摘要:

Donor failure refers to graft edema present within the first 24 h after penetrating keratoplasty that persists in spite of maximal medical therapy. We reviewed the case histories of 1,351 penetrating keratoplasties. Of these, 17 (1.2%) were considered donor failures. Five cases were histopathologically consistent with Fuchs' dystrophy. Seven cases demonstrated mechanical stripping of the endothelium. Five cases, all from the same eye bank, revealed an absence of posterior stromal keratocytes. Storage medium at the eye bank of origin was found to have an alkaline pH. Careful preoperative evaluation of donor corneas is emphasized, but if an apparent “epidemic” of donor failure occurs, a thorough investigation of the eye bank methodology should be initiated.

ISSN:0277-3740    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Regeneration of corneal epithelium following injury is essential for visual rehabilitation. A limited number of approaches are available for treating patients who fail to heal epithelial injuries adequately. The presence of specific receptors for epidermal growth factor (EGF) on epithelial cells suggests that this potent mitogen may play a role in normal epithelial wound healing. Topical application of biosynthetic human EGF significantly accelerated epithelial regeneration in primates following epikeratophakia surgery. Epidermal growth factor alone and with fibronectin accelerated epithelial regeneration of rabbits following mild alkali burns. Since prolonged exposure of cells to EGF is necessary to induce mitosis, the dynamics of EGF in the eye and with various lenses was studied. When applied in methylcellulose-based eye drops, 90% of the EGF was lost from tear film within 10 min, while a small amount (10%) remained associated with conjuctival tissue. Soft contact lenses or epikeratophakia lenticles took up substantial amounts of EGF (50 μg) and released 85% of the EGF within 24 h, with a half-life of 4 h in vitro. Epidermal growth factor did not diffuse through corneas or lenticles and did not promote epithelial down-growth along sutures in primate corneas. These results suggest that biosynthetic growth factors may be useful in the treatment of some epithelial injuries.

ISSN:0277-3740    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

A case of bilateral cornea plana with high hypermetropia is reported in a 20-year-old woman. Neither routine spectacles nor polymethylmethacrylate (PMMA) contact lenses could achieve satisfactory visual and cosmetic results. Comprehensive visual and cosmetic rehabilitation was accomplished with a high-plus, low-water-content, lenticular soft lens. This new concept of management of cornea plana appears promising in cases not amenable to routine spectacles or hard contact lenses.

ISSN:0277-3740    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Use of the relief mode of specular microscopy to differentiate corneal endothelial changes in anterior segment disease from retrocorneal deposits facilitates understanding of the nature of the endothelial changes. The retrocorneal deposits may be pigment granules or inflammatory deposits. The inflammatory deposits may be due to fibrin or WBCs, are more irregular than pigment, and may coalesce to form large, rounded, keratic precipitates. Pigment granules are smaller, denser, usually more regular and, although sometimes confluent, do not form keratic precipitates. Both are distinct from subendothelial blebs, both the smaller blebs up to one cell in diameter and larger blebs of two to three cells in diameter. These blebs are probably due to edema, disappear quickly on resolution of the pathologic process, and are evidence of stress to the endothelium, which shows significant change in morphology and fall in cell numbers when the blebs are of long-standing.

ISSN:0277-3740    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Control of intraocular pressure (IOP) in patients with severe alkaline burns is one of the most difficult problems facing the corneal specialist. Currently, when medical therapy cannot control intraocular pressure, the usual procedure of choice is cyclocryotherapy. This procedure, however, can be complicated by phthisis, retinal detachment, or macular edema. We have used transscleral YAG laser cyclophotocoagulation (TSYLC) to control the IOP in a patient with severe glaucoma after an alkali burn. This patient had previously had an unsuccessful cyclocryotherapy. After the TSYLC procedure, he suffered no complications and his IOP was normal. Our experience with this patient indicated that the TSYLC procedure might be an effective alternate to cyclocryotherapy, especially in corneal patients with uncontrollable inflammatory glaucoma.

ISSN:0277-3740    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

It is well established that the corneal endothelium reflects the trauma it experiences by changing its morphological appearance. We have studied the effect of mild trauma to the rabbit endothelium by replacing the aqueous humor with air. After either 2 or 4 h, the air was removed and then replaced with either physiological saline or balanced salt solution (BSS). Specular microscopy was then performed for 1 week to observe endothelial changes. Various transient morphological changes observed during this period included many nonhexagonal cells, enlarged cells, and clusters of small cells. The changes produced were more dramatic for the saline replacement group than the BSS replacement group, indicating that the recovery process of the endothelium following this mild trauma depends on the material used to replace the air. The air appears to sensitize the endothelium to subsequent insult. This model can perhaps be used to evaluate the relative safety of the various solutions that are used in the anterior chamber during ocular surgery.

ISSN:0277-3740    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Central penetrating excisional wounds were made in the corneas of 12 rabbits and 10 trout. The scar tissue and the surrounding cornea were compared using a new method for assessing inorganic elements in the cornea: the scanning electron microscopy and energy dispersive analysis of x-ray (EDAX). Semiquantitative determination of inorganic elements within the range of atomic numbers 9–93 in the periodic system was performed, comparing the relative concentration of those elements in the scar tissue to the surrounding cornea. Results showed that calcium was the only element higher in the healing wound than in the surrounding cornea.

ISSN:0277-3740    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

To determine the diagnostic usefulness of routine staining of corneal buttons with alcian blue, we evaluated 150 consecutive corneal specimens with hematoxylin and eosin and alcian blue stains. Overall, 67% of specimens demonstrated deposition of acid mucopolysaccharide. More specifically, positive alcian blue staining was observed in 88% of specimens with pannus, 83% of specimens with stromal downgrowth, 71% of specimens with stromal scarring, and 67% of specimens with interstitial keratitis. In 80% of these cases, the positive alcian blue stain correlated to pathology noted on hematoxylin and eosin sections. In 20% of cases, we could not explain the reason for the presence of alcian blue staining. Except for macular dystrophy of the cornea, the presence, strength, and location of staining did not provide useful information in terms of making a specific clinical diagnosis. Consequently, alcian blue should be used only in those settings in which the pathologist needs to document or confirm the abnormal presence or absence of acid mucopolysaccharide deposition.

ISSN:0277-3740    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

A modified relaxing incision technique for postkeratoplasty astigmatism is described in this article. Following the initial, standard relaxing incision techniques, a planned spreading and recutting of the initial relaxing incision was performed at 1–3-week intervals following the initial surgery. The wound may be deepened and lengthened if more effect is needed. The number of spreading and recutting procedures is also dependent on the effect required. This additional procedure may be performed for late regression of the desired effect. The endpoint for the procedure is corneal astigmatism that will allow either spectacle or contact lens correction, depending on the patient's visual needs. Corrections of >10 D of astigmatism are possible. The technique allows for evaluation of the corneal astigmatism with no sutures in place. No complications of the recutting and spreading procedure have been noted. There have been no microperforations or macroperforations requiring suturing, no infections, and no graft rejections following the procedures. Seven cases using the modified relaxing incision technique are described.

ISSN:0277-3740    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The photokeratoscope has increased the understanding of the aspheric nature of the cornea as well as a better understanding of normal corneal topography. This has significantly affected the development of newer and more predictable models of surgical astigmatic correction. Relaxing incisions effectively flatten the steeper meridian an equivalent amount as they steepen the flatter meridian. The net change in spherical equivalent is therefore negligible. Poor predictability is the major limitation of relaxing incisions. Wedge resection can correct large degrees of postkeratoplasty astigmatism. Resection of 0.10 mm of tissue results in approximately 2 diopters of astigmatic correction. Prolonged postoperative rehabilitation and induced irregular astigmatism are limitations of the procedure. Transverse incisions flatten the steeper meridian an equivalent amount as they steepen the flatter meridian. Semiradial incisions result in two times the amount of flattening in the meridian of the incision compared to the meridian 90° away. Combination of transverse incisions with semiradial incisions describes the trapezoidal astigmatic keratotomy. This procedure may correct from 5.5 to 11.0 diopters depending upon the age of the patient. The use of the surgical keratometer is helpful in assessing a proper endpoint during surgical correction of astigmatism.

ISSN:0277-3740    

出版商:OVID    

年代:1988

数据来源: OVID