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Biomedical subjects

R C Morgan

Publications and source records attributed to R C Morgan.

28 records · Page 2Linked to original sources
PubMed1991

Anterior capsular tears and loop fixation of posterior chamber intraocular lenses.

Two hundred fifty consecutive postmortem eyes containing posterior chamber intraocular lenses (PC IOLs) were analyzed according to the presence and number of radial anterior capsular tears. Over 90% of cases had been done with the "can opener" technique. A surprisingly high percentage of cases, 86%, had one to five radial tears. Furthermore, our analysis showed that the most consistent and most permanent in-the-bag fixation was achieved when only one tear or less was present in the anterior capsule. Because this study shows that the incidence of radial tears is very high after nuclear expression with "can opener" capsulectomy, it provides a scientific basis supporting the transition toward the continuous circular capsulorhexis technique that is slowly evolving. The latter technique has been shown to minimize the incidence of anterior capsular radial tears. This may ultimately serve to decrease the incidence of PC IOL decentration, an important goal if the use of bimultifocal IOLs and IOLs with small or aspheric optics is to be successful.

Aged↗
PubMed1991

An analysis of flexible anterior chamber lenses with special reference to the normalized rate of lens explantation.

A survey of 1204 closed-loop anterior chamber intraocular lenses (AC-IOLs) and 310 open-loop AC-IOLs accessioned between November 1982 and January 1990 was conducted at the Center for Intraocular Lens Research. An analysis of complication rates was done after normalization of data with respect to market share totals. The results establish that an unacceptable complication rate is associated with the closed-loop design when compared with either the tripod or quadripod lens styles. Furthermore, the closed-loop designs, while comprising an estimated 45% of the total number of AC-IOLs estimated to be implanted in the United States (n = 674,000), were responsible for 80% of the AC-IOLs explanted after complications and accessioned at the authors' center. A rethinking of the extreme condemnation of all anterior chamber IOLs that has surfaced in recent years is warranted. This is particularly true with respect to indications for use of sutured posterior chamber (PC) IOLs as well as with regard to possible use of open-loop AC-IOLs in less-industrialized nations.

Anterior Chamber↗
PubMed1991

The relationship between the stretching capability of the anterior capsule and zonules.

The stretching capability of the zonules was studied in 40 human eyes obtained postmortem from 27 patients. A continuous circular capsulorhexis (CCC) (2.2-6.8 mm) was performed, and the lenses were removed by either phacoemulsification (26 eyes) or planned extracapsular cataract extraction (ECCE) (14 eyes). Maximal zonular stretch was calculated as the difference in distance between the ciliary processes and the zonular insertion at rest and after maximal stretch. This zonular stretch test showed that zonules can stretch to a mean distance of 3.82 mm before rupturing. Capsular elasticity was measured in 35 of the eyes by gradually opening a modified caliper until the capsular opening was torn. The ratio between the circumference at rupture and the circumference at rest was used as an index of capsular elasticity. Circumference of the intact capsulorhexis could be enlarged an additional 62% before a radial tear occurred. In most cases, no significant correlation was seen between the capsular and zonular capability to stretch. Maximal zonular stretch decreased significantly with age by approximately 0.5 mm for every 5 yr, whereas capsular elasticity did not show a significant correlation with age. Two eyes with pseudoexfoliation had relatively friable zonules but the capsular elasticity was within normal limits. Patient age is probably the best indicator of the stretching capability of the zonules.

Age Factors↗
PubMed1990

Preparation and study of human eyes obtained postmortem with the Miyake posterior photographic technique.

A modification of the original Miyake technique of posterior photography of human eyes obtained postmortem is presented. A detailed description of globe preparation and equipment is described. Use of modern technology including a high magnification microscope system and video camera permits dynamic or realtime observations of tissue effects of various surgical procedures such as the cataract operation. This technique provides both a research and educational tool that can be used by ophthalmologists to improve the quality of surgery. Most important, it is an instructional tool that should reduce the "learning curve" that is inherent when modifying one's surgical technique.

Eye↗
PubMed1986

Surgical management of tarsal coalition in adolescent athletes.

The authors studied 12 adolescent patients with a known diagnosis of tarsal coalition. These patients were also active participants in athletics. Of the 12 patients studied, there were eight with calcaneonavicular bars and four with talocalcaneal bars. Even though nonoperative treatment was not successful, only eight of the 12 elected to have surgery. Following surgical resection of the tarsal coalition, five of six patients who had calcaneonavicular bar excisions as well as two patients with talocalcaneal bar excisions were able to return to competitive athletics. Nonoperative treatment of the tarsal coalition did not result in alleviation of symptoms and full return to athletics. The surgical excision of the calcaneonavicular bar with extensor digitorum brevis arthroplasty afforded the best results.

Adolescent↗
PubMed1986

Hexachlorobenzene in hazardous waste sites.

Hexachlorobenzene (HCB) has been measured in the water, soil, air or biota at several uncontrolled hazardous waste sites. At one of these sites in Louisiana, 9,500,000 ppb have been measured in the oily fraction of an oil-water mixture taken from a monitoring well, and in water of nearby wells at concentrations up to 28 ppb. HCB has been detected in solid wastes and sediments at concentrations up to 6,000,000 ppb at a site in Michigan, while fish in a nearby creek contained up to 50 ppb. At other sites, HCB has been detected in air. Thus, exposure to this chemical may occur by several routes. Hazardous waste sites containing HCB, which are now being cleaned up under Superfund, include sites used for disposal of by-products of rubber manufacture, liquid-waste processing and incineration, and pesticide production. The variety of known sources of HCB suggests that its occurrence in hazardous waste sites may be widespread.

Animals↗
PubMed1985

The arcuate skin staple: its influence on pain of staple penetration and removal.

The purpose of this study was to measure the degree of pain elicited by either staple implantation and by removal in human subjects. Included in the study were conventional rectangular staples and the new arcuate staples. The pain associated with staple implantation was significantly greater than that associated with staple removal. The configuration of the staple did not influence the magnitude of pain associated with either staple implantation or staple removal.

Equipment Design↗
PubMedDate not supplied

The "anteater nose": a direct sign of calcaneonavicular coalition on the lateral radiograph.

On the lateral foot or ankle film of patients at least 9 years old with calcaneonavicular bar (CNB), there is a tubular prolongation anteriorly of the superior calcaneus which fancifully resembles the nose of an anteater. This prolongation approaches or overlaps the midportion of the navicular. Such a configuration was present in all 30 feet reviewed with CNB, but not in 125 feet of 100 subjects, in their second decade, without CNB.

Bone Diseases↗
PubMedDate not supplied

Cytologic diagnosis of intravenous talc granulomatosis by fine needle aspiration biopsy. A case report.

A fine needle aspiration specimen from the right lung of a 44-year-old former drug addict was submitted for cytologic evaluation. The specimen consisted of numerous mononucleate and multinucleate macrophages containing aggregates of silicate crystals, as seen by light microscopic examination using a polarizing filter. The background of the slides included fibroblasts, lymphocytes and other inflammatory cells. The finding within foreign-body giant cells of large groups of strongly birefringent, platelike crystals varying widely in size led to the conclusive cytologic diagnosis of intravenous talc granulomatosis.

Adult↗