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Biomedical subjects

S I Brown

Publications and source records attributed to S I Brown.

At least 19 recordsLinked to original sources
PubMed1992

11-0 mersilene as running suture for penetrating keratoplasty.

We evaluated astigmatic results and complications of the combined suturing technique in penetrating keratoplasty by using 11-0 Mersilene as a running suture. Twenty-seven grafts were studied for a follow-up that ranged between ten and 46 months (mean, 27.2 months). During the study, complications included three graft failures, one instance of inadvertent breakage of the running suture, one instance of one suture bite cutting through the recipient cornea, and suture microabscesses in two eyes. Keratometric astigmatism was 2.5 +/- 2.1 diopters at six months, was 2.4 +/- 2.3 diopters at 12 months, and was 2.5 +/- 2.0 diopters at 24 months. Our data indicate that 11-0 Mersilene is suitable for the running suture in corneal transplants in the combined technique. Spontaneous suture dissolution did not occur throughout the follow-up period. The use of a less biodegradable suture enables the maintenance of low levels of astigmatism for longer periods when compared with a previous study that used 11-0 nylon suture.

Adult↗
PubMed1992

Running nylon suture dissolution after penetrating keratoplasty.

We attempted to evaluate whether the low degrees of astigmatism achieved early in the postkeratoplasty period with the combined interrupted/running suturing technique were maintained for long periods of time. For 13 to 70 months (mean, 30.2 months), we monitored a group of patients (25 eyes) who had previously undergone the combined interrupted/running suturing technique (12 interrupted 10-0 nylon sutures and one running 11-0 nylon suture). Nine running sutures broke spontaneously, causing a significant increase of the keratometric astigmatism of the entire population from 1.7 +/- 1.6 to 3.4 +/- 2.6 diopters (mean +/- standard deviation). The mean vector-corrected change in astigmatism after suture breakage was 4.9 +/- 2.6 diopters. Surgical procedures to reduce astigmatism were required in many of the eyes in which the 11-0 running nylon suture broke. Our results suggested that 11-0 nylon is not an ideal material for the running suture because its high rate of spontaneous disruption leads to undesired, statistically significant increases in postkeratoplasty astigmatism. Further, our results indicated that the selective suture technique can maintain low degrees of astigmatism only if the sutures remain intact. Studies of the effect of keratoplasty suturing techniques on astigmatism should probably include a follow-up that is sufficiently long to indicate its long-term value to the patient.

Adult↗
PubMed1992

Fibrin-enmeshed tobramycin liposomes: single application topical therapy of Pseudomonas keratitis.

Treatment of bacterial keratitis requires frequent application of topical antibiotics. We studied the efficacy of a single topical administration of tobramycin incorporated in large multivesicular liposomes and enmeshed in a fibrin sealant on rabbit corneas infected with Pseudomonas aeruginosa. One cornea each of 25 New Zealand albino rabbits was infected with P. aeruginosa. Twenty-four hours later, the animals were randomly divided into five groups of five. Group A received single hourly drops (50 microliters) of fortified tobramycin (14.5 mg/ml, total of 17.4 mg). Group B received a single topical application of 3.5 mg tobramycin, in 0.1 ml multivesicular liposomes, enmeshed in a fibrin sealant with an overlaying bandage contact lens. Group C was treated in the same manner as group B without the addition of fibrin sealant. Groups D and E served as nondrug-treated controls, with group D receiving topical fibrin-enmeshed liposomes devoid of tobramycin and group E receiving hourly topical balanced salt solution (BSS) drops. All animals were killed 24 h after initiation of therapy. Significantly fewer colonies of Pseudomonas were present in corneas of all three treated groups, as compared with the two nondrug-treated control groups (p less than 0.02). There were significantly fewer colonies of Pseudomonas in groups A and B as compared with group C (p less than 0.02). No significant difference was noted between a single administration of topical fibrinen-meshed tobramycin-encapsulated liposomes (group B) and 24 doses of hourly fortified topical tobramycin (group A, p greater than 0.05). Tobramycin-encapsulated megaliposomes may serve as a useful adjunct in treatment of Pseudomonas keratitis.

Administration, Topical↗
PubMed1990

Experimental radial thermokeratoplasty in rabbits.

Radial thermokeratoplasty is a new technique designed to reduce hyperopia. We evaluated the histopathological effect at 2, 4, and 30 days following radial thermokeratoplasty in rabbit corneas. Surgical complications included variable-sized coagulations and microperforations in two eyes. Light microscopy disclosed that the burns were 90% in depth and healing occurred by epithelial ingrowth. The stroma surrounding the coagulation was acellular early but keratocyte repopulation was apparent by 30 days. A retrocorneal membrane four to five cells thick was noted at the early time points; however, by 30 days only a double layer of spindle-shaped cells remained. By electron microscopy, damage to surrounding endothelial cells was estimated to be 300 microns (from the center of the coagulation). Our results suggest that radial thermokeratoplasty, which utilizes a temperature of 600 degrees C placed within the cornea to a depth of 90%, will cause significant damage to the corneal endothelium beneath and surrounding the coagulation site.

Animals↗
PubMed1989

The effect of increased intraocular pressure on visual acuity and corneal curvature after radial keratotomy.

To detect the effect of increased intraocular pressure on visual acuity and corneal curvature after radial keratotomy, we measured these variables in the sitting and inverted positions in 18 patients who underwent radial keratotomy (Group 1) and compared their results with those from the unoperated on eyes of seven patients (Group 2). We also compared the results before and after inversion within each group. Intraocular pressure increased to approximately two times normal in each group. Significant improvement in visual acuity and reduction in central keratometry were noted only in Group 1. By multiple regression analysis, visual improvement correlated with the number of incisions but not the time since surgery. Our study provides evidence that increased intraocular pressure may account for transient changes in vision and corneal curvature after radial keratotomy.

Adult↗
PubMed1979

HLA antigens in ocular cicatricial pemphigoid.

HLA antigen frequencies were studied in 45 patients with ocular cicatricial pemphigoid. HLA-B12 was found to have an increased frequency of 44.4% in patients with ocular cicatricial pemphigoid, which was statistically significant when compared with a frequency of 19.6% in the control population (P less than .001 or P less than .031 when corrected for the number of antigens tested). The results of this study suggest that there is an immunogenetic susceptibility to the development of ocular cicatricial pemphigoid.

Eye Diseases↗
PubMed1979

Chalazia and rosacea.

Fifty-seven percent of patients scheduled for excision of chalazia over 19 years of age and 64% of patients over the age of 29 were found to have rosacea. This compares to an incidence in our control group of 12% and 13%, respectively. Rosacea was almost twice as common in patients with recurrent chalazia as in those with only one occurrence.

Adult↗
PubMed1979

Marginal corneal ulcers with acute beta streptococcal conjunctivitis and chronic dacryocystitis.

A 73-year-old woman had right dacryocystitis, intense conjunctival hyperemia and chemosis, marginal corneal ulcers, and abscesses and conjunctival cultures that were positive for beta hemolytic streptococci. A distinct lucid interval separated the peripheral corneal ulcers and infiltrates from the corneoscleral limbus. Gram stain of corneal scrapings revealed polymorphonuclear leukocytes but no bacteria, and corneal cultures were negative for bacteria. The peripheral corneal ulcers and abscesses in our patient with the lacrimal conjunctivitis of Morax clinically resembled the catarrhal ulcers found with staphylococcal blepharitis. A hypersensitivity or toxic reaction to streptococci or their products may have played a role in the development of the marginal ulcers in this patient.

Aged↗
PubMed1979

Graft edema after suture removal.

Graft edema developed after removal of continuous monofilament sutures in six eyes of six patients in whom no wound dehiscence occurred. All sutures were removed at least one year after penetrating keratoplasty, and graft edema was noted one day after suture removal. In all cases, partial or total resolution of graft edema occurred after treatment with corticosteroids. In two of the grafts, the edema resolved after treatment with topical corticosteroids alone, whereas the remaining four grafts required the addition of systemic or subtenon corticosteroids, or both, for resolution. The trauma associated with suture removal may cause endothelial decompensation either by direct injury to the cornea or by a secondary iritis. To the best of our knowledge, graft edema after suture removal is a late complication of penetrating keratoplasty that has not been previously emphasized.

Adrenal Cortex Hormones↗
PubMed1979

Ocular rosacea.

Ocular rosacea was diagnosed in 49 patients. The most common signs and symptoms were foreign body sensation, burning, superficial punctate erosions, chalazia, and belpharitis. Less common but dangerous to the vision was corneal thinning, vascularization, and infiltrates. Three new associated symptoms were found. These were mapdot subepithelial opacities, recurrent erosions, and moderately severe foreign body sensation, pain or burning with minimal associated signs. Of the 49 patients, 37 were treated with 250 mg of oral tetracycline four times a day, which resulted in improvement in almost all patients from four to 17 days after initiation of therapy. Most of the patients have been able to taper, or taper and stop therapy without recurrence of their symptoms. Those patients with foreign body sensation, burning, and pain required the most prolonged therapy in order to taper or stop treatment with tetracycline.

Adolescent↗
PubMed1979

The acute manifestations of ocular cicatricial pemphigoid: diagnosis and treatment.

Seven patients with ocular cicatricial pemphigoid displayed acute inflammatory activity that could not be attributed to secondary bacterial infections, trichiasis, or lagophthalmos secondary to symblepharon. This acute inflammatory activity was manifested either as a localized conjunctival mound that was ulcerated and intensely hyperemic or as diffuse and intense conjunctival hyperemia and chemosis. Acute disease activity developed shortly after conjunctival biopsy in three patients and appeared spontaneously in the other four patients. Conjunctival biopsy specmens disclosed a heavy infiltrate of polymorphonuclear leucocytes within and beneath the conjunctival epithelium in addition to the chronic inflammatory cells typically found in this condition. The acute manifestations of ocular cicatricial pemphigoid cause rapid shrinkage and scarring of the conjunctiva. Systemic corticosteroids suppressed the acute disease activity and prevented additional scarring in all five patients treated.

Aged↗
PubMed1979

Results of excision of advanced epithelial downgrowth.

Advanced epithelial downgrowth was excised in 14 patients. The technique involved excision under direct observation of the epithelium found as bands in the anterior chamber and as membranes in the front and back of the iris, over the ciliary body, on the front and back surfaces of intraocular lenses, and over the vitreous face. In the first nine cases, cryoapplication was used to destroy the epithelium on the back of the cornea. In three patients, in spite of repeated applications, the epithelium was unaffected by freezing. In these cases the epithelial downgrowth was excised by scraping it free from the back of the cornea. In four eyes the whole cornea was removed both for visualization of the extent of the growth of the epithelium throughout the anterior and posterior chamber and to scrape the epithelium free. Thereafter the cornea was replaced. Eleven of the 14 eyes have remained free of epithelial downgrowth from 18 months to eight years postoperatively. Penetrating corneal transplantations were performed in six eyes because of corneal edema; these have remained transparent. Although two eyes have vision better than 20/40, the majority have 20/200.

Anterior Chamber↗
PubMed1979

Significance of donor age in penetrating keratoplasty.

Because the significance of donor age in penetrating keratoplasty remains controversial, a study was undertaken to analyze the results of keratoplastics performed with older (greater than 70) and younger (less than 55) donor corneas. Thirty-seven eyes which received older donor corneas were divided into 4 diagnostic categories and were compared with 37 eyes having the same diagnosis which received younger donor corneas. The average follow-up for both groups was 24 months. There was no significant difference between the number of clear grafts in each group. It would appear that older donor corneas can withstand the surgical trauma of transplantation and remain clear for a relatively significant period.

Age Factors↗
PubMed1979

Biochemical characterization of procollagen-collagen synthesized by rabbit corneal endothelial cells in culture.

Collagen synthesis was studied in monolayer cultures of rabbit corneal endothelial cells by following [14C]proline and [3H]glucosamine or [3H]fucose incorporation into a fraction enriched for collagen and its precursor molecules. Sodium dodecyl sulfate gel electrophoresis of this fraction showed that it consisted of a high-molecular-weight (greater than 300,000 daltons) polypeptide. This component was collagenase sensitive and, in the presence of dithiothreitol, gave rise to two polypeptides of the apparent molecular weights of 200,000 and 160,000 daltons. Pepsin digestion of this material destroyed all the high-molecular-weight material and gave rise to a single collagenase-sensitive component of an apparent molecular weight of 115,000 daltons. This 115,000 dalton material is similar to previously observed basement membrane collagens, and the 160,000 and 200,000 dalton components are probably precursor chains of basement membrane collagen. The very-high-molecular-weight material (greater than 300,000 daltons) may represent a disulfide-linked complex of these precursor chains. DEAE-cellulose column chromatography confirmed the presence of a single procollagen species distinct from the collagen fraction. Amino acid analysis of collagen and procollagen fractions showed a decreased hydroxyproline value as compared with previously reported basement membrane collagens or collagen precursors.

Amino Acids↗
PubMed1978

Alternate pathway activation of complement in a Proteus mirabilis ulceration of the cornea.

A 63-year-old patient had an extensive infiltration, ulceration, and eventual perforation of the cornea caused by Proteus mirabilis. Histopathological examination of corneal tissue that was obtained at keratoplasty disclosed that the stroma was ulcerated with a diffuse infiltration of polymorphonuclear leukocytes. Immunopathological examination of the cornea revealed prominent and diffuse staining for properdin and C3 complement. There was an absence of staining for IgG, IgA, IgM, IgE, and C4 complement. These findings suggest that the alternate pathway of complement was activated in this ulcerated cornea and that immunopathological phenomena contribute to the polymorphonuclear infiltration found with Gram-negative ulcerations of the human cornea.

Complement C3↗