pharmacokinetics of an intravitreal sustained-release triamcinolone acetonide and 5-fluorouracil (TA/5-FU) codrug in the treatment of experimental proliferative vitreoretinopathy (PVR). The therapeutic efficacy of the TA/5-FU codrug was determined in a rabbit model that simulates human PVR. Intravitreal levels of triamcinolone and 5-fluorouracil were measured at different time points and drug release in vitro was tested. Toxic effects were evaluatedby electroretinograpy, clinical examination, and light microscopy. Both the severity of PVR grade and the percentage of eyes with moderate or worse tractional detachment were significantly less in eyes treated with the codrug. The therapeutic effect of the intravitreal codrug was paralleled by sustained intravitreal levels of triamcinolone and 5-fluorouracil. There were no drug-related toxic effects evident on clinical or histopathologic examination of eyes containing the TA/5-FU codrug. The intravitreal sustained-release TA/5-FU codrug effectively inhibits the progression of PVR in a rabbit model that closely resembles PVR in humans. The TA/5-FU codrug may simultaneously target different components of the wound-healing response.

Neurotoxicologic examination of rats exposed to 1,1,2,2-tetrachloroethylene (perchloroethylene) vapor for 13 weeks.

Large evoked potential and EEG changes occurred in a pilot study in Fischer 344 rats during exposure to 800 ppm of 1,1,2,2-tetrachloroethylene [perchloroethylene (Perc)], a cleaning solvent with anesthetic properties. In the main study, rats were evaluated for persistent nervous system effects the week following exposure to 0, 50, 200, or 800 ppm Perc for 6 h/day, 5 days/week, for 13 weeks. The only effect related to treatment was in the flash evoked potential (FEP-V), recorded from the visual cortex. The longer latency potentials (N3) of the FEP-V had a greater amplitude in the 800 ppm Perc group. The FEP-Vs were of normal shape and latency. Although mild neurotoxicity could not be ruled out completely, amplitude changes in N3 can occur for a variety of psychophysiological reasons other than neurotoxicity. Consequently, as a stand-alone finding, the toxicologic significance of the larger FEP in the 800 ppm exposure group was unknown. Other data did not support a diagnosis of neurotoxicity. No treatment-related alterations were noted in expanded clinical observations, in the FEP recorded from the cerebellum (as opposed to visual cortex FEP-V), or in auditory, somatosensory, or caudal nerve evoked potentials. No treatment-related lesions were noted during histopathologic examination of eyes, optic nerves, optic tract, or multiple sections of brain, spinal cord, peripheral nerves, or limb muscles. The no-observed-effect-level (NOEL) was 200 ppm, based on increased amplitude of the longer latency potentials of the FEP at 800 ppm.

An intravitreal device providing sustained release of cyclosporine and dexamethasone.

A device that releases cyclosporine and dexamethasone into the eye for extended periods of time might be beneficial in diseases such as proliferative vitreoretinopathy and uveitis. In this study we examine the pharmacokinetics and toxicity of cyclosporine and dexamethasone combined in an intravitreal sustained-release device and the toxicity of a similar device containing only dexamethasone in rabbits. Rabbits were divided into three groups for (1) evaluation of the drug tissue levels and device release kinetics following implantation of a device containing 100 micrograms of cyclosporine labeled with 2 microCi of 3H-cyclosporine and 2 mg of dexamethasone; (2) evaluation of the toxicity of this intravitreal device; and (3) evaluation of the toxicity of a similar device containing 2 mg of dexamethasone only. Cyclosporine was measured using a scintillation counter and dexamethasone was measured by high pressure liquid chromatography (HPLC). Toxicity was evaluated by electroretinography, clinical examination, and light microscopy. Vitreous concentrations of cyclosporine (+/- standard deviation) averaged 0.06 (+/- 0.02) microgram/ml over 10 weeks. The average dexamethasone concentration over the 10 week period was 2.9 (+/- 0.9) micrograms/ml. Devices containing cyclosporine and dexamethasone released each drug at rates similar to devices containing cyclosporine or dexamethasone alone. Devices containing both cyclosporine and dexamethasone caused reversible depressions in the b-wave amplitude of photopic and scotopic electroretinograms (ERG's). There was no evidence of toxicity associated with the devices containing dexamethasone only. There was no drug-related toxicity evident on clinical or histopathologic examination of eyes with devices containing the combination of cyclosporine and dexamethasone or dexamethasone alone. We conclude that the device maintains potentially therapeutic levels of both cyclosporine and dexamethasone in the vitreous. Reversible electroretinographic abnormalities are attributable to cyclosporine. A sustained-release device containing cyclosporine and dexamethasone may be useful for reducing inflammation in diseases such as proliferative vitreoretinopathy and uveitis.

CHAPTER VIII: Histopathological Examination of Eyes from the Canary Islands

CHAPTER VIII: Histopathological Examination of Eyes from the Canary Islands

Intravenous miconazole therapy for experimental keratomycosis in rabbits.

Intravenous miconazole (90 mg daily for 3 weeks) reduced the intensity of experimental fungal keratitis due to Candida albicans in a group of 10 rabbits. Clinical scores of affected eyes were statistically significantly lower in the treated group than in a control group of 10 untreated rabbits. All cultures of corneal scrapings were negative on 18th day after inoculation in the treated group, but four cultures were still positive on the 21st day in the control animals. Histopathological examination of eyes from treated and untreated rabbits showed great differences in the severity of inflammatory changes in the two groups.

Oral ketoconazole therapy for experimentalCandida albicanskeratitis in rabbits

Oral ketoconazole (100 mg daily for 3 weeks) markedly reduced the severity of experimental Candida albicans keratitis in a group of 10 rabbits. Clinical scores of affected eyes were statistically significantly lower in the treated group than in a control group of 10 untreated rabbits. All cultures of corneal scrapings in the treated eyes were negative on the 15th day after the inoculation, whilst three positive cultures were still obtained on the 21st day in the control animals. Histopathological examination of eyes from treated and untreated rabbits showed great differences in the intensity of inflammatory changes in the two groups.