Limbale Stammzellinsuffizienz nach Verätzung

Cell therapy in the cornea: The emerging role of microenvironment

The cornea is an ideal testing field for cell therapies. Its highly ordered structure, where specific cell populations are sequestered in different layers, together with its accessibility, has allowed the development of the first stem cell-based therapy approved by the European Medicine Agency. Today, different techniques have been proposed for autologous and allogeneic limbal and non-limbal cell transplantation. Cell replacement has also been attempted in cases of endothelial cell decompensation as it occurs in Fuchs dystrophy: injection of cultivated allogeneic endothelial cells is now in advanced phases of clinical development. Recently, stromal substitutes have been developed with excellent integration capability and transparency. Finally, cell-derived products, such as exosomes obtained from different sources, have been investigated for the treatment of severe corneal diseases with encouraging results. Optimization of the success rate of cell therapies obviously requires high-quality cultured cells/products, but the role of the surrounding microenvironment is equally important to allow engraftment of transplanted cells, to preserve their functions and, ultimately, lead to restoration of tissue integrity and transparency of the cornea.

First Evaluation of a Retinal Imaging Laser Eyewear System Based Low Vision Aid

Purpose

We conducted this trial to investigate a new wearable laser-eyewear (LEW). Images of an integrated camera are projected to the retina by a RGB-Laser (<1µW) and MEMS-mirror system. This enables a full-color live video as augmented reality embedded in the field of vision of the wearer. Thin parallel laser beams are projected following the principle of Maxwellian view through the center of the ocular lens to ensure independency of refractive errors. We performed a study with healthy subjects to test this independency.

Materials and Methods

LEW was tested in 20 healthy subjects (aged between 21 and 60 years) with hyperopia, myopia, astigmatism and/or presbyopia. Subjects underwent standardized visual acuity (VA) measurements (ETDRS) without any correction, with LEW and with best correction.

Results

We found no significant correlation between refraction and VA while using LEW in linear regression (r=0.17). Still, younger participants performed better in terms of VA with the device compared to older participants despite no differences in BCVA (p<0.01). The achievable VA with LEW was in general reduced compared to uncorrected VA (0.50 vs 0.40 logMAR). Only myopic subjects reached a significantly higher VA using LEW (p<0.001). Presbyopic subjects showed enhanced near VA (0.25 logMAR) by reading at 15cm with LEW without any further necessary refractive correction. Nearly all patients (80%) showed stereopsis without need for additional adjustments.

Conclusion

Our investigation could verify the independence of LEW of refractive errors. Therefore, the technology seems to be especially useful in patients with untreatable corneal conditions, e.g., after corneal burns, to achieve higher VA since the thin laser should penetrate even corneal opacities with less scattering.

Visual rehabilitation of patients with corneal diseases

BACKGROUND

Although most patients with visual impairment due to corneal diseases can be treated successfully with surgery, some require visual rehabilitation to restore reading ability. To evaluate the best LVAs especially in terms of reading speed and characterize this specific patient group we performed a prospective, randomized cross-over trial.

METHODS

All 34 patients underwent a detailed examination (slit-lamp, funduscopy, SD-OCT, ETDRS) as screening. Only patients with corneal diseases without other ocular diseases were included. Reading-speed was assessed with International-Reading-Speed-Texts (IReST) consecutively with five different LVAs (low vision aids) during one day in a randomized cross-over design. Corneal haze was quantified with corneal densitometry (Pentacam).

RESULTS

Patients were either visually impaired (n = 28), severely impaired (n = 4) or legally blind (n = 2). Patients read significantly faster with LVAs (p < 0.0001). Fastest reading speed could be achieved with video magnifier (CCTV). Optical magnifier and portable-electronic magnifier enabled significantly lower reading speeds (p < 0.01). In a subgroup of patients (VA < 3/60,n = 6) black background enabled patients to read significantly faster compared to white background (p = 0.03).

CONCLUSION

Patients with low magnification requirement can be treated successfully with optical LVAs and portable-electronic magnifiers. More severely afflicted patients need a CCTV. Black background enables fastest reading-speeds, probably due to less blinding. Visual impairment can be estimated with corneal densitometry. Our trial confirms the capability of LVAs to successfully restore the reading ability in patients with corneal diseases, which is a crucial part of visual rehabilitation.

TRIAL REGISTRATION

This trial was registered at the German Clinical Trials Register as DRKS00010887 at 09.08.2016.

[Autologous transplantation of cultivated limbal epithelium]

OBJECTIVE

In this study the clinical outcome of ex vivo expansion of autologous limbal epithelial cells on intact amniotic membranes (AM) for ocular surface reconstruction in limbal stem cell deficiency (LSCD) was investigated.

PATIENTS AND METHODS

A total of 30 eyes in 28 patients (22 male and 6 female) with total (n=18) or partial (n=12) LSCD were treated by transplantation of autologous limbal epithelial cells after expansion on intact AM. The causes of LSCD in the patients were chemical and thermal burns (n=16), pterygium (n=9), tumor excision (n=2), perforating injury, mitomycin C-induced LSCD and epidermolysis bullosa (each n=1). Only eyes with a follow-up time of at least 9 months were included in the analysis. The main outcome criteria were restoration of ocular surface integrity and improvement of visual acuity (VA).

RESULTS

The mean follow-up time was 28.9±15.5 months. An entirely stable corneal surface was reconstructed in 23 (76.7%) eyes. Visual acuity increased significantly in 21 (70%) eyes, was stable in 8 (26.7%) eyes and decreased in 1 (3.3%) eye. The mean visual acuity increased significantly (p<0.0001) from a preoperative value of 1.58±0.97 LogMAR to 0.6±0.49 LogMAR.

CONCLUSION

Transplantation of limbal epithelium cultivated on intact AM restores a stable corneal surface and results in a significant increase in visual acuity in most cases of LSCD. Autologous transplantation of cultivated limbal epithelium showed an excellent prognosis and outcome after long-term follow-up.