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Biomedical subjects

S W Rice

Publications and source records attributed to S W Rice.

4 recordsLinked to original sources
PubMed1986

Trapezoidal astigmatic keratotomy. Quantification in human cadaver eyes.

The mechanism by which surgical procedures correct astigmatism are incompletely understood and, therefore, the results are often unpredictable. In this study, a Terry keratometer was used to analyze the effect of each component part of a 3-, 4-, and 5-mm trapezoidal astigmatic keratotomy. Semiradial incisions along the horizontal meridian produced corneal flattening along the horizontal meridian twice that of the vertical meridian, therefore inducing positive cylinder astigmatism at 90 degrees. A single pair of tangential incisions placed 5 mm apart, when added to the semiradial incisions, accounted for 100%, 87%, and 78% of the maximal effect from the 3-, 4-, and 5-mm completed trapezoidal astigmatic keratotomies, respectively. This study suggests that maximal correction of astigmatism may be attained with a single set of tangential incisions placed 5 mm apart between two sets of semiradial incisions.

Astigmatism↗
PubMed1983

Absence of an effect of topical dexamethasone on endothelial permeability and flow of aqueous humor.

Twenty-four normal human subjects were studied before and after one week of treatment with 0.1% topical dexamethasone. Intraocular pressure, corneal thickness and endothelial cell size were measured. The flow of aqueous humor and the endothelial permeability to fluorescein were determined using fluorophotometry. In addition, the relationship between the initial location of an iontophoretic depot of fluorescein and its kinetics was studied. There was a small and significant increase in intraocular pressure in the eyes treated with dexamethasone but no significant change in corneal thickness, endothelial permeability or the rate of aqueous humor flow. The elimination of fluorescein from the eye was slightly higher when the fluorescein depot was placed adjacent to the superior limbus than when the depot was placed in the central cornea. Smaller right to left differences were observed when fluorescein was placed peripherally than when it was placed centrally. The increased precision with peripheral placement is probably due to the improved signal-to-noise ratio for fluorescence measurements of the anterior chamber through the unstained cornea.

Administration, Topical↗
PubMed1981

Influence of inorganic cations and histone proteins on the terbium(III)-nucleic acid interaction.

We have studied the interaction of the fluorescent lanthanide, terbium(III) (Tb3+), with polynucleotides and linear and superhelical DNA, through employment of mono- and multivalent cations as competitive inhibitors. Increasingly effective competitive inhibiton of the Tb3+-nucleic acid interaction was achieved, for the most part, in the cation order monovalent less than divalent less than tetravalent. The divalent cation Cu2+ proved to be an exception to this trend, and was the strongest competitive inhibitor or all cations tested, exhibiting an affinity for Tb3+ binding sites over twice that of Tb3+ itself. Unexpectedly, a narrow range of low sodium ion concentration (8--20 mM) was found to be effective in inducing localized unwinding or unstacking of linear and supercoiled DNA double helices, a phenomenon detectable through the use of both Tb3+ fluorescence enhancement and ultraviolet spectroscopy. Within a similar range of low sodium ion concentration, moreover, histone H1 was substantially more effective in displacing terbium ion from DNA than either histones H2B or H4, but at higher ionic strength, this difference was absent. These results further confirm the sensitivity and specificity of Tb3+ as a conformational probe of nucleic acids.

Animals↗