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Biomedical subjects

F M Polack

Publications and source records attributed to F M Polack.

At least 37 records · Page 2Linked to original sources
PubMed1982

A retrospective study of endophthalmitis.

The results of a survey of 50 cases of endophthalmitis following surgery, trauma, corneal ulcers, or of endogenous origin are described. Most of the post-surgical cases followed intracapsular cataract surgery and in 48.1% of the eyes, the predominant organisms were gram positive bacteria. In cases where the infected eyes were treated with topical, intravenous and subconjunctival injections of antibiotics, 57.2% of the eyes were lost; however, in 6 cases, where vitrectomy and intravitreal injection of antibiotics was performed, only 1 of the 6 eyes was lost (16.6%). In this eye, however, the vitreous removal and antibiotic injection was done in advanced stage of the disease. In one case where the vitrectomy and antibiotic therapy was performed early, the patient attained good vision.

Corneal Ulcer↗
PubMed1981

Endothelial damage after anterior radial keratotomy. An electron microscopic study of rabbit cornea.

Anterior radial keratotomy was performed on the left eyes of 21 rabbits. Specimens were taken for electron microscopic examination at intervals during a three-month period. The corneas were acutely inflamed for three days after surgery. Some endothelial cells beneath the incisions were damaged, and distended intercellular spaces were seen. Deeper incisions seemed to produce more severe damage. With increasing time after surgery, some of the damaged endothelial cells seemed to be recovering, while others in the areas between the incisions and in the center of the cornea were degenerating. Three months after surgery, the endothelium had recovered, but some of the peripheral intercellular spaces still were distended. These findings may be the result of continuous blinking in combination with the structural weakness of the cornea, rather than a result of chronic postsurgical inflammation.

Animals↗
PubMed1981

Electron microscopic study of epithelial downgrowth after penetrating keratoplasty.

An electron microscope study of 2 cases of epithelial downgrowth after penetrating keratoplasty is presented. Several differences were observed between the normal epithelium and downgrowth epithelium at the ultrastructure level. At the advancing edge of the downgrowth a flattened and fibroblastic endothelium was still present. An interaction area was observed between these 2 tissues. The epithelial downgrowth usually has 5 to 6 layers of cells and either replaces damaged endothelium or destroys it as it advances. The attachment of this downgrowth tissue to the Descemet's membrane at the centre of the graft seemed looser than attachment of a normal epithelium to Bowman's membrane. Near the host-graft junction the downgrowth epithelium, with basement membrane, was tightly attached to a fibrous retrocorneal membrane. Clinical and histological findings suggest that the absence of endothelium assists in the advance of the epithelial downgrowth, but it is not an essential factor. The causes of this downgrowth are thought to be (1) a thin host cornea; (2) incomplete cutting and wound incarceration of Descemet's membrane; and (3) tight sutures with disruption of an old cataract wound.

Adult↗
PubMed1981

Adherence of Pseudomonas aeruginosa to the injured cornea: a step in the pathogenesis of corneal infections.

Keratitis caused by Pseudomonas aeruginosa usually occurs in the setting of corneal injury. This investigation was carried out to ascertain whether injury predisposes to infection by permitting this organism to adhere to the cornea. P. aeruginosa was found to adhere to injured corneas in preference to uninjured ones. Adherence was not immediate and required that the organisms remain on the corneal surface for some time. The number of adhering bacteria appeared to increase with the time the bacteria were allowed to remain on the corneal surface. Use of inocula concentrations of 10(7) to 10(9) was best for studying this phenomenon quantitatively and by microscopy. We conclude that injury allows Ps. aeruginosa to adhere to the corneal surface and suggest that this is the explanation for the clinical observation of a relationship between corneal and injury and Pseudomonas keratitis.

Adhesiveness↗
PubMed1980

Scanning electron microscopy of posterior polymorphous corneal dystrophy.

An 8 1/2-year-old girl had posterior polymorphous dystrophy that required keratoplasty. Similar lesions were found in the patient's mother, thus establishing the genetic trend of the disease. Scanning electron microscopy studies showed areas of endothelial cell degeneration and multiple depressions or pits. These seemed the most advanced and characteristic lesions of posterior polymorphous dystrophy. Transmission electron microscopy studies in areas adjacent to the pits showed an abnormally developed Descemet's membrane covered by two or more layers of elongated endothelial-like cells. Cells over Descemet's membrane seemed to deposit some Descemet's membrane material and both fine and coarse collagen fibrils. Cells had prominent mitochondria, normal endoplasmic reticulum, and desmosomal attachments. Cytoplasmic fibrils and microvilli were usually found in cells lining the anterior chamber. Specular microscopy and scanning electron microscopy recorded the image of only the innermost cells and these appeared as endothelium.

Child↗
PubMed1980

Electron microscopic study of recurrent Reis-Bücklers' corneal dystrophy.

We studied the cornea of a 51-year-old woman with recurrent Reis-Bücklers' dystrophy with the transmission electron microscope. The patient had had a superficial keratectomy nine years earlier. The epithelium removed in a second keratectomy contained distended endoplasmic reticulum and swollen mitochondria. The basal layer showed some cells in mitosis and a slight increase in the number of dark cells. The anterior portion of the removed stroma contained dense collagen fibrils, with the appearance of curly fibrils, which is characteristic of this disease. There were also severe degenerative changes in the stroma. These changes in the collagen fibers and alterations in keratocytes of the deeper layers were less severe than those of the superficial layer. A biopsy of the bulbar conjunctiva showed reduplication of the basement membrane.

Adult↗
PubMed1980

Management of anterior segment complications of intraocular lenses.

Corneal edema was found in 24 of 43 eyes with anterior segment complications of intraocular lenses. Keratoplasty was performed in 20 eyes. Three eyes required other surgical therapy for edema while medical treatment of edema was done in one case. Thirty-two lenses were removed because of pain, inflammation, bleeding or glaucoma. Nineteen of these were removed at the time of keratoplasty. Three eyes were enucleated because of absolute glaucoma, retinal detachment and endophthalmitis.

Corneal Diseases↗
PubMed1980

Ceramic keratoprostheses.

This paper describes a new type of corneal prosthesis made of aluminum oxide ceramic. The implant consists of a retaining plate with a 3-mm central performation to which an optical cylinder is threaded. The cylinder also made of ceramic material, has a high refractive index and 60 diopters of power. Experimental study has shown that soft tissue adheres to the surface of the material, thus preventing its extrusion and surface epithelial ingrowth. The techniques of implantation and the early results in seven patients are described.

Adolescent↗
PubMed1980

Isolation of the plasma membrane from corneal endothelial cells.

The plasma membtanes of normal rabbit endothelail cells were isolated by the use of an aqueous two-phase polymer system. The membrane fraction was identified by electron microscopy, and a fivefold to eightfold increase in the specific activity of two plasma membrane markers. Na+-K+-ATPase and 5'nucleotidase was found. Recovery of the enzyme markers averaged 45% and 22%, respectively. Analysis of the purified membranes for glucose-6-phosphatase, a marker for endoplasmic reticulum, showed no contamination by this structure. This method for cell membrane characterization is promising in determining the enzymatic alterations of diseased corneas.

Adenosine Triphosphatases↗
PubMed1980

Keratoplasty in aphakic eyes with corneal edema: results in 100 cases with 10-year follow-up.

Penetrating keratoplasties were performed in 100 patients with bullous keratopathy and aphakia. In 85% of cases, edema was due to Fuchs' dystrophy. Cases were divided into eyes with good, fair, and poor prognosis, depending on the presence of glaucoma, anterior segment pathology and corneal vascularization. The three combined groups had 78% clear grafts during the first year, but when results were correlated with the prognostic groups, there were 85% of clear grafts in Group I, 78% in Group II, and 60% in Group III. The number of clear grafts dropped prominently in Groups II and III after the second year. At the end of ten years, 7 of 15 clear grafts corresponded to Group I. The most common possible causes of graft failure not related to donor tissue were: Vitreous in contact with the graft, glaucoma, and anterior segment pathology.

Aged↗
PubMed1979

Scanning electron microscopy of congenital corneal leukomas (Peters' anomaly).

Specimens of three corneas in two patients with Peter's anomaly were obtained at the time of penetrating keratoplasty and studied by scanning and transmission electron microscopy. In one patient, the anomaly was monocular, and the endothelial surface showed a central defect in Descemet's layer with isolated rounded defects in the midperiphery. Fine collagenous material covered the posterior surface. The other two specimens were obtained from a patient with rubella syndrome without cataracts. The cornea showed malformation of Descemet's membrane with fibroblastic overgrowth on the endothelial layer. Epithelial-like cells and leukocytes were also found. The congenital central leukoma we believe was caused by adhesion of the pupillary membrane in our first patient, and possibly was inflammatory in our second patient.

Cornea↗
PubMed1979

[Ocular pathology related to intraocular lenses (author's transl)].

This study describes the ultramicroscopic alterations in several types of intraocular lenses removed from eyes with persistent ocular inflammation or elevated intraocular pressure. In some instances the alterations found in the lens material could have caused ocular disease. The corneal edema present in eyes with intraocular lenses sometimes is related to trauma at the trauma at the time of intraocular lens implantation. In most cases the alterations are similar to those found in Fuchs' dystrophy. The presence of warts in Descemet's membrane indicate previous corneal pathology, an obvious contraindication to the use of these devices.

Cornea↗
PubMed1978

Autoradiographic study of retrocorneal membranes.

Fibrous membranes in the posterior cornea occur in failed transplants. The purpose of these studies was to investigate the role of corneal endothelium in the formation of these membranes. The corneal cellular components of rabbit corneas were labeled with tritiated thymidine. Labeled rabbit corneal stroma was replaced with unlabeled tissue (pre-Descemet's lamellar graft), leaving only labeled endothelium. Weeks later small unlabeled penetrating grafts, without endothelium, were placed inside this lamellar graft. The surrounding labeled host endothelial cells were found in a fine retrograft membrane and in the scar of grafts. The experiment demonstrated that host endothelial cells participate in the formation of retrograft membranes, but it does not exclude other origin of fibroblasts.

Animals↗