B. Bachmann

Changes in donor corneal lenticule thickness after Descemet’s stripping automated endothelial keratoplasty (DSAEK) with organ-cultured corneas

Aims: The aim of the study was to quantify changes in donor and host corneal tissue after Descemet’s stripping automated endothelial keratoplasty (DSAEK) using organ-cultured corneas and to correlate these findings with the visual acuity during intermediate-term follow-up. Methods: Fifteen eyes of 15 consecutive patients, with Fuchs’ endothelial dystrophy treated with DSAEK using organ-cultured corneas, underwent ophthalmological examination, including slit lamp-adapted optical coherence tomography, at 1, 3 and 7 days, and 4 weeks, 8 weeks and 6 months after the surgery. Results: The mean best spectacle-corrected visual acuity (BSCVA) improved from 20/100 pre-operatively to 20/40 at 6-months post-operatively (p<0.0001). A continuous decrease of thickness of the grafted lenticule was observed during the follow-up (mean thickness immediately after surgery 191(SD 56) μm, compared with 100 (SD 38) μm 6 months after surgery, p<0.001). The central corneal thickness decreased from 1057 (SD 86) μm at the first post-operative day to 661 (SD 74) μm after 6 months. Both central corneal thickness and the thickness of the posterior donor lamella correlated with the 6-month BSCVA (Pearson correlations −0.745 and −0.589, respectively, p<0.05). Conclusions: Organ-cultured corneas can be used successfully for DSAEK. The thickness of the grafted corneal lenticule correlated with the BSCVA 6 months after the surgery. It decreased continuously during the follow-up period.

One-year outcome after Descemet membrane endothelial keratoplasty (DMEK) comparing sulfur hexafluoride (SF6) 20% versus 100% air for anterior chamber tamponade

Purpose To investigate 1-year clinical outcome and complication rates following Descemet membrane endothelial keratoplasty (DMEK) with sulfur hexafluoride 20% (SF620%) anterior chamber tamponade compared with conventionally used 100% air for primary graft attachment during DMEK surgery. Methods Records of 1112 consecutive DMEKs were reviewed retrospectively and grouped by anterior chamber tamponade used during DMEK surgery (SF620% vs 100% air). Outcome measures included intraocular pressure (IOP), best spectacle-corrected visual acuity (BSCVA), endothelial cell density (ECD) and central corneal thickness (CCT) at 1, 3, 6 and 12 months after DMEK surgery. Complication rates were assessed, including intraoperative and postoperative complications, and graft detachment rate requiring rebubbling. Results A total of 854 cases were included in this study. In 105 cases (12.3%), DMEK was performed with SF620%, and in 749 cases (87.7%) 100% air was used for anterior chamber tamponade. Outcome results for IOP, BSCVA, ECD and CCT at all follow-up time points were comparable for both anterior chamber tamponade groups without statistical significant differences (p≥0.05), but graft detachment rate requiring rebubbling was significantly lower in the SF620% group (p<0.001). Conclusion Whereas SF620% anterior chamber tamponade does not seem to negatively affect the clinical outcome of DMEK surgery within the first postoperative year, use of SF620% significantly reduces the rate of rebubblings.

Errata: Advantages of microscope-integrated intraoperative online optical coherence tomography: usage in Boston keratoprosthesis type I surgery.

Boston keratoprosthesis (KPro) type I is a technique to treat patients with corneal diseases that are not amenable to conventional keratoplasty. Correct assembly and central implantation of the prosthesis are crucial for postoperative visual recovery. This study investigates the potential benefit of intraoperative optical coherence tomography (OCT) to monitor KPro surgery. Retrospective case series are presented for two patients who underwent Boston KPro type I implantation. The surgery in both patients was monitored intraoperatively using a commercially available intraoperative OCT (iOCT) device mounted on a surgical microscope. Microscope-integrated intraoperative OCT was able to evaluate the correct assembly and implantation of the KPro. All parts of the prosthesis were visible, and interfaces between the corneal graft and titanium backplate or anterior optics were clearly depictable. Moreover, iOCT visualized a gap between the backplate and graft in one case, and in the other case, a gap between the anterior optic and graft. Neither gap was visible with a conventional surgical microscope. The gap between the anterior optic and the graft could easily be corrected. Microscope-integrated iOCT delivers enhanced information, adding to the normal surgical microscope view during KPro surgery. Correct assembly can be controlled as well as the correct placement of the Boston KPro into the anterior chamber.

Einfluss von 20 % Schwefelhexafluorid (SF6) auf humane korneale Endothelzellen

BACKGROUND In posterior lamellar keratoplasties, such as Descemet membrane endothelial keratoplasty (DMEK) and Descemets stripping automated endothelial keratoplasty (DSAEK) an air bubble is left inside the anterior chamber to promote graft attachment during the early postoperative period. In the case of insufficient graft adhesion a renewed intracameral air injection is often necessary. The use of sulfur hexafluoride diluted with air (SF6 20 %) as an alternative to pure air may further enhance graft attachment and reduce the rebubbling rate. The effect of SF6 20 % on corneal endothelium is currently unclear and was therefore examined in vitro. MATERIAL AND METHODS For this study 12 human corneoscleral discs were mounted in artificial anterior chambers, the systems were continuously filled with culture medium and the anterior chambers with air (n = 5) or SF6 20 % (n = 7) as tamponade. After 6 days of storage in the incubator endothelial cell density, toxicity on endothelial cells and corneal thickness were evaluated. RESULTS There were no significant differences in endothelial cell loss (p = 1.000), endothelial cell count (p = 0.648), toxicity on endothelial cells (p = 0.048) and central corneal thickness (p = 0.905) between the two groups after 1 week. The level of significance was defined as p ≤ 0.05 and adjusted to p ≤ 0.0056 according to the Bonferroni correction for multiple testing. CONCLUSION The use of SF6 20 % as tamponade in the anterior chamber for posterior lamellar keratoplasty can be proposed as a safe alternative to pure air filling related to endothelial cell loss. Increased toxic effects on the corneal endothelium by SF6 20 % were not detected in this study; however, further prospective clinical trials are needed to examine the long-term effects in humans.

Topical inhibition of angiogenesis at the cornea. Safety and efficacy

ZusammenfassungHintergrundSicherheit und Effektivität neuer topischer antiangiogener Therapieansätze an der Hornhaut werden diskutiert.MethodeDarstellung von eigenen experimentellen und klinischen Ergebnissen sowie Literaturübersicht nach PUBMED Recherche.ErgebnisseSowohl der Off-Label-Gebrauch von Avastin®-Augentropfen als auch die in Phase II getesteten GS101-Augentropfen scheinen eine relativ sichere und effektive Hemmung progressiver kornealer Neovaskularisationen zu ermöglichen. Andere VEGF-Antagonisten wie Pegaptanib- und Ranibizumab-Augentropfen hemmen ebenfalls korneale Neovaskularisation.SchlussfolgerungenMit neuen antiangiogenen Augentropfen steht erstmals eine Möglichkeit zur spezifischen antiangiogenen Therapie an der Hornhaut für den klinischen Einsatz zur Verfügung.AbstractBackgroundThe efficacy and safety of novel topical inhibitors of corneal neovascularisation will be discussed.MethodsA literature review after a PUBMED search and own clinical and experimental results are presented.ResultsThe off-label use of Avastin® eye drops and GS101 eye drops against insulin receptor substrate (IRS)-1, which have been tested in phase II trial, both seem to be relatively efficient and safe ways to inhibit progressive corneal neovascularisation. Other VEGF antagonists, such as ranibizumab and pegaptanib eye drops also inhibit corneal neovascularisation.ConclusionsAvastin® and GS101 eye drops are the first specific angiogenesis inhibitors for topical inhibition of corneal angiogenesis available for clinical use.BACKGROUND The efficacy and safety of novel topical inhibitors of corneal neovascularisation will be discussed. METHODS A literature review after a PUBMED search and own clinical and experimental results are presented. RESULTS The off-label use of Avastin eye drops and GS101 eye drops against insulin receptor substrate (IRS)-1, which have been tested in phase II trial, both seem to be relatively efficient and safe ways to inhibit progressive corneal neovascularisation. Other VEGF antagonists, such as ranibizumab and pegaptanib eye drops also inhibit corneal neovascularisation. CONCLUSIONS Avastin and GS101 eye drops are the first specific angiogenesis inhibitors for topical inhibition of corneal angiogenesis available for clinical use.

[Influence of 20 % sulfur hexafluoride (SF6) on human corneal endothelial cells : An in vitro study].

BACKGROUND In posterior lamellar keratoplasties, such as Descemet membrane endothelial keratoplasty (DMEK) and Descemets stripping automated endothelial keratoplasty (DSAEK) an air bubble is left inside the anterior chamber to promote graft attachment during the early postoperative period. In the case of insufficient graft adhesion a renewed intracameral air injection is often necessary. The use of sulfur hexafluoride diluted with air (SF6 20 %) as an alternative to pure air may further enhance graft attachment and reduce the rebubbling rate. The effect of SF6 20 % on corneal endothelium is currently unclear and was therefore examined in vitro. MATERIAL AND METHODS For this study 12 human corneoscleral discs were mounted in artificial anterior chambers, the systems were continuously filled with culture medium and the anterior chambers with air (n = 5) or SF6 20 % (n = 7) as tamponade. After 6 days of storage in the incubator endothelial cell density, toxicity on endothelial cells and corneal thickness were evaluated. RESULTS There were no significant differences in endothelial cell loss (p = 1.000), endothelial cell count (p = 0.648), toxicity on endothelial cells (p = 0.048) and central corneal thickness (p = 0.905) between the two groups after 1 week. The level of significance was defined as p ≤ 0.05 and adjusted to p ≤ 0.0056 according to the Bonferroni correction for multiple testing. CONCLUSION The use of SF6 20 % as tamponade in the anterior chamber for posterior lamellar keratoplasty can be proposed as a safe alternative to pure air filling related to endothelial cell loss. Increased toxic effects on the corneal endothelium by SF6 20 % were not detected in this study; however, further prospective clinical trials are needed to examine the long-term effects in humans.

Therapie von Hornhautendothelerkrankungen mittels DMEK und UT-DSAEK

Various techniques for posterior lamellar keratoplasty have been established for the clinical routine and continuously improved during the last 15 years so that an extremely rapid recovery of vision is possible due to very thin transplants. Descemet membrane endothelial keratoplasty (DMEK) is the method of choice for simple corneal endothelial diseases and has already been applied in complex conditions of the anterior segment. The learning curve for DMEK is comparatively long and the risk of complications in complex anterior segment pathologies is higher than in Descemets stripping automated endothelial keratoplasty (DSAEK); however, DMEK results in better visual outcome and less graft rejections than DSAEK. The latest evolution in posterior lamellar transplant surgery is ultrathin DSAEK (UT-DSAEK), where the grafted lamella is much thinner than in conventional DSAEK. Currently available data suggest that the resulting visual acuity after UT-DSAEK is close to the visual acuity seen after DMEK; however, studies comparing the results after DMEK and UT-DSAEK are so far lacking. Whether the transplantation of these very thin DSAEK grafts also results in endothelial cell densities and graft rejection rates comparable to DMEK has to be proven.

[Treatment of corneal endothelial disorders by DMEK and UT-DSAEK. Indications, complications, results and follow-up].

Various techniques for posterior lamellar keratoplasty have been established for the clinical routine and continuously improved during the last 15 years so that an extremely rapid recovery of vision is possible due to very thin transplants. Descemet membrane endothelial keratoplasty (DMEK) is the method of choice for simple corneal endothelial diseases and has already been applied in complex conditions of the anterior segment. The learning curve for DMEK is comparatively long and the risk of complications in complex anterior segment pathologies is higher than in Descemets stripping automated endothelial keratoplasty (DSAEK); however, DMEK results in better visual outcome and less graft rejections than DSAEK. The latest evolution in posterior lamellar transplant surgery is ultrathin DSAEK (UT-DSAEK), where the grafted lamella is much thinner than in conventional DSAEK. Currently available data suggest that the resulting visual acuity after UT-DSAEK is close to the visual acuity seen after DMEK; however, studies comparing the results after DMEK and UT-DSAEK are so far lacking. Whether the transplantation of these very thin DSAEK grafts also results in endothelial cell densities and graft rejection rates comparable to DMEK has to be proven.

[Update: Deep anterior lamellar keratoplasty (DALK) for keratoconus. When, how and why].

BACKGROUND The treatment of keratoconus has been significantly expanded in recent years. In addition to the previous options for correction by fitting hard contact lenses and penetrating keratoplasty (PK), corneal cross-linking and lamellar transplantation techniques have been added. OBJECTIVE The aim of this review article is to highlight currently available options for minimization of complications and standardization of deep anterior lamellar keratoplasty (DALK) for keratoconus. MATERIAL AND METHODS This article summarizes our own data and gives a review of the literature in PubMed. RESULTS Performing DALK can provide keratoconus patients with corneal grafts with considerably longer graft survival and a reduced risk of complications. CONCLUSION The DALK procedure provides numerous advantages over PK, especially the reduced intraoperative opening of the eye, which thus reduces the risk of serious intraoperative complications. A further benefit is the complete absence of postoperative endothelial immune reactions as the recipients endothelium remains untouched. The absence of endothelial immune reactions is especially advantageous for young patients with keratoconus and patients with an increased risk of graft rejection, e.g. in atopic dermatitis; however, there are also typical complications of DALK that do not occur during PK. The outlined strategies for standardization of DALK and avoidance of intraoperative and postoperative complications should make DALK safer and more reproducible and lead to possible establishment as a standard procedure in keratokonus.

Update: Tiefe anteriore lamelläre Keratoplastik (DALK) bei Keratokonus

BACKGROUND The treatment of keratoconus has been significantly expanded in recent years. In addition to the previous options for correction by fitting hard contact lenses and penetrating keratoplasty (PK), corneal cross-linking and lamellar transplantation techniques have been added. OBJECTIVE The aim of this review article is to highlight currently available options for minimization of complications and standardization of deep anterior lamellar keratoplasty (DALK) for keratoconus. MATERIAL AND METHODS This article summarizes our own data and gives a review of the literature in PubMed. RESULTS Performing DALK can provide keratoconus patients with corneal grafts with considerably longer graft survival and a reduced risk of complications. CONCLUSION The DALK procedure provides numerous advantages over PK, especially the reduced intraoperative opening of the eye, which thus reduces the risk of serious intraoperative complications. A further benefit is the complete absence of postoperative endothelial immune reactions as the recipients endothelium remains untouched. The absence of endothelial immune reactions is especially advantageous for young patients with keratoconus and patients with an increased risk of graft rejection, e.g. in atopic dermatitis; however, there are also typical complications of DALK that do not occur during PK. The outlined strategies for standardization of DALK and avoidance of intraoperative and postoperative complications should make DALK safer and more reproducible and lead to possible establishment as a standard procedure in keratokonus.