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Biomedical subjects

R J Olson

Publications and source records attributed to R J Olson.

At least 145 records · Page 8Linked to original sources
PubMed1980

Intraocular lens optical quality: update 1979.

One hundred and twenty lenses from 12 manufacturers were randomly selected for optical studies using an optical bench. Resolution efficiency was measured with an Air Force target, and measurements of back focal length in air were used to calculate back focal length in aqueous. There were no lenses with: less than 50% resolution efficiency, more than a 0.5-D variation from the stated power, or more than 0.25 D of toricity. Seventy-five percent of the lenses had at least 74% resolution efficiency; 93% were within 0.25 D of the stated power; 95% had 0.1 D or less toricity. Lenses of recent manufacture exhibit a marked improvement in optical quality. Optical parameters for all lenses observed in this study were within good clinical ranges.

Humans↗
PubMed1980

The Shearing intraocular lens: where does it go and what does it do in the eye?

Seven Shearing lenses were inserted in four dogs that were selected because their ciliary body sulcus diameter was approximately equal to that of humans. These animals were killed at intervals ranging from 4.5 to 11 months and the eyes submitted for histopathology. In all instances, gross examination revealed the lenses to be well tolerated; however in two eyes there was migration of the peripheral loop into the peripheral iris stroma and in one case, ciliary body sulcus necrosis was seen. No vitreous hemorrhage was found in any of the eyes. One intraocular lens was removed before the animal was killed and the eye did not appear to be damaged. This study raises the possibility of ciliary body damage in those eyes in which the lens is slightly displaced so that one loop exerts pressure on the ciliary body. For this reason, we feel that posterior vitreous hemorrhages must be carefully looked for.

Animals↗
PubMed1980

Aphakic keratoplasty: visual acuity and optical errors.

Sixty-four consecutive patients with aphakic penetrating keratoplasty and penetrating keratoplasty combined with intracapsular cataract extraction were reviewed in a prospective fashion with a minimum of a one-year follow-up. Five were lost to follow-up. There were seven graft failures at the end of one year. Five of these were from 11 patients who underwent second operations because of failed grafts. Visual acuity was 20/80 or better in 29 of the patients. Pathology accounted for decreased visual acuity in all of those with visual acuity less then 20/80. Problems wre macular degeneration in 11 of the 23 patients with poor visual acuity (48%); marked cystoid macular edema in four patients (17%), advanced glaucoma in three patients (13%) and amblyopia in three patients (13%). Graft size had no significant effect on visual acuity. In terms of the final refractive error and astigmatism, there were no significant differences seen in those in whom a larger donor was used compared with those in whom a donor the same size as the recipient opening was used. Aphakic penetrating keratoplasty has shown outstanding technical success with poor visual acuity representing a difficulty in screening for non-corneal pathology. With an otherwise normal eye, the chances for excellent optical success are very good at the present time with modern techniques in aphakic penetrating keratoplasty.

Aphakia↗
PubMed1980

Steady-state Growth of the Marine Diatom Thalassiosira pseudonana: UNCOUPLED KINETICS OF NITRATE UPTAKE AND NITRITE PRODUCTION.

Seasonal studies of the vertical distribution of nitrate, nitrite, and phytoplankton in the oceans and studies using (15)N as a tracer of nitrate metabolism indicate that the reduction of nitrate by phytoplankton is a source of nitrite in the upper waters of the ocean. To better understand this process, the relationship between nitrate uptake and nitrite production has been examined with continuous cultures of the small marine diatom Thalassiosira pseudonana. In a turbidostat culture, the rates of nitrite production by T. pseudonana increase with light intensity. This process is only loosely coupled to rates of nitrate assimilation since the ratio of net nitrite production to total nitrate assimilation increases with increased rates of growth. In continuous cultures where steady-state concentrations of nitrate and nitrite were varied, T. pseudonana produced nitrite at rates which increased with increasing concentrations of nitrate. Again, the rates of nitrite production were uncoupled from rates of nitrate assimilation. The study was used to derive a mathematical description of nitrate and nitrite metabolism by T. pseudonana.The validity of this model was supported by the results of a study in which (15)N-labeled nitrite was introduced into the continuous culture, and the model was used to examine patterns in distribution of nitrite in the Antarctic Ocean and the Sargasso Sea.

Journal Article↗
PubMed1980

Resistance of Pseudomonas aeruginosa to modern eye-banking technique.

Rabbit eyes were inoculated with different concentrations of Pseudomonas aeruginosa. Copious irrigation and topical Neosporin solution decreased surface contamination by 90% as compared to controls. Ps. aeruginosa added to M-K medium and stored at 4 degree C remained viable for 6 days and multiplied rapidly when the medium was incubated at 35 degree C. Adding penicillin and streptomycin (125 units/ml each) suppressed, but did not prevent this growth. Gentamicin (100 micrograms/ml) suppressed growth in all vials by 72 hours at 4 degree C. These studies show that gentamicin is clearly superior to penicillin and streptomycin in preventing Ps. aeruginosa contamination of donor corneas. It is suggested that donor eyes and M-K media be routinely cultured upon arrival at the eye-bank and the time of surgery in order to avoid or immediately treat gentamicin-resistant donor cornea contamination.

Animals↗
PubMed1980

Corneal curvature changes associated with penetrating keratoplasty: a mathematical model.

A mathematical derivation of the effect of penetrating keratoplasty on corneal curvature was used to examine many variables in corneal surgery. The amount of wound disparity taken up by the recipient cornea was found to be the major factor in determining the amount of astigmatism induced by host wound/donor tissue size disparities. The amount of disparity showed as essentially linear relationship with the amount of astigmatism, approximately 0.4 diopters for each 0.1 mm of wound disparity for each 10% of the amount of the distortion taken up by the cornea (7.5 mm trephine). The smaller the trephine, the more distortion could be expected for each increment of wound disparity. Variations in the corneal curvature of the donor cornea had a minimal effect on the amount of keratoplasty-induced astigmatism.

Astigmatism↗
PubMed1980

A corneal punch: feasibility and accuracy.

A corneal punch used for making circular holes in the aorta was tried on pig eyes to check for efficacy and accuracy. This approach was rejected as being clinically useless because the incision necessary to introduce the punch was larger than the diameter of the cut, intraocular trauma was felt to be inevitable due to the large amount of effort necessary to punch, the tissue removed was oval and the internal diameter was much larger than the external diameter of the tissue cut.

Animals↗
PubMed1980

An abscess associated with a through-the-lid keratoprosthesis one year after intraocular lens insertion.

A through-the-lid keratoprosthesis in a patient with severe Stevens-Johnson syndrome resulted in 20/20 vision for one year, at which time the patient experienced a sudden and painless loss of vision. Surgical exploration revealed a Staphylococcus aureus intraocular abscess and a 10-mm-thick cyclitic membrane. Electrophysiology had shown normal retinal function by ERG and VER at the time of this surgery. Vision has since deteriorated to no light perception.

Abscess↗
PubMed1980

Reshaping the cat corneal anterior surface using a high-speed diamond fraise.

A specially-designed diamond fraise was used on three cats in an attempt to change the anterior corneal surface. After controlled grinding at 30,000 revolutions per minute, healing was rapid. By specular microscopy, there was no evidence of endothelial damage. Examination revealed areas with a defect in the anterior stroma and slightly thickened epithelium. Some superficial vascular ingrowth did occur in the three eyes when healing was slow. This study shows the feasibility of corneal grinding; a prototype instrument is suggested for superficial keratectomy.

Animals↗
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↗