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Biomedical subjects

R H Keates

Publications and source records attributed to R H Keates.

At least 37 records · Page 2Linked to original sources
PubMed1988

Effect of excimer laser on microbiological organisms.

The effect of radiation emitted from an excimer laser filled with argon fluoride gas at 193 nm on Serratia marcescens, Pseudomonas aeruginosa, Staphylococcus aureus, streptococcus faecalis, Hemophilus influenzae, Candida albicans, and Aspergillus niger (collectively labeled "the microorganisms") was examined. Colonies were subjected to a variable number of radiation pulses from the excimer laser applied after a 36-hour period of incubation at 37 degrees C, at which time the colonies were fully grown and showed no viability. The lack of viability was confirmed with a subculture from each area that received radiation; all subcultures were negative. The characteristics of the radiation paralleled those used by Serdavic, Darrell, Krueger, et al in 1985.(1) This radiation treatment is believed to be within a therapeutic range, which suggests that the excimer laser, pending further investigation, may be useful in the treatment of corneal infections.

Bacteria↗
PubMed1987

The nationwide study of epikeratophakia for aphakia in adults.

In the nationwide study of epikeratophakia, 154 ophthalmic surgeons who had attended a training course performed 519 procedures for the correction of aphakia in adults: 310 of the eyes had 30 or more days of follow-up after suture removal. Of 229 eyes, 172 (75%) were within 3 diopters of emmetropia after surgery. Of 259 eyes, 245 (95%) demonstrated improved uncorrected visual acuity; 138 (53%) improved by four or more Snellen lines. Of 265 eyes, 209 (78%) achieved within two lines or improved their best corrected visual acuity. Of the 119 patients who achieved or improved their preoperative best corrected visual acuity, 110 (92%) were within two Snellen lines or better by 30 to 60 days after suture removal. Of the 127 patients with more than three months of follow-up after suture removal, 124 (98%) of those between 18 and 70 years of age but only 13 of 23 (54%) of those between 81 and 87 years of age achieved within two lines or better of their best corrected visual acuity. Corneal astigmatism measured by keratometry changed from a preoperative mean (+/- S.D.) of 2.1 +/- 1.8 diopters to a postoperative mean of 2.7 +/- 2.6 diopters. Of the 519 tissue lenses, 22 (4%) were removed, and one third of these patients underwent a second, successful epikeratophakia procedure.

Adolescent↗
PubMed1987

The nationwide study of epikeratophakia for aphakia in children.

In the nationwide study of epikeratophakia, 97 surgeons performed a total of 335 procedures in 314 eyes for the correction of aphakia in children under the age of 8 years 1 month. Fifteen children underwent bilateral surgery. Thirty-six tissue lenses were removed and 21 of these eyes underwent a second epikeratophakia procedure. Overall, the success rate for procedures was 89%, and with repeated surgery it was 95% for eyes. Seventy-three percent of the patients were within 3 diopters of emmetropia after surgery. Visual acuity results in patients able to provide verbal responses to the illiterate E, Allen card, or Snellen line chart testing showed improvement in most cases. The safety of epikeratophakia makes it a desirable option for the correction of aphakia in children who are spectacle or contact-lens intolerant, and the permanence of the correction eliminates the problem of optical noncompliance.

Aphakia↗
PubMed1987

The nationwide study of epikeratophakia for myopia.

In the nationwide study of epikeratophakia, 116 ophthalmic surgeons performed 352 procedures for the correction of myopia; 256 of the eyes had 30 or more days of follow-up after suture removal. Of 204 eyes, 153 (75%) were within 30% of emmetropia after surgery. Of 208 eyes, 202 (97%) had postoperative best corrected visual acuity within two Snellen lines or better of their preoperative visual acuity. All but one patient improved uncorrected visual acuity. Of the 120 patients who equaled or improved their preoperative best corrected visual acuity, 116 (97%) were within two Snellen lines of their preoperative measurement between 30 and 60 days after suture removal. Corneal astigmatism changed from a preoperative mean (+/- S.D.) of 1.4 +/- 0.8 diopters to a postoperative mean of 2.6 +/- 2.1 diopters. Of 352 tissue lenses, 36 (10%) were removed, largely as a result of inaccurate power, decay, or failure to reepithelialize, and 17 of these eyes underwent a second successful epikeratophakia procedure.

Adolescent↗
PubMed1987

Effect of the Nd:YAG laser on polymethylmethacrylate, HEMA copolymer, and silicone intraocular materials.

Recent trends of cataract extraction feature both small surgical wounds and preservation of posterior capsules. The development of safe, reliable, and flexible implant materials that can withstand near impact with a Nd:YAG laser during secondary posterior capsule discissions are required. An in vitro experiment was performed to analyze the effects of Nd:YAG laser irradiation on polymethylmethacrylate (PMMA), hydroxyethylmethacrylate (HEMA), hydroxyethylhydroxymethylmethacrylate (HEMA-MEMA) copolymer combination, and a silicone compound. The HEMA and HEMA-MEMA compounds were the least susceptible to Nd:YAG laser damage in this laboratory setting.

Acrylates↗
PubMed1987

Carbon dioxide laser use in wound sealing and epikeratophakia.

This paper presents current clinical and experimental uses of the carbon dioxide laser and the results of our human and animal tissue fusion investigations. Trials were conducted with human scleral and corneal eye bank tissue and in albino rabbits. With power settings of 100 to 200 mW, optimal laser effect consisting of slight whitening and minimal edge shrinkage occurred between 10 and 70 mJ of total energy. No tissue adherence could be demonstrated with the parameters tested. A final study was made on the feasibility of sealing an epikeratophakia lenticle to its recipient bed using the carbon dioxide laser. The average force required to remove the button in the control experiments was 6.45 g and this increased to 6.99 g after laser treatment although no fusion was apparent. This was statistically significant (P less than .05).

Adhesiveness↗
PubMed1987

Clinical results of the multifocal lens.

The multifocal posterior chamber intraocular lens was implanted in 46 eyes of 38 patients as part of the first clinical trial of this target-type implant. No major complications were reported. Visual acuity results for distance and near vision were excellent, with best case visual acuities better than 20/40 in over 95% of eyes in the first three months.

Clinical Trials as Topic↗
PubMed1987

Early results of epikeratophakia.

One hundred and seven patients underwent epikeratophakia for either adult or pediatric aphakia, keratoconus or myopia at the Ohio State University. Minimum follow-up was 3 months. There were four graft removals. Objective postoperative refractions revealed that an average of 70, 72, and 54% of all patients achieved at least 20/40 acuity in adult aphakia, keratoconus and myopia, respectively. In pediatric aphakia, postoperative refraction revealed that an average of 31% of patients achieved at least 20/50 acuity. These results are presented and complications necessitating graft removal are discussed.

Adult↗
PubMed1987

Coated intraocular lenses.

We found that an intraocular lens with a bonded coating of sodium hyaluronate caused less cell damage than an uncoated lens. We also found that an intraocular lens bonded with sodium hyaluronate will provide not only better adherence to viscoelastic materials and endothelial protection, but also may allow for better manipulation of the lens intraocularly. This is the first report of a sodium hyaluronate-coated intraocular lens used to prevent cell damage.

Animals↗
PubMed1987

The effect of chitosan on corneal wound healing.

Chitosan, a suspected inducer of vascular endothelium regeneration, was applied topically to the eyes of rabbits after they had sustained central corneal wounds. The rabbits were given chitosan tid for seven days in one experimental set and for 14, 17, and 21 days in subsequent sets. For all time sets, there were no apparent statistical differences in corneal wound tensile strength between the chitosan-treated eyes and control eyes.

Animals↗
PubMed1986

Epikeratophakia for pediatric aphakia.

We used epikeratophakia for rehabilitation in 11 contact lens-intolerant aphakic children aged 9 months to 14 years. Minimum follow-up was five months; the longest was 12 months. There were no graft failures, and no patients were unavailable for follow-up. Objective postoperative overrefractions on all patients revealed that an average of 93% of the desired correction was obtained. Residual corrections ranged from -3.75 diopters spherical equivalent to +2.87 D. Nine of the 11 children were of verbal age; their spectacle visual acuities averaged 20/50, with a range of 20/20 to 20/80. Preverbal children all tolerated occlusive therapy, although accurate visual acuities could not be obtained. Our early results with this modality as therapy for monocular aphakia in the pediatric population have demonstrated improvement in visual function in all patients to date.

Adolescent↗
PubMed1986

Epikeratophakia for keratoconus. The nationwide study.

The nationwide study of epikeratophakia for the treatment of keratoconus involved 69 surgeons in the United States; they operated on 177 eyes as of Dec 31, 1985. In this first report, the results from 35 surgeons involving 82 cases with 30 or more days of follow-up after suture removal are described. In all but two patients, uncorrected visual acuity improved; 17 patients showed improvement of three Snellen lines, and 38 patients showed improvement of four or more lines. The majority of patients' vision returned to within one line of their best corrected acuity; in 78% it was 20/40 or better postoperatively. Eight patients needed no postoperative overrefraction at all. The mean flattening by keratometry readings was 9.36 diopters, and the mean decrease in myopia in terms of spherical equivalent was 5.26 D. No significant changes in intraocular pressure or endothelial cell counts were noted. Some advantages of epikeratophakia for keratoconus over the traditional penetrating keratoplasty include the lack of serious, vision-threatening complications or permanent vision loss, the reversible nature of the surgery, and the absence of potential immunogenic rejection phenomena.

Adolescent↗
PubMed1986

Report of an incarcerated Lynell anterior chamber intraocular lens.

This is the first report to document that the polyimide loops of a Lynell glass intraocular lens can cause erosion into the ocular structure and become incarcerated by peripheral anterior synechias. A technique for removal of this anterior chamber lens is described.

Anterior Chamber↗
PubMed1986

Epikeratophakia following previous refractive keratoplasty surgery: two case reports.

Epikeratophakia is becoming a significant and worthwhile surgical modality for selected cases of pediatric and adult aphakia, keratoconus, and myopia. Ultimately, it may also provide a safe and effective means of obtaining satisfactory surgical correction when the results from a previous refractive technique are insufficient. We present two successful cases of epikeratophakia following refractive keratoplasty: one following radial keratotomy for myopia and one following penetrating keratoplasty for keratoconus.

Adult↗
PubMed1986

Elimination of sodium hyaluronate-induced decrease in outflow facility with hyaluronidase.

The use of intraocular sodium hyaluronate is complicated by a postoperative rise in intraocular pressure (IOP). The rise in IOP is thought to stem from a "clogging" at the trabecular meshwork by the large molecules of hyaluronate. This study uses serial tonographic measurements in an animal model to document this change in outflow facility. Furthermore, we investigate the ability of the enzyme hyaluronidase to cleave the hyaluronate into smaller molecular weight fragments, in vivo, and thereby eliminate the change in outflow facility. This report demonstrates the potential usefulness of this enzyme and documents the lack of harmful side effects histopathologically.

Animals↗
PubMed1985

Use of a short wavelength filter in an operating microscope.

There is growing concern over the potential phototoxic effect on the patient's retina from the coaxial illumination of the operating microscope. By replacing the existing red-free filter in the body of a Zeiss operating microscope, with a 470-nm filter, the ultraviolet and low wavelength blue light can be easily and effectively filtered from the transmitted white light. In this location, the filter can be quickly and safely rotated into or out of line with the transmitted light depending on the preference of the ophthalmologist.

Filtration↗
PubMed1985

Potential hazards of blepharopigmentation.

Blepharopigmentation, or deposition of various colored particles near the lash line in a linear fashion, is becoming an increasingly popular form of cosmetic periocular surgery. This technique was employed on human cadaver globes and New Zealand white rabbits to evaluate several potential hazards to the globe. The lesions were noted and examined by histopathology.

Animals↗