Clinical, confocal, and morphological investigations on the cornea in human mucopolysaccharidosis IH-S

Mucopolysaccharidosis

Mucopolysaccharidosis are group of inherited metabolic diseases caused by the absence or malfunctioning of lysosomal enzymes resulting in accumulation of glycosaminoglycans. Over time this accumulation damages cells, tissues, and organs. There are seven types of MPS and 13 subtypes that are associated with multiple organ systems, such as the respiratory, liver, spleen, central nervous systems, arteries, skeletons, eyes, joints, ears, skin, and/or teeth. The various types share some common ocular features that differ in terms of the severity of the affection. Visual loss in MPS patients is varied and can be due to corneal clouding, glaucoma, retinopathy, and optic neuropathy. The primary focus of this review is on changes in the cornea and anterior segment in MPS patients, including clinical and novel investigative modalities, current surgical management, effects of systemic therapy like hematopoietic stem cell transplants (HSCT)and enzyme replacement therapy (ERT), as well as significant research developments.

Ocular Manifestations of Hurler-Scheie Syndrome: Recurrence of Host Disease in the Corneal Transplant

Introduction

Hurler-Scheie syndrome is a type of mucopolysaccharidosis I (MPS). In MPS I the decreased activity of alpha-L-iduronidase lysosomal enzyme leads to glycosaminoglycan (GAG) deposition in the intra- and extracellular matrix. Excessive amounts of GAG can accumulate in most layers of the cornea, including epithelial cells, stromal keratocytes, and endothelial cells.

Case Presentation

A 25-year-old female patient suffering from Hurler-Scheie syndrome with multiple ocular manifestations is reported. Due to significant bilateral corneal opacification, penetrating keratoplasty was performed on both eyes. Histopathologic examination of the corneal buttons showed disorganized collagen fibers with heterogenous thickness and many granule-containing keratocytes with excessive cytoplasm. Despite receiving enzyme replacement therapy, in vivo confocal microscopy revealed characteristic vacuoles in the basal epithelium and corneal stroma 96 months after transplantation. High resolution anterior segment optical coherence tomography demonstrated hyperreflective opacities superficial and deeper in the stroma which was consistent with recurrence of host disease in the graft.

Conclusion

To the best of our knowledge, this is the first documented Hurler-Scheie syndrome case of recurrence after penetrating keratoplasty demonstrated by in vivo confocal microscopy. Additionally, this patient manifested severe ocular involvement of MPS which might be an explanation of the progressive course of corneal opacification after transplantation.

Multimodal ocular imaging of known and novel corneal stromal disorders in dogs

Background

Imaging features obtained with Fourier-domain optical coherence tomography (FD-OCT) and in vivo confocal microscopy (IVCM) for corneal stromal disorders have been sparsely reported in dogs. This case report is a compilation of imaging features for three cases of different stromal disorders of the canine cornea which have not yet been reported elsewhere.

Case presentation

Lipid deposition in case 1 appeared as needle-shaped hyperreflective lines along the collagen lamellae, which correlated histologically with lipid clefts. In case 2, glycosaminoglycan accumulation by mucopolysaccharidosis type 1 caused diffuse stromal hyperreflectivity and depletion of keratocytes on IVCM and was associated with secondary corneal degeneration presumed to be calcium deposition. In case 3, posterior corneal stromal opacities in the absence of ocular inflammation were identified. Hyperreflective particles were scattered in the middle and posterior corneal stroma on FD-OCT. With IVCM, hyperreflective deposits were identified within keratocytes and the number of enlarged keratocytes containing hyperreflective deposits increased towards the posterior stroma. The bilateral, non-inflammatory nature and unique appearance with IVCM is most consistent with a posterior stromal dystrophy reminiscent of pre-Descemet corneal dystrophy described in humans.

Conclusions

In vivo multimodal corneal imaging facilitated instantaneous microstructural analysis and may be valuable in the differential diagnosis of corneal stromal disorders in veterinary clinical practice. The non-specific nature of imaging findings occurs in some conditions such as mucopolysaccharidosis, thus in vivo corneal imaging should be complemented with other gold standard methods of definitive diagnosis.

In Vivo Confocal Microscopy and Anterior Segment Optical Coherence Tomography Findings in Two Cases with Mucopolysaccharidoses

The mucopolysaccharidoses are a group of disorders caused by inherited defects in lysosomal enzymes resulting in widespread intracellular and extracellular accumulation of glycosaminoglycans. Due to the mucopolysaccharidoses subtype, glycosaminoglycans can be deposited in many organs and tissues including cornea. In this report, we presented in vivo confocal microscopy and anterior segment optical coherence tomography findings in a 39-year old man with Scheie syndrome and a 41-year old woman with Morquio syndrome (Heidelberg Retina Tomograph 3 Rostock module, Germany) and reviewed the literature. On in vivo confocal microscopy, there were multiple small and larger hyperreflective deposits in the epithelium, Bowman layer and anterior stroma and abnormally shaped, elongated keratocytes with hyporeflective round structures, which might be vacuoles in the anterior-mid stroma. In anterior segment optical coherence tomography images, accumulation of glycosaminoglycans deposits lead to an increased hypereflective appearance throughout the thickened cornea.

Multimodal imaging of Hurler syndrome-related keratopathy treated with deep anterior lamellar keratoplasty

Background

Hurler syndrome-associated keratopathy is an exceedingly rare corneal disorder that requires corneal transplantation in advanced stages. Precise assessment of the corneal condition is necessary for deciding which type of keratoplasty (i.e., deep anterior lamellar or penetrating) should be proposed. We aimed to confront the results of multimodal imaging with those of histology in a case of Hurler syndrome-associated keratopathy.

Case presentation

A 16-year-old patient with Hurler’s syndrome treated with hematopoietic stem cell transplantation was referred for decreased vision related to advanced keratopathy. The patient was treated with deep anterior lamellar keratoplasty (DALK) in both eyes with uncomplicated outcome. Visual acuity improved from 0.1 (20/200) preoperatively to 0.32 (20/63) and 0.63 (20/32) after transplantation. The corneal endothelial cell density was 2400 cells/mm² in both eyes 3 years after transplantation. In vivo confocal microscopy (IVCM) and spectral domain optical coherence tomography (SD-OCT) were performed preoperatively. The corneal buttons retrieved during keratoplasty were processed for histology. In SD-OCT scans, corneal opacities appeared as diffuse stromal hyperreflectivity associated with increased corneal thickness. IVCM showed diffuse cytoplasmic granular hyperreflectivity and rounded/ellipsoid aspects of keratocytes, presence of small intracellular vacuoles, and hyperreflective epithelial intercellular spaces. Bowman’s layer was thin and irregular. The corneal endothelium was poorly visualized but no endothelial damage was observed. Histology showed irregular orientation and organization of stromal lamellae, with the presence of macrophages whose cytoplasm appeared clear and granular. A perinuclear clear halo was visible within the epithelial basal cells. Bowman’s layer featured breaks and irregularities.

Conclusions

The observed corneal multimodal imaging features in mucopolysaccharidosis-related keratopathy were concordant with histology. Compared with standard histology, multimodal imaging allowed additional keratocyte features to be observed. It revealed both morphological and structural changes of all corneal layers but the endothelium. This information is essential for therapeutic management which should include DALK as the first-choice treatment in case of impaired visual acuity.

Anterior segment optical coherence tomography and in vivo confocal microscopy in cases of mucopolysaccharidosis

Purpose

To report anterior segment evaluation in patients with mucopolysaccharidosis 1 using anterior segment optical coherence tomography and in vivo confocal microscopy.

Observations

Case 1 involved a 26-year-old man with mucopolysaccharidosis 1 Hurler-Scheie syndrome who presented with a corrected distance visual acuity of 20/67 in the right eye and 20/50 in the left eye because of bilateral corneal opacification. He had undergone bone marrow transplantation at the age of 7 years. Anterior segment optical coherence tomography revealed a very narrow anterior chamber angle; a flat, thickened cornea; and astigmatism with the rule. Confocal microscopy demonstrated hyper-refractive deposits in the corneal epithelial basal layer, decreased subepithelial nerves, and depletion of keratocytes in the anterior and posterior stroma. Endothelial cells were not visible.Case 2 involved an 18-year-old woman who presented with increased corneal opacity in both eyes. Her medical history included mucopolysaccharidosis 1 Hurler syndrome and bone marrow transplantation at the age of 2 years. Her corrected distance visual acuity could not be measured because of severe intellectual disability. Anterior segment optical coherence tomography demonstrated a flat and thick cornea.

Conclusions and importance

Anterior segment optical coherence tomography can provide detailed morphological information for the anterior segment in patients with severe corneal opacification associated with mucopolysaccharidosis 1. Moreover, in vivo confocal microscopy facilitates the detailed observation of corneal cellular changes. Thus, these tools can provide data that would contribute to an increased understanding of corneal changes in patients with mucopolysaccharidosis 1.

Avoiding big bubble complications: outcomes of layer-by-layer deep anterior lamellar keratoplasty in children

BACKGROUND/AIMS

To describe the visual and clinical outcomes of manual layer-by-layer deep anterior lamellar keratoplasty (DALK) in a paediatric population.

METHODS

The charts of all children who underwent DALK surgery between January 2007 and January 2015 were reviewed retrospectively. Data collected included preoperative and postoperative spectacle-corrected distance visual acuity (CDVA), intraoperative and postoperative complications including graft rejection and failure. Residual posterior lamellar thickness (RPLT) and endothelial cell density (ECD) were measured in eyes with follow-up longer than 6 months.

RESULTS

Fifty-one eyes of 42 patients were included in the study. The mean patient age at surgery was 11.2±5.2 years and the mean follow-up time was 36.5±23.7 months. The most common indications for surgery were mucopolysaccharidosis (29.4%) and keratoconus (23.5%). Nine eyes (17.6%) had intraoperative microperforation, none of which were converted to penetrating keratoplasty (PKP). Only one eye (2.0%) was converted to PKP. Five eyes (9.8%) had a stromal rejection episode of which one eye failed. Another four eyes (7.8%) experienced graft failure among which three eyes (75%) had infectious keratitis. Three of the five failed grafts had a successful repeat DALK. The average RPLT was 81.9±36.5μm. ECD was significantly lower in the operated eye compared with the normal eye (3096±333 cells/mm² vs 3376±342 cells/mm², n=11, P=0.003). The mean postoperative CDVA was 0.5±0.4 logarithm of the minimum angle of resolution (logMAR) reflecting a gain of 0.3 logMAR (P<0.001).

CONCLUSION

Manual dissection DALK is a safe procedure in children with stromal opacities. Despite successful structural rehabilitation, functional recovery is still suboptimal mostly due to amblyopia.

Structural, ultrastructural, and morphometric study of the zebrafish ocular surface: a model for human corneal diseases?

PURPOSE

A morphological and morphometric study of the adult zebrafish ocular surface was performed to provide a comprehensive description of its parts and to evaluate its similarity to the human.

MATERIALS AND METHODS

The eyes of adult zebrafish were processed for light, transmission and scanning electron microscopy, and for immunohistochemical stain of corneal nerves; a morphometric analysis was also performed on several morphological parameters.

RESULTS

The corneal epithelium was formed by five layers of cells. No Bowman's layer could be demonstrated. The stroma consisted of lamellae of different thickness with few keratocytes. The Descemet's membrane was absent as the flat and polygonal endothelial cells directly adhered to the deepest corneal lamella. The immunohistochemical stain of neurofilaments failed to demonstrate corneal nerve fibers. The conjunctival epithelium was stratified, overlying the stroma formed by a subepithelial and a deep layer, this latter connected to the scleral cartilage. In the peripheral cornea and in the conjunctiva, many goblet and rodlet cells were observed. The morphometric analysis showed that the peripheral cornea epithelium was thicker when compared to the other parts of the ocular surface, with smaller superficial cells. Desmosomes and hemidesmosomes in the conjunctiva were significantly fewer in number than the other parts of the ocular surface. The stroma was thinner in the conjunctiva than in the cornea, while corneal lamellae were thicker in the intermediate stroma.

CONCLUSIONS

The zebrafish ocular surface showed significant differences compared to the human, such as the absence of Bowman's layer, Descemet's membrane and corneal nerve fibers, the reduced stromal thickness, and the presence of rodlet cells. On the basis of these original findings, it is suggested that the use of the zebrafish as a model for studying normal or pathological human corneas should be undertaken with particular caution.

Use of new imaging in detecting and monitoring ocular manifestations of the mucopolysaccharidoses

The aim of this review is to summate the eye involvement in patients with mucopolysaccharidoses (MPS) using current ocular imaging techniques, their advantages and disadvantages and how they may aid diagnosis, management and monitoring. We critically reviewed the current literature surrounding MPS and recent imaging technology as well as histology. Primary searches of PubMed and Web of Science were performed. We reviewed all papers on the topic published and summarized the findings of each medical device as well as the advantages and disadvantages of using these for the MPS patient. We discussed the potential of each of these devices to monitor potential ocular pathology in the MPS cohorts in the order of MPS subtype. We reviewed imaging techniques involving use of the Iris Camera, Pentacam, Optical Coherence Tomography (OCT) as well as ultrasound and Heidelberg OCT. The need for reliable objective quantification of eye findings in MPS has led to utilization of new imaging technologies described here, and future use will enhance our understanding of the unique eye features in MPS. In particular, we note that the Pentacam and iris camera are able to provide objective measurements of corneal haze and monitor ocular response to treatment.

Ocular manifestations and management recommendations of lysosomal storage disorders I: mucopolysaccharidoses

The mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by inborn errors of glycosaminoglycan (GAG) metabolism. These diseases are classified by enzyme deficiency into seven groups: type I, II, III, IV, VI, VII, and IX. GAG accumulation leads to characteristic clinical features. Some ophthalmic findings that are characteristic of MPS diseases include corneal clouding, retinal degeneration, decreased electroretinogram wave amplitude, optic atrophy, papilledema, and glaucoma. Current treatments such as hematopoietic stem cell transplantation and enzyme replacement therapy have increased the life span of many MPS patients and created the need to improve management of ocular symptoms. This article aims to provide a comprehensive review of ocular manifestations and treatment options for the various types of MPS.

Macular corneal dystrophy: in vivo confocal and structural data

OBJECTIVE

To demonstrate the corneal morphologic aspects obtained with in vivo confocal microscopy (CM) and light and electron microscopy of specimens obtained from the same patients with macular corneal dystrophy (MCD).

DESIGN

Case series.

PARTICIPANTS

Five consecutive patients affected by MCD undergoing penetrating keratoplasty (PK) in 1 eye.

METHODS

The patients were examined with the slit-lamp, optical pachymetry, and CM before undergoing PK. The corneal buttons were processed for light, transmission, and scanning electron microscopy.

MAIN OUTCOME MEASURES

Corneal in vivo CM, corneal light, and electron microscopy.

RESULTS

Confocal microscopy showed areas of altered reflectivity in basal epithelial cells, which appeared hyperreflective or completely white. In the anterior stroma, rectilinear hyperreflective areas were shown. The stroma was characterized by a granular appearance of both keratocytes and extracellular matrix. Dark striae of different length and orientation were present in the middle and posterior stroma. The corneal endothelium showed polymegethism and cells containing bright granules in their cytoplasm. The histopathologic study demonstrated areas of thickened Bowman's layer covered by an epithelium reduced in height. The Bowman's layer thickenings were due to the accumulation of free or vesiculated material of different electron density. The keratocytes showed intracytoplasmatic vesicles, whereas the extracellular matrix presented a large quantity of intercellular electron-lucent material and parallel lamellae with an undulated course. Occasional macrophages, filled with vesicles of granular-filamentous material and evident podosomes, were observed. Descemet's membrane was formed by a normal anterior banded zone and a posterior nonbanded zone of honeycombed aspect. The endothelial cells showed a large number of intracytoplasmic vesicles.

CONCLUSIONS

The structural changes observed with the histopathologic methods give an account and provide an explanation for the pathologic changes demonstrated by CM in the course of MCD. This may contribute to the understanding of in vivo imaging, allowing a better, noninvasive study of the disease evolution.