Expression of type XII collagen and hemidesmosome-associated proteins in keratoconus corneas.

PURPOSE: Keratoconus is a disease characterized by thinning of the central and paracentral cornea and scarring in advanced cases. This study was performed to examine the expression of type XII collagen, proteins associated with hemidesmosomes, and beta1 integrin in keratoconus corneas. METHODS: Corneal buttons were collected from normal subjects and patients with keratoconus and other corneal diseases. Immunofluorescence staining was performed on frozen sections for type XII collagen, bullous pemphigoid antigen (BP180), and integrin subunits alpha6, beta4, and beta1. RESULTS: To varying degrees, all proteins examined were expressed in normal human corneas. The staining intensity of type XII collagen was diminished in keratoconus corneas in the epithelial basement membrane zone and the stromal matrix. No significant variation was found in either the staining patterns or intensities for BP180, or integrins alpha6, beta4, and beta1. CONCLUSIONS: The level of type XII collagen was reduced in the epithelial basement membrane zone and stromal matrices in keratoconus corneas. These alterations may affect critical interactions of the corneal epithelium with the under-lying basement membrane, and cell-matrix interactions and matrix organization in the stroma.

Mucolipidosis IV in an African American patient with new findings on electron microscopy.

PURPOSE: We report an unusual case of mucolipidosis IV in a patient of African ancestry, with intracytoplasmic inclusions of the corneal endothelium found on electron microscopy. METHOD: Clinical description with light and electron microscopy. RESULTS: We describe a case of mucolipidosis IV diagnosed in a patient of African ancestry after penetrating keratoplasty. Electron microscopic evaluation revealed intracytoplasmic inclusions in both the corneal epithelium and endothelium. CONCLUSION: The diagnosis of mucolipidosis in a patient of African ancestry is unusual, as this genetic disorder is found predominantly in individuals of Jewish descent. Corneal endothelial involvement in mucolipidosis IV has not previously been reported.

Intrastromal clefts in keratoconus patients with hydrops.

PURPOSE: To report the clinical appearance and course of intrastromal clefts occurring with acute hydrops in keratoconus. METHODS: In eight patients with bilateral keratoconus, nine eyes developed acute corneal hydrops complicated by intrastromal cleft formation. One patient developed this complication in both eyes. The patients, three female and five male, had a mean age of 20 years (range, 11 to 36 years) and were followed after onset of acute hydrops for a median of 8 months (range, 2.5 to 21 months). The patients in this retrospective study were identified and had been treated at one of two institutional cornea referral practices. RESULTS: In eight of nine eyes with intrastromal clefts, complete cleft closure occurred between 6 weeks and 6 months. In one eye, cleft closure was nearly complete in a patient followed up for only 4.5 months after onset of hydrops. Corneal stromal neovascularization developed in six of the nine of eyes. At the last follow-up visit, four of the six untreated eyes had a best-corrected visual acuity of 20/200 or worse. The patient with intrastromal clefts in both eyes did not develop stromal neovascularization and achieved a contact lens corrected visual acuity of 20/40 or better in each eye without surgical intervention. CONCLUSIONS: Intrastromal cleft formation is a manifestation of corneal hydrops in keratoconus. Single or multiple clefts can occur, and bilateral involvement is possible. Clefts generally close over a period of months, but stromal neovascularization is common and may compromise future graft survival.

Expression of degradative enzymes and protease inhibitors in corneas with keratoconus.

PURPOSE: Keratoconus is characterized by thinning and scarring of the central region of the cornea. Previous research showed that, in corneas obtained from patients with keratoconus, lysosomal enzyme activities are elevated, whereas levels of protease inhibitors such as alpha1-proteinase inhibitor are reduced. This study was undertaken to examine further the expression of a spectrum of proteolytic enzymes and protease inhibitors. METHODS: Corneal buttons were collected from patients with keratoconus, healthy subjects, and patients with other corneal diseases. Immunohistochemical staining was performed on paraffin sections. Enzymatic assays and western blot analysis were carried out for cathepsins B and G. In addition, an in situ zymography procedure was used to examine the gelatin- and casein-digesting activities in corneas with keratoconus. RESULTS: An enhanced staining was found with antibodies to cathepsins B and G. Enzymatic assays and western blotting confirmed that the levels of these two enzymes were elevated in corneas with keratoconus. No alteration was noted with any of the matrix metalloproteinase (MMP) family members and other enzymes and inhibitors examined, although in situ zymography did indicate an increase in net gelatin- and casein-digesting activities in corneas with keratoconus. These activities were mostly abolished by inhibitors for serine and cysteine proteinases, but not by those for MMPs and aspartic proteinases. CONCLUSIONS: Levels of cathepsins B and G are increased in corneas with keratoconus. These enzymes may contribute to the heightened in situ gelatin- and casein-digesting activities, leading to abnormalities in keratoconus.

Cathepsin G, acid phosphatase, and alpha 1-proteinase inhibitor messenger RNA levels in keratoconus corneas.

PURPOSE: Keratoconus is characterized by thinning and scarring of the central region of the cornea. The authors have shown, in corneas obtained from patients with keratoconus, that lysosomal enzyme activities are elevated, whereas levels of protease inhibitors such as alpha 1-proteinase inhibitor (alpha 1-PI) are reduced. This study was undertaken to examine further the gene expression of cathepsin G, acid phosphatase, and alpha 1-PI in keratoconus corneas. METHODS: Corneal buttons were collected from patients with keratoconus, normal subjects, and patients with other corneal diseases. In situ hybridization was performed on paraffin sections using a tritium-labeled probe for cathepsin G or alpha 1-PI. Competitive polymerase chain reaction (PCR) was used to determine the messenger RNA (mRNA) levels for lysosomal acid phosphatase and alpha 1-PI in epithelial and stromal cells of keratoconus corneas. RESULTS: Silver grains, indicative of positive in situ hybridization products, were observed in all three cell types of normal corneas for both DNA probes. Compared with normal and other diseased controls, the labeling was enhanced for cathepsin G but was diminished for alpha 1-PI in the epithelium of keratoconus corneas. Competitive PCR showed that the mRNA level for acid phosphatase was higher and that the mRNA level for alpha 1-PI was lower in keratoconus corneas. CONCLUSIONS: These results indicate that the mRNA level for degradative enzymes in increased and that for alpha 1-PI it is reduced in keratoconus corneas. This study provides the first evidence that the altered expression of multiple enzymes and inhibitors in keratoconus occurs at the gene level. Furthermore, it implicates a possible role of coordinated transcriptional regulation of gene expressions in keratoconus.

Expression of wound healing and stress-related proteins in keratoconus corneas.

PURPOSE: Keratoconus is characterized by thinning and scarring of the central portion of the cornea. This study was performed on keratoconus corneas to examine the expression of proteins related to wound healing including vimentin, an intermediate filament protein, and tenascin, and extracellular matrix protein. The expression of stress-related cytokines, heat shock proteins and ubiquitin was also investigated. METHODS: Corneal buttons were collected from patients with keratoconus, normal subjects and patients with other corneal diseases such as pseudophakic bullous keratopathy. Immunofluorescence staining was performed on frozen sections for vimentin and tenascin, and immunoperoxidase staining was carried out on paraffin sections for cytokines, heat shock proteins and ubiquitin. RESULTS: To varying degrees, all proteins examined, except tenascin and heat shock protein 90, were found to be expressed in normal human corneas. The expression of vimentin, tenascin, transforming growth factor-beta, interleukin-1, heat shock protein 27, and ubiquitin was enhanced in keratoconus corneas. A similar enhancement however was also observed in other diseased corneas. CONCLUSIONS: Altered expression of several wound healing or stress-related proteins was noted in keratoconus corneas. The alterations appear to be nonspecific injury or wound responses in association with corneal diseases.

Alpha 2-macroglobulin levels in normal human and keratoconus corneas.

PURPOSE: To compare the levels of alpha 2-macroglobulin, one of the major proteinase inhibitors, in corneas with keratoconus to those in normal human corneas and corneas with other diseases. METHODS: An immunoperoxidase technique was used to visualize the presence of alpha 2-macroglobulin in the corneas. Western blot analysis was performed, and the levels of this inhibitor in extracts of keratoconus and normal human corneas were subsequently analyzed by a dot blot assay. RESULTS: alpha 2-Macroglobulin was demonstrated immunohistochemically in the epithelium, stroma, and endothelium of all corneal sections. Compared with normal human control specimens, the staining intensity in the epithelium of keratoconus corneas was markedly reduced. The majority of scarred and other diseased corneas exhibited normal staining intensity for alpha 2-macroglobulin. Dot blot assays showed that the alpha 2-macroglobulin levels in the epithelial and stromal extracts of keratoconus corneas were lower than those found in normal human control counterparts. CONCLUSION: Keratoconus corneas contained a reduced level of alpha 2-macroglobulin. This result lends further support to the hypothesis that degradation processes may be aberrant in keratoconus.

Subepithelial mucinous corneal dystrophy. Clinical and pathological correlations.

We describe a family with an unusual autosomal dominant anterior corneal dystrophy. The onset was characterized by frequent, recurrent corneal erosions in the first decade. This subsided during adolescence and was followed by progressive decreased vision. Slit-lamp examination revealed bilateral subepithelial opacities and haze, involving the entire cornea, but most dense centrally. Histopathological study revealed a subepithelial band of eosinophilic, periodic acid-Schiff-positive, alcian blue-positive, hyaluronidase-sensitive material anterior to Bowman's layer. Electron microscopy demonstrated subepithelial deposition of fine fibrillar material consistent with glycosaminoglycan. Immunohistochemical analysis indicated that the accumulated material contained a combination of chondroitin 4-sulfate and dermatan sulfate. This unique condition clinically resembled Grayson-Wilbrandt dystrophy, but differed histochemically. To our knowledge, this anterior corneal dystrophy has not previously been reported, and it is best described by the name "subepithelial mucinous corneal dystrophy."

Acne rosacea with keratitis in childhood.

We present three cases of acne rosacea keratitis that developed in childhood. All three children were prepubescent and demonstrated characteristic dermatologic findings involving the nose, cheeks, and/or chin. The patients had complained of ocular irritation for at least 6 months, and in one case symptoms were reported by the family to have occurred intermittently since age 4 years. All three children showed evidence of meibomian gland inflammation; two patients demonstrated bilateral keratitis, the third had only unilateral involvement. In each case, oral tetracycline hydrochloride or doxycycline hyclate was necessary to relieve symptoms. Rosacea keratitis should be considered in the differential diagnosis of chronic keratoconjunctivitis during childhood.

Lattice corneal dystrophy type IIIA. Clinical and histopathologic correlations.

All three types of lattice corneal dystrophy are inherited and localized, and they largely involve linear corneal amyloid deposits. We encountered two white families with lattice corneal dystrophy which closely resembled type III. Four generations of one family and three of another family exhibited lattice corneal dystrophy. Because both families are from Caccamo, Sicily, Italy, we believe it is likely that both are from a single mutation. Thick, ropy lattice lines were seen to traverse the corneas almost from limbus to limbus and were easily detected with direct illumination. Histopathologic examination revealed accumulations of varying sized amyloid deposits in the stroma and ribbons of amyloid between the stroma and Bowman's layer typical of lattice corneal dystrophy type III. We have named the disease in this family lattice corneal dystrophy type IIIA, because of three differences from lattice corneal dystrophy type III: the presence of corneal erosions, the occurrence in whites, and the autosomal dominant inheritance pattern.

The diagnosis of epithelial downgrowth after keratoplasty.

During a two-year period we diagnosed and managed four cases of epithelial downgrowth in aphakic patients (two men and two women, 42 to 76 years old) after keratoplasty. Several clinical findings seemed typical of epithelial downgrowth in this setting. When iritis was present, it was unusual in that the aqueous humor contained large clumps of cellular material and the degree of apparent inflammation was out of proportion to the ciliary flush or symptoms. A posterior corneal line was present in two cases. It resembled an endothelial graft rejection line, but there were no associated keratic precipitates. Also, no graft edema occurred peripheral to a retrocorneal line in either case. Glaucoma was abrupt in onset and difficult to treat. Cytopathologic studies of aqueous aspirate may be needed to confirm the diagnosis. The long-term prognosis for useful vision in our patients was poor but early diagnosis and surgical intervention might possibly lead to a more favorable outcome.

Can macrophages cause obstruction to aqueous outflow in rabbits?

We describe a technique by which large numbers of peritoneal macrophages can be harvested without harming the experimental animal. The macrophages can be reintroduced into the same animal avoiding possible immune reactions associated with injection of foreign cells or other antigenic materials. In an attempt to obstruct aqueous outflow rabbit peritoneal macrophages engorged with mineral oil were injected intracamerally in the same rabbit's eye. The number of cells per single injection varied from 4.0 X 10(4) to 1.4 X 10(6) in eight rabbits. In three animals daily injections of 1 X 10(6) cells were performed. Using the Perkins applanation tonometer daily and hourly, no pressure elevation could be detected.

Conjunctival resection for the treatment of the rheumatoid corneal ulceration.

Conjunctival resection is an effective therapeutic modality for the treatment of a marginal furrow associated with rheumatoid arthritis. Rapid reepithelialization was observed following this procedure for the treatment of five such stromal ulcers that occurred in three rheumatoid patients. Keratoconjunctivitis sicca was diagnosed in two of these patients. In four of five ulcers, minimal healing resulted from a prior trial of patching. Conjunctival resection was performed as the primary therapeutic procedure in one case in which perforation seemed possible. A literature review uncovered an additional nine such ulcers in six rheumatoid patients treated by conjunctival resection. In each case corneal healing was observed soon after the procedure. No recurrences were reported on 4- to 24-month follow-ups. This procedure has proven to be effective in each of our rheumatoid corneal ulcers and in each of the case reports in the literature. It would appear to work more reliably than subconjunctival heparin, topical anticollagenases, or immunosuppression. Conjunctival resection is a simple minor room procedure performed under topical anesthesia. It carries minimal risk for the patient. The early use of this technique for rheumatoid stromal ulcers is advocated, especially when the area of ulceration is extensive, when the stromal loss is progressive, and when stromal reserve is minimal. Early conjunctival resection can shorten the hospital stay, and in more severe cases could prevent perforation. Based on successful treatment in a combined total of 14 peripheral rheumatoid corneal ulcerations, the authors believe conjunctival resection should have a more prominent place in the treatment of this condition.

Keratoconus and related noninflammatory corneal thinning disorders.

Keratoconus and other noninflammatory corneal thinning disorders (keratoglobus, pellucid marginal degeneration and posterior keratoconus) are characterized by progressive corneal thinning, protrusion and scarring; the result is distorted and decreased vision. The etiology and pathogenesis of these disorders are unknown but may be associated with a variety of factors, including contact lens wear, eye rubbing, Down's syndrome, atopic disease, connective tissue disease, tapetoretinal degeneration and inheritance. Recent advances in techniques for biochemical and pathological investigation are now allowing further exploration in these areas. Early diagnosis is aided by the finding of irregular corneal astigmatism with inferior corneal steepening. Treatment ranges from simple spectacle correction to keratoplasty. In this review, the past and present literature on corneal thinning disorders is reviewed and practical approaches to diagnosis and management are outlined.