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Biomedical subjects

R H Keates

Publications and source records attributed to R H Keates.

At least 55 records · Page 3Linked to original sources

Long-term follow-up of Nd:YAG laser posterior capsulotomy.

A Nd:YAG laser developed for ophthalmic surgery was studied for safety and efficacy in secondary discission of the posterior capsule in aphakic and pseudophakic subjects. The study involves 6,800 subjects, 526 of whom had completed the six-month postoperative course by the time the data base was closed for analysis. Of the 526 subjects who were treated with the laser, 87.8% had improved vision, with 82.9% achieving a visual acuity of 20/40 or better. This result compares favorably with results for the surgically treated population in which only 68.4% experienced improved vision, with 80.2% achieving a visual acuity of 20/40 or better. Approximately four times more surgically treated subjects than laser-treated subjects experienced diminished vision (14.8%). Cumulative complication rates in the laser-treated population were very low (CME 2.3%, secondary glaucoma 3.6%, retinal detachment 0.4%, overall rate 4.8%). Persistent complications (present at the six-month postoperative period) were present at an overall incidence of 2.3%, comprised primarily of CME, 0.2%, retinal detachment, 0.2%, and secondary glaucoma, 0.8%. Only 5.7% of subjects experienced an intraocular pressure (IOP) rise to 30 mm Hg or greater. Return to the preoperative IOP level occurred in 89% of subjects in the first 24 hours to one week. Predictors of IOP rise to 30 mm Hg or greater were determined to be preoperative glaucoma and/or preoperative IOP of greater than 20 mm Hg.

Aged↗

Clinical trial of flurbiprofen to maintain pupillary dilation during cataract surgery.

Thirty-four patients undergoing elective extracapsular cataract extraction were divided into a control group (18 patients) and treatment group (16 patients) in a double-blinded study to evaluate the nonsteroidal, anti-inflammatory drug flurbiprofen as an aid for maintaining pupil dilation during surgery. Both groups received the routine preoperative dilating drops, and the treatment group also received 0.03% topical flurbiprofen. After lens extraction, the change in pupil diameter from the preoperative measurement averaged -2.5 mm in the treatment group and -3.9 mm in the control group. The difference between groups was significant (p = 0.003), favoring flurbiprofen for maintaining pupil dilation.

Adult↗

Effect of beta-aminopropionitrile (BAPN) on corneal wound strength.

BAPN (beta-aminopropionitrile), a known inhibitor of collagen cross-linking, was instilled topically three times a day for 11 to 14 days in the eyes of rabbits after they had sustained central corneal wounds. In eight of nine rabbits, corneal wound tensile strength was significantly less in BAPN-treated eyes as compared to controls. This finding has important implications in all areas of ocular surgery and injury for control of collagen maturation and its complications in healing.

Aminopropionitrile↗

The effect of topical indomethacin ophthalmic solution in maintaining mydriasis during cataract surgery.

One hundred six consecutive patients undergoing elective cataract surgery were divided into a control group and treatment group in a double-blinded study to evaluate the non-steroidal, anti-inflammatory drug indomethacin as an aid for maintaining pupil dilation during surgery. Both groups received the routine preoperative dilating drops, and the treatment group also received 1% indomethacin. After lens extraction, the change in pupil diameter from the preoperative measurement averaged 0.27 mm in the treatment group and 0.84 mm in the control group. The difference in control groups was significant (p = 0.001), favoring indomethacin for maintaining pupil dilation.

Cataract Extraction↗

Unilateral pseudophakia and extended-wear aphakic contact lenses. A comparative study in a single patient population.

Twenty-nine patients who were pseudophakic in one eye and wearing a Permalens in the other eye were evaluated. Pseudophakic correction provided the patient with good, stable visual acuity, minimal risks, and an excellent long-term prognosis. Permalens aphakic correction also provided the patient with good, but fluctuating visual acuity. Risks such as deposit formation, tight lens syndrome, and corneal infections were not infrequently associated with the Permalens, and Permalens patients were also faced with the recurring cost of lens replacement. While both modalities of aphakic visual rehabilitation are acceptable, pseudophakia appears to provide the patient with better visual acuity, fewer risks, and lower financial costs in the long run.

Aged↗

Amvisc in extracapsular cataract extraction.

Amvisc, a purified fraction of sodium hyaluronate, was evaluated and compared with Healon in cataract extraction and primary intraocular lens implantation. Both visco-elastic solutions are valuable adjuncts to intraocular surgery. A number of patients had moderately elevated IOP after these solutions had been used in the anterior chamber. This moderate elevation was observed less frequently with Amvisc than with Healon, and may be attributed to the lower viscosity of Amvisc. Both visco-elastic solutions provide good endothelial protection as evidenced by the minimal corneal edema seen in both groups. Postoperative anterior chamber inflammation was minimal in all patients in this study.

Aged↗

Evaluation of the neodymium-YAG laser for treatment of ocular opacities.

The Neodymium:YAG Laser was used to find damage thresholds for glass and PMMA IOLs. In addition, optimal cone angles of the laser in regard to laser safety was determined along with consideration of suitability of other laser wavelengths. Lastly, investigation of substitute solutions for optical breakdown compared to vitreous was evaluated.

Cataract Extraction↗

Two-stage Neodymium-YAG laser trabeculotomy.

A preliminary report of a newly devised glaucoma operation is presented. This procedure combines a non-penetrating trabeculectomy with Neodymium:Yittrium-Aluminum-Garnet (Nd:YAG) trabeculotomy. This thus creates a through and through filtration under a scleral flap without actually entering the anterior chamber.

Adult↗

UV radiation.

Explore the source record for details and available documents.

Humans↗

Ultraviolet light transmission of the lens capsule.

A Cary, Model 118, spectrophotometer was used to measure spectral absorbence by the human lens capsule of wavelengths 200 nm to 400 nm. The lens capsule transmits greater than 90% of the incident UV light, and thus does not appear to provide significant protection for the retina from UV radiation. This suggests that the lower incidence of aphakic cystoid macula edema in the eye with an intact posterior capsule is not related to UV light absorption by the lens capsule.

Adolescent↗

Carbon dioxide laser beam control for corneal surgery.

Precise control of output power and beam divergence of a CO2 laser resulted in focused beam diameters down to 25 microns and essentially continuous control of energy deposition on target. Application of controlled laser beams on cow, hog, and human eye-bank reject corneal tissue give evidence of well-defined, narrow cuts. The controllable penetration depth and width of the CO2 laser incisions seem to make the laser an ideal "knife" for such corneal modifications as radial keratotomy and epikeratophakia. Our results indicate that the CO2 laser, when successfully integrated with the standard slit lamp, may be a safer and useful tool in laser surgery of the cornea.

Animals↗

Detachment of descemet's membrane with insertion of an intraocular lens.

The complication of Descemet's membrane detaching during cataract surgery is rare. Awareness that this can happen is especially important now that so many intraocular lenses are being implanted. A case is presented where a detachment was not noticed and an intraocular lens stripped Descemet's membrane from the corneal stroma.

Aged↗

The adjustable slide knot--an alternate technique.

A new method of typing an adjustable slide knot is presented. This knot retains the advantages of previously described slide knots and does not show undue slippage. This technique allows additional precision of wound closure in ophthalmic microsurgery.

Cataract Extraction↗