[Contribution of confocal microscopy and anterior chamber OCT to the study of corneal endothelial pathologies]

[The irido-corneo-endothelial syndrome. The loss of the control of corneal endothelial cell cycle. A review]

The three major symptoms of the irido-corneo-endothelial syndrome are the alterations of the corneal endothelium and of the iris with a loss of the regulation of the cell cycle, and the progressive obstruction of the irido-corneal angle. This rare pathology attacks mainly young adult women. Most of the symptoms and complications originate from the excessive proliferation of the corneal endothelial cells accompanied by the evolution of their phenotype towards that of the epithelial cells. In normal conditions the corneal endothelial cells do not divide, they are blocked in the G1 stage of the cell cycle, mainly because of the action of the inhibitors of cyclin-dependent kinases. Still these cells retain a good capacity for proliferation, which can be induced by the down-regulation of the expression of the inhibitors of the cyclin-dependent kinases. This proliferative capacity declines with age and is also different according to the localization of the cells: it is more intense with those originating from the central area then in those from the peripheral area of the cornea. The age-related decline of the proliferative capacity is not due to the shortening of the telomers, but to the stress-induced accelerated senescence of the cells.

[Role of in vivo confocal microscopy in irido-corneo-endothelial syndromes]

INTRODUCTION

In vivo confocal microscopy (IVCM) is an increasingly utilized tool in studying complex corneal and anterior segment pathologies. We illustrate the role of this imaging technique in the irido-corneo-endothelial (ICE) syndromes through a case report.

CASE REPORT

A 47-year-old woman presented unilateral decreased vision associated with ocular hypertension and peripheral anterior synechiae. Slit lamp examination of the cornea was unremarkable but IVCM showed pleomorphism and polymegathism of the corneal endothelium and highly reflective nuclei resulting in an epithelial-like cell morphology. This appearance led to the diagnosis of ICE syndrome.

DISCUSSION

Confocal microscopic findings in ICE syndromes are similar to histopathologic findings. This technique may be for a useful diagnostic adjunct in ICE syndromes by revealing specific characteristics, particularly in difficult diagnostic situations, such as when corneal edema impedes specular microscopy or when the iris fails to demonstrate pathognomonic anomalies.

Optical coherence tomography anatomy of the corneal endothelial transplantation wound

PURPOSE

The goal of this study was to prospectively assess the deep lamellar endothelial keratoplasty (DLEK) wound anatomy and its evolution during the 12 months after surgery, using optical coherence tomography (OCT).

METHODS

The eyes of 8 patients (1 eye per patient) who consecutively underwent DLEK for Fuchs dystrophy or pseudophakic bullous keratopathy were prospectively studied before and 1, 3, 6, and 12 months after surgery. The Stratus OCT apparatus (Carl Zeiss Meditec, Dublin, CA) was used to acquire central and radial scans perpendicular to the wound at 3-, 6-, 9-, and 12-o'clock positions. The following parameters were analyzed: central total thickness, posterior donor-recipient edges gap, donor-recipient height mismatch, tissue compression, and graft detachment.

RESULTS

A posterior gap was observed in 4 of the 8 DLEK eyes. At 12 months, the mean gap contour, depth, and width were 242 +/- 67, 101 +/- 45, and 87 +/- 29 microm, respectively. A step was documented in all DLEK eyes (average step height 108 +/- 24 microm). A micrograft detachment was observed in one case and tissue compression in another. In all corneas, the mean central corneal thickness returned to normal range and almost normal anatomy with time after surgery.

CONCLUSIONS

OCT was found to be a very useful tool for DLEK corneal wound architecture analysis. It revealed microscopic wound irregularities and allowed their quantitative follow-up with time.

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.

[Schnyder's crystalline-like corneal dystrophy: a case report]

Schnyder's crystalline corneal dystrophy is a rare bilateral hereditary disease with various clinical features. It typically presents as a central disc-like opacification with or without crystalline deposits. We report the case of a particular crystalline-free and ring-like pattern dystrophy resembling Schnyder's corneal dystrophy in an 82-year-old woman. In addition, we describe the aspects of this dystrophy with in vivo confocal microscopy using the Heidelberg Retina Tomograph II-Rostock Cornea Module and with anterior segment optical coherence tomography (OCT-Visante((R))). These techniques can be useful in the diagnosis or the therapeutic process, showing crystalline structures that are not clinically distinguishable or validating the histological localization of the corneal disease.

Use of ultra-high-resolution optical coherence tomography to detect in vivo characteristics of Descemet's membrane in Fuchs' dystrophy

PURPOSE

To demonstrate the capability of ultra-high-resolution (UHR) anterior segment optical coherence tomography (OCT) to image Descemet's membrane (DM) and measure its thickness in vivo. (2) To evaluate the use of DM characteristics and thickness in the diagnosis of Fuchs' dystrophy.

DESIGN

Case-control study.

PARTICIPANTS

Twenty eyes of 12 Fuchs' dystrophy patients, 20 eyes of 13 young normal, and 20 eyes of 15 elderly normal subjects.

METHODS

Subjects were imaged using novel, custom-built UHR-OCT. Images were used to describe the characteristics of DM. Custom-made software was used to measure DM thickness and central corneal thickness (CCT). Specimens of DM obtained from Fuchs' dystrophy patients who underwent endothelial keratoplasty (EK) were histopathologically examined. Regression analyses were used to assess the correlation of DM thickness measured by UHR-OCT in vivo and by light microscopy and to determine the intergroup correlations between age, CCT, and DM thickness.

MAIN OUTCOME MEASURES

We assessed DM characteristics and thickness, CCT, and age.

RESULTS

Using UHR-OCT, the DM seemed in normal young subjects as a single, opaque, smooth line and in normal elderly subjects as a band of 2 smooth opaque lines with a translucent space in between. In Fuchs' dystrophy, DM appeared as a thickened band of 2 opaque lines; the anterior line was smooth whereas the posterior line had a wavy and irregular appearance with areas of localized thickenings. The DM thickness measured in vivo by UHR-OCT correlated significantly with that measured by light microscopy in 5 Fuchs' dystrophy eyes that underwent EK. The average central thicknesses of DM in normal young, in normal elderly and in Fuchs' dystrophy eyes were 10+/-3, 16+/-2, and 34+/-11 microm, respectively (P<0.001). There was a significant correlation between age and DM thickness only in normal groups. In Fuchs' dystrophy patients, there was a significant correlation between CCT and DM thickness that was not significant for normal groups.

CONCLUSIONS

Ultra-high-resolution OCT is an innovative technique for the in vivo imaging of DM. Determining DM characteristics and thickness by UHR-OCT could be a new approach for the diagnosis of Fuchs' dystrophy.