Keratoplastik: Lamellieren oder perforieren?: Teil 2: Lamelläre Keratoplastik

Gene Therapy for Modulation of T-Cell-Mediated Immune Response Provoked by Corneal Transplantation

Corneal transplantation (keratoplasty) is the most common type of tissue replacement in the world. The increased rate of graft rejection after keratoplasty is a central problem for repeated transplantations and in inflamed host corneas. It has been shown that apoptosis of grafted epithelium has a role in corneal allograft rejection. This study focused on the T-cell response triggered in BALB/c mice after allogeneic corneal transplantation with and without anti-apoptotic p35-transduced epithelium. To restrict p35 expression to the epithelial cells, modified allogeneic composite grafts were created. As a result, it was found that the proportion of alloreactive CD4⁺ T cells in postoperatively removed cervical lymph nodes was reduced in the p35-transduced group compared to the allogeneic control group. Diminished priming of the CD4⁺ T cells was supported by significantly decreased proliferation and lower interferon gamma secretion when compared to allogeneic engraftments. The reduced priming of CD4⁺ lymphocytes is the first confirmation of the functionality of p35 in the epithelium of corneal grafts to alter the development of the recipient's immune response. Thus, modification of allosensibilization seems to be a promising tool for reducing graft-mediated immune response following corneal transplantation.

Changes in Corneal Densitometry in Patients with Fuchs Endothelial Dystrophy after Endothelial Keratoplasty

PURPOSE

The aim of the study was to quantify corneal densitometry in patients with Fuchs endothelial dystrophy (FED) after endothelial keratoplasty.

MATERIALS AND METHODS

We retrospectively reviewed the charts and anterior segment data of patients with FED before and after endothelial keratoplasty. Patients were examined using the Scheimpflug-based Oculus Pentacam corneal densitometry module. Densitometry parameters in different corneal layers and in different annuli were extracted and analyzed.

RESULTS

27 eyes of 27 patients after endothelial keratoplasty (11 DSAEK, 16 DMEK) were included. After endothelial keratoplasty the total corneal light backscatter at total corneal thickness in the central cornea (0-2 mm annulus) was significantly lower than before (DSAEK: p = 0.026, DMEK: p = 0.001). In the entire group the total corneal light backscatter at total corneal thickness and at total diameter before surgery correlated with the postoperative values (Pearson correlation = 0.49, p = 0.01). The strongest correlation was found in the central layer in the DMEK group (Pearson correlation = 0.79, p < 0.001).

CONCLUSIONS

Corneal densitometry is a useful, objective method for quantification of the outcome of posterior lamellar keratoplasty irrespective of visual acuity. There is a significant correlation between preoperative and postoperative corneal light backscatter values after endothelial keratoplasty, especially in the case of the DMEK procedure.

[Perforating keratoplasty versus Descemet stripping automated endothelial keratoplasty in the partner eye: Functional results and patient satisfaction]

BACKGROUND

This study compared the postoperative results and patient satisfaction between penetrating keratoplasty (PK) and Descemet stripping automated endothelial keratoplasty (DSAEK) in patients who underwent PK in one eye and DSAEK in the other eye.

METHODS

A total of 15 patients were identified from the corneal database register and the medical charts were analyzed for best corrected visual acuity (BCVA), keratometric astigmatism, endothelial cell density and postoperative complications. Patient satisfaction was evaluated by a standardized interview.

RESULTS

Median follow-up time for PK was 55 months and 18 months for DSAEK (p < 0.01). Median BCVA in PK was 0.8 and 0.5 in DSAEK (p = 0.01) at the end of follow-up. Median keratometric astigmatism was 3.1 diopters after PK and 1.9 diopters after DSAEK (p = 0.2). Median endothelial cell density was 831 cells/mm(2) after PK and 860 cells/mm(2) after DSAEK (p = 0.63). For the interventions 57 % of the patients preferred PK, 36 % preferred DSAEK and 7 % were undecided. Patients assigned the better performing eye to the PK side in 64 % and in 29 % to the DSAEK side and 7 % perceived equal visual performance in both eyes.

CONCLUSION

The results leave doubt about the superiority of DSAEK compared to PK; however, exceptionally good refractive results of the 15 PK eyes analyzed and significantly longer follow-up times after PK could be the reason for the unexpectedly high patient preference for PK.

Correlation between visual acuity and interface reflectivity measured by pentacam following DSAEK

PURPOSE

Descemet-stripping automated endothelial keratoplasty (DSAEK) is an advanced method of lamellar endothelial keratoplasty. In comparison with penetrating keratoplasty, visual rehabilitation seems to be faster. Final visual outcome of DSAEK, however, seems to be limited, especially in comparison with Descemet membrane endothelial keratoplasty (DMEK). DSAEK cases without graft failure often do not show any definite correlate for the reduced optical performance. In this study, we tried to correlate visual acuity following DSAEK with interface reflectivity as measured by a rotating Scheimpflug system.

METHODS

We examined 14 eyes of 13 patients with the pentacam for 2-11 months following DSAEK. Reflectivity of the interface region in the centre of the optical axis as well as central corneal thickness was determined. Statistical correlation between interface reflectivity and best spectacle-corrected visual acuity, central corneal thickness and follow-up time was drawn (multifactorial linear regression analysis).

RESULTS

Statistically significant correlation between interface reflectivity and BSCVA as well as follow-up time was found. Reflectivity was highest in regions of interface (metal) particles. There was no statistically significant correlation between interface reflectivity and central corneal thickness.

CONCLUSION

We present a measurable correlate for reduced visual outcome following DSAEK despite a clear graft. Inverse correlation between interface reflectivity and best spectacle-corrected visual acuity (BSCVA) indicates that irregularities or scarring in the interface region may influence the optical quality following DSAEK.

Descemet stripping endothelial keratoplasty--rapid recovery of visual acuity

BACKGROUND

Technical innovations in corneal transplantation have now made it possible to replace only the diseased part of the cornea, rather than the entire cornea as in penetrating keratoplasty (PKP). Patients with endothelial insufficiency due to Fuchs endothelial dystrophy, bullous keratopathy, or endothelial failure after keratoplasty can be treated with the new methods of posterior lamellar corneal transplantation: Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK). It remains unclear which of these methods is better in the individual case.

METHODS

We review the pertinent literature retrieved by a selective search in Medline and the Cochrane Library employing the terms "DMEK," "DSAEK," "DSEK," and "posterior lamellar keratoplasty." The publications considered in this article are those that contain important clinical information on the operative techniques.

RESULTS

No randomized controlled trials of these techniques have been published to date. Numerous case series have shown that patients who undergo DSAEK (postoperative visual acuity ≥0.5 in 38-100%), and especially those who undergo it in early or intermediate stages of endothelial insufficiency, achieve a better functional result more rapidly than patients treated with PKP (postoperative visual acuity ≥0.5 in 47-61%). Only 23-47% of DSAEK patients achieve a visual acuity of 0.8 or more, compared to 36-79% of DMEK patients. Moreover, transplant rejection is seen in only 1-3% of cases of DMEK, compared to 0-8% after DSAEK and 1-23% after PKP.

CONCLUSION

Numerous case series show clear advantages of DMEK over DSAEK, which, in turn, has better results than PKP. Nonetheless, randomized controlled trials are needed to determine which operative method is best in each stage of corneal disease.

[Visual acuity and endothelial cell density following Descemet membrane endothelial keratoplasty (DMEK)]

PURPOSE

To assess the clinical outcomes of DMEK in the first series of 120 eyes operated for the treatment of Fuchs endothelial dystrophy in terms of visual acuity and endothelial cell density.

METHODS

The first 120 consecutive eyes that underwent DMEK (i.e. transplantation of an isolated donor Descemet membrane with its endothelium) were evaluated. In all eyes, the best corrected visual acuity (BCVA) before and at 1, 3 and 6 months after surgery, as well as the endothelial cell density (ECD) before and at 6 months were measured.

RESULTS

In eyes with a functional DMEK graft and good visual potential (n=96), the BCVA was ≥ 20/40 (≥ 0.5) in 77% after 1 month, 92% after 3 months, and 95% after six months; ≥ 20/25 (≥ 0.8) in 50%, 63%, and 73% of the cases, and ≥ 20/20 (≥ 1.0) in 23%, 34%, and 45% of the cases at 1, 3, and 6 months respectively. In this group, ECD averaged 2610 (± 185) cells/mm(2) before, and 1770 (± 520) cells/mm(2) at six months after surgery (n=96). In 15 eyes, a secondary Descemet stripping endothelial keratoplasty (DSEK) was performed. In this group, 91% of patients reached a BCVA of ≥ 20/40 (≥ 0.5) and only one patient achieved a BCVA of 0.8 at 6 months after surgery (n=11). Furthermore, ECD averaged 2580 (± 185) cells/mm(2) before and 1310 (± 740) cells/mm(2) at six months (n=13).

CONCLUSION

DMEK provides a fast and high visual rehabilitation. Endothelial cell density loss may be similar to earlier types of endothelial keratoplasty.

Femtosecond laser-assisted decagonal penetrating keratoplasty

PURPOSE

To assess the use of a new polygonal trephination pattern for penetrating keratoplasty (PK) assisted by femtosecond laser.

DESIGN

Prospective, nonrandomized clinical study.

METHODS

Sixteen eyes underwent decagonal PK. Nine had Fuchs dystrophy, 4 had pseudophakic bullous keratopathy, 1 had experienced trauma, 1 had corneal amyloidosis, and 1 had keratoconus. A Femtec (Tecnolas PerfectVision) laser was used to create decagonal penetrating cuts on both donor and recipient corneas. All patients were evaluated for uncorrected visual acuity, best spectacle-corrected visual acuity, pachymetry, topography, and endothelial cell density. Scanning electron microscopy was performed on corneal tissue after surgery.

RESULTS

All eyes were treated successfully without intraoperative complications. The mean follow-up ± standard deviation was 9.75 ± 3.5 months. Mean postoperative best spectacle-corrected visual acuity was 20/53, and there was a significant improvement in both uncorrected visual acuity (P = .0019) and best spectacle-corrected visual acuity (P = .001). At 6 months, mean ± standard deviation manifest astigmatism was 1.90 ± 1.20 diopters. Mean endothelial cell density was 1502 ± 458 cells/mm². Scanning electron microscopy displayed straight decagonal cut margins and minor remaining tissue bridges.

CONCLUSIONS

Use of the decagonal trephination profile was effective and safe to perform PK. Short-term visual results and refractive results are encouraging compared with those of conventional PK studies. Longer-term follow-up and comparative studies are necessary to determine precisely advantages the and optimal surgical settings of this technique.