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Biomedical subjects

R J Olson

Publications and source records attributed to R J Olson.

At least 127 records · Page 7Linked to original sources
PubMed1983

Vaulting characteristics of flexible loop anterior chamber intraocular lenses.

Fourteen flexible loop anterior chamber intraocular lenses were tested under controlled laboratory conditions. Lens vault was precisely measured as a function of loop compression and of force applied to the loops. A wide range of vaulting characteristics were observed. Some lenses did not vault at all while others vaulted more than the amount of compression. Advantages, disadvantages, and possible clinical implications of lens vault are discussed.

Biomechanical Phenomena↗
PubMed1983

Laboratory analysis of the Lieberman Corneal Punch.

The Lieberman Corneal Punch, an instrument for the trephination of corneal donor tissue, was tested in the laboratory on human corneas preserved in McCarey-Kaufman (M-K) medium. Excellent corneal buttons were produced using 7.5-and 8.0-mm trephine blades, but trephination quality was variable using 8.5 and 9.0 mm blades. Modification of the curvature of the punching well may improve the trephination quality with the larger trephine blades.

Corneal Transplantation↗
PubMed1982

Intraocular lens quality control.

A mislabeled lens was found to have a diopter power of 19.66 on the optical bench, although it was labeled as a 13.00 diopter lens. Both the surgeon and patient were unnecessarily frustrated. In addition, three consecutive posterior chamber lenses examined from one manufacturer showed poor loop quality. It is obvious from these examples that implant surgeons must continue their vigil over lens manufacturers to ensure implant lens quality and accuracy.

Equipment Failure↗
PubMed1982

Complications associated with running 11-0 nylon suture in penetrating keratoplasty.

In a series of 100 penetrating keratoplasties, an 11-0 nylon suture was placed after first running a 10-0 suture. Three suture-related complications presented. One complication resulted from inadvertently cutting the 11-0 nylon as the 10-0 nylon was removed. The second complication was that of a traumatic rupture of the 11-0 nylon, which occurred ten months after surgery. The third complication arose from exposure of the 11-0 nylon through the epithelium due to wound contracture. The management of each suture-related complication is discussed.

Adolescent↗
PubMed1982

The contact lens corneal cutter: accuracy and reproducibility.

The contact lens corneal cutter was used on ten freshly enucleated pig eyes in an attempt to determine its accuracy and reproducibility. We felt that a circular opening could be obtained; however, there was variability in the size of the tissue cut and a disparity between the internal and external openings, which was caused by the sharp angle of the cutting blade.

Animals↗
PubMed1981

A histopathologic study of the Choyce VIII intraocular lens.

We performed a postmortem ocular examination on a 52-year-old man who had had Choyce VIII intraocular lenses implanted in both eyes. Visual acuity with both lenses was 6/6 (20/20). There were no clinical complications before the patient's death. Marked stretching of the chamber angle occurred at all points of fixation, with ultimate loop fixation into the substance of the ciliary body and, in some instances, erosion close to the greater arterial circle of the ciliary body. Where iris tucking had occurred, the iris tucked over the foot of the lens was extremely thin with the foot and the tucked iris in the pars ciliaris region.

Anterior Chamber↗
PubMed1981

The effect of scleral fixation ring placement and trephine tilting on keratoplasty wound size and donor shape.

To examine the effect of trephine tilting and scleral ring placement on wound size, five corneas from McCarey-Kaufman medium and ten whole eyes were trephined centrally under controlled conditions and the major and minor axes measured. It was found that, even with great care taken to hold the trephine perpendicular to the cornea, a fair amount of disparity between the major and minor axes of the donor tissue was seen. The scleral fixation ring produced much distortion, although removal allowed the peripheral cornea to return to more normal configuration. The relationship between amount of trephine tilting and increase in the major axis of the cornea is examined, and all of these concepts are discussed in terms of current keratoplasty technique.

Adult↗
PubMed1981

Intraocular lens implantation in cats.

An intraocular lens without loops was inserted in a cat eye using a suture through the iris and holes in the superior lens haptic for fixation. Excellent results were obtained in 37 of 54 implanted intraocular lenses. Among the 17 with complications, 5 eyes were lost because of death. One case of probable endophthalmitis and one of wound rupture occurred. The remaining ten problems were related to contact between intraocular lens and cornea. The mean cell loss in 21 eyes with intraocular lenses and no postsurgical corneal touch was 24%. In ten control eyes (wound only, no lens insertion) the mean cell change was +4%. This difference was statistically significant. This technique may be useful in testing the lens-cornea endothelial toxicity of other intraocular lens modifications.

Animals↗
PubMed1980

Fungal endophthalmitis following intraocular lens implantation. A surgical epidemic.

Thirteen cases of fungal endophthalmitis were caused by Paecilomyces lilacinus. In all cases an intraocular lens was inserted that had been sterilized in sodium hydroxide and neutralized in sodium bicarbonate. In 12 of the 13 cases, it was absolutely determined that a manufacturer's lot 128 was the neutralizing solution used. The same fungus that caused the endophthalmitis was cultured from several of the neutralizing solutions from lot 128. Eight of the 13 eyes eventually required enucleation. Of the remaining five eyes, one eventually recovered 20/25 vision, one recovered 20/80 vision, one had light perception, and two lost light perception (one of these became phthisical). This surgically induced epidemic of fungal endophthalmitis clearly shows the major consequences of a breakdown in quality control for any substance or material used intraocularly.

Aged↗
PubMed1980

Air and the corneal endothelium: an in vivo specular microscopy study in cats.

In 25 cat eyes 0.7 mL of air and in 11 cat eyes 0.7 mL of balanced salt solution were injected into the anterior chamber after paracentesis. This air persisted for three to four days, and specular microscopy was performed before and two months after air injection. There was an overall significant decrease in the endothelial cell density as a percentage of the preinjection density for the eyes with air when compared with those with balanced salt solution (102% +/- 7% for balanced salt solution and 93% +/- 11% for air). Thus, while air is generally well tolerated by the corneal endothelium, it is a toxic material in the anterior chamber and probably can cause endothelial damage. If not otherwise indicated and if safe to do so, it seems best to avoid its use or to replace it with physiologic solutions after its use.

Air↗
PubMed1980

Polyvinyl alcohol as a protective coating on intraocular lenses.

Sixty-eight intraocular lenses were implanted in cats to compare the efficacy of a new polyvinyl alcohol coating in protecting the corneal endothelium from lens-cell contact damage. The mean endothelial density after implantation of the coated lens was significantly higher than the cell density in those eyes receiving the uncoated lens. We saw no clinical signs of unusual inflammation; whole-eye histopathologic study disclosed no signs of inflammation or toxicity related to the coating. Ten coated lenses were placed in balanced salt solution or perfused with balanced salt solution at 0.5 mL/min. The coating remained intact for 60 minutes, affording corneal endothelial protection for this period. In a rabbit anterior chamber toxicity study, using balanced salt solution as a control, no differencs in reaction in the anterior chamber or intraocular pressure were noted.

Animals↗
PubMed1980

The clinical use, accuracy, and reliability of the Veri-Vu lensometer.

One hundred forty-six lenses from 11 manufactures were tested with the Veri-Vu lensometer and optical power plus resolution compared with results from an optical bench. Accuracy was found to be +/- 0.2 diopter in 95% of the lenses tested. The greatest error was 0.37 D. The lensometer correctly identified 125 of 128 lenses that were greater than 160 line pairs per millimeter (LP/mm) resolution and correctly identified nine lenses that had less than 100-LP/mm resolution. All other important optical aberrations were identified with the lensometer. The greatest problem was the variation from company to company in terms of the calculated power in aqueous as determined from the back focal length in air. This, however, was felt to be an asset for those doing A-scan intraocular lens power determination in giving one simple reliable power for all lens companies.

Humans↗
PubMed1980

Commonly used intraocular medications and the corneal endothelium.

Forty-one cats had balanced salt solution, chymotrypsin, epinephrine hydrochloride with preservatives in varying concentrations, acetylcholine chloride, and carbachol injected intracamerally to determine the toxic effects on the endothelium. Specular microscopy was performed both before and after injection, and for each of the medications, the cell densities were compared with the results obtained with the balanced salt solution. The mean postinjection density as compared with the preinjection density for the medications varied between 98% and 108%, and there were no statistically significant differences between each medication group and the balanced salt solution results. From the results of this study, it is believed that when indicated, these medications probably do not produce substantial toxic effects on the corneal endothelium.

Acetylcholine↗