Search PubMed⌕ Search

Biomedical subjects

R J Olson

Publications and source records attributed to R J Olson.

At least 73 records · Page 4Linked to original sources
PubMed1991

Penetrating keratoplasty 1981-1988: clinical indications and pathologic findings.

We analyzed 740 penetrating keratoplasty specimens received at the Intermountain Ocular Research Center from 1981 through 1988. These corneal specimens were categorized by clinical indications for removal and pathologic confirmation of the clinical findings. Keratoconus was the most common indication for a penetrating keratoplasty (22.8%). This was closely followed by pseudophakie bullous keratopathy (21.8%), regraft (13.2%), scarring (8.9%), aphakic bullous keratopathy (6.4%), and Fuchs' endothelial dystrophy (5.8%). Since 1984, pseudophakic bullous keratopathy has surpassed keratoconus as the most common indication for penetrating keratoplasty (27.3% vs. 20.2%). Pseudophakic bullous keratopathy was found more commonly than keratoconus in each of the last four years of this study. The most common type of intraocular lens associated with pseudophakic bullous keratopathy was an anterior chamber lens (52.8%), with iris-fixated (26.7%) and posterior chamber (17.4%) lenses seen less frequently.

Adolescent↗
PubMed1991

Noninvasive repositioning of a posterior chamber intraocular lens following pupillary capture.

A case of pupillary capture of a posterior chamber intraocular lens (IOL) is presented. A nonsurgical approach that may help reposition an IOL optic entrapped in a pupillary capture when chemical mydriasis fails is described. Suggestions for a logical progression of nonsurgical procedures to help release optic capture are presented. Possible causes and preventative measures to decrease the incidence of pupillary capture of a posterior chamber IOL are discussed.

Adult↗
PubMed1991

Protective effects of Healon and Occucoat against air bubble endothelial damage during ultrasonic agitation of the anterior chamber.

An important aspect of any new viscoelastic substance is the corneal endothelial protection. We compared the protective effects of sodium hyaluronate (Healon) and hydroxypropylmethylcellulose (Occucoat) by introducing a controlled volume of air bubbles into the anterior chamber of human eye bank eyes during ultrasonic agitation of the anterior chamber. Eight eyes received Healon and 11 eyes received Occucoat. Damage to endothelial cells in the central cornea was quantified by vital staining. Endothelial damage averaged 4.5% in eyes in which no viscoelastic was used (positive control); damage was 0.4% in eyes in which a viscoelastic was injected but no air bubbles were introduced (negative control). We found that endothelial damage averaged 4.25% in specimens that received air plus Healon and 1.4% in specimens that received air plus Occucoat. Occucoat appeared to have somewhat better protective effects than Healon against air bubble damage to the corneal endothelium during ultrasonic agitation of the anterior chamber.

Air↗
PubMed1991

A comparison of rust-ring removal methods in a rabbit model: small-gauge hypodermic needle versus electric drill.

Corneal rust rings are common findings after removal of a metallic foreign body. These rings should be removed to prevent inflammation and scarring. We compared the corneal damage in rabbit eyes caused by rust-ring removal using two different methods: a small-gauge hypodermic needle and a hand-held electric ophthalmic drill. No significant difference was found in the amount of corneal scarring as graded by a masked observer. However, there was a trend toward deeper stromal damage in the drill-treated subjects (207 +/- 73 microns) than in the needle-treated subjects (172 +/- 61 microns). In light of this finding, we suggest caution in removing central rust rings with an electric drill since an avoidable, permanent scar may result.

Animals↗
PubMed1991

A new look at postoperative instructions following cataract extraction.

We sought to determine whether, given the decreasing rate of complications associated with cataract surgery and IOL implantation, postoperative restrictions placed on patients undergoing these procedures could be significantly and safely relaxed. We reviewed the charts of 216 patients who had undergone capsulorhexis or "can-opener" capsulotomy, phacoemulsification, and insertion of an oval IOL over a 3-year period, noting any operative or postoperative complications. All of these patients had been examined the day after surgery and, if no complications were noted, had been instructed only to refrain from activities that produced pain. No shield was required, and no instructions were given to restrict showering, hair washing, or any other normal physical activity. We found no complications related to any postoperative activity. These results suggest that current postoperative instructions typically restricting such patients' activities should be reevaluated.

Aged↗
PubMed1991

Phacoemulsification combined with pars plana vitrectomy.

Phacoemulsification combined with pars plana vitrectomy was performed on seven patients with both cataracts and vitreoretinal disease. Six of the seven had a posterior chamber intraocular lens (PC-IOL) placed in the capsular bag following cataract extraction. Visual acuities ranging from light perception to hand movement preoperatively, postoperatively ranged from hand movement to 20/25. There were no perioperative complications. During an average follow-up of more than 6 months, neovascular glaucoma developed in one patient, and a conjunctival cyst in another. The PC-IOLs were well tolerated. The small limbal incision used in phacoemulsification allows better control during the vitrectomy procedure and ensures a water-tight wound. In addition, with the limbal approach, the posterior lens capsule is maintained, with all the attendant advantages.

Adult↗
PubMed1990

Air bubble endothelial damage during phacoemulsification in human eye bank eyes: the protective effects of Healon and Viscoat.

Following insertion of either Healon (sodium hyaluronate) or Viscoat (sodium chondroitin sulfate-sodium hyaluronate) into the anterior chamber of human eye bank eyes, a controlled amount of small air bubbles was introduced into the anterior chamber during phacoemulsification. After vital staining, damage to endothelial cells in the central cornea was quantified. Endothelial damage averaged 4.5% in eyes in which no viscoelastic was used (positive control), whereas damage was only 0.4% (P less than .001) in eyes in which a viscoelastic was inserted but no air bubbles were introduced (negative control). Endothelial damage in test specimens using air plus Healon averaged 4.9%. Damage in test specimens using air plus Viscoat averaged 0.3% (P less than .02). As demonstrated by scanning electron microscopy, many areas in the positive controls and in the Healon test specimens were damaged too extensively to quantitate accurately by the method we used. Thus, Viscoat may prevent or lessen damage to the corneal endothelium by small air bubbles during phacoemulsification.

Air↗
PubMed1990

Corneal-scleral melt in association with cataract surgery and intraocular lenses: a report of four cases.

Four patients with rheumatoid arthritis had cataract extraction with implantation of an intraocular lens (IOL). Postoperatively three patients developed progressive scleromalacia perforans. All three cases required patch grafting of the sclera and two of them developed progressive melting of the sclera and graft. The fourth case involved progressive corneal melting with extrusion of the IOL despite treatment with penetrating keratoplasties. All four cases developed retinal detachments with loss of vision and three of the eyes were subsequently enucleated. We describe each case and discuss the clinicopathologic correlations of this condition. The need for careful evaluation of rheumatoid arthritis patients with cataract surgery and IOL implantation is emphasized.

Aged↗
PubMed1990

Combination of 16S rRNA-targeted oligonucleotide probes with flow cytometry for analyzing mixed microbial populations.

Fluorescent oligonucleotide hybridization probes were used to label bacterial cells for analysis by flow cytometry. The probes, complementary to short sequence elements within the 16S rRNA common to phylogenetically coherent assemblages of microorganisms, were labeled with tetramethylrhodamine and hybridized to suspensions of fixed cells. Flow cytometry was used to resolve individual target and nontarget bacteria (1 to 5 microns) via probe-conferred fluorescence. Target cells were quantified in an excess of nontarget cells. The intensity of fluorescence was increased additively by the combined use of two or three fluorescent probes complementary to different regions of the same 16S rRNA.

Base Sequence↗
PubMed1989

Use of a neural net computer system for analysis of flow cytometric data of phytoplankton populations.

Flow cytometry has been used over the past 5 years to begin detailed exploration of the distribution and abundance of picoplankton in the oceans. Light scattering and fluorescence measurements on individual plankton cells in seawater samples allow construction of population signatures from size and pigment characteristics. The use of "list mode" data has made these studies possible, but on-shore analysis of copious data does not permit on-site reexamination of important or unexpected observations, and overall effort is greatly handicapped by data analysis time. Here we describe the application of neural net computer technology to the analysis of flow cytometry data. Although the data used in this study are from oceanographic research, the results are general and should be directly applicable to flow cytometry data of any sort. Neural net computers are ideally suited to perform the pattern recognition required for the quantitative analysis of flow cytometry data. Rather than being programmed to perform analysis, the neural net computer is "taught" how to analyze the cell populations by presenting examples of inputs and correct results. Once the system is "trained," similar data sets can be analyzed rapidly and objectively, minimizing the need for laborious user interaction. The neural network described here offers the advantages of 1) adaptability to changing conditions and 2) potential real-time analysis. High accuracy and processing speed near that required for real-time classification have been achieved in a software simulation of the neural network on a Macintosh SE personal computer.

Computer Systems↗