摘要:

Corneal homograft rejection occurs spontaneously in 15% of feline penetrating keratoplasties. The incidence of rejection can be increased to 100% by exchanging full-thickness skin grafts between matched corneal donor pairs after successful corneal transplantation. Rejecting corneal grafts initially develop keratic precipitates with aqueous cell and flare. Subsequently, the cornea opacities due to endothelial decompensation with associated bullous keratopathy and stromal vascularization. Surviving endothelial cells undergo compensatory hypertrophy as the rejection progresses. Rejecting corneal grafts exhibit an extensive population of mononuclear cells adhering specifically to the graft endothelium with eventual loss of the endothelium.Cats with successful corneal homografts before induced rejection exhibit systemic cellular immune suppression based upon mixed lymphocyte cultures. During rejection, the same animals exhibit an enhanced systemic cellular immune reactivity with clonal expansion of cultured lymphocytes. Sequential hematologic examinations also emphasize the importance of the host cellular immune system in feline graft rejection.

ISSN:0277-3740    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

A rat model of ocular contact hypersensitivity was employed to investigate migration of Langerhans' cells (LCs) into the central corneal epithelium. One group of rats was cutaneously sensitized with 5 μl of 50% dinitrochlorobenzene (DNCB) in olive oil. Subsequently, both sensitized animals and nonsensitized controls were topically challenged with 5 μl of 10% DNCB in olive oil applied to the external surface of the eye. Corneas were excised at various time intervals ranging from 0 to 21 days following challenge, and whole-mounted epithelial sheets were histochemically stained. Quantitative cell counting of a 12.5-mm2area of central corneal epithelium revealed significantly greater numbers of LCs in epithelium of sensitized animals as compared to controls with a maximal difference on day 14 (p= 0.013). The abnormal presence of LCs in central cornea may play a role in the perpetuation of corneal inflammation resulting from contact hypersensitivity reactions of the eye.

ISSN:0277-3740    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

A characteristic “hurricane”-shaped epithelial keratitis was seen in 15 cases of recent penetrating keratoplasty. The keratitis appeared to be caused by the use of Maxitrol. The pattern of the keratitis was believed to be a manifestation of the normal healing pattern of the corneal epithelium. The fact that the toxicity reported here appeared only in grafted corneas indicates that the epithelium of the corneal graft is highly sensitive to topical medications. Therefore, this pattern might be expected to be seen with the use of other epithelial toxic drugs.

ISSN:0277-3740    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

We investigated cefoperazone, a new third generation cephalosporin, for its possible use against bacterial eye infections. One hundred eighty strains of bacterial isolates of ocular significance were subjected toin vitrotesting. Excellent results were noted, with only two species,Streptococcus faecalisandAcinetobacter anitratus, showing resistance. Minimum inhibitory concentration determinations were done on a few strains ofStreptococcus aureus.All strains ofS. pneumoniaeandS. viridanswere highly sensitive. S.aureusstrains were moderately sensitive. Four strains ofPseudomonas aeruginosawere testedin vitrofor synergy with a combination of cefoperazone and tobramycin using a two-dimensional checkerboard titration procedure. Two strains showed synergy and two were equivocal. Anin vivotreatment study was done on 28 rabbits with a pseudomonas ulcerative keratitis. The animals were treated with cefoperazone alone, tobramycin alone, or a combination of the two drugs. Control rabbits were treated with saline. When the corneas were excised and cultured, the combined therapy resulted in fewer colonies than when cefoperazone or tobramycin were used alone; the differences were not significant for tobramycin, although they were significant for cefoperazone. Clinical evaluation showed that the combined therapy was significantly more effective than either antibiotic used alone.

ISSN:0277-3740    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Over a 4-year period (1978–1981), 22 eyes of 19 patients developed microbial keratitis following keratoplasty. Most infections (68%) occurred within the first year following penetrating keratoplasty. The most common indication for keratoplasties which subsequently became infected was corneal perforation (32%), and the most common predisposing factor for infection was the use of a soft contact lens (45%).Twenty-three organisms were cultured from 20 eyes representing a 91% rate of positive cultures. Of the bacterial organisms, (20), 80% were gram-positive withS. epidermidisrepresenting the most common isolate (35%). There were three cases of fungal keratitis.The use of low-dose prophylactic antibiotics was associated with infection caused by resistant organisms in 8/13 patients. The use of topical steroids was identified in 68% of patients but was not unequivocably related to an enhanced rate of infection.Only three patients (14%) retained visual acuity greater than 6/60 and eight patients (36%) required therapeutic surgical intervention.

ISSN:0277-3740    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

This paper reports a prospective clinical investigation of radial keratotomy using the Fyodorov method and instrumentation. One hundred forty-seven eyes were evaluated 1-year postoperatively. The preoperative mean myopia was 5.33 diopters (range 1.75–11.75D). Eighty percent of the 147 eyes obtained 20/40 or better uncorrected vision. One hundred percent of the low myopia group and 68% of the high myopia group achieved this level of vision. The degree of preexisting myopia, patient age, fellow eye experience, and surgeon experience significantly influenced the surgical result and facilitated the predictability of the procedure. The surgical result is directly related to the incision depth.The low myopia group experienced stabilization of surgical effect by 3 months. With higher degrees of initial myopia, stabilization tended to occur much later. A 1.5% incidence of moderate glare and a 4.0% incidence of severe variation of vision is reported. A non-progressive endothelial cell loss of 5.2% and the absence of major complications and low incidence of side effects is encouraging. Both interviews by an independent observer and written patient subjective questionnaires revealed a high level of patient satisfaction.

ISSN:0277-3740    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Using a rabbit model of lamellar keratoplasty (LKP), we examined the effect of standardized Barraquer cryolathe freeze injury on corneal structure and keratocyte biochemistry. Cryolathe corneal freeze injury caused immediate disruption of the stromal keratocytes and initiated an inflammatory cell reaction peaking at 3 days following freeze injury. Frozen rabbit LKP corneas were hazy in the early postoperative period, an appearance analogous to the postoperative appearance of human keratomileusis and keratophakia cases. The clinical appearance correlated with keratocyte death and increased interfiber collagen distance.Keratocyte regeneration occurred within 21 days. The regenerating “keratoblasts” were characterized by active mitochondria and an increase in the rough endoplasmic reticulum. Keratocyte counts in the central cornea were found to correlate significantly with corneal clarity.Collagen synthesis by regenerating keratocytes in frozen LKP corneas was characterized by a decrease in the proportion of type V collagen relative to type I collagen when compared to that synthesized by fresh LKP corneas. Although the collagen phenotypic expression of type I and type V collagen was unaltered, there was a change in the solubility characteristics of newly-synthesized collagen in frozen LKP corneas, with a significant decrease in the salt-solubilized collagen. This finding suggests that the collagen synthesized by regenerating keratocytes was more quickly incorporated into mature collagen forms.These studies suggest that freeze injury produced by cryolathe refractive surgical procedures induces a significant early effect on corneal structure and keratocyte biochemistry.

ISSN:0277-3740    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Barraquer keratorefractive cryo techniques currently utilize frozen and lyophilized corneal tissue. Using a Boyden chemotactic assay, we studied the effect of freezing and lyophilization of rabbit corneas on thein vitrorelease of chemotactic factors for both polymor-phonuclear leukocytes (PMNs) and keratocytes. Treated and untreated corneal buttons (8 mm) were incubated in organ culture (two corneas/ml) for 24 hours at 37C in a 5% CO2in air incubator. The incubating media was then collected and tested for chemotactic activity using homologous PMNs and keratocytes. Conditioned media with either frozen or lyophilized corneas resulted in significant PMN and keratocyte migration when compared to untreated corneas. When the epithelium and endothelium was removed from the corneas prior to treatment, the level of migratory response decreased but remained significantly above that of untreated corneas. Using a Zigmond-Hirsch checkerboard analysis, the migration activity was demonstrated to be in response to a chemotactic factor rather than to a chemokinetic agent. Heat inactivation of media derived from lyophilized corneas resulted in a decrease in the level of migration activity for both PMNs (45%) and keratocytes (30%). Heat inactivation of media derived from corneal stroma abolished the chemotactic activity for PMNs but resulted in only a 20% decrease in the migration activity for keratocytes. These results indicate that freezing and lyophilization of corneas, as occurs for keratorefractive surgery, results in the generation from the stroma of chemotactic factors for both PMNs and keratocytes. The possible sources of PMN and keratocyte chemotactic factor generated from injured corneas are discussed. The source of the keratocyte chemotactic factor remains unknown but may include fibronectin and collagen fragments.

ISSN:0277-3740    

出版商:OVID    

年代:1983

数据来源: OVID

ISSN:0277-3740    

出版商:OVID    

年代:1983

数据来源: OVID

ISSN:0277-3740    

出版商:OVID    

年代:1983

数据来源: OVID