In vivo confocal microscopy of pre-Descemet's membrane corneal dystrophy

Microdot Accumulation in the Anterior Cornea with Aging - Quantitative Analysis with in Vivo Confocal Microscopy

PURPOSE

Degenerative 'microdot' deposits in healthy and hypoxic corneas are believed to represent lipofuscin-like material aggregation in the stroma. To accurately assess microdot deposits in a clinical setting, we sought to quantify these deposits for the first time using the non-invasive clinical imaging technique of in vivo confocal microscopy (IVCM).

METHODS

The corneas of 102 healthy subjects aged 15-88 years were examined by IVCM and microdot density was quantified using a 6-point grading scale by two masked, trained examiners. Microdot density was analyzed with respect to age, sex and stromal depth, and inter-eye and inter-observer differences were evaluated.

RESULTS

In healthy subjects, microdot density decreased from the anterior to posterior stroma, with the greatest accumulation observed in the most anterior stroma (subepithelial region). In this region, microdot density correlated strongly with age (P < .0001), with increased microdot deposition in older subjects (>60 years) relative to younger ones (<45 years) (P < .001). Microdot density between eyes of the same subject was highly correlated (r = 0.92, P < .0001), while no association with sex was noted (P ≥ 0.05). The mean inter-observer difference in microdot assessment was 0.62 ± 0.09 grades, with a high correlation of grading between observers (r = 0.77, P < .0001).

CONCLUSIONS

IVCM can be used to non-invasively quantify microdot deposits in the subepithelial corneal stroma with good inter-observer reproducibility. Microdot assessment may provide a novel means of quantifying age-related or pathologic degeneration of the corneal stroma in a clinical setting.

Multimodal imaging of pre-Descemet corneal dystrophy

PURPOSE

The aim of this study was to assess structural and histological changes associated with pre-Descemet corneal dystrophy with multimodal in vivo imaging.

METHODS

Retrospective case series including eight corneas from four unrelated male patients with pre-Descemet corneal dystrophy characterized by the presence of punctiform gray opacities located just anterior to the Descemet membrane at slit-lamp examination of both eyes. In vivo confocal microscopy images were obtained in the central, paracentral, and peripheral corneal zones from the superficial epithelial cell layer down to the corneal endothelium in both eyes. Spectral domain optical coherence tomography scans (central and limbal zones) and mapping of both corneas were acquired.

RESULTS

Diffuse small extracellular stromal deposits, presence of enlarged hyperreflective keratocytes in the posterior stroma with either hyperreflective or hyporeflective intracellular dots, and presence of activated keratocytes in the very anterior stroma were observed in all corneas with in vivo confocal microscopy. Spectral domain optical coherence tomography scans showed a hyperreflective line anterior to Descemet's membrane running from limbus to limbus and associated with a second thinner hyperreflective line just beneath Bowman's layer. Fine hyperreflective particles were observed in the posterior, mid, and anterior stroma on optical coherence tomography scans.

CONCLUSION

The clinical presentation and structural anomalies found in isolated sporadic pre-Descemet corneal dystrophy are in favor of a degenerative process affecting corneal keratocytes with no epithelial or endothelial involvement. The maximum damage is found just anterior to the Descemet membrane resulting in pre-Descemet membrane location of stromal opacities. Multimodal imaging of cornea reveals that the disorder affects the whole stroma and it permits better understanding of pre-Descemet corneal dystrophy pathophysiology together with ascertained diagnosis.

Confocal biomicroscopy in four patients with polychromatic corneal dystrophy

INTRODUCTION

Polychromatic corneal dystrophy is an unusual pre-descemet dystrophy, about which there are very few publications. The findings are presented in a case series of four patients with polychromatic corneal dystrophy, using a slit lamp, specular biomicroscopy, and confocal microcospy.

CLINICAL CASES

Four women, between 36 and 72 year-old, with the diagnosis of polychromatic corneal dystrophy in routine reviews. None reported visual symptoms or ocular history of interest. Anterior biomicroscopy showed multiple and small multicoloured brilliant opacities in the posterior area of the corneal stroma, with normal epithelium and anterior stroma. The opacities were bilateral and distributed throughout the entire cornea. Direct family members were examined, but none of them showed opacities. In the specular biomicroscopy, a normal endothelium, with pre-descemet hypereflective particles, was observed. With confocal microscopy, there were no abnormalities in epithelium, Bowman layer, or sub-basal nervous plexus. In two cases, the anterior stroma showed hyper-reflective keratocytes and with small hypereflective particles among them. In the middle stroma, hyper-reflective keratocytes were seen in the four cases, two of them showed tiny hypereflective particles, and in the other two there were abnormal keratocytes with prominent cytoplasmic processes. Posterior stroma in the four cases showed a lot of hypereflective keratocytes and hypereflective particles of different sizes. These particles prevented examining the endothelium.

CONCLUSIONS

Polychromatic corneal dystrophy has typical signs that allow it to be diagnosed and characterised. Although the biomicroscopy image only seems to show alterations in the posterior stroma, confocal microscopy shows that the dystrophy affects the entire corneal stroma.

Heredity and in vivo confocal microscopy of punctiform and polychromatic pre-Descemet dystrophy

PURPOSE

To describe and analyze the biomicroscopic features and in vivo confocal microscopy of the crystalline form of pre-Descemet corneal dystrophy (PDCD).

METHODS

We examined two non-related families using biomicroscopy, in vivo confocal microscopy, and a genetic study using a gene panel test, looking for mutations in the PIKFYVE gene.

RESULTS

A slit-lamp examination of the first family revealed polychromatic crystalline punctiform opacities distributed all over the stroma in 8 of 11 family members in three generations with an autosomal dominant inheritance. The second family showed in three of four members in two generations the same opacities located in the pre-Descemet region. It was also a hint for autosomal dominant inheritance. The in vivo confocal microscopy identified numerous rounded and hyperreflective stromal particles measuring 10-15 μm in diameter, with the highest density in the posterior stroma and with normal keratocytes. No systemic disease was diagnosed. No variants or mutations were identified in PIKFYVE gene.

CONCLUSIONS

Polychromatic deposits in patients with Punctiform and Polychromatic Pre-Descemet corneal dystrophy can be located not only in the deep stroma but also in the anterior and middle stroma. Our presentation reveals the possibility of considering this characteristic corneal disorder as a corneal dystrophy of its own and not as a subtype of pre-Descemet corneal dystrophy.

Characteristics of Pre-Descemet Membrane Corneal Dystrophy by Three Different Imaging Modalities-In Vivo Confocal Microscopy, Anterior Segment Optical Coherence Tomography, and Scheimpflug Corneal Densitometry Analysis

PURPOSE

To evaluate the characteristics of pre-Descemet membrane corneal dystrophy by 3 different imaging modalities: in vivo confocal microscopy (IVCM), anterior segment optical coherence tomography (ASOCT), and Scheimpflug corneal densitometry analysis.

METHODS

A 32-year-old male patient with pre-Descemet membrane corneal dystrophy was subjected to imaging by IVCM, ASOCT, and Scheimpflug tomography.

RESULTS

Slit-lamp biomicroscopy showed the presence of tiny pleomorphic opacities in the posterior stroma, immediately anterior to Descemet membrane bilaterally. On IVCM, pleomorphic, hyperreflective punctate particles were seen both intracellularly and extracellularly in the anterior and mid stroma with increased reflectivity of some keratocytes that, however, were of normal size. These changes increased in severity from the anterior to mid stroma. The posterior stroma had grossly enlarged hyperreflective keratocytes with prominent processes. The hyperreflective particles were also seen scattered on the endothelium. ASOCT revealed a well-delineated homogenous band of increased reflectivity of approximately 70 μm width in the posterior stroma of both eyes with a normal-appearing anterior and mid stroma. Corneal densitometry measured by Scheimpflug optical analysis revealed a higher amount of backscattered light from the posterior stroma with a posterior to anterior ratio of 0.8.

CONCLUSIONS

In pre-Descemet membrane corneal dystrophy, although the structural changes seem to be limited to the posterior stroma as seen clinically and on ASOCT, IVCM demonstrates that the pathology is more extensive involving the entire corneal stroma and endothelium.

In vivo confocal microscopic corneal images in health and disease with an emphasis on extracting features and visual signatures for corneal diseases: a review study

There is an evolution in the demands of modern ophthalmology from descriptive findings to assessment of cellular-level changes by using in vivo confocal microscopy. Confocal microscopy, by producing greyscale images, enables a microstructural insight into the in vivo cornea in both health and disease, including epithelial changes, stromal degenerative or dystrophic diseases, endothelial pathologies and corneal deposits and infections. Ophthalmologists use acquired confocal corneal images to identify health and disease states and then to diagnose which type of disease is affecting the cornea. This paper presents the main features of the healthy confocal corneal layers and reviews the most common corneal diseases. It identifies the visual signatures of each disease in the affected layer and extracts the main features of this disease in terms of intensity, certain regular shapes with both their size and diffusion, and some specific region of interest. These features will lead towards the development of a complete automatic corneal diagnostic system that predicts abnormalities in the confocal corneal data sets.

Corneal confocal microscopy findings in sporadic cases of pre-descemet corneal dystrophy

PURPOSE

To present corneal confocal microscopy (CCM) findings in a series of patients with pre-Descemet corneal dystrophy (PDCD).

METHODS

A 28-year-old man, a 50-year-old man, a 30-year-old woman, and a 31-year-old man were clinically diagnosed with PDCD on slit lamp microscopic evaluation. All patients were evaluated by means of CCM. The parents of the patients were clinically evaluated. Two of the patients underwent photorefractive keratectomy.

RESULTS

In all the patients, CCM revealed highly reflective stromal particles and pleomorphic structures that included particles in the deep stroma, immediately anterior to the Descemet membrane extending up to 60 μm from endothelium. No evidence of PDCD was observed clinically in the parents of the patients. Postoperative course of photorefractive keratectomy was uneventful for both of the patients.

CONCLUSIONS

With the use of CCM, a specific pattern of findings seemed to be related with PDCD in this series of sporadic cases.

A Case of Bilateral Descemet's Membrane and Subepithelial Opacity: In vivo Laser Confocal Microscopic Study

Purpose

To report the in vivo laser confocal microscopy findings from a patient with Descemet's membrane and subepithelial opacity OU.

Case Report

A healthy 41-year-old male with Descemet's membrane and subepithelial opacity OU was studied. Routine ophthalmic examination, standard slit-lamp biomicroscopy, and in vivo laser confocal microscopic analysis of the entire corneal layer were performed. Slit-lamp biomicroscopy revealed subepithelial opacity in the mid-peripheral to peripheral cornea and numerous opacities located at the level of Descemet's membrane. It was difficult to distinguish the precise histological location of the opacity. In vivo laser confocal microscopy showed numerous hyperreflective particles in the subepithelium to superficial stroma and hyperreflectivity of Descemet's membrane. No abnormalities could be detected in the epithelial cell layer, midstromal layer, deep stromal layer, or endothelial cell layer.

Conclusion

Although the origin of the corneal opacities was unclear, in vivo laser confocal microscopy was useful for observing microstructural abnormalities in a case of Descemet's membrane and subepithelial opacity.

Confocal microscopy of corneal dystrophies

In vivo confocal microscopy (IVCM) of the cornea is becoming an indispensable tool in the cellular study of corneal physiology and disease. This technique offers non-invasive imaging of the living cornea with images comparable to that of ex vivo histology. The ability to provide high-resolution images of all layers in the living cornea has resulted in new discoveries of corneal pathology at the cellular level. The IVCM analysis of corneal dystrophies is of importance to clinicians, as current methods of diagnosis involve slit-lamp characteristics, genetic analysis, and invasive biopsy. IVCM is helpful in evaluating the morphological characteristics of corneal dystrophies at the histological level and may be helpful in diagnosis, determination of progression, and understanding the pathophysiology of disease. The purpose of this review is to describe the principles, applications, and clinical correlation of IVCM in the study of corneal dystrophies.

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.