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Biomedical subjects

M A Terry

Publications and source records attributed to M A Terry.

27 records · Page 2Linked to original sources
PubMed1994

Hydration changes in cadaver eyes prepared for practice and experimental surgery.

OBJECTIVES: To identify reliable and efficient methods of thinning postmortem corneas for surgical experiments and to develop methods of maintaining stable corneal thickness. METHODS: Three methods of corneal thinning were evaluated by group: group A, increased intraocular pressure; group B, exchange of anterior chamber fluid with dextran solution and immersion in dextran solution; and group C, immersion in dextran solution without aqueous replacement. The stability of the thinned central cornea was then evaluated by exposing 30 corneas thinned by methods used in groups B and C to air, Balanced Salt Solution drops (Alcon, Fort Worth, Tex), or dextran solution drops. RESULTS: By 1 hour, the thinning method used in group A resulted in only three of 11 eyes achieving normal central corneal thickness. The method used in group B resulted in normal central thickness in 14 of 14 corneas and in group C, in nine of 15 corneas, at 1 hour. Once thinned by methods used in group B or C, air exposure further thinned the 30 additional corneas by 22% to 26%, Balanced Salt Solution drops thickened the corneas by 16% to 22%, and dextran solution drops stabilized the corneas with only 5% to 13% additional thinning. CONCLUSIONS: Hyperosmolar solutions were more efficient than pressure gradients in thinning the cadaver central cornea. Hydration shifts of the de-epithelialized cornea were dramatic with use of Balanced Salt Solution drops or drying and were minimized with use of hyperosmolar topical solutions.

Aged↗
PubMed1992

Writing a multiple-choice test question.

Multiple-choice test questions are the most widely used and highly regarded of the presently available objective or selective test items. They can be used to test all levels of learning and are applicable to the measurement of most important educational outcomes. Although it is difficult to construct these questions well, they are versatile and can be used in settings involving large numbers of students.

Education, Medical, Graduate↗
PubMed1986

Microwave sterilization of hydrophilic contact lenses.

We used standard 2,450-MHz microwave irradiation to achieve sterilization of hydrophilic contact lenses contaminated with a variety of bacterial, fungal, and viral corneal pathogens. A three-dimensional rotisserie was used to overcome the problem of "cold spots" within the microwave oven. The contact lenses became dehydrated in approximately two minutes. Rehydration with normal saline restored their shape and appearance. The time necessary to prohibit all growth of the bacterial and fungal organisms studied ranged from 45 seconds to eight minutes. All viral contaminants were completely inactivated after four minutes of microwave exposure. Refractive properties were unaffected after 101 exposures to microwaves for ten minutes. Slit-lamp examination and scanning electron microscopy disclosed minute particles on the surface of these contact lenses but no damage to the lens matrix from irradiation.

Bacteria↗
PubMed1986

Dynamic shifts in corneal topography during the modified Ruiz procedure for astigmatism.

We utilized ten eye bank eyes to evaluate and quantitate the immediate corneal topographic shifts that occur after each stage of a modified Ruiz procedure for astigmatism. Computer digitization of photokeratoscope (Corneascope) photographs revealed that the initial two central paired tangential incisions induced an average of 5.10 diopters (D) of central astigmatism by flattening the meridian perpendicular to the incisions and by steepening the meridian 90 degrees away. Additional tangential incisions did not significantly alter the topography after placement of the first two central incisions. Addition of corridor incisions produced an additional 5.25 D of induced astigmatism by further extensive flattening of the incised meridian. The completed procedure produced an average of 11.03 D of astigmatic shift, but with a wide range of effect (7.15 to 12.96 D). With modification, the Ruiz procedure is a powerful keratorefractive surgical technique.

Astigmatism↗
PubMedDate not supplied

Community-based care management: a framework for delivery of services.

Care management must be marketed by home healthcare agencies as a formalized, separate entity for which reimbursement is received. The authors explore this new venture from the perspectives of the care management process and resulting service delivery issues.

Continuity of Patient Care↗
PubMedDate not supplied

Variability in corneal thickness before, during, and after radial keratotomy.

BACKGROUND: Precision in radial keratotomy requires accurate pachymetry for safety and efficacy. We evaluated the location, timing, and extent of changes in corneal thickness between those determined by preoperative measurement in the clinic and those determined by pre-incision and post-incision measurement in the operating room. METHODS: Sixty eyes of 37 patients had ultrasonic pachymetry measurements of the central and paracentral cornea taken in the clinic 20 minutes before each patient underwent radial keratotomy. The pachymetry was repeated intraoperatively immediately before and, in a subset of 17 eyes, immediately after incisions were made, and the readings were compared. RESULTS: The thinnest of the four paracentral readings measured just prior to placing the radial keratotomy incisions was located temporally in 92% of the eyes and inferiorly in 8%. Corneas progressively thinned from clinic to surgery by an average of 7 +/- 12 microns centrally and 10 +/- 18 microns temporally. Additional thinning of 13 +/- 14 microns centrally and 22 +/- 23 microns temporally occurred during surgery. CONCLUSION: The thinnest paracentral corneal region measured in an eye was not always located in the same quadrant preoperatively and intraoperatively. During the time of incision placement, significant corneal thinning had occurred at each incision site. Individual variations in corneal thickness between that measured preoperatively and that measured during surgery cautions against the use of clinic readings for diamond knife settings during radial keratotomy.

Cornea↗
PubMedDate not supplied

Use of keratoscopy, slit-lamp biomicroscopy, and retinoscopy in the management of astigmatism after penetrating keratoplasty.

Selective suture removal following corneal transplant surgery can facilitate the reduction of astigmatism. We present concepts concerning astigmatism analysis after keratoplasty related to suture compression by reviewing keratoscopy, slit-lamp biomicroscopy, and retinoscopy findings. Keratoscopy observations indicating tight sutures include peripheral indentation of the keratoscope rings, individual keratoscope ring images between tight sutures, and decentration of the corneal apex away from a tight suture. The utilization of the Van Loenen keratoscope at the slit-lamp in "dynamic keratoscopy" allows the surgeon to readily recognize these findings and also proves useful intraoperatively. Slit-lamp biomicroscope observations indicative of tight sutures include a doughnut of tissue compression, Kaye's epithelial white dots, and epithelial or endothelial stress lines. Retinoscopy observations demonstrate that tight sutures induce astigmatism with the narrowest side of the retinoscopy beam pointing directly toward the tightest suture. Astigmatism management plays a major role in the future success of ophthalmology and needs to be increasingly integrated into the practice of the general ophthalmologist.

Aged↗