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Biomedical subjects

R J Olson

Publications and source records attributed to R J Olson.

At least 19 recordsLinked to original sources
PubMed1992

Changing trends in the indications for penetrating keratoplasty.

The indications for penetrating keratoplasty have changed over the past several years. Nine hundred ninety-nine penetrating keratoplasty specimens from 1981 through 1990 were analyzed. Overall, keratoconus was the most common indication for penetrating keratoplasty (24.2%). This was followed by pseudophakic bullous keratopathy (23.0%), regraft (13.1%), scarring (8.2%), and Fuchs' endothelial dystrophy (5.8%). Pseudophakic bullous keratopathy was the most common indication for penetrating keratoplasty in each year from 1984 through 1989 with a peak in 1987 (33%). Since 1987, the number of pseudophakic bullous keratopathy cases has decreased; and in 1990, keratoconus (33.1%) surpassed pseudophakic bullous keratopathy (24.1%) as the most common indication for penetrating keratoplasty. This decreasing incidence of pseudophakic bullous keratopathy may reflect the discontinued use of closed-looped anterior chamber and iris-plane intraocular lenses most commonly associated with this complication.

Cataract Extraction↗
PubMed1992

Quantitative microdialysis of dopamine in the striatum: effect of circadian variation.

Two quantitative microdialysis methods were used to determine the concentration of extracellular dopamine in the anterior striatum of the rat. In the first method, the slow perfusion flow rate method, perfusion was at 57 nl/min and dialysate samples were collected every 90 min for 18 h and assayed for dopamine (DA), DOPAC (3,4-dihydroxy-phenylacetic acid), homovanillic acid (HVA) and 5-hydroxy-indoleacetic acid (5-HIAA). There was a significant increase in the concentration of dopamine during the dark cycle compared with the light cycle (14.7 +/- 1 nM vs. 9.3 +/- 0.7 nM; mean +/- SEM; P less than 0.0001), indicating possible circadian variations in the extracellular concentration of DA. There was a steady decrease in the level of DOPAC and HVA, and no change in the level of 5-HIAA. For the point of no-net-flux method, animals were perfused with 4 concentrations of DA or DOPAC, bracketing the extracellular concentrations. The extracellular concentrations of DA and DOPAC using this method were 10.2 +/- 1.7 nM and 17.4 +/- 2.6 microM, respectively. The in vivo recoveries for DA and DOPAC as derived from the slope of the linear regression curves were 72 +/- 3% and 43 +/- 5%. These values were shown to be significantly different (P less than 0.001). Both methods gave similar results for the level of DA in the striatum.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

Toxic anterior segment inflammation following cataract surgery.

Cataract extraction with posterior chamber intraocular lens implantation is rarely complicated by an acute, sterile, anterior segment inflammation. We report three unrelated cases of acute intraocular inflammation following uncomplicated cataract extraction and posterior chamber intraocular lens placement. A constellation of clinical features were found in these cases. The hallmark of this entity was an acute toxic inflammatory reaction occurring in the anterior segment on the first postoperative day. Typically, widespread corneal edema with diffuse corneal endothelial damage occurred, accompanied by a fixed, dilated pupil with significant iris atrophy and sometimes a severe secondary glaucoma. Since all cultures were negative, the resulting inflammatory processes were not a result of endophthalmitis. We believe that a toxic insult introduced into the anterior chamber at the time of surgery precipitated the acute inflammatory processes seen in these cases.

Aged↗
PubMed1992

Hyperopia, anisometropia, and irregular astigmatism in a patient following revisional radial keratotomy.

We present a patient who underwent bilateral radial keratotomy (RK) followed by a bilateral revisional RK for undercorrection. After the second procedure, the patient had a severely flattened left cornea, with marked hyperopia and irregular astigmatism. The right eye, however, remained myopic, causing extreme anisometropia. We hypothesize that the different results in these two eyes may have been due to a critical number of damaged left corneal stromal fibers. Patients undergoing revisional RK or requiring additional incisions may be at increased risk for such a complication.

Anisometropia↗
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↗
PubMed1979

The position of the posterior chamber intraocular lens.

Six human cadaver eyes were used for intraocular lens (Shearing) insertion, and the results were photographed. It was found that with the posterior capsule intact, insertion was relatively simple and the feet were found to lie in the ciliary body sulcus with good fixation. Some decentering was common and difficult to correct, but not optically important. With the posterior capsule torn or missing, misplacement was common. After correct insertion, the lens was well fixated without pseudophakodonesis, and there was still found to be room for an additional 1.5 to 2.0 mm of movement.

Humans↗
PubMed1979

Variation in corneal graft size related to trephine technique.

To determine the range of variation in corneal transplant tissue size induced by slight changes in trephination technique, four human corneas that had been stored in McCarey-Kaufman medium and 11 intact human globes were used. Endothelial surface trephination yielded a smaller corneal button than epithelial trephination. In the intact eye, the higher the intraocular pressure was, the larger the resulting corneal diameter. With use of a trephine with a central plunger, the higher the obturator was, the larger the diameter of the resulting tissue. Also, the duller the trephine was, the larger the diameter of the cut, due to difficulty in tissue penetration. Thus, slight variations can markedly affect the match in size between donor and recipient.

Corneal Transplantation↗
PubMed1979

Refractive variation and donor tissue size in aphakic keratoplasty. A prospective randomized study.

Forty-six patients were examined in a prospective, randomized clinical study to compare the use of the same size trephine on both donor and recipient with the use of a 0.5-mm larger trephine on the donor in aphakic keratoplasty and in keratoplasty combined with lens extraction. The results showed no statistically significant difference in refractive error, either in spherical equivalents or in astigmatism. The larger donor tissue may have some value in reducing high plus-refractive error and in reducing intraocular pressure after surgery.

Aphakia↗
PubMed1979

Polypoid sinusitis mimicking orbital malignancy.

A 15-year-old boy developed a rapidly progressive exophthalmos of 6 mm within two months. Radiologic evidence showed bony erosion, a palpable firm mass in the right upper eyelid, and mass blocking the right nares. This tumor was found to be polypoid sinusitis emanating through the lamina papyracea.

Adolescent↗
PubMed1979

The optical quality of currently manufactured intraocular lenses.

We selected 95 intraocular lenses from ten lens manufacturers for a study of optical quality. Tremendous variation in resolution from a high of 313 line pairs per millimeter to a low of 40 line pairs per millimeter was seen. All of the lenses from eight manufacturers showed greater than 100 line pairs per millimeter resolution, the American National Standards Institute proposed minimum. Five of the 95 lenses had greater than 1.0 diopter error, whereas 79 of the 95 lenses had less than 0.5 diopter error from the stated power. With respect to toricity, there were 11 lenses with greater than 0.25 diopter (built-in astigmatism), however, no lenses showed more than 0.5 diopter astigmatism. Two lenses had a built-in double image, another clinically significant problem. We believe the optical quality of the lenses from some lens manufacturers cannot be guaranteed.

Lenses, Intraocular↗
PubMed1979

Donor cornea contamination with McCarey-Kaufman medium preservation.

A patient had corneal infection with Staphylococcus aureus after keratoplasty from tissue preserved in McCarey-Kaufman medium. The small, successfully treated corneal infection was from the same organism cultured from the tissue culture medium at the time of transplantation. Possible sources of donor-tissue contamination included the increase in ocular flora seen in postmortem eyes, blood-borne bacteria, lack of sterile technique in securing donor tissue, inadequate irrigation of the tissue, and inadequate use of topical antibiotics on the tissue. Preservation medium and specimens from medium-preserved and refrigerated corneas should be cultured before and during surgery.

Administration, Topical↗
PubMed1979

Apneic spells associated with timolol therapy in a neonate.

A 2-week-old premature child with congenital glaucoma secondary to anterior cleavage syndrome was treated with timolol maleate and cyclocryotherapy. The patient had apneic spells of up to 30 seconds that stopped soon after timolol maleate therapy was discontinued. No apnea was seen before timolol maleate administration, and no further spells were noted after subsequent cyclocryotherapy without timolol maleate treatment. Possible central nervous system toxicity of timol maleate or its metabolic by-products in neonates with immature blood-brain barriers was noted.

Acetazolamide↗