A new, band-shaped and whorled microcystic dystrophy of the corneal epithelium

Definitive Treatment of Lisch Epithelial Corneal Dystrophy via Staged Keratectomy and Targeted Minor Limbal Excision With Cautery

PURPOSE

We demonstrate a novel approach for the definitive treatment of Lisch epithelial corneal dystrophy via an unintentionally staged alcohol keratectomy and intentionally targeted minor limbal excision with cautery.

METHODS

A 46-year-old woman presented with visually significant corneal changes, suspected to be Lisch epithelial corneal dystrophy after clinical examination, anterior segment optical coherence tomography, and confocal microscopy. Alcohol keratectomy was performed with complete resolution, but there was visually significant recurrence at 2 years. As the abnormal epithelial recurrence originated in a linear tapered pattern from a focal superior limbal region, minor limbal excision with cautery and alcohol keratectomy was performed.

RESULTS

Histopathological analysis demonstrated cytoplasmic vacuolation and glycogen granules. The limbal tissue demonstrated normal histological features. The patient's vision returned to baseline on reepithelialization with a clear cornea, with no recurrence in over 5-year follow-up.

CONCLUSIONS

Our targeted two-staged approach provides definitive treatment for Lisch epithelial corneal dystrophy and highlights the focal limbal origin of abnormal cells.

[The latest IC3D classification of corneal dystrophies-Overview and changes of the 3rd edition]

The International Committee on Classification of Corneal Dystrophies (IC3D) was founded in 2005 to address difficulties arising from the outdated nomenclature for corneal dystrophies (CD) and to correct misconceptions in the literature. For each of the 22 CDs, a separate template was created to represent the current clinical, pathological and genetic knowledge of the disease. In addition, each template contains representative clinical photographs as well as light and electron microscopic images and, if available, confocal microscopic and coherence tomographic images of the respective CD. After the first edition was published in 2008, the revised version followed in 2015. The third edition of the IC3D was published as open access in February 2024. The latest edition is intended to serve as a reference work in everyday clinical practice and facilitate the diagnosis of CD, which might sometimes be difficult. This article provides an overview of the diagnostic and treatment principles of CD and presents the IC3D and its changes over time.

Lisch Epithelial Corneal Dystrophy Is Caused by Heterozygous Loss-of-Function Variants in MCOLN1

PURPOSE

To report the genetic etiology of Lisch epithelial corneal dystrophy (LECD).

DESIGN

Multicenter cohort study.

METHODS

A discovery cohort of 27 individuals with LECD from 17 families, including 7 affected members from the original LECD family, 6 patients from 2 new families and 14 simplex cases, was recruited. A cohort of 6 individuals carrying a pathogenic MCOLN1 (mucolipin 1) variant was reviewed for signs of LECD. Next-generation sequencing or targeted Sanger sequencing were used in all patients to identify pathogenic or likely pathogenic variants and penetrance of variants.

RESULTS

Nine rare heterozygous MCOLN1 variants were identified in 23 of 27 affected individuals from 13 families. The truncating nature of 7 variants and functional testing of 1 missense variant indicated that they result in MCOLN1 haploinsufficiency. Importantly, in the homozygous and compound-heterozygous state, 4 of 9 LECD-associated variants cause the rare lysosomal storage disorder mucolipidosis IV (MLIV). Autosomal recessive MLIV is a systemic disease and comprises neurodegeneration as well as corneal opacity of infantile-onset with epithelial autofluorescent lysosomal inclusions. However, the 6 parents of 3 patients with MLIV confirmed to carry pathogenic MCOLN1 variants did not have the LECD phenotype, suggesting MCOLN1 haploinsufficiency may be associated with reduced penetrance and variable expressivity.

CONCLUSIONS

MCOLN1 haploinsufficiency is the major cause of LECD. Based on the overlapping clinical features of corneal epithelial cells with autofluorescent inclusions reported in both LECD and MLIV, it is concluded that some carriers of MCOLN1 haploinsufficiency-causing variants present with LECD.

Recurrent Lisch Epithelial Corneal Dystrophy Treated With 5-Fluorouracil: A Case Report and Review of the Literature

PURPOSE

The aim of the study was to describe a case of Lisch epithelial corneal dystrophy (LECD), review its clinical and histopathological features and diagnostic imaging, and introduce a novel treatment approach using topical 5-fluorouracil (5-FU).

METHODS

A 65-year-old woman presented with a recurrent left-sided corneal lesion consistent with LECD. The lesion was evaluated clinically, with high-resolution optical coherence tomography (HR-OCT), and histologically. The lesion was successfully treated with two 1-week cycles of topical 5-FU.

RESULTS

Slit-lamp examination showed an opalescent, whorl-shaped corneal lesion. HR-OCT revealed a trapezoidal area of normal thickness epithelial hyperreflectivity. Histopathology demonstrated a mucosal epithelium with foamy cytoplasm and increased cell size consistent with LECD. Treatment with topical 5-FU resulted in marked clearance of the corneal lesion on slit-lamp examination and HR-OCT.

CONCLUSIONS

5-FU may be considered as a treatment option for LECD.

Topical use of alcohol in ophthalmology - Diagnostic and therapeutic indications

Alcohol (ethanol) has been used in medicine since time immemorial. In ophthalmic practice, besides as an antiseptic, it was given as retrobulbar injections to relieve severe ocular pain. Alcohol can be applied topically to the surface of neoplastic or suspicious lesions to kill cells that might desquamate and seed during surgical excision, to treat epithelial ingrowth that can occur following corneal surgeries, particularly laser in situ keratomileusis (LASIK), and to treat superficial infectious keratitis. In view of its ability to achieve a smooth cleavage plane between the epithelium and the Bowman's layer, alcohol-assisted delamination (ALD) of the corneal epithelium has been used widely and effectively for a variety of diagnostic and therapeutic indications, at times delivering both outcomes. Diagnostically, ALD yields an intact epithelial sheet which can be fixed flat to provide excellent orientation for histopathological evaluation. Therapeutically, it is most commonly used to treat recurrent corneal erosion syndrome, where its efficacy is comparable to that of phototherapeutic keratectomy but with several advantages. It has also been used to treat various forms of epithelial/anterior stromal dystrophies, which can obviate or delay the need for corneal transplantation for several years. In addition, ALD is performed in corneal collagen cross-linking and corneal refractive surgery for relatively atraumatic removal of the epithelium. In this review, we aimed to provide a comprehensive overview of the diagnostic and therapeutic use of topical alcohol in ophthalmology, to describe the surgical and fixation techniques of ALD, and to highlight our experience in ALD over the past decade.

High-Resolution Optical Coherence Tomography Findings of Lisch Epithelial Corneal Dystrophy

PURPOSE

To describe a case of Lisch epithelial corneal dystrophy (LECD) and present its unique characteristics on high-resolution optical coherence tomography (HR-OCT).

METHODS

A 78-year-old man with whorled corneal epithelial opacities in the right eye was referred for the evaluation of ocular surface squamous neoplasia. Clinical evaluation, photographs, and HR-OCT images of the cornea involved were obtained and scrapings of the affected cornea were sent for histopathologic analysis.

RESULTS

Clinically, the patient presented with an opalescent whirling epithelium in a linear pattern encroaching on the visual axis. HR-OCT showed normal thickness epithelial hyperreflectivity of involved cornea without stromal involvement, along with sharply demarcated borders of unaffected tissue. Histopathologic findings demonstrated vacuolated periodic acid-Schiff (PAS) positive cells throughout the epithelial layers consistent with LECD.

CONCLUSIONS

HR-OCT was able to provide useful information to rule out ocular surface squamous neoplasia and confirm the clinical impression of LECD at the time of clinical examination. HR-OCT shows promise as an adjunctive diagnostic tool for ocular surface lesions and pathologies.

Keratolimbal autograft transplantation as a possible new treatment of Lisch epithelial corneal dystrophy

CASE REPORT

The case concerns 64-year-old woman with visual acuity of 20/40 in the right eye. Slit-lamp examination revealed a grey, feathery corneal opacification with intraepithelial microcysts compatible with Lisch epithelial corneal dystrophy (LECD). It was treated with epithelial debridements, contact lenses and mitomycin C, but the opacification recurred within months. The removal of limbus sector and autologous limbal transplantation (KLAT) were used successfully without recurrence.

CONCLUSIONS

After removal of damaged limbus, KLAT should be considered as a treatment option for asymmetric LECD when other treatments have failed.

In vivo confocal microscopic findings in Lisch corneal dystrophy

PURPOSE

To describe the in vivo confocal microscopic and clinicopathologic correlations in Lisch corneal dystrophy.

METHODS

This is a retrospective case series of 2 patients with Lisch corneal dystrophy. The diagnosis was made based on clinical findings in both cases and was confirmed histopathologically following epithelial debridement in case 1. In vivo laser scanning confocal microscopy using the Heidelberg Retina Tomograph III with the Rostock Cornea Module was carried out in both cases.

RESULTS

Clinical examination of the corneas revealed areas of epithelial opacification that were sharply demarcated in juxtaposition with normal corneal epithelium. The gray feathery appearance of the epithelial lesions in both cases was characteristic of Lisch corneal dystrophy. The central visual axis was involved in case 1, and corneal topography showed irregular astigmatism. Histological analysis of the epithelial cells in this case showed intracytoplasmic vacuoles, confirming the diagnosis of Lisch corneal dystrophy. In vivo confocal microscopy in both cases demonstrated highly hyperreflective epithelial cytoplasm with hypo-reflective nuclei. There was involvement of all epithelial layers extending to the limbus and findings on imaging were confined to the clinically observed areas of corneal opacity. The lesion in case 1 recurred after epitheliectomy of the central cornea without removal of affected limbal cells.

CONCLUSIONS

The unique features on in vivo confocal microscopy correlated with the clinical and histopathologic features of Lisch corneal dystrophy may be used to distinguish this disorder from other corneal epithelial conditions. The affected epithelial cells appear to originate from abnormal limbal stem cells.

Corneal dystrophies

The term corneal dystrophy embraces a heterogenous group of bilateral genetically determined non-inflammatory corneal diseases that are restricted to the cornea. The designation is imprecise but remains in vogue because of its clinical value. Clinically, the corneal dystrophies can be divided into three groups based on the sole or predominant anatomical location of the abnormalities. Some affect primarily the corneal epithelium and its basement membrane or Bowman layer and the superficial corneal stroma (anterior corneal dystrophies), the corneal stroma (stromal corneal dystrophies), or Descemet membrane and the corneal endothelium (posterior corneal dystrophies). Most corneal dystrophies have no systemic manifestations and present with variable shaped corneal opacities in a clear or cloudy cornea and they affect visual acuity to different degrees. Corneal dystrophies may have a simple autosomal dominant, autosomal recessive or X-linked recessive Mendelian mode of inheritance. Different corneal dystrophies are caused by mutations in the CHST6, KRT3, KRT12, PIP5K3, SLC4A11, TACSTD2, TGFBI, and UBIAD1 genes. Knowledge about the responsible genetic mutations responsible for these disorders has led to a better understanding of their basic defect and to molecular tests for their precise diagnosis. Genes for other corneal dystrophies have been mapped to specific chromosomal loci, but have not yet been identified. As clinical manifestations widely vary with the different entities, corneal dystrophies should be suspected when corneal transparency is lost or corneal opacities occur spontaneously, particularly in both corneas, and especially in the presence of a positive family history or in the offspring of consanguineous parents. Main differential diagnoses include various causes of monoclonal gammopathy, lecithin-cholesterol-acyltransferase deficiency, Fabry disease, cystinosis, tyrosine transaminase deficiency, systemic lysosomal storage diseases (mucopolysaccharidoses, lipidoses, mucolipidoses), and several skin diseases (X-linked ichthyosis, keratosis follicularis spinolosa decalvans). The management of the corneal dystrophies varies with the specific disease. Some are treated medically or with methods that excise or ablate the abnormal corneal tissue, such as deep lamellar endothelial keratoplasty (DLEK) and phototherapeutic keratectomy (PTK). Other less debilitating or asymptomatic dystrophies do not warrant treatment. The prognosis varies from minimal effect on the vision to corneal blindness, with marked phenotypic variability.

The IC3D classification of the corneal dystrophies

BACKGROUND

The recent availability of genetic analyses has demonstrated the shortcomings of the current phenotypic method of corneal dystrophy classification. Abnormalities in different genes can cause a single phenotype, whereas different defects in a single gene can cause different phenotypes. Some disorders termed corneal dystrophies do not appear to have a genetic basis.

PURPOSE

The purpose of this study was to develop a new classification system for corneal dystrophies, integrating up-to-date information on phenotypic description, pathologic examination, and genetic analysis.

METHODS

The International Committee for Classification of Corneal Dystrophies (IC3D) was created to devise a current and accurate nomenclature.

RESULTS

This anatomic classification continues to organize dystrophies according to the level chiefly affected. Each dystrophy has a template summarizing genetic, clinical, and pathologic information. A category number from 1 through 4 is assigned, reflecting the level of evidence supporting the existence of a given dystrophy. The most defined dystrophies belong to category 1 (a well-defined corneal dystrophy in which a gene has been mapped and identified and specific mutations are known) and the least defined belong to category 4 (a suspected dystrophy where the clinical and genetic evidence is not yet convincing). The nomenclature may be updated over time as new information regarding the dystrophies becomes available.

CONCLUSIONS

The IC3D Classification of Corneal Dystrophies is a new classification system that incorporates many aspects of the traditional definitions of corneal dystrophies with new genetic, clinical, and pathologic information. Standardized templates provide key information that includes a level of evidence for there being a corneal dystrophy. The system is user-friendly and upgradeable and can be retrieved on the website www.corneasociety.org/ic3d.

Lisch corneal dystrophy

PURPOSE

To report a case of a patient with a corneal band-shaped microcystic dystrophy.

METHODS

Case report.

RESULTS

A 70-year-old woman with unilateral painless loss of visual acuity presented an epithelial feathery corneal opacification involving visual axis that showed an intraepithelial dense microcystic pattern. Histopathologic examination of the epithelial scraping revealed scattered areas of vacuolization within almost the entire epithelium. Visual acuity improved after treatment, and no recurrence was observed.

CONCLUSIONS

Clinical and histopathologic features correspond with those described by Lisch in his original report of 1992.

Lisch corneal dystrophy is genetically distinct from Meesmann corneal dystrophy and maps to xp22.3

PURPOSE

There is an ongoing discussion whether Lisch corneal dystrophy (band-shaped and whorled microcystic dystrophy of the corneal epithelium) represents a disorder that is different from Meesmann corneal dystrophy. The purpose of this study was to evaluate at the molecular level if Lisch and Meesmann corneal dystrophies are genetically distinct.

METHODS

We examined at the slit lamp a total of 48 members of a family with an aggregation of Lisch corneal dystrophy. Genomic DNA was extracted from leukocytes of the peripheral blood of seven affected and six unaffected members of this family. Mutational hotspots in the cornea-specific keratin genes K3 and K12 were scanned for mutations by single-strand conformation analysis. To test for linkage to the keratin K3 or K12 loci or for X-chromosomal inheritance, six (K3) and four (K12) microsatellite markers each flanking the keratin loci as well as 22 microsatellite markers covering the X-chromosome were typed. Linkage was analyzed using the MLINK and FASTMAP procedures.

RESULTS

A total of 19 trait carriers were identified in six generations of the family. No hereditary transmission from father to son was observed. Linkage was excluded for the keratin K3 and K12 genes. Furthermore, single-strand conformation analysis detected no mutations in these genes. Multipoint linkage analysis revealed linkage with a maximum likelihood of the odds (LOD) score of 2.93 at Xp22.3. Linkage was excluded for Xp22.2 to Xqter.

CONCLUSIONS

Lisch corneal dystrophy is genetically different from Meesmann corneal dystrophy. Evidence was found for linkage of the gene for Lisch corneal dystrophy to Xp22.3.

Band-shaped and whorled microcystic dystrophy of the corneal epithelium

OBJECTIVE

To report the clinical, histopathologic, and electron microscopic features of band-shaped and whorled microcystic corneal epithelial dystrophy.

DESIGN

Two interventional case reports.

PARTICIPANTS

Two patients, two eyes.

INTERVENTION

The involved area of corneal epithelium was scraped from each cornea.

RESULTS

Histopathologic examination showed microscopic vacuoles in the epithelial cytoplasm in both cases. Electron microscopic examination revealed mainly empty cytoplasmic vacuoles with scant nonspecific osmophilic material. The process recurred clinically in one patient. Changes in corneal topography are documented in one patient.

CONCLUSION

Clinical findings and pathologic studies seem nearly identical to those in the original report. No pattern of systemic disorder or medication use was found. The cause of this condition remains unknown.