Superficial juvenile granular dystrophy

Superficial Keratectomy: A Review of Literature

Superficial keratectomy (SK) is the manual dissection of the superficial corneal layers (epithelium, Bowman's layer, and sometimes superficial stroma). SK is done using a surgical blade or diamond burr. Some surgeons use intraoperative mitomycin C 0.02% or amniotic membrane transplantation to improve surgical outcomes. This literature review shows that SK remains an effective method for different indications, including tissue diagnosis, excision of corneal degenerations, dystrophies, scarring, recurrent corneal erosions, and retained corneal foreign body.

A pathogenic variant in the transforming growth factor beta I (TGFBI) in four Iranian extended families segregating granular corneal dystrophy type II: A literature review

OBJECTIVES

Granular and lattice corneal dystrophies (GCDs & LCDs) are autosomal dominant inherited disorders of the cornea. Due to genetic heterogeneity and large genes, unraveling the mutation is challenging.

MATERIALS AND METHODS

Patients underwent comprehensive clinical examination, and targeted next-generation sequencing (NGS) was used for mutation detection. Co-segregation and in silico analysis was accomplished.

RESULTS

Patients suffered from GCD. NGS disclosed a known pathogenic variant, c.371G>A (p.R124H), in exon 4 of TGFBI. The variant co-segregated with the phenotype in the family. Homozygous patients manifested with more severe phenotypes. Variable expressivity was observed among heterozygous patients.

CONCLUSION

The results, in accordance with previous studies, indicate that the c.371G>A in TGFBI is associated with GCD. Some phenotypic variations are related to factors such as modifier genes, reduced penetrance and environmental effects.

TGF-β1 enhanced myocardial differentiation through inhibition of the Wnt/β-catenin pathway with rat BMSCs

OBJECTIVES

To investigate and test the hypotheses that TGF-β1 enhanced myocardial differentiation through Wnt/β-catenin pathway with rat bone marrow mesenchymal stem cells (BMSCs).

MATERIALS AND METHODS

Lentiviral vectors carrying the TGF-β1 gene were transduced into rat BMSCs firstly. Then several kinds of experimental methods were used to elucidate the related mechanisms by which TGF-β1 adjusts myocardial differentiation in rat BMSCs.

RESULTS

Immunocytochemistry revealed that cTnI and Cx43 expressed positively in the cells that were transduced with TGF-β1. The results of Western blot (WB) test showed that the levels of intranuclear β-catenin and total β-catenin were all significantly decreased. However, the cytoplasmic β-catenin level was largely unchanged. Moreover, the levels of GSK-3β were largely unchanged in BMSCs, whereas phosphorylated GSK-3β was significantly decreased in BMSCs. When given the activator of Wnt/β-catenin pathway (lithium chloride, LiCl) to BMSCs transducted with TGF-β1, β-catenin was increased, while phosphorylated β-catenin was decreased. In addition, cyclinD1, MMP-7, and c-Myc protein in BMSCs transducted with Lenti-TGF-β1-GFP were significantly lower.

CONCLUSION

These results indicate that TGF-β1 promotes BMSCs cardiomyogenic differentiation by promoting the phosphorylation of β-catenin and inhibiting cyclinD1, MMP-7, and c-Myc expression in Wnt/β-catenin signaling pathway.

Phototherapeutic keratectomy

Phototherapeutic keratectomy is an excimer laser-based surgical procedure widely performed by corneal surgeons for treating anterior corneal stromal pathologies. Phototherapeutic keratectomy helps by ablating the corneal stroma, thereby improving corneal clarity and smoothening the surface. Transient discomfort and induced hyperopia from corneal flattening are the immediate postoperative concerns. The long-term course is often marked by the recurrence of original corneal pathology and corneal haze formation. Phototherapeutic keratectomy, however, allows for repeat stromal ablation for managing recurrences, as the corneal thickness permits, without affecting the outcome of future keratoplasty. Adjunctive methods such as topical mitomycin-C may be additionally used to reduce recurrence rates. Also, various masking agents such as carboxymethyl cellulose, sodium hyaluronate, and dextran are used in eyes with irregular corneal surface to allow for uniform stromal ablation. Overall, phototherapeutic keratectomy has provided corneal surgeons an additional surgical tool, particularly those residing in developing nations where the availability of donor corneal tissue is an important limiting factor.

Recurrent Granular Dystrophy of the Cornea

PURPOSE

To describe a case of severe corneal granular dystrophy with clinicopathologic and molecular genetic findings.

METHODS

The DNAs of a 53-year-old male patient suffering from corneal granular dystrophy and nonaffected family members were analyzed by molecular genetic methods. Clinical features, and histopathologic and immunohistochemical findings from the penetrating keratoplasty specimen, are described.

RESULTS

Histopathologic and molecular genetic findings confirmed the diagnosis. A new genetic polymorphism is described. Histopathologic evidence supports the assumption of the epithelial origin of the described dystrophy.

CONCLUSIONS

A severe course of corneal granular dystrophy can be present in the absence of evidence of a homozygous mutational status, or a novel mutation. Molecular genetic analysis revealed a new polymorphism in this patient. The histopathologic findings support the assumption of an epithelial origin of the granular corneal deposits. Phototherapeutic keratectomy and penetrating keratoplasty may improve vision, but cannot prevent recurrence of the disease.

Morphometric analysis of deposits in granular and lattice corneal dystrophy: histopathologic implications for phototherapeutic keratectomy

OBJECTIVE

To quantify the distribution and size of deposits in granular and lattice corneal dystrophies and to estimate the impact of these findings on the potential benefit of phototherapeutic keratectomy (PTK) as primary treatment in these corneal disorders.

METHODS

Central histologic sections of consecutive corneal buttons (34 granular dystrophy specimens of 27 patients (mean age 53 +/- 12 years) and 20 lattice dystrophy specimens of 20 patients (mean age 50 +/- 17 years) obtained from central penetrating keratoplasty were examined by light microscopy using Masson trichrome and Congo Red stains. Localization and anterioposterior diameter of the most superficial, the deepest, and the largest deposits were quantified in the central and the two peripheral thirds of the specimens. Bowman layer status and thickness of the epithelium were recorded. The clear central corneal zone size before and after a hypothetical superficial PTK (100-microm ablation) was calculated.

RESULTS

Central deposits in granular dystrophy were mostly superficial (mean distance from the epithelium 28 +/- 19 microm) and associated with Bowman layer and epithelial changes. In lattice dystrophy, deposits were mostly midstromal (mean distance from the epithelium 79 +/- 54 microm, P < 0.001) with a larger scatter, showing minor superficial involvement. After a fictitious PTK, a significant increase in mean clear central zone was achieved (P = 0.004). This increase in mean clear central zone was more pronounced in granular (from 484 +/- 389 microm to 1451 +/- 1954 microm) than in lattice (from 258 +/- 183 microm to 846 +/- 784 microm) dystrophy (P = 0.004). Deposits were completely removed in 22% of the granular dystrophy samples. In both dystrophies, a clear central "pinhole" greater than 1 mm in diameter was achieved in around one third of corneas.

CONCLUSION

According to the histopathologic corneal deposit size and distribution, PTK may be an effective treatment to increase visual acuity in patients with granular dystrophy more than in those with lattice dystrophy, to delay or even avoid penetrating keratoplasty.

BIGH3 gene mutations and rapid detection in Korean patients with corneal dystrophy

PURPOSE

Mutations in the BIGH3 gene on chromosome 5q31 cause four distinct autosomal dominant corneal dystrophies. We sought to determine whether the BIGH3 gene mutation was responsible for corneal dystrophy in Korean patients.

METHODS

Polymerase chain reaction single strand conformational polymorphism (PCR-SSCP) analysis was performed with the DNA from patients and healthy individuals. We sequenced the PCR products with the aberrant SSCP pattern to identify the mutation. Mutant-specific reverse primers were used to screen genomic DNA for the identified mutations.

RESULTS

We identified mutations R124C in the CDL1 family and R124H in four families with a granular dystrophy. We identified our granular dystrophy to be Avellino corneal dystrophy (ACD). Eighteen of 20 patients with a granular dystrophy contained the same R124H mutation, indicating that mutation R124H was very common in Korean patients with ACD. During this study, we identified a new polymorphism (T1667C, F540F).

CONCLUSIONS

This is the first report of mutations found in the BIGH3 gene in Korean families with corneal dystrophy. We report that the majority (90%) of ACD patients in Korea carry the R124H mutation. Mutant-specific reverse primers can be used to screen efficiently for CDL1 and ACD.

Two patterns of opacity in corneal dystrophy caused by the homozygous BIG-H3 R124H mutation

PURPOSE

To investigate the opacity pattern in corneas with an Arg124His (R124H) homozygous mutation of the BIG-H3 gene.

METHODS

Slit-lamp examination was performed on eight patients with corneal dystrophy resulting from a genetically confirmed BIG-H3 R124H homozygous mutation. The birthplace of each patient also was determined.

RESULTS

Slit-lamp examination disclosed two types of opacity patterns in corneas with the BIG-H3 R124H homozygous mutation. Type I (n = 4) is a spot-like opacity present in the anterior stroma in which the lesions are confluent. Type I is the same pattern that previous reports have shown to be caused by the BIG-H3 R124H homozygous mutation. The type II corneal opacity pattern (n = 4) is a reticular opacity in the anterior stroma with round translucent spaces. Type II opacity has not been reported previously in association with any corneal dystrophy. The patients with the type I opacity do not share a common birthplace; however, interestingly, the patients with the type II opacity traced their origin to Tottori prefecture in western Japan.

CONCLUSION

The BIG-H3 homozygous R124H mutation induces the development of two distinct patterns of corneal opacity, the recognition of which can establish an accurate diagnosis of corneal dystrophy caused by the homozygous BIG-H3 R124H mutation independent of genetic analysis. In addition, genetic factors or circumstantial influences other than the gene responsible for the corneal dystrophy may influence the pattern of corneal opacity.

Histologic phenotype-genotype correlation of corneal dystrophies associated with eight distinct mutations in the TGFBI gene

PURPOSE

To establish a phenotype-genotype correlation of various autosomal-dominant corneal dystrophies among French subjects.

DESIGN

Retrospective molecular genetic study and clinicopathologic correlation.

PARTICIPANTS

Forty-four subjects from 26 unrelated French families were included in this study, and 60 corneal buttons could be examined at the histologic and ultrastructural levels.

METHODS

Light microscopy and transmission electron microscopy were performed on corneal specimens obtained during keratoplasty. Blood samples were collected for DNA analysis.

MAIN OUTCOME MEASURES

After genomic DNA extraction from peripheral blood leukocytes of each family member, exons of the TGFBI gene were amplified by polymerase chain reaction (PCR), and the PCR products were directly sequenced on both strands.

RESULTS

Four different mutations were found to be responsible for dystrophy of granular type (R555W, R124L, R124H, and R124L+delT125-delE126), three other different mutations produced a lattice type (R124C, H626R, and A546T), and the last mutation identified was associated with the honeycomb-shaped dystrophy (R555Q). Each subtype of dystrophy showed, histologically and ultrastructurally, specific characteristics that are easily recognizable. However, besides these stereotyped forms, differential histologic diagnosis of atypical forms remains difficult, and these forms could be misdiagnosed.

CONCLUSIONS

The characteristic biomicroscopic appearance and histopathologic features of each "classic" dystrophy present a significant degree of specificity and generally provide an accurate diagnosis. However, atypical forms in which clinical and histologic data alone could be misleading, are unequivocally diagnosed after DNA analysis.

Granular dystrophy of the cornea

BACKGROUND: Granular corneal dystrophy is the commonest of the dystrophies and usually results in visual disability in the fourth or fifth decades. CASE HISTORY: A patient with granular corneal dystrophy is reported and the clinical characteristics described. DISCUSSION: The classical clinical features and the pathology and management of granular dystrophy are reviewed. Two unusual variations of the corneal dystrophy, namely, juvenile granular dystrophy and Avellino dystrophy, which is a concurrence of the features of granular and lattice dystrophies, are also described.

Confocal microscopy in Bowman and stromal corneal dystrophies

OBJECTIVE

To use confocal microscopy to demonstrate the similarity among three autosomal-dominant corneal dystrophies and the diversity of the deposit patterns within a single dystrophy.

DESIGN

A prospective, comparative case series.

PARTICIPANTS

Twenty patients (40 eyes) from 10 families suffering from Bowman or stromal dystrophy agreed to take part: 3 with Reis-Bückler dystrophy, 12 with granular dystrophy, and 5 with lattice type-I dystrophy. Of these, nine had recurrence in their grafts or after phototherapeutic keratectomy before the confocal examination. The confocal images of affected corneas were compared with those of ten normal control eyes (ten subjects).

INTERVENTION

All patients were examined by slit-lamp biomicroscopy. Confocal microscopy was performed with Achroplan 40x/numeric aperture (NA) = 0.75 and 63x/NA = 0.9 water immersion objectives. Image analysis was used to identify the corneal epithelial and stromal deposits correlated with each disorder.

MAIN OUTCOMES MEASURES

Selected images of the corneal layers were evaluated qualitatively for the size, shape, light scattering, and reflection of the deposits.

RESULTS

Slit-lamp biomicroscopy showed stromal involvement in all affected eyes. Confocal microscopy identified epithelial deposits in 30% of the eyes and stromal deposits in all eyes. The deposits within the epithelium were revealed more clearly with the 63x/NA = 0.9 objective (higher numeric aperture). Some of the confocal findings near the Bowman layer were common for all three dystrophies. Normal control eyes showed no epithelial or stromal deposits, either by biomicroscopy or confocal microscopy.

CONCLUSIONS

Confocal microscopy provides an in vivo evaluation of the deposits in the cornea, with a higher resolution than biomicroscopy. The confocal findings common to the three dystrophies may agree with previous hypotheses of the same genetic origin. It may be a useful adjunct to slit-lamp biomicroscopy, particularly when histopathologic studies cannot be performed.

Severe form of juvenile corneal stromal dystrophy with homozygous R124H mutation in the keratoepithelin gene in five Japanese patients

AIM

To confirm the mutation of the keratoepithelin gene in patients with a severe form of superficial juvenile granular corneal dystrophy (GCD).

METHODS

Five Japanese probands in whom GCD was diagnosed after histopathological examination and who developed severe manifestations of GCD in their first decade of life were investigated. Other affected family members of two probands were also examined. All probands were the offspring of consanguineous parents. DNA was extracted from their peripheral blood leucocytes and mutational analysis of the gene was performed by the polymerase chain reaction and direct sequencing.

RESULTS

Four of the five probands underwent their first keratectomy or keratoplasty in their teens and subsequently underwent a second or third keratoplasty. Each proband had a homozygous G-->A transition at codon 124, replacing Arg-->His, of the keratoepithelin gene. Their moderately affected family members were heterozygous for the mutation.

CONCLUSIONS

This finding suggests that the severity of the corneal phenotype depends on the dose effect of the mutant gene.

Homogeneity of kerato-epithelin codon 124 mutations in Japanese patients with either of two types of corneal stromal dystrophy

Images

Severe granular dystrophy: a pedigree with presumed homozygotes

Three siblings with severe granular corneal dystrophy are described. They are most likely to be homozygous for the dominantly inherited gene. They are offspring of a consanguineous marriage, with both parents affected with corneal dystrophies. The case reports describe the severe course of this condition, requiring multiple grafting procedures. Clinical pictures of the family are shown.