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D C Metrikin

Publications and source records attributed to D C Metrikin.

8 recordsLinked to original sources
PubMed1995

Blood-retinal barrier breakdown following experimental retinal ischemia and reperfusion.

The purpose of this study was to examine the effects of acute ischemia and reperfusion on blood-retinal barrier (BRB) function in the rabbit eye. Hydrostatic pressure (140 mmHg) was used to create total retinal ischemia for intervals of 20, 40, 60, 80 or 100 min in the rabbit eye. The location, size and permeability-surface-area product normalized to the area of retinal leakage (PS') of ischemia-induced BRB lesions were then measured using contrast-enhanced magnetic resonance imaging (MRI) after various intervals of reperfusion. Diffuse outer BRB leakage occurred in most eyes subjected to 80 or 100 min of ischemia. A posterior region of outer BRB sparing was found in eyes that underwent lesser durations of ischemia. On day 1 after retinal ischemia, a linear relationship was found between mean PS' and duration of ischemia for periods of ischemia between 20 and 100 min [slope: 5.65 x 10(-6) to 5.96 x 10(-6) cm min-1 (min ischemia)-1; r2 > or = 0.69]. Lesion size also increased between 20 and 100 min of ischemia. In a longitudinal study, eyes exposed to 60 min of ischemia showed a decrease in PS' and a lesion size over an 8-week period of observation. However, leakage was still present on post-ischemia day 57 in two of three eyes examined. Data obtained in these experiments are expected to prove useful in future studies aimed at understanding how BRB damage relates to neuroretinal damage after ischemia-reperfusion injury.

Animals↗
PubMed1995

Measurement of blood-retinal barrier breakdown in endotoxin-induced endophthalmitis.

PURPOSE: Endophthalmitis is a severe inflammatory disorder with profound visual consequences. Treatment of this disorder has been limited by the lack of quantitative information regarding retinal responses to severe inflammation. The purpose of this study was to measure the effect of endotoxin-induced endophthalmitis on blood-retinal barrier (BRB) function in vivo using contrast-enhanced magnetic resonance imaging (MRI). METHODS: Endophthalmitis was produced by injecting Escherichia coli endotoxin into the midvitreous of pigmented rabbits. Contrast-enhanced MRI was performed at selected intervals thereafter. In all cases, a clinical grading system was used to assess the severity of inflammation before imaging. In a dose-response experiment, total vitreous protein was measured from vitreous specimens obtained 1 day after endotoxin injection and immediately after the imaging procedure. RESULTS: At 1 day after injection, endotoxin produced a selective breakdown of the inner BRB at all doses evaluated (0.01 microgram to 500 micrograms). Permeability-surface area product normalized to the area of leaky retina (PS') increased from 1.35 +/- 0.78 x 10(-4) cm/minute (mean +/- SEM, n = 4 eyes) at a dose of 0.01 microgram to 8.15 +/- 2.22 x 10(-4) cm/minute n = 4) eyes) at a dose of 10 micrograms. Inner BRB integrity was restored by day 28 after injection. In general, changes in PS', blood-aqueous barrier leakage, mean clinical score, and vitreous protein concentration were found, but the correlation between any two of these parameters was poor. CONCLUSION: Leakage of contrast appears early in the course of endotoxin-induced endophthalmitis and is a self-limited process. In future studies, these quantifiable changes in BRB permeability should prove useful in the assessment of various therapeutic interventions.

Animals↗
PubMed1994

Intravitreal drug administration with depot devices.

The administration of medications by depot devices is a rapidly developing technology in ocular therapeutics. Sustained delivery of ophthalmic medications is a novel approach to treating chronic ocular conditions where systemic therapy may be accompanied by unwanted side effects and where repeated intravitreal drug administration carries significant risks. Eye diseases particularly suitable to this form of treatment include proliferative vitreoretinopathy and chronic intraocular infections such as cytomegalovirus retinitis. Liposomes, which have been extensively investigated over the last two decades, have not found any acceptable clinical application. Nonerodible polymers such as the ethylvinyl acetate/polyvinyl alcohol cup are in advanced phase III trials. The current status of microsphere development in the treatment of posterior segment disease is examined in the review and studies investigating the potential uses of the osmotic minipump are mentioned.

Drug Administration Routes↗
PubMed1994

Transscleral repair of recalcitrant, inadvertent, postoperative cyclodialysis cleft.

We present a patient with a cyclodialysis cleft in whom, after established medical, laser, and initial surgical interventions had failed to close the cleft, we successfully used ab externo suture placement to appose and close it. Although we present only one case, we believe this procedure, which may be useful in pseudophakic and aphakic eyes, is easier to perform than previously described techniques.

Cataract Extraction↗
PubMed1992

Incidence of vitreous loss among third-year residents performing phacoemulsification.

The incidence of vitreous loss among third-year residents learning phacoemulsification was retrospectively evaluated. One hundred thirty-six cases of phacoemulsification were performed by six different third-year residents with the same attending physician supervising all cases. The incidence of vitreous loss was 14.7%. This study demonstrates that the rate of vitreous loss among residents learning phacoemulsification is higher than the reported incidence of vitreous loss for residents learning planned extracapsular cataract surgery with expression of the lens nucleus.

Cataract Extraction↗
PubMed1992

Treating dry eye.

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Dry Eye Syndromes↗