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Biomedical subjects

D M Colvard

Publications and source records attributed to D M Colvard.

At least 19 recordsLinked to original sources
PubMed1999

Randomized clinical comparison of Healon GV and Viscoat.

PURPOSE: To compare the ability of Healon GV (sodium hyaluronate 1.4%) and Viscoat (sodium chondroitin sulfate 4.0%-sodium hyaluronate 3.0%) to protect the corneal endothelium during endocapsular phacoemulsification and foldable intraocular lens (IOL) implantation. SETTING: A small ophthalmology group practice. METHODS: One hundred forty patients were randomized, 70 per group, in a prospective, partially masked study of cataract surgery using Healon GV or Viscoat. One ophthalmologist performed all surgery. Primary outcome variables were the 2 week postoperative changes in corneal thickness, endothelial cell density, mean endothelial cell size, and endothelial cell hexagonality. Several secondary variables were measured, and an analysis of the statistical power of the study was performed. RESULTS: There were no statistically significant differences between groups in terms of age (P = .856), cataract density (P = .117), preoperative best corrected visual acuity (BCVA) (P = .892), postoperative BCVA (P = .969), amount of viscoelastic material used during surgery (P = .444), amount of irrigating solution used (P = .125), or phacoemulsification time (P = .088). It took longer to remove the Viscoat than the Healon GV (P < .001), and total operating time for the Viscoat group was longer (P < .001). Two weeks after surgery, there were no significant differences between groups in corneal thickness (P = .362), endothelial cell density (P = .351), or mean endothelial cell size (P = .610). However, Viscoat preserved the hexagonal shape of endothelial cells slightly better than Healon GV (P = .043). The study had sufficient power to detect clinically significant differences in corneal thickness, endothelial cell density, and endothelial cell size. CONCLUSIONS: Healon GV and Viscoat were comparable in their ability to protect the corneal endothelium during endocapsular phacoemulsification and foldable IOL implantation. Results may vary, however, if phacoemulsification is performed anterior to the iris plane.

Aged↗
PubMed1997

Bimanual technique to manage subincisional cortical material.

The aspiration of subincisional cortical material using a standard irrigation/aspiration (I/A) handpiece can be a difficult maneuver in phacoemulsification. Access to the cortex is restricted and made more problematic by an incision carried into clear cornea and a continuous curvilinear capsulotomy. A bimanual technique for I/A has been developed that provides better access to subincisional cortex and improved chamber maintenance during aspiration.

Anterior Chamber↗
PubMed1990

Intraocular lens centration with continuous tear capsulotomy.

This study was designed to determine whether continuous tear capsulotomy was associated with improved posterior chamber lens centration. Two hundred eyes were divided into two subgroups of 100 patients each. In one subgroup a standard can-opener capsulotomy was performed and in the other, a continuous tear capsulotomy. All other factors including the cataract extraction technique, intraocular lens (IOL) style, the capsular bag placement of the IOL, and the use of viscoelastic material were constant. In this study, IOLs implanted after a continuous tear capsulotomy were found to center more reliably than IOLs implanted after a can-opener capsulotomy (P less than .01).

Cataract Extraction↗
PubMed1984

Operating microscope light-induced retinal injury: mechanisms, clinical manifestations, and preventive measures.

Experimental and clinical evidence of light-induced retinal injury associated with the operating microscope is reviewed. The mechanism of photochemical injury is discussed, as well as the concept of reversible phototoxic insults. Factors that influence retinal recovery and measures that can be taken by the surgeon to reduce light exposure to the retina are also discussed.

Biomechanical Phenomena↗
PubMed1981

Endothelial cell loss following phacoemulsification in the pupillary plane.

Endothelial cell loss following posterior chamber phacoemulsification with and without posterior chamber lens implantation was studied. Postoperative cell counts were taken four months after surgery. Three surgeons participated in this study. Posterior chamber phacoemulsification alone (30 patients) resulted in a mean cell loss of 9%, with a maximum cell loss of 22% in one patient. Posterior chamber phacoemulsification with posterior chamber lens implantation (30 patients) resulted in a mean cell loss of 8% with a maximum cell loss of 26% in one patient. Statistical analysis shows no difference in postoperative cell loss between these two groups.

Aged↗
PubMed1981

Secondary posterior chamber intraocular lens implants.

Secondary posterior chamber lens implants were performed on sixty-nine patients. Although technically the insertions were slightly more difficult than in a primary case, the results were excellent. Only one eye had vision significantly lower than preoperative level, and this, only a drop from 20/25 to 20/40. Three eyes required a second procedure to suture the lens. One eye suffered detachment later with count fingers vision as the final result.

Aged↗
PubMed1981

The Terry surgical keratometer: a 12-month follow-up report.

Postoperative astigmatism was studied in two groups of patients. All patients had undergone phacoemulsification with implantation of a posterior chamber intraocular lens. The incision closure techniques in both groups were identical, with one exception: One group was closed using the Terry keratometer intraoperatively, the second group was closed without the use of this instrument. Two observations are made from the twelve-month data. First, astigmatic error in the Terry group remained constant from the postoperative keratometer readings at six weeks to the twelve-month keratometer readings. Second, while there was a considerable difference in astigmatism at six weeks between the Terry group and the control group (less astigmatism in the Terry group), the differences were no longer apparent at twelve months. Sutures were removed as necessary to improve astigmatism in the control group. No sutures were cut in the Terry group during this twelve-month period.

Astigmatism↗
PubMed1981

The Shearing intraocular lens: a report of 1,000 cases.

Implantation of Shearing and Shearing-style J-loop posterior chamber lenses in 1000 cases was associated with an absence of corneal decompensation and a low incidence of glaucoma, cystoid macular edema, iritis, vitritis and retinal detachment. The low complication rate was attributed to the posterior chamber position of the J-loop lens, which may reduce the movement of intraocular fluid and tissue.

Adult↗
PubMed1980

Clinical evaluation of the Terry surgical keratometer.

A study was designed to evaluate the usefulness of the Terry quantitative surgical keratometer as a tool to minimize surgically induced astigmatism. Two hundred and twenty-five phacoemulsifications with Shearing-style implants were performed, using identical technique. Seventy-five control cases were closed without the keratometer and 150 were closed with the keratometer. In the control group, 29.3% cases had corneal astigmatism of 3D or more, compared to 4.6% cases in the keratometer group (P < .01). The total change in astigmatism was 2.64D in the control group and 0.91D in the keratometer group (P < .02). We believe that these data demonstrate the usefulness of the Terry keratometer.

Astigmatism↗
PubMed1979

Sterilization of scleral homografts with ionizing irradiation.

We devised a method of sterilization and preservation of sclera that we have found reliable and convenient. Gamma irradiation is a highly effective method of sterilization. Airtight, watertight, plastic packaging of frozen irradiated sclera allows for safe long-term storage and for convenient use in the operating room.

Freezing↗
PubMed1979

Radiation absorbed dose to the lens in dacryoscintigraphy with 99mTcO4-.

Calculations of the radiation dose to the lens for 99mTcO4- in dacryoscintigraphy are developed in some detail. The results indicate that the absorbed dose to the germinal epithelium of the lens is 2.2 X 10(-5) to 1.4 X 10(-4) rad/microCi (5.9 x 10(-12) to 3.8 x 10(-11) Gy/Bq) 99mTcO4- under physiological conditions. With blockage of the lacrimal drainage apparatus, the dose to the lens could increase to 4 X 10(-3) rad/microCi (1 X 10(-9) Gy/Bq).

Cornea↗
PubMed1979

Usher's syndrome with unusual otologic manifestations.

Usher's syndrome is characterized by a congenital hearing loss and retinitis pigmentosa. Ocular symptoms and signs are usually established at adolescence, and the hearing loss, the onset of which is at a young age, generally remains stable. The following case is of interest, therefore, because the hearing loss that had been present since birth progressed suddenly to total bilateral deafness in adulthood. There were no ocular symptoms at any time; the classic findings of retinitis pigmentosa were disclosed only on routine examination of the eyes.

Adult↗