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Biomedical subjects

M P Vrabec

Publications and source records attributed to M P Vrabec.

At least 19 recordsLinked to original sources
PubMed1996

Human excimer laser keratectomy. Immunohistochemical analysis of healing.

OBJECTIVE: To analyze human corneal responses to excimer laser by immunohistochemistry. METHODS: Corneas cultured for 3 weeks after laser ablation or taken from patients 5 to 16 months after laser treatment were exposed to antibodies to beta, integrin; types VII, IV, and III collagen; fibronectin; type I procollagen; and prolyl 4-hydroxylase. Antibody distributions were compared with those of normal corneas and unablated regions of treated corneas. RESULTS: After 3 weeks, distribution of beta, integrin, and types VII and IV collagen was patchy; heavy deposits of fibronectin appeared subepithelially. Keratocytes stained for prolyl-4-hydroxylase and type I procollagen. With increasing postoperative time, fibronectin diminished, and beta 4 integrin and type VII collagen became linear, stromal staining of types III and IV collagen increased and their diminished. CONCLUSIONS: Components of basement membrane, attachment complexes, and stromal matrix are synthesized shortly after laser treatment. Changes in these elements persist for 16 months in the human cornea.

Adult↗
PubMed1996

A new scleral suction trephine for retrieval of corneoscleral donor tissue.

BACKGROUND: Removal of donor corneo-scleral shell from a cadaver, leaving the remainder of the eye in place, has become a popular technique. Manual removal can result in excessive trauma to the corneal endothelium or an uneven scleral rim. METHODS: We describe a new technique for corneal retrieval using a sceral suction trephine. RESULTS: The scleral suction trephine was cut evenly in our eyebank study. There was no additional trauma to the endothelium and the scleral rim was regular. CONCLUSION: Suction trephination of the sclera in retrieval of corneal donor tissue appears to be safe and effective.

Aged↗
PubMed1994

Human excimer laser keratectomy. Clinical and histopathologic correlations.

PURPOSE: To understand the healing capabilities of the diseased human cornea after excimer laser photoablation by morphologic analysis of laser-treated corneas. METHODS: Twelve corneal specimens were obtained 5 to 16 months after lamellar or full-thickness keratoplasty following phototherapeutic keratectomy for undercorrected myopic epikeratoplasty (2 eyes), corneal leukomas (2 eyes), herpes zoster corneal scarring (1 eye), band keratopathy (2 eyes), adenoviral subepithelial opacity (1 eye), keratoconus (1 eye), herpes simplex corneal scarring (2 eyes), granular corneal dystrophy (1 eye), and recurrent lattice dystrophy (1 eye). The morphology of the corneas was examined by light and electron microscopy. RESULTS: Epithelial hyperplasia, abnormal epithelial attachment, and disorganized stromal matrices were observed. Evidence of residual disease frequently observed in these specimens indicated that the pathology either was not excised at the time of laser keratectomy or was recurrent. CONCLUSIONS: The response of the diseased cornea to excimer laser treatment has similar characteristics to the responses previously observed in animal studies. Incomplete ablation of diseased tissue and/or recurrence of the initial disease was the major reason for failure of the treatment. Possible causes for the inability to remove diseased tissues and superficial scars with the excimer laser include (1) insufficiently achieved ablation depth and/or diameter and (2) decreased laser ablation rates of scarred cornea.

Adult↗
PubMed1994

Lamellar keratoplasty performed with a corneal scleral button.

Tissue for lamellar corneal surgical procedures is usually harvested from whole eyes. We describe a surgical technique for the rehabilitation of corneoscleral defects with lamellar keratoplasty in which the donor tissue is obtained from a preserved corneoscleral button instead of a whole globe. This technique is illustrated with a case involving the treatment of a limbal dermoid in a 26-month-old boy.

Child, Preschool↗
PubMed1994

Electron microscopic findings in a cornea with recurrence of herpes simplex keratitis after excimer laser phototherapeutic keratectomy.

Excimer laser phototherapeutic keratectomy is emerging as an alternative therapy to corneal transplantation for the treatment of multiple corneal diseases. We report three cases of recurrence of herpes simplex keratitis after treatment of herpetic corneal scars with the excimer laser. In two cases, the patients underwent subsequent corneal transplantation. One corneal button examined with transmission electron microscopy (TEM) demonstrated a well-differentiated epithelium over the area of ablation, a linear, continuous basal lamina, and no viral particles. Anterior stromal scarring may have resulted from the laser treatment itself or may represent incomplete ablation of previous scars. Whether reactivation of the virus was stimulated by the laser or occurred as part of the natural history of the disease is uncertain. We recommend that patients who undergo excimer laser treatment for herpes simplex scarring receive careful follow-up including antiviral coverage.

Adult↗
PubMed1993

A prospective, randomized comparison of thermal cautery and argon laser for permanent punctal occlusion.

Permanent punctal occlusion was performed by two techniques on 27 patients (73 puncta). Patients were randomly assigned to be treated with either thermal cautery or argon laser for keratitis sicca. Follow-up assessment disclosed that the puncta to which thermal cautery was applied remained closed significantly longer than those to which laser treatment was applied (P < .05, log-rank test). Using time to recanalization of a punctum as the end point, we found a long-term advantage of thermal cautery over argon laser treatment.

Cautery↗
PubMed1993

Subconjunctival fibrosis after conjunctival autograft.

While largely successful, the use of a conjunctival autograft in the exposed scleral bed following a pterygium excision can result in postoperative complications. We report two cases of a previously undescribed complication: subconjunctival fibrosis at the harvest site of the graft. In one case, the fibrosis caused an asymptomatic, purely cosmetic defect; however, in the other case, the scar tissue constricted the extraocular movement with resultant diplopia. We call attention to this complication as it can affect visual function; we discuss its management and prevention.

Adolescent↗
PubMed1990

Cholesterol localization in ultrathin frozen sections in Schnyder's corneal crystalline dystrophy.

We examined a 57-year-old woman who had bilateral corneal crystalline deposits associated with xanthelasma. The patient's son had bilateral stromal haze. Plasma cholesterol and apolipoprotein A-I and B levels were normal. Histopathologic examination disclosed lipid deposits, particularly in the superficial stroma and Bowman's layer. These deposits stained with oil red O and filipin, a fluorescent probe that specifically detects unesterified cholesterol. Cryoultramicrotomy disclosed more specific ultrastructural localization of unesterified cholesterol with an array of crystals resembling multiple plates in extracellular corneal tissue.

Cataract↗
PubMed1990

The pathology of posterior amorphous corneal dystrophy.

The youngest affected member of a family with a five-generation history of posterior amorphous corneal dystrophy underwent penetrating keratoplasty. The corneal button was studied by light and electron microscopy, representing the first pathologic description of this condition. Light microscopy demonstrated fracturing of the most posterior collagen layers of the stroma and focal attenuation of endothelial cells. Electron microscopy showed the collagen fibers in the most posterior stromal lamellae to be disorganized. Descemet's layer was interrupted by a band of collagen fibers resembling stroma, and there was loss of endothelial cells. These findings suggest a developmental abnormality in the formation of the posterior stroma and Descemet's membrane in posterior amorphous corneal dystrophy.

Child, Preschool↗
PubMed1988

Ophthalmic observations in lecithin cholesterol acyltransferase deficiency.

Lecithin cholesterol acyltransferase is an enzyme that esterifies free cholesterol. A complete deficiency of this enzyme results in a diffusely cloudy cornea. This deficiency is thought to be transmitted as an autosomal recessive trait. We studied a family in which four members were homozygote recessive. In the homozygote recessive condition, a central corneal haze caused by deposition of numerous minute gray dots was consistently present. In the heterozygote condition, arcuslike changes were present in some of the patients studied. We found the corneal change in the recessive state to be sensitive and specific as a marker of this condition. Heterozygotes appear to have a higher incidence of arcuslike corneal changes.

Adolescent↗
PubMed1988

Elevated corneal epithelial lines in Acanthamoeba keratitis.

Elevated corneal epithelial lines are another clinical sign in Acanthamoeba corneal infection. In this report, one patient wore extended wear soft contact lenses, and another wore daily wear soft contact lenses. Both patients used distilled water and salt tablets in their lens care. Histopathologic examination of these lines revealed trophozoites and cysts. In one of the patients following penetrating keratoplasty, Acanthamoeba castellani and Acanthamoeba polyphaga were cultured by impression cytology of an epithelial line, as well as from the bulbar and tarsal conjunctiva. In the other patient who did not undergo penetrating keratoplasty, these lines appeared in the cornea one month after initial symptoms.

Acanthamoeba↗