Kazuaki Mishima

Acute Corneal Epithelial Change after Instillation of Benzalkonium Chloride Evaluated Using a Newly Developed in vivo Corneal Transepithelial Electric Resistance Measurement Method

Objective: Acute corneal permeability change after instillation of benzalkonium chloride (BAC) was evaluated using a newly developed in vivo corneal transepithelial electric resistance (TER) measurement method. Method: Corneal TER was measured by Ag/AgCl electrodes placed in the anterior aqueous chamber and on the cornea of live rabbit eyes. TER was measured and TER change after instillation of 0.05% BAC solution was monitored. After TER measurement, cornea was excised and fixed for transmission and scanning electron microscopy. For the control study, physiologic saline was used instead of BAC. Results: The TER of normal rabbit cornea was 602.3 ± 195.0 Ωcm2. TER decreased instantly after instillation of 0.05% BAC. In 5 s, TER decreased to 58.3 ± 5.2%. In 60 s, TER decreased to 18.5 ± 3.2%. At all time points, TER after instillation of 0.05% BAC was significantly lower than that of the control (p < 0.0001). Dissociation of tight junctions and the destruction of superficial cell membranes were observed under electron microscopy. Conclusion: Corneal epithelial change with increased permeability is rapid and intense after the instillation of highly concentrated BAC solution, accompanied by disorder of tight junctions and cell membranes of superficial cells. The newly developed in vivo corneal TER measurement method is suitable for assessing acute corneal change after drug instillation.

Methylmethacrylate implants: a scanning electron microscopic study.

Two methylmethacrylate orbital implants used for 34 and 5 years, respectively, were examined with a scanning electron microscope. One of the implants was a combination of a prosthesis and an implant containing a magnet. The magnetic force had decreased markedly, and rust crystals were apparent. The methylmethacrylate surface was irregular and rough.

Reversible visual disturbance due to cryptococcal uveitis in a non-HIV individual

A 52-year-old man without underlying diseases visited a local hospital with symptoms of memory deficit and mild headache. Radiological examination of the brain with computed tomography (CT) revealed hydrocephalus. Etiology was not revealed by cerebrospinal fluid (CSF) analysis and a ventricular-atrial (V-A) shunt was installed. The patient had congestion and dacryorrhea of the right eye and uveitis was diagnosed three months after placement of the V-A shunt. The serum cryptococcal antigen (CrAg) tested positive at a titration of 64 times. Additionally, samples of the right eye anterior chamber aqueous humor (ACAH), cerebrospinal fluid (CSF) and prostate fluid were positive for Cryptococcus antigen at a titration of 128 times. In addition, Cryptococcus neoformans var. grubii was isolated from the peripheral blood, CSF and ACAH, resulting in a diagnosis of disseminated cryptococcosis. Fluconazole (FLCZ) at 800 mg/day was administered for the first two days, followed by a 400 mg/day maintenance dose. After six months of treatment, his visual power recovered. This is a rare case of disseminated cryptococcosis involving uveitis, which was successfully treated by FLCZ. Disseminated cryptococcosis should be considered in cases with mild symptoms and V-A shunt installation for hydrocephalus.

Acknowledgements to Referees

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Analytical and scanning electron microscopic study of intra-ocular foreign bodies

The surface characteristics of 16 intraocular foreign bodies (IOFB) were studied by scanning electron microscopy (SEM) and with an energy dispersive X-ray analyzer (EDXA). The surfaces of all the IOFBs were rough, stringy and nodular in form, and rusted with sharp edges. Many particle-like contaminants were also adhering to the surface. The nature of these particles could be determined with the use of the EDXA. The spectrum showed two peaks, oxygen and iron, indicating that iron foreign bodies are always oxidized.