Dual in-plane electronic speckle pattern interferometry system with electro-optical switching and phase shifting.

A dual in-plane electronic speckle pattern interferometry (ESPI) system has been developed for in situ measurements. The optical setup is described here. The system uses an electro-optical switch to change between the illumination directions for x and y sensitivity. The ability of the electro-optic device to change the polarization of the laser light forms the basis of this switch. The electro-optic device is a liquid-crystal layer cemented between two optically flat glass plates. An electric field can be set up across the layer by application of a voltage to electrodes. The speckle interferometry system incorporates two additional liquid-crystal devices to facilitate phase shifting, and the overall system is controlled by advanced software, which allows switching between the two perpendicular planes in quasi real time. The fact that there are no moving parts is an advantage in any ESPI system for which mechanical stability is vital.

Propionibacterium acnes-enhanced lens-induced granulomatous uveitis in the rat.

Propionibacterium acnes (Corynebacterium parvum) is being implicated more frequently as a cause of intraocular inflammation following cataract surgery. In addition to its role as an infectious agent, P. acnes also may possess adjuvant-like or adjuvant-enhancing properties. The presence of this organism in an eye with residual lens material after extracapsular cataract surgery could augment inflammation resulting from a phacoantigenic (phacoanaphylactic) response. We have modified an established rat model of lens-induced granulomatous uveitis (LIGU) to examine the adjuvant properties of P. acnes. Our results suggest that P. acnes effectively potentiates LIGU.

An in vitro study of the potency and stability of fortified ophthalmic antibiotic preparations.

We studied the potency of fortified ophthalmic antibiotic preparations of cefazolin sodium (50 mg/ml) and tobramycin sulfate (15 mg/ml), as measured by the minimum inhibitory concentration, against Streptococcus pneumoniae and Pseudomonas aeruginosa, respectively. We also examined absorbance spectra, pH, and the effect of storage temperature on these fortified solutions to determine their stability over a four-week period. Cefazolin and tobramycin maintained a constant potency throughout the experiment. There was no difference in potency if the fortified solutions were stored at 4 C or 24 C. Cefazolin stored at 24 C exhibited changes in both its absorbance spectra and pH after seven days. Cefazolin stored at 4 C and tobramycin stored at 24 C and 4 C remained stable throughout the four-week period.

Propionibacterium acnes isolated from explanted intraocular lens in pseudophakic bullous keratopathy.

Propionibacterium acnes is an anaerobic bacterium that has been reported to produce ocular infection or inflammation following surgery or penetrating trauma. It has been well documented as an etiologic agent associated with infections of prosthetic implants, including intraocular lenses (IOLs). P. acnes is part of the natural flora of the external eye and has biological properties that may promote, heighten, or prolong an inflammatory response. It not only resists in vitro degradation by reticuloendothelial cells, but also demonstrates adjuvant properties in vivo. In this study, we cultured the IOLs removed from patients undergoing routine penetrating keratoplasty for pseudophakic bullous keratopathy (PBK). Four of the 12 IOLs were culture positive for P. acnes as late as 36 months postimplantation. Although this does not describe a role for P. acnes in PBK, it does suggest that the organism can remain in the pseudophakic eye for an extended time.

Demonstration of herpes group virus in acute retinal necrosis syndrome.

Tissue for pathologic examination was obtained from three cases of acute retinal necrosis syndrome. Virus particles belonging to the herpesvirus family were demonstrated in retinal biopsies from two patients, one of whom was immunosuppressed. Despite removal of large biopsy specimens, the retina has remained attached for 20 months postoperatively in one case and for three months in the other. In a third patient with acquired immune deficiency syndrome, the clinical course and postmortem immunopathology were suggestive of a herpes simplex virus infection, initially affecting the retina and subsequently the optic nerves, chiasm, tracts, and central nervous system. These cases illustrate that the virus associated with the acute retinal necrosis syndrome is easily demonstrable using vitrectomy and endoretinal biopsy in the acute phase of the disease, but may be difficult to demonstrate in chronically detached atrophic retinas.

Modulation of lens-induced uveitis by dimethyl sulfoxide.

Experimental lens-induced uveitis was produced in Lewis rats by sensitization with bovine lens protein prior to disruption of the lens capsule. Treatment of these animals by intraperitoneal injection of dimethyl sulfoxide resulted in reduction in retinal vasculitis, hemorrhage and necrosis. Furthermore, morphometric analysis of choroidal inflammation revealed significant reduction of choroidal thickness in the treated animals. These findings suggest that hydroxyl radicals play a role in producing ocular tissue damage in the acute Arthus-type of ocular inflammation.

Modulation of lens-induced uveitis by superoxide dismutase.

Recent studies on reactive oxygen metabolites have suggested that these products may be important mediators in the early tissue damage that develops from immunopathologic inflammations. The superoxide anion appears to be the principal product of the respiratory burst. In order to determine the effects of removing superoxide with superoxide dismutase on modulating the inflammation in experimental phacoanaphylactic endophthalmitis, the animals with this experimental disorder were treated with superoxide dismutase. The treatment resulted in significant reduction of choroidal inflammation, retinal edema and vasculitis, suggesting phlogogenic role of superoxide in the ocular immune-complex disease.