Descemet membrane endothelial keratoplasty in eyes with COL8A2-associated corneal dystrophy

Purpose

The p.(Leu450Trp) COL8A2 mutation, associated with an early-onset corneal endothelial dystrophy, can result in bullous keratopathy within the first few decades of life. People with this condition frequently experience anterior corneal changes in keratometry as the disease worsens, which may potentially affect refractive error after endothelial keratoplasty. We describe outcomes of the first cases of Descemet Membrane Endothelial Keratoplasty (DMEK) for patients with known mutations in this gene.

Observations

Four eyes from two patients with COL8A2-associated corneal dystrophy underwent DMEK for this condition at a tertiary academic center. Preoperative and postoperative Scheimpflug imaging and manifest refraction was conducted. Mean central corneal thickness decreased from 713 μm preoperatively to 529 μm at one month. Despite long-standing corneal haze, all eyes reached between 20/20 and 20/30 best corrected visual acuity, and minimum postoperative central corneal thickness reached 482, 479, 479 and 533 μm. Refractive changes frequently occurred during the first postoperative year, with 3.6 D, 3.3 D, 3 D, and 0.8 D shifts in spherical equivalent taking place within this time period in the four eyes.

Conclusions and Importance

In two patients with the p.(Leu450Trp) mutation in COL8A2 who underwent DMEK, resolution of corneal edema resulted in centrally thin corneas and refractive shifts postoperatively. Despite chronic edema, excellent visual acuity was achieved in all eyes.

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Descemet Membrane Endothelial Keratoplasty can be safely performed for eyes affected by the p.(Leu450Trp) variant in COL8A2.

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Large swings in refractive error may occur for up to one year after surgery, but stabilize over time.

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Descemet membrane is markedly thickened and a large Descemetorhexis can be beneficial.

Pluripotent stem cell-derived corneal endothelial cells as an alternative to donor corneal endothelium in keratoplasty

Here, we evaluate the efficacy of cryopreserved human embryonic stem cell (hESC)-derived corneal endothelial cells (CECs) to form a functional monolayer of corneal endothelium (CE) in rabbits and monkeys. We injected cryopreserved hESC-derived CECs into the anterior chamber of rabbits and monkeys either immediately after mechanical scraping of the central CE or a few days later when corneal edema developed. All preclinical models developed deturgesced and clear corneas following the injection of cryopreserved hESC-derived CECs and remained comparable to the corneas of the untreated eye. Confocal scanning microscopy confirmed an intact structure of hexagonal/polygonal cells and immunohistochemical analysis illustrated a monolayer expressing barrier and pump function proteins in the regenerated CE. The necropsy examination confirmed no remarkable change in multiple tissues assessed for teratoma formation. In conclusion, our data demonstrate the efficacy of cryopreserved hESC-derived CECs to form a functional CE on the denuded Descemet's membrane.

Cigarette Smoke Triggers Loss of Corneal Endothelial Cells and Disruption of Descemet's Membrane Proteins in Mice

Purpose

To investigate changes at a molecular level in the mouse corneal endothelium (CE) exposed to chronic cigarette smoke (CS).

Methods

Pregnant mice (gestation days 18–20) were placed in a whole-body exposure smoking chamber, and a few days later pups were born. After 3.5 months of CS exposure, a ConfoScan4 scanning microscope was used to examine the corneal endothelial cells (CECs) of CS-exposed and control (Ct) mice. The CE was peeled under a microscope and maintained as four biological replicates (two male and two female) for CS-exposed and Ct mice; each replicate consisted of 16 CEs. The proteome of the CE was investigated through mass spectrometry.

Results

The CE images of CS-exposed and Ct mice revealed a difference in the shape of CECs accompanied by a nearly 10% decrease in CEC density (P < 0.00003) following CS exposure. Proteome profiling identified a total of 524 proteins exhibiting statistically significant changes in CE from CS-exposed mice. Importantly, proteins associated with Descemet's membrane (DM), including COL4α1, COL4α2, COL4α3, COL4α4, COL4α5, COL4α6, COL8α1, COL8α2, and FN1, among others, exhibited diminished protein levels in the CE of CS-exposed mice.

Conclusions

Our data confirm that exposure to CS results in reduced CEC density accompanied by diminished levels of multiple collagen and extracellular matrix proteins associated with DM.

Generation and Proteome Profiling of PBMC-Originated, iPSC-Derived Corneal Endothelial Cells

Purpose

Corneal endothelial cells (CECs) are critical in maintaining clarity of the cornea. This study was initiated to develop peripheral blood mononuclear cell (PBMC)-originated, induced pluripotent stem cell (iPSC)-derived CECs.

Methods

We isolated PBMCs and programmed the mononuclear cells to generate iPSCs, which were differentiated to CECs through the neural crest cells (NCCs). The morphology of differentiating iPSCs was examined at regular intervals by phase contrast microscopy. In parallel, the expression of pluripotent and corneal endothelium (CE)-associated markers was investigated by quantitative real-time PCR (qRT-PCR). The molecular architecture of the iPSC-derived CECs and human corneal endothelium (hCE) was examined by mass spectrometry–based proteome sequencing.

Results

The PBMC-originated, iPSC-derived CECs were tightly adherent, exhibiting a hexagonal-like shape, one of the cardinal characteristics of CECs. The CE-associated markers expressed at significantly higher levels in iPSC-derived CECs at days 13, 20, and 30 compared with their respective levels in iPSCs. It is of importance that only residual expression levels of pluripotency markers were detected in iPSC-derived CECs. Cryopreservation of iPSC-derived CECs did not affect the tight adherence of CECs and their hexagonal-like shape while expressing high levels of CE-associated markers. Mass spectrometry–based proteome sequencing identified 10,575 proteins in the iPSC-derived CEC proteome. In parallel, we completed proteome profiling of the hCE identifying 6345 proteins. Of these, 5763 proteins were identified in the iPSC-derived CECs, suggesting that 90.82% of the hCE proteome overlaps with the iPSC-derived CEC proteome.

Conclusions

We have successfully developed a personalized approach to generate CECs that closely mimic the molecular architecture of the hCE. To the best of our knowledge, this is the first report describing the development of PBMC-originated, iPSC-derived CECs.

Pilot Study of Audiometric Patterns in Fuchs Corneal Dystrophy

PURPOSE

Although Fuchs corneal dystrophy (FCD) is considered an eye disease, a small number of studies have identified genes related to both FCD and hearing loss. Whether FCD is related to hearing loss is unknown.

METHOD

This is a case-control study comparing pure-tone audiometry hearing thresholds in 180 patients with FCD from a hospital-based ophthalmology clinic with 2,575 population-based controls from a nationally representative survey, the National Health and Nutrition Examination Survey (from cycles 2005-06 and 2009-10). Generalized estimating equations were used to compare mean better-hearing ear thresholds in the 2 groups adjusted for age, sex, race, and noise exposure.

RESULTS

Patients with FCD had higher hearing thresholds (worse hearing) in lower frequencies (mean difference at 0.5 kHz = 3.49 dB HL) and lower hearing thresholds (better hearing) in higher frequencies (difference at 4 kHz = -4.25 dB HL) compared with population-based controls.

CONCLUSION

In the first study to use objectively measured hearing, FCD was associated with poorer low-frequency and better high-frequency audiometric thresholds than population controls. Further studies are needed to characterize this relationship.

CTG18.1 Expansion in TCF4 Among African Americans With Fuchs' Corneal Dystrophy

Purpose

Studies of Fuchs' dystrophy have largely focused on individuals of European origin. Characterization of disease among African Americans is required to ensure prognostic factors and therapeutic approaches are applicable across diverse patient populations.

Methods

We assessed all self-reported black and white patients aged older than 40 years at a tertiary care institution with a diagnosis of cataract over a 3-year period for concurrent diagnosis of Fuchs' dystrophy. Affected patients in a longitudinal cohort were invited to provide a blood sample from which we extracted genomic DNA. The CTG18.1 trinucleotide repeat length was determined using a two-step, triplet repeat primed PCR protocol. Expansion was defined as >40 CTG repeats. Demographic information, including race, was documented.

Results

Of 59,365 self-reported black and white adults who presented for cataract evaluation, the odds ratio of presenting with Fuchs' dystrophy among black compared to white patients was 0.6992 (95% confidence interval [CI], 0.6210–0.7872). A total of 60 black and 549 white patients with Fuchs' corneal dystrophy enrolled in the longitudinal study, of which 21 (35.0%) black and 343 (62.5%) white patients demonstrated trinucleotide repeat expansion, a significant difference (P = 7.7 × 10⁻⁵). In a multivariable linear regression model, repeat expansion but not race was significantly associated with mean clinical grading of severity.

Conclusions

Black patients with Fuchs' dystrophy were less likely than white patients to demonstrate CTG18.1 allele expansion. The data contribute to our understanding of population differences in clinical presentation, and highlight the need for considering diversity of patient populations in clinical research.

Genome-wide association study identifies three novel loci in Fuchs endothelial corneal dystrophy

The structure of the cornea is vital to its transparency, and dystrophies that disrupt corneal organization are highly heritable. To understand the genetic aetiology of Fuchs endothelial corneal dystrophy (FECD), the most prevalent corneal disorder requiring transplantation, we conducted a genome-wide association study (GWAS) on 1,404 FECD cases and 2,564 controls of European ancestry, followed by replication and meta-analysis, for a total of 2,075 cases and 3,342 controls. We identify three novel loci meeting genome-wide significance (P<5 × 10-8): KANK4 rs79742895, LAMC1 rs3768617 and LINC00970/ATP1B1 rs1200114. We also observe an overwhelming effect of the established TCF4 locus. Interestingly, we detect differential sex-specific association at LAMC1, with greater risk in women, and TCF4, with greater risk in men. Combining GWAS results with biological evidence we expand the knowledge of common FECD loci from one to four, and provide a deeper understanding of the underlying pathogenic basis of FECD.

Expansion of CTG18.1 Trinucleotide Repeat in TCF4 Is a Potent Driver of Fuchs' Corneal Dystrophy

PURPOSE

To analyze the expansion of CTG18.1 allele associated with Fuchs' corneal dystrophy (FCD) in our large cohort of late-onset FCD cases.

METHODS

CTG repeats within the CTG18.1 allele were estimated by short tandem repeat (STR) and triplet primed PCR (TP-PCR) assays in our large cohort of 574 late-onset FCD cases and 354 controls and large multigeneration familial cases. The age versus severity relationships were analyzed in FCD genotypes, namely, nonexpanded (N/N), monoallelic expansion (N/X), and biallelic expansion (X/X) with N ≤ 40 CTG monomers. The threshold for causality conferred by an expansion of CTG18.1 was identified by excluding the population of FCD cases who harbored an allele length equivalent to the maximum CTG monomers observed in the controls.

RESULTS

The expanded CTG18.1 for (CTG)n>40 showed a strong association (P = 1.56 × 10(-82)) with FCD. Importantly, we delineated the threshold of expansion to 103 CTG repeats above which the allele confers causality in 17.8% of FCD cases. Regression analyses demonstrated a significant correlation between disease severity and age in individuals who harbor either a monoallelic expansion or a biallelic expansion at (CTG) n > 40. These analyses helped predict FCD in two previously unaffected individuals based on their CTG18.1 expansion genotype.

CONCLUSIONS

A monoallelic expansion of CTG18.1 contributes to increased disease severity and is causal at (CTG)n>103, whereas a biallelic expansion is sufficient to be causal for FCD at (CTG)n>40. This study highlights the largest contributory causal allele for FCD.

Fuchs Corneal Dystrophy

Fuchs corneal dystrophy (FCD) is a hereditary, progressive disease of the posterior cornea which results in excrescences of Descemet membrane, endothelial cell loss, corneal edema, and, in late stages, bullous keratopathy. Structural changes are noted principally in Descemet membrane and the endothelium, with thickening of Descemet membrane, loss of barrier function, and increased corneal hydration, although secondary effects occur throughout all layers. Multiple chromosomal loci and, more recently, causal genetic mutations have been identified for this complex disorder, including in TCF8, SLC4A11, LOXHD1, and AGBL1. A trinucleotide repeat in TCF4 correlates strongly with disease status and interacts in common pathways with previously identified genes. Dysregulation of pathways involving oxidative stress and apoptosis, epithelial-to-mesenchymal transition, microRNA, mitochondrial genes, and unfolded protein response has been implicated in FCD pathogenesis.

Overview of the Cornea: Structure, Function, and Development

The cornea is a transparent tissue with significant refractive and barrier functions. The epithelium serves as the principal barrier to fluid and pathogens, a function performed through production of tight junctions, and constant repopulation through differentiation and maturation of dividing cells in its basal cell layer. It is supported posteriorly by basement membrane and Bowman's layer and assists in maintenance of stromal dehydration. The stroma composes the majority of corneal volume, provides support and clarity, and assists in ocular immunity. The posterior cornea, composed of Descemet membrane and endothelium, is essential for stromal dehydration, maintained through tight junctions and endothelial pumps. Corneal development begins with primitive formation of epithelium and lens, followed by waves of migration from cells of neural crest origin between these two structures to produce the stroma and endothelium. Descemet membrane is secreted by the latter and gradually thickens.

The genetics of Fuchs' corneal dystrophy

Fuchs' corneal dystrophy (FCD) is a common late-onset genetic disorder of the corneal endothelium. It causes loss of endothelial cell density and excrescences in the Descemet membrane, eventually progressing to corneal edema, necessitating corneal transplantation. The genetic basis of FCD is complex and heterogeneous, demonstrating variable expressivity and incomplete penetrance. To date, three causal genes, ZEB1, SLC4A11 and LOXHD1, have been identified, representing a small proportion of the total genetic load of FCD. An additional four loci have been localized, including a region on chromosome 18 that is potentially responsible for a large proportion of all FCD cases. The elucidation of the causal genes underlying these loci will begin to clarify the pathogenesis of FCD and pave the way for the emergence of nonsurgical treatments.

Prevalence and severity of fuchs corneal dystrophy in Tangier Island

PURPOSE

To investigate the clinical and genetic features of late-onset Fuchs corneal dystrophy (FCD) on Tangier, an island in the Chesapeake Bay with an isolated population of approximately 500 individuals.

DESIGN

Observational, cross-sectional study.

METHODS

A total of 156 individuals born to inhabitants of Tangier Island volunteered to undergo ophthalmic evaluation. Medical history was ascertained prior to examination. All participants underwent anterior segment examination with slit-lamp biomicroscopy. Retroillumination photographs were acquired from affected individuals and the disease severity was compared with individuals from large families ascertained previously. Genomic DNA samples were investigated for the presence of the recently identified risk allele rs613872, an intronic variant of TCF4.

RESULTS

Of the 148 examined individuals who were at least 30 years of age, 32 showed the classical symptoms of late-onset FCD (21.6%), providing a minimum prevalence of 11% among individuals over the age of 50 years. Severity was significantly lower compared to 51 cases from unlinked families, among individuals either 50 to 70 or above 70 years of age (P = .05 and P = .01, respectively). Retroillumination photography analyses were suggestive of mild severity when compared with the disease phenotype associated with FCD1- and FCD2-linked families. The rs613872 variant was associated with a higher affectation rate (P = .01), while the wild-type allele was correlated with a higher proportion of subclinical disease (P = .01).

CONCLUSIONS

In this study population in Tangier, late-onset FCD manifests clinically with a mild phenotype and increased prevalence. The rs613872 variant correlates with increased affectation and a clinical disease phenotype.

A single-base substitution in the seed region of miR-184 causes EDICT syndrome

PURPOSE

To investigate the cause of the syndrome characterized by endothelial dystrophy, iris hypoplasia, congenital cataract, and stromal thinning (EDICT).

METHODS

Previously a multigenerational family was reported that comprised 10 individuals affected by syndromal anterior segment dysgenesis. Blood samples were re-collected from eight affected and two unaffected individuals, and genomic DNA was extracted. A total of 24 candidate genes and 4 microRNAs residing within the critical interval were sequenced bidirectionally. In silico analyses were performed to examine the effect of the causal variant on the stability of the pre-microRNA structure.

RESULTS

Bidirectional sequencing identified the single-base substitution +57C>T in miR-184. This variation segregated with the disease phenotype and was absent in the 1000 Genomes project, 1130 control chromosomes, and 28 nonhuman vertebrates.

CONCLUSIONS

The single-base-pair substitution in the seed region of miR-184 is responsible for the disease phenotype observed in EDICT syndrome.

Replication of the TCF4 intronic variant in late-onset Fuchs corneal dystrophy and evidence of independence from the FCD2 locus

PURPOSE

Fuchs corneal dystrophy (FCD) is an autosomal dominant disease of the corneal endothelium with variable penetrance and expressivity. Recently, rs613872, an intronic variation of TCF4 associated with late-onset FCD, was reported. The present study was undertaken to examine this association in our cohort of FCD patients, to assess the significance of this finding, and to investigate the candidacy of TCF4 in the context of the mapped FCD2 locus.

METHODS

The authors recruited 170 patients with late-onset FCD and 180 age-matched controls. Blood samples were collected, and genomic DNA was extracted. A panel of nine SNPs spanning the entire TCF4 locus was genotyped both on this cohort and on three previously reported FCD2-linked families. The association of an individual SNP with late-onset FCD was evaluated with the Fisher exact test, and the coding exons and exon-intron boundaries of TCF4 were sequenced in 96 affected persons.

RESULTS

The risk allele G of rs613872 is associated significantly with late-onset FCD (odds ratio, 4.2; P = 4.28 x 10⁻¹⁵) and was present in male and female affected persons without any sex bias, replicating recent findings, though the authors found no apparent correlation with the severity of the disease phenotype. Moreover, the risk allele did not cosegregate with the disease phenotype in any of the three FCD2-linked families. The authors did not identify any pathogenic variants in the coding region of TCF4.

CONCLUSIONS

The authors report the first independent replication of rs613872 conferring risk of late-onset FCD. Their data suggest that this risk factor is likely independent of the FCD2 locus, whose causality remains unknown.

Replication of TCF4 through association and linkage studies in late-onset Fuchs endothelial corneal dystrophy

Fuchs endothelial corneal dystrophy (FECD) is a common, late-onset disorder of the corneal endothelium. Although progress has been made in understanding the genetic basis of FECD by studying large families in which the phenotype is transmitted in an autosomal dominant fashion, a recently reported genome-wide association study identified common alleles at a locus on chromosome 18 near TCF4 which confer susceptibility to FECD. Here, we report the findings of our independent validation study for TCF4 using the largest FECD dataset to date (450 FECD cases and 340 normal controls). Logistic regression with sex as a covariate was performed for three genetic models: dominant (DOM), additive (ADD), and recessive (REC). We found significant association with rs613872, the target marker reported by Baratz et al.(2010), for all three genetic models (DOM: P = 9.33×10(-35); ADD: P = 7.48×10(-30); REC: P = 5.27×10(-6)). To strengthen the association study, we also conducted a genome-wide linkage scan on 64 multiplex families, composed primarily of affected sibling pairs (ASPs), using both parametric and non-parametric two-point and multipoint analyses. The most significant linkage region localizes to chromosome 18 from 69.94cM to 85.29cM, with a peak multipoint HLOD = 2.5 at rs1145315 (75.58cM) under the DOM model, mapping 1.5 Mb proximal to rs613872. In summary, our study presents evidence to support the role of the intronic TCF4 single nucleotide polymorphism rs613872 in late-onset FECD through both association and linkage studies.

Missense mutations in the sodium borate cotransporter SLC4A11 cause late-onset Fuchs corneal dystrophy

Homozygous mutations in the Borate Cotransporter SLC4A11 cause two early-onset corneal dystrophies: congenital hereditary endothelial dystrophy (CHED) and Harboyan syndrome. More recently, four sporadic patients with late-onset Fuchs corneal dystrophy (FCD), a common age-related disorder, were also reported to harbor heterozygous mutations at this locus. We therefore tested the hypothesis that SLC4A11 contributes to FCD and asked whether mutations in SLC4A11 are responsible for familial cases of late-onset FCD. We sequenced SLC4A11 in 192 sporadic and small nuclear late-onset FCD families and found seven heterozygous missense novel variations that were absent from ethnically matched controls. Familial data available for one of these mutations showed segregation under a dominant model in a three-generational family. In silico analyses suggested that most of these substitutions are intolerant, whereas biochemical studies of the mutant protein indicated that these alleles impact the localization and/or posttranslational modification of the protein. These results suggest that heterozygous mutations in SLC4A11 are modest contributors to the pathogenesis of adult FCD, suggesting a causality continuum between FCD and CHED. Taken together with a recent model between FCD and yet another early onset corneal dystrophy, PPCD, our data suggest a shared pathomechanism and genetic overlap across several corneal dystrophies.

Age-severity relationships in families linked to FCD2 with retroillumination photography

PURPOSE

Fuchs corneal dystrophy (FCD) is a progressive disorder of the corneal endothelium and is pathologically defined by the presence of guttae, which are excrescences of the Descemet membrane. The present study was undertaken to investigate the age-severity relationship of the FCD2-linked disease phenotype using retroillumination photography and to compare it with the characteristics of FCD1.

METHODS

Two large families with multiple affected members were recruited. Exclusion analyses of the known late-onset FCD loci were completed with closely spaced STR markers, whereas genes associated with early- and late-onset FCD were investigated by bidirectional sequencing. Haplotypes were constructed, and two-point LOD scores were calculated. To document age-severity relationships, retroillumination photographs were acquired from members of both families.

RESULTS

Parametric linkage and haplotype analysis mapped both families to FCD2 with significant two-point LOD scores. A total of 70,249 guttae were counted in 14 persons from both families. A significant increase in guttae density in the inferotemporal region (P = 0.016) was observed, a pattern similarly observed in a family linked to FCD1. Similarly, FCD2-linked families display an exponential trend in severity with age, as was observed in a family linked to FCD1. Finally, comparison of FCD1 and FCD2 exponential models suggested that the FCD1 phenotype is significantly more severe (P = 0.01).

CONCLUSIONS

A combination of genetic mapping and retroillumination photography was used to quantify the severity of the disease phenotype associated with FCD2 and to compare it to the disease characteristics of FCD1. These data suggest that this approach might have sufficient resolution to discriminate between discrete genetic FCD backgrounds, which will potentially aid in patient management.

Fuchs' corneal dystrophy

Fuchs' corneal dystrophy (FCD) is a progressive, hereditary disease of the cornea first described a century ago by the Austrian ophthalmologist Ernst Fuchs. Patients often present in the fifth to sixth decade of life with blurry morning vision that increases in duration as the disease progresses. Primarily a condition of the posterior cornea, characteristic features include the formation of focal excrescences of Descemet membrane termed 'guttae', loss of endothelial cell density and end-stage disease manifested by corneal edema and the formation of epithelial bullae. Recent advances in our understanding of the genetic and pathophysiological mechanisms of the disease, as well as the application of new imaging modalities and less invasive surgical procedures, present new opportunities for improved outcomes among patients with FCD.

Missense mutations in TCF8 cause late-onset Fuchs corneal dystrophy and interact with FCD4 on chromosome 9p

Fuchs corneal dystrophy (FCD) is a degenerative genetic disorder of the corneal endothelium that represents one of the most common causes of corneal transplantation in the United States. Despite its high prevalence (4% over the age of 40), the underlying genetic basis of FCD is largely unknown. Here we report missense mutations in TCF8, a transcription factor whose haploinsufficiency causes posterior polymorphous corneal dystrophy (PPCD), in a cohort of late-onset FCD patients. In contrast to PPCD-causing mutations, all of which are null, FCD-associated mutations encode rare missense changes suggested to cause loss of function by an in vivo complementation assay. Importantly, segregation of a recurring p.Q840P mutation in a large, multigenerational FCD pedigree showed this allele to be sufficient but not necessary for pathogenesis. Execution of a genome-wide scan conditioned for the presence of the 840P allele identified an additional late-onset FCD locus on chromosome 9p, whereas haplotype analysis indicated that the presence of the TCF8 allele and the disease haplotype on 9p leads to a severe FCD manifestation with poor prognosis. Our data suggest that PPCD and FCD are allelic variants of the same disease continuum and that genetic interaction between genes that cause corneal dystrophies can modulate the expressivity of the phenotype.

Treatment with voriconazole in 3 eyes with resistant Acanthamoeba keratitis

PURPOSE

To report the use of topical voriconazole 1% (Vfend; Pfizer Inc, New York, New York, USA) ophthalmic solution for Acanthamoeba keratitis (AK) resistant to treatment with chlorhexidine (PerioChip; Dexel Pharma Technologies, Jerusalem, Israel).

DESIGN

Retrospective case series.

METHODS

Three eyes of 2 patients with culture-proven AK were treated at a tertiary care institution, and their charts were reviewed. Topical voriconazole 1% was instituted as second-line treatment for AK unresponsive to standard treatment with chlorhexidine and hexamidine. Treatment with voriconazole 1% was started at 1-hour intervals. Improvement was assessed and defined by absence of clinical signs of active infection and visual improvement.

RESULTS

One patient with unilateral AK and 1 patient with bilateral AK who remained culture-positive for Acanthamoeba despite ongoing treatment with chlorhexidine and hexamidine were treated with voriconazole 1% topical solution as an adjuvant. Both patients were contact lens wearers. Of 3 eyes additionally treated with voriconazole, 2 eyes had clinical resolution of disease. One eye demonstrated recurrent disease after penetrating keratoplasty that resolved after intrastromal injection of voriconazole.

CONCLUSIONS

We report the use of topical and intrastromal voriconazole in successfully treating AK in cases of chlorhexidine- and hexamidine-resistant Acanthamoeba. Voriconazole may be a promising adjuvant agent in treating AK.

Progression of Fuchs corneal dystrophy in a family linked to the FCD1 locus

PURPOSE

Fuchs corneal dystrophy (FCD) is a progressive corneal disease marked by the development of guttae, focal excrescences of Descemet's membrane. Retroillumination photography is a useful technique for illuminating the presence of guttae and has been used to document progression of disease. This study was undertaken to quantitatively assess disease progression in a cohort of individuals with late-onset FCD linked to chromosome 13.

METHODS

Retroillumination photography was performed on 13 related individuals (26 eyes) with the FCD1 disease haplotype at a 30- to 34-month interval. Individual guttae were counted in each image and the distribution recorded. A polar coordinate system was used to delineate regional differences in development of guttae.

RESULTS

An increase of 29.1% was found in the total number of guttae over approximately 30 months (mean increase of 669 guttae/eye, P < 0.001) among 26 eyes. A rapid rate of progression begins at approximately age 50, representing an exponential increase (r(2) = 0.60) among individuals mildly affected for decades. Individuals with the disease haplotype but with two affected parents demonstrated an earlier disease onset. A significantly greater proportion of guttae were present in the inferotemporal quadrant of the cornea (P < 0.001), an effect that grew in significance over time.

CONCLUSIONS

The study demonstrated quantitative progression of FCD with the use of retroillumination photography in an FCD1-linked pedigree. Comparison of severity versus age suggests a rapid increase in the number of guttae at approximately age 50. Individuals with the FCD1 disease haplotype and a second likely genetic lesion exhibit a markedly increased disease severity suggestive of genetic interaction between FCD loci.

A Common Locus for Late-Onset Fuchs Corneal Dystrophy Maps to 18q21.2-q21.32

PURPOSE

To identify the genetic basis of late-onset Fuchs corneal dystrophy (FCD).

METHODS

Phenotypes and genotypes at 1107 short tandem repeat polymorphism markers were obtained for 43 affected and 33 unaffected individuals in three large families. Two-point genetic linkage analysis was performed with MLINK and multipoint linkage with SimWalk 2.89.

RESULTS

In each family, the most significant cluster of two-point lod scores mapped to chromosome 18, at 18q21.2-q21.3. The highest two-point lod score for each family was at D18S1129, with scores of 3.41, 2.89, and 2.45, with a combined two-point lod score of 7.70. Multipoint analysis yielded a maximum score of 5.94 at D18S1129 for a dominant Mendelian trait exhibiting 85% penetrance and 15% phenocopy rate. Disease interval haplotypes for each family are different.

CONCLUSIONS

FCD2, at 18q21, is the second genetic locus identified for late-onset FCD. Presence of this same locus in all three families may indicate its widespread involvement in late-onset FCD. Allelic differences between disease-associated haplotypes in the families leave open the possibility of independent mutations in the same gene. The incomplete penetrance and high phenocopy rate observed at FCD2 suggest that the origin of FCD in these three families is complex and also depends on other genetic loci or environmental factors.

Analysis and documentation of progression of Fuchs corneal dystrophy with retroillumination photography

PURPOSE

Fuchs corneal dystrophy (FCD) is a degenerative disorder of the cornea that is characterized by the progressive accumulation of guttae, which are small excrescences of Descemet's membrane. We describe a method for documenting the location and number of guttae, and ask whether disease progression can be observed during relatively short periods.

METHODS

Patients with FCD were imaged by standard retroillumination photography with a slit lamp. Scanned photographs were analyzed by using NIH ImageJ software to determine the number of individual guttae and areas of confluence.

RESULTS

In 4 FCD patients, photographs taken 23 to 30 months apart revealed that, once formed, individual guttae and their relative positions persisted during this period. Very few guttae disappeared, and the emergence of many new guttae was observed. Determination of the area with confluent guttae was used to quantify disease stage.

CONCLUSIONS

Computer-assisted analysis of retroillumination photographs is proposed as an effective way to document the number and distribution of individual guttae. Although the disease typically progresses slowly during decades, we have been able to detect the formation of new guttae within only 2 years. This rapid assessment of disease progression could be used to measure phenotypic differences between genetic subtypes of FCD. It also could provide important baseline information and methodology for clinical trials of therapeutic options, should these become available.

Linkage of late-onset Fuchs corneal dystrophy to a novel locus at 13pTel-13q12.13

PURPOSE

To identify the gene locus underlying the inheritance of late-onset Fuchs corneal dystrophy (FCD) in a large white kindred.

METHODS

Genotypes of small tandem repeat polymorphisms were obtained from 17 affected and 3 unaffected family members, followed by genetic linkage analysis.

RESULTS

In this family, classic late-onset FCD appeared to be inherited as a single, dominant Mendelian trait. In two exceptional sibships, however, children aged 10 and 13 years had FCD. In each sibship, both parents were found to be affected, opening the possibility that this unusually early age of onset was the result of homozygosity for an FCD mutation. Genotype results, however, were not consistent with consanguinity of the parents, who appear to have independent cases of FCD. A whole-genome linkage scan mapped FCD to a single locus at 13pTel-13q12.13, with significant two-point LOD scores of 3.91 at D13S1236 and 3.80 at D13S1304. The 26.4-Mb disease interval contains the chromosome 13 nucleolus organizer (RNR1), the centromere, and 44 annotated protein-encoding genes. So far, exons of 10 of these genes have been screened, but no mutations have been found.

CONCLUSIONS

FCD1 is the first genetic locus to be identified for late-onset FCD, a common disease of the aging cornea. The exceptional early onset of the disease observed in two children is unusual and might be the result of digenic interaction between FCD1 and an independent late-onset FCD mutation.

Fuchs corneal dystrophy: aberrant collagen distribution in an L450W mutant of the COL8A2 gene

PURPOSE

To characterize histologically Descemet's membrane in an early-onset Fuchs corneal dystrophy (FCD) COL8A2 mutant and compare these findings with corneas from late-onset FCD and normal corneas.

METHODS

A corneal explant from a patient with the L450W COL8A2 mutation and others with late-onset disease were studied with antibodies to collagens IV, VIIIA1, VIIIA2, fibronectin, and laminin. Transmission electron microscopy was performed on a portion of the explant. Control explants included eye bank corneas without known disease and surgical explants from unrelated conditions.

RESULTS

In normal corneas, a regular array of colocalized COL8A1 and COL8A2 was observed in the anterior half of Descemet's membrane. In the L450W mutant, Descemet's membrane was several times thicker than normal and traversed by refractile strands and blebs that stained intensely for COL8A2, a feature also observed in late-onset FCD. Both the alpha1 and alpha2 subtypes of collagen VIII were observed at high levels along the anterior edge of Descemet's, another abnormal feature also found in late-onset FCD. Ultrastructure of the L450W cornea revealed a well-formed anterior banded layer more than three times thicker than normal. An unusual, thin internal layer was rich in patches of wide-spaced collagen. The layer is a distinctive pathologic structure that is associated with FCD and is characterized by approximately 120 nm periodicity and the presence of collagen VIII. Depositions of collagen IV, fibronectin, and laminin were also greatly increased in the of posterior Descemet's membrane, yet another general feature shared between early- and late-onset disease.

CONCLUSIONS

Early-onset COL8A2 L450W disease involves massive accumulation and abnormal assembly of collagen VIII within Descemet's membrane, a process that is presumed to begin during fetal development. Both early- and late-onset subtypes of FCD appear to be the result of abnormal basement membrane assembly rather than a primary defect in endothelial metabolism.

Immunohistochemistry and electron microscopy of early-onset fuchs corneal dystrophy in three cases with the same L450W COL8A2 mutation

PURPOSE

A rare, familial early-onset form of Fuchs corneal dystrophy (FCD) is caused by mutation in the COL8A2 gene. This study describes the aberrant pattern of distribution of collagen type VIII and basement membrane components in Descemet's membrane (DM) and endothelium of three individuals with the same L450W mutation that represent different stages of early-onset FCD.

METHODS

Immunohistochemical studies with bright field, fluorescence, and confocal microscopy characterized the pathology of sectioned corneal buttons with antibodies against COL8A1, COL8A2, COL4, laminin, and fibronectin. A portion of each was processed for electron microscopy.

RESULTS

Histologic examination of pathologic changes in case 1 demonstrated relative preservation of the endothelium, whereas in case 2 much of this layer was atrophic and in case 3 there was complete loss of the endothelium. DM also increased in thickness to 25 mum for case 1, to 31 mum for case 2, and to 38 mum for case 3. Case 1 was the only specimen to reveal shallow warts along the posterior surface of DM, whereas the most advanced specimen, case 3, showed evidence of earlier nodularity that had been buried by the accretion of further extracellular matrix material. The posterior aspect of DM in this specimen had the unusual property of lighter staining relative to the anterior region of DM, laid down earlier in life. Immunocytochemistry revealed increased expression and complex, sharply defined patterns of deposition of collagen VIII, collagen IV, laminin, and fibronectin. Ultrastructurally, the posterior nonbanded layer of DM was intermixed with banded collagen, and the posterior region of DM showed a high density of foci of spindle-shaped structures with intense-staining bands, spaced at approximately 120 nm. Finally, ultrastructural studies of the endothelium in case 1 revealed unusual accumulation of swelling mitochondria. The endothelial cells also had large amounts of abnormal prominent rough endoplasmic reticulum. Type VIII collagen alpha 2 immunogold signal was associated with the highly granular ribosomes of the rough endoplasmic reticulum of these patients.

CONCLUSIONS

Microscopic and electron microscopic examination revealed pathological changes in DM of L450W COL8A2 mutants that were consistent with several-fold increased growth of the extracellular matrix and progressive deposition and synthesis of extracellular material by endothelial cells. As with late-onset FCD, this is accompanied by attenuation and eventual loss of the endothelium itself. Whether the abnormal deposition of collagen, laminin, and fibronectin contributes to the dysfunction and death of the endothelium remains to be determined.

Inheritance of a novel COL8A2 mutation defines a distinct early-onset subtype of fuchs corneal dystrophy

PURPOSE

To characterize the genetic basis and phenotype of inherited Fuchs corneal dystrophy (FCD).

METHODS

DNA from blood was used for genome-wide linkage scans with tandem repeat polymorphisms. Mutation detection involved sequencing PCR-amplified exons. Families with FCD were clinically evaluated and graded on the Krachmer severity scale. Confocal specular microscopy visualized the morphology of endothelial guttae, small protrusions of Descemet's membrane that are characteristic of FCD.

RESULTS

Linkage was obtained to 1p34.3-p32 for the autosomal dominant kindred originally reported by Magovern in 1979. All 21 cases with FCD and one with posterior polymorphous dystrophy were heterozygous for L450W, a novel point mutation in the COL8A2 gene. Of 62 independent cases of familial FCD, none had the previously reported mutations in COL8A2. Corneal guttae in COL8A2 patients were small, rounded, and associated with the endothelial cell center. This contrasts with common FCD, in which guttae were larger, sharply peaked, and initially positioned at edges of endothelial cells. The profile of age and disease severity for the L450W FCD kindred suggested that disease onset occurred in infancy, compared with an average age of onset of 50 years estimated for 201 familial FCD patients in 62 other families.

CONCLUSIONS

A novel pathogenic L450W COL8A2 mutation was identified and its highly distinctive pathology characterized. This indicates that COL8A2 mutations give rise to a rare subtype of FCD. This study also provides the first direct evidence that COL8A2-FCD progresses from early to late stages in 25 years, a rate similar to that estimated for late-onset FCD.

Light-induced oxidative stress in choroidal endothelial cells in mice

PURPOSE

Although light-induced oxidative stress in the retina has been extensively reported, little information regarding light-induced oxidative stress in choroidal endothelial cells (CECs) is available. In the current study, light-induced DNA oxidation and the activation of nuclear factor-kappaB (NF-kappaB), a major oxidative responsive transcription factor, were investigated in mouse CECs.

METHODS

Mice were exposed to green light. Light-induced DNA oxidation in CECs was detected by in situ 8-hydroxy-2-deoxyguanosine (8-oxo-dG) immunolabeling. CECs were isolated from the retinal pigment epithelium (RPE)/choroid by using immunomagnetic beads. The isolated CECs were immunochemically characterized by the expression of endothelial markers, CD31, and P1H12. The quality of total RNA from CECs was assessed by a bioanalyzer and RT-PCR. NF-kappaB activation in situ and in isolated CECs was investigated.

RESULTS

After a 3-hour exposure to light, the immunoreactivity to anti-8-oxo-dG antibody or anti-NF-kappaB p65 antibody in CECs in situ was significantly increased when compared with unexposed mice. Isolated CECs expressed CD31 and P1H12. The 28S/18S rRNA ratio of RNA isolated from CECs was 1.5:1. CD31 and von Willebrand Factor (vWF) transcripts were predominantly expressed in the RNA from isolated CECs. IkappaBalpha was more heavily phosphorylated in light-exposed than untreated CECs. IkappaBalpha expression levels were increased fivefold in isolated CECs after exposure to light compared to unexposed control subjects.

CONCLUSIONS

Exposure to light induces oxidative stress in CECs in vivo. A method for CEC isolation from the mouse RPE/choroid with preservation of RNA quality has been developed. The results of this study may facilitate the ability to identify CEC-specific genes and gene products that respond to photo-oxidative stress.

A Morphologic Study of Fuchs Dystrophy and Bullous Keratopathy

PURPOSE

To describe the morphologic features of Fuchs corneal dystrophy and compare them with those of bullous keratopathy.

METHODS

This was an observational case series. The study group consisted of 32 corneal buttons with a diagnosis of Fuchs dystrophy and the comparison group consisted of 22 corneal buttons with bullous keratopathy. Morphologic analysis was performed of corneal buttons from patients with the clinical diagnosis of Fuchs dystrophy or bullous keratopathy by light and electron microscopy.

RESULTS

The main outcome measure was identification of degenerated keratocytes, granular material in and around keratocytes, and lipid keratopathy. The overall morphologic features of Fuchs dystrophy and bullous keratopathy are similar to those described in previous literature. A high proportion of keratocytes exhibited degenerative changes (78.9% in Fuchs dystrophy versus 50.5% in bullous keratopathy). Granular material was identified in and around variably degenerated keratocytes in all cases of Fuchs dystrophy and in 14 of 22 (64%) of the corneas with bullous keratopathy. The percentage of keratocytes with granular deposits was higher in Fuchs dystrophy corneas as compared with corneas with bullous keratopathy (51.7% versus 14.1%, P < 0.0005). Lipid keratopathy was a common occurrence in both Fuchs dystrophy and bullous keratopathy (23/32 [72%] versus 12/22 [55%]).

CONCLUSIONS

Histopathologic changes in the corneal stroma and keratocytes occur in Fuchs dystrophy. Secondary lipid keratopathy ensues and may contribute to corneal haze. A higher proportion of keratocytes in Fuchs dystrophy have granular deposit than in bullous keratopathy. That a high proportion of keratocytes had degenerative changes in both Fuchs dystrophy and bullous keratopathy suggests that keratocytes may degenerate secondary to altered stromal microenvironment because of endothelial cell loss.

Cataract surgery in patients with Fuchs' corneal dystrophy

OBJECTIVE

To evaluate the use of preoperative pachymetry in patients with Fuchs' dystrophy who are undergoing cataract extraction to predict the need for future penetrating keratoplasty and to compare these findings with current published recommendations.

DESIGN

Retrospective noncomparative case series.

PARTICIPANTS

A series of patients with Fuchs' dystrophy (136 eyes) undergoing cataract surgery.

METHODS

We reviewed the medical records of 136 patients with Fuchs' dystrophy who underwent phacoemulsification and intraocular lens implantation between October 1990 and May 2002.

MAIN OUTCOME MEASURES

Preoperative and postoperative visual acuity, pachymetry, and postoperative corneal decompensation requiring penetrating keratoplasty.

RESULTS

The average preoperative corneal thickness was 584+/-39.5 microm (range, 482-674 microm). Fifty eyes (36.8%) had preoperative corneal thickness of > or =600 microm. The average postoperative best-corrected visual acuity (BCVA) was 20/33 (range, 20/15-20/250). Of the 50 eyes with preoperative pachymetry measurements of > or =600 microm, 5 (10%) progressed to penetrating keratoplasty; 90% of the 50 eyes did not need corneal transplants within the first year after cataract surgery and had an average postoperative BCVA of 20/35 (range, 20/20-20/200). Of those with a corneal thickness of > or =640 microm, 83% did not need a corneal transplant within this same time period and had an average postoperative BCVA of 20/50 (range, 20/20-20/200).

CONCLUSIONS

To avoid unnecessary cost and delay in visual rehabilitation, we suggest changing the current recommendations for an initial triple procedure for eyes with preoperative pachymetry measurements of >600 microm. Our data suggest that current cataract removal techniques allow for excellent visual rehabilitation in patients with Fuchs' dystrophy who have a preoperative corneal thickness of >600 microm, and we suggest that preoperative pachymetry measurements of >640 microm may be a better guideline. This recommendation can be further expanded above 640 mum if a visual acuity of less than 20/20 is acceptable. A prospective randomized controlled study is required for validation of this analysis.

A randomized trial of topical cyclosporin 0.05% in topical steroid–resistant atopic keratoconjunctivitis

OBJECTIVE

To evaluate the short-term efficacy and safety of topical cyclosporin A 0.05% in the treatment of patients with severe, steroid-resistant atopic keratoconjunctivitis (AKC).

DESIGN

Multicenter, placebo-controlled, double-masked, randomized trial.

PARTICIPANTS

Twenty-two patients with AKC refractory to topical steroid treatment.

INTERVENTION

Patients were randomly assigned (1:1) to treatment with topical 0.05% cyclosporin A eyedrops or a placebo (artificial tears) for a period of 28 days, 6 times daily during the first 2 weeks and 4 times daily during the last 2 weeks.

MAIN OUTCOME MEASURES

Symptoms (itching, tearing, discomfort, mucous discharge, and photophobia) and signs (bulbar conjunctival hyperemia, upper tarsal conjunctival papillae, punctate keratitis, corneal neovascularization, cicatrizing conjunctivitis, and blepharitis) of AKC recorded on the day of enrollment and at the end of the treatment period.

RESULTS

A composite score computed by summing the severity grade over all 5 symptoms and 6 signs of AKC for each patient indicated a greater improvement in the cyclosporin A group relative to the placebo at the end of the 4-week treatment period (P = 0.048 and P = 0.002, for symptoms and signs, respectively). No adverse effects of the treatment with cyclosporin A 0.05% eyedrops were observed.

CONCLUSIONS

Topical cyclosporin A 0.05% seems to be safe and have some effect in alleviating signs and symptoms of severe AKC refractory to topical steroid treatment.

Immune defense at the ocular surface

The ocular surface is constantly exposed to a wide array of microorganisms. The ability of the outer ocular system to recognize pathogens as foreign and eliminate them is critical to retain corneal transparency, hence preservation of sight. Therefore, a combination of mechanical, anatomical, and immunological defense mechanisms has evolved to protect the outer eye. These host defense mechanisms are classified as either a native, nonspecific defense or a specifically acquired immunological defense requiring previous exposure to an antigen and the development of specific immunity. Sight-threatening immunopathology with autologous cell damage also can take place after these reactions. This article discusses the innate and acquired corneal elements of the immune defense at the ocular surface. The relative roles of the various factors contributing to prevention of eye infection remain to be fully defined.

Combined phacoemulsification, intraocular lens implantation, and vitrectomy for eyes with coexisting cataract and vitreoretinal pathology

PURPOSE

To report the preoperative, intraoperative, and postoperative outcomes of combining phacoemulsification and posterior chamber intraocular lens (IOL) implantation with pars plana vitrectomy in eyes with significant cataract and coexisting vitreoretinal pathology.

DESIGN

Retrospective, consecutive, interventional case series.

METHODS

Charts of patients undergoing combined procedures at the Wilmer Ophthalmologic Institute between March 1995 and May 2000 were reviewed.

RESULTS

In all, 122 eyes of 111 patients were identified. Patient ages ranged from 27 to 89 years (mean 65). Forty-three eyes had diabetic retinopathy; 11 had undergone vitrectomy previously. Macular pathology (hole, membrane, choridal neovascularization) was present in 69 eyes. The most common indications for surgery were diabetic vitreous hemorrhage, macular hole, epiretinal membrane, and retinal detachment. In all cases, phacoemulsification and IOL implantation were performed before vitreoretinal surgery. Preoperative vision ranged from 20/30 to light perception and postoperative vision ranged from 20/20 to no light perception. In 105 patients vision improved, in 7 there was no change, and in 10 vision decreased. Postoperative complications included opacification of the posterior capsule, increased intraocular pressure, corneal epithelial defects, vitreous hemorrhage, retinal detachment and iris capture by the IOL.

CONCLUSIONS

Combined surgery is a reasonable alternative in selected patients. Techniques that may simplify surgery and reduce complications include: careful, limited, curvilinear capsulorhexis; in-the-bag placement of IOLs; use of IOLs with larger optics; suturing of cataract wounds before vitrectomy; use of miotics and avoidance of long-acting dilating drops in patients with intravitreal gas; and use of wide-field viewing systems.

Surgical management of anterior chamber epithelial cysts

PURPOSE

To review management strategies for treatment of anterior chamber epithelial cysts.

DESIGN

Retrospective review of consecutive interventional case series.

METHODS

Charts of patients treated for epithelial ingrowth over a 10-year period by a single surgeon were reviewed. Cases of anterior chamber epithelial cysts were identified and recorded, including details of ocular history, preoperative and postoperative acuity, intraocular pressure (IOP), and ocular examination, type of surgical intervention, and details of further procedures performed.

RESULTS

Seven eyes with epithelial cysts were identified. Patient age ranged from 1.5 to 53 years at presentation. Four patients were children. In four eyes, cysts were secondary to trauma, one case was presumably congenital, one case developed after corneal perforation in an eye with Terrien's marginal degeneration, and one case developed after penetrating keratoplasty (PK). Three eyes were treated with vitrectomy, en bloc resection of the cyst and associated tissue, fluid-air exchange and cryotherapy. The last four eyes were treated with a new conservative strategy of cyst aspiration (three cases) or local excision (one keratin "pearl" cyst), and endolaser photocoagulation of the collapsed cyst wall/base. All epithelial tissue was successfully eradicated by clinical criteria; one case required repeat excision (follow-up, 9 to 78 months, mean 45). Two eyes required later surgery for elevated IOP, two for cataract extraction and one for repeat PK. Final visual acuity ranged from 20/20 to hand motions, depending on associated ocular damage. Best-corrected visual results were obtained in the more conservatively managed eyes.

CONCLUSIONS

Anterior chamber epithelial cysts can be managed conservatively in selected cases with good results. This strategy may be particularly useful in children's eyes, where preservation of the lens, iris, and other structures may facilitate amblyopia management.

Gene expression in donor corneal endothelium

OBJECTIVE

To report gene expression profiles of normal human corneal endothelium with microarray analysis and serial analysis of gene expression (SAGE).

METHODS

Corneal endothelium was removed from normal human corneas obtained from eye banks. Total RNA was isolated and SAGE analysis was performed. The same RNA source was used to construct a complementary DNA library that was hybridized to microarrays containing 12 558 transcripts.

RESULTS

A total of 9530 SAGE tags were sequenced, representing 4724 unique tags. Microarray analysis identified 542 distinct transcripts. A database of human corneal endothelial gene expression was compiled. Of the SAGE tags, 1720 matched known genes, 478 corresponded to expressed sequence tags, and 2526 had no known match to public databases. The 5 most abundantly expressed SAGE tags were cytochrome c oxidase subunit II, adenosine triphosphate synthase F(0) subunit 6, carbonic anhydrase XII, 12S ribosomal RNA, and ferritin, heavy polypeptide 1. Thirty-four percent of the transcripts (n = 1616) were specific to the corneal endothelium, when compared with other publicly available SAGE libraries. The 5 most abundant unique tags were keratin 12, angiopoietinlike factor, annexin A8, and 2 tags with no match to the database. Many endothelial pump function enzymes were confirmed, including several plasma membrane Na( +)/K(+) adenosine triphosphatases and a recently reported bicarbonate transporter.

CONCLUSIONS

Corneal endothelial gene expression profiles by the current analysis provide an understanding of endothelial metabolism, structure, and function; enable comparisons to diseased endothelium; and provide baseline data that may lead to the discovery of novel endothelial genes.

Serial analysis of gene expression in the corneal endothelium of Fuchs' dystrophy

PURPOSE

To compare the gene expression profiles of normal human corneal endothelium with Fuchs' corneal endothelium, by using serial analysis of gene expression (SAGE).

METHODS

Three pairs of normal human corneas were obtained from eye banks. Thirteen bisected Fuchs' corneal buttons were processed at the time of corneal transplantation. The endothelia of normal and Fuchs'-affected corneas were stripped, and total RNA was isolated. Serial analysis of gene expression (SAGE) was performed to identify and quantify gene transcripts. Genes over- and underexpressed by Fuchs' endothelium were limited to P < 0.01 by the method of Audic and Claverie.

RESULTS

A total of 19,136 tags were identified with 9,530 from normal and 9,606 from Fuchs' endothelium. The expression of 18 transcripts was upregulated, and 36 transcripts were downregulated in Fuchs' endothelium compared with normal tissue. Upregulated transcripts included serum amyloid A1 and A2, metallothionein, and apolipoprotein D. Of the downregulated transcripts, 26 matched known genes, 3 matched expressed sequence tags (ESTs), and 7 were unknown to current databases. One downregulated transcript involved a newly reported bicarbonate transporter. Decreased transcripts related to antioxidants and proteins conferring protection against toxic stress were noted in Fuchs' versus normal endothelium including nuclear ferritin, glutathione S-transferase-pi, and heat shock 70-kDa protein. Nine different SAGE tags matching mitochondrial sequences accounted for 25% of the ESTs that were decreased in Fuchs' endothelium.

CONCLUSIONS

SAGE analysis comparing normal to Fuchs' endothelium demonstrates diminished expression of mitochondrial, pump function, and antiapoptotic cell defense genes.

Endothelial dystrophy, iris hypoplasia, congenital cataract, and stromal thinning (edict) syndrome maps to chromosome 15q22.1-q25.3

PURPOSE

To localize a gene causing a newly described autosomal dominant anterior segment dysgenesis characterized by corneal endothelial dystrophy, iris hypoplasia, congenital cataracts, and corneal stromal thinning (EDICT syndrome).

DESIGN

Experimental study.

METHODS

A set of microsatellite markers spanning the 22 human autosomes was used to perform linkage analysis on affected and unaffected individuals within a single family.

RESULTS

Linkage analysis of the anterior segment dysgenesis endothelial dystrophy, iris hypoplasia, congenital cataract, and stromal thinning (EDICT) syndrome in this family revealed a logarithm of the odds (LOD) score of 2.71 on chromosome 15q22.1-25.3 between markers D15993 and D15S202. These results suggest a gene for EDICT syndrome lies in this chromosomal region.

CONCLUSIONS

A LOD score of 2.71 suggests a novel locus associated with the newly described EDICT syndrome lies in a region of chromosome 15 between markers D15S993 and D15S202. Identification of the disease-causing gene in this region may yield insights into a broad range of disorders affecting the corneal stroma, endothelium, iris, and lens.

Identification of paramyosin as a binding protein for calgranulin C in experimental helminthic keratitis

PURPOSE

Calgranulin C (CaGC) is a protein released by activated neutrophils and involved in host defense against filarial infections. This study involved the identification of binding protein(s) of the helminth Brugia malayi to CaGC and the ability of binding complexes to induce keratitis.

METHODS

Parasitic extracts prepared from B. malayi microfilariae and adult worms were incubated with recombinant CaGC protein. Parasite binding protein-CaGC complex was isolated by affinity chromatography. A B. malayi microfilariae cDNA library was immunoscreened with antisera from rats immunized with the isolated parasitic CaGC-binding protein. All positive clones contained paramyosin sequences. Paramyosin was thus considered the major CaGC-binding protein in the parasite. To delineate the binding of CaGC to native and recombinant paramyosin, 125I-CaGC was used as a binding tracer in SDS-PAGE analysis to identify a CaGC-binding complex. To determine whether the complex of CaGC and its binding protein could induce keratitis mimicking the onchocercal human corneal disease, BALB/c mice preimmunized with the binding complex were challenged with intracorneal binding complex or live Brugia microfilariae. In addition, splenocytes harvested from the same animals were assessed for their ability to elicit cellular immune responses to the binding complex by [3H]thymidine assay.

RESULTS

In vitro binding of CaGC to paramyosin was confirmed using recombinant paramyosin and 125I-CaGC. Test animals showed development of severe keratitis that mimicked, clinically and histopathologically, the human onchocercal corneal disease, demonstrating the antigenic specificity of the paramyosin-CaGG-binding complex.

CONCLUSIONS

Paramyosin is identified as a CaGC-binding protein in B. malayi.

Clinical and ultrastructural features of a novel hereditary anterior segment dysgenesis

OBJECTIVE

To describe the clinical, histopathologic, and hereditary features of a novel familial anterior segment dysgenesis.

DESIGN

Prospective, observational case series and interventional case report.

PARTICIPANTS

Ten individuals from three generations of a single family with iris and corneal abnormalities associated with congenital cataracts.

MAIN OUTCOME MEASURES

An ophthalmic evaluation including slit-lamp examination, corneal topography, pachymetry, and specular biomicroscopy of all family members, and histopathologic and ultrastructural evaluation of one excised corneal button.

RESULTS

The proband was an 81-year-old man with bilateral aphakia and diffuse corneal haze, and thinning associated with corneal guttae. His pupils were small, mildly eccentric, and difficult to dilate. Pachymeter readings were 335 microm (right eye) and 330 microm (left eye). Topography confirmed advanced steepening of both corneas. Light microscopic and transmission electron microscopic examinations of the corneal button revealed an attenuated endothelium with prominent intracellular random aggregates of small-diameter filaments staining positively for cytokeratin. Descemet's membrane was thickened and had marked posterior nodularity. Various-sized polymorphic vacuoles containing layered electron-dense material were present within and between collagen lamellae and within keratocytes throughout the stroma and Bowman's membrane. Secondary bullous changes of the epithelium with thickening of the basement membrane were also observed. The family pedigree demonstrated an autosomal dominant inheritance pattern.

CONCLUSIONS

This constellation of autosomal dominantly inherited corneal endothelial and stromal disorder, with congenital cataracts and iris abnormalities, represents a novel anterior segment disorder. Its etiology may involve an abnormal migration of the secondary mesenchyme.

Surgical approaches to the management of epithelial cysts

PURPOSE

The purpose of this study was to review management strategies for treatment of epithelial cysts.

STUDY DESIGN

Retrospective consecutive interventional case series.

METHODS

Charts of patients treated for epithelial ingrowth over a 10-year period by a single surgeon (J.A.H.) were reviewed. Cases of epithelial cysts were identified and the following data were recorded: details of ocular history, preoperative and postoperative visual acuity, intraocular pressure (IOP), ocular examination findings, type of surgical intervention, and details of subsequent procedures performed.

RESULTS

Seven eyes with epithelial cysts were identified. Patients ranged in age from 1 1/2 years to 53 years at presentation. Three patients were children. Four cysts were due to trauma, one was presumably congenital, one developed after corneal perforation in an eye with Terrien's marginal degeneration, and one developed after penetrating keratoplasty. Three patients were treated with vitrectomy, en bloc resection of the cyst and associated tissue, fluid-air exchange, and cryotherapy. Four patients were treated with conservative strategy consisting of cyst aspiration (three cases) or local excision (one "keratin pearl" cyst) and endolaser photocoagulation of the collapsed cyst wall or base. In all cases, the epithelial tissue was successfully eradicated; one case required a second excision (follow-up, 9 months to 78 months; mean, 45 months). Two eyes required subsequent surgery for elevated IOP, two for cataract extraction, and one for a second penetrating keratoplasty. Final visual acuity ranged from 20/20 to hand motions, depending on associated ocular damage. Best visual results were obtained in the more conservatively managed eyes.

CONCLUSION

Epithelial cysts can be managed conservatively in selected patients with good results. This strategy may be particularly useful in children, in whom preservation of the lens, iris, and other structures may facilitate amblyopia management.