Friederike Schaub

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.

Neuroretinal rim in non-glaucomatous large optic nerve heads: a comparison of confocal scanning laser tomography and spectral domain optical coherence tomography

Background/aims To compare margin-based rim area measurements from confocal scanning laser tomography (CSLT) with Bruchs membrane opening (BMO)-based measurements from spectral domain optical coherence tomography (SD-OCT) by analysis of a group of non-glaucomatous eyes with large optic discs, so-called macrodiscs (disc size >2.45 mm2 in CSLT). Objective is to create a reference base for large optic nerve heads in SD-OCT diagnostics. Methods 102 eyes received CSLT and SD-OCT measurements and clinical examination on the same day. Visual field testing confirmed absence of glaucomatous defects. Statistical and correlation analysis was performed for rim area by CSLT as well as retinal nerve fibre layer thickness (RNFLT) and BMO minimal rim width (BMO-MRW) by SD-OCT. Results Mean disc size in CSLT was 2.98±0.4 mm2 (range 2.45–4.23), mean rim area of 1.55±0.4 mm2. BMO area was 2.51±0.33 mm2 (range 1.61–3.51), mean global RNFLT was 79.55±17.2 μm, mean global BMO-MRW was 234.84±48.3 μm. Correlation of BMO-MRW to global RNFLT was stronger (r=0.60, p<10−5) than correlation of CSLT rim area to global RNFLT (r=0.26, p=0.24). BMO-MRW and CSLT rim area correlated with r=0.59 (p<10−5). BMO-MRW and RNFLT significantly decreased with increasing age (p<0.001). Annual loss of BMO-MRW was 0.8 μm/year (R2=0.14, p<0.001), loss of RNFLT was 0.27 μm/year (R2=0.17, p=0.001). Conclusions In large optic discs, BMO-MRW is thinner compared with normal-sized discs and correlates better than CSLT parameters with the RNFLT. An age-depended loss of BMO-MRW needs to be taken into account in evaluation of the neuroretinal rim.

Novel Bruch's Membrane Opening Minimum Rim Area Equalizes Disc Size Dependency and Offers High Diagnostic Power for Glaucoma

Purpose The purpose of this study was to assess the diagnostic power of the novel two-dimensional parameter Bruchs membrane opening minimal rim area (BMO-MRA) in spectral-domain optical coherence tomography (SD-OCT) for detection of glaucoma compared to minimal rim width (BMO-MRW) and retinal nerve fiber layer (RNFL) thickness in large and small optic discs. Methods In this case-control, cross-sectional study, 207 eyes of 207 participants, including 89 controls and 97 patients with glaucoma and 21 with ocular hypertension (OHT), with a disc size <1.63 mm2 or >2.43 mm2 underwent SD-OCT, confocal laser scanning tomography (CSLT), visual field testing, and clinical examination. Bruchs membrane opening-MRA BMO-MRW, RNFL thickness of SD-OCT and disc margin rim area (DM-RA) of CSLT were evaluated and analyzed for diagnostic power to detect glaucoma. Results In healthy eyes with macrodiscs, mean BMO-MRW of 243.14 ± 43.12 μm was significantly smaller than BMO-MRW in microdiscs (338.97 ± 69.39; P < 0.001). Bruchs membrane opening-MRA was comparable between disc size groups with 1.22 ± 0.25 mm2 for macrodiscs and 1.26 ± 0.27 mm2 for microdiscs (P = 0.51), as was RNFL thickness (82.69 ± 15.76 μm versus 78.53 ± 11.01 μm, respectively; P = 0.28). Perimetric mean deviation was -8.7 ± 6.3 dB in glaucoma and -0.6 ± 1.60 dB in OHT patients. Correlation of BMO-MRA and visual field function was rho (ρ) = 0.70 (P < 0.001). Diagnostic power to differentiate glaucoma patients was highest for BMO-MRA. Partial area under the curve (pAUC) for BMO-MRA was 0.14 for specificity between 0.8 and 1.0, exceeding pAUCs of BMO-MRW (P < 0.001), RNFL thickness (P = 0.03), and DM-RA (P = 0.01). Conclusions Bruchs membrane opening-based minimum rim area measurements offer advantages compared to one-dimensional parameters assessing neuroretinal rim by SD-OCT. In nonglaucomatous eyes, BMO-MRA values seem comparable for the full range of disc sizes. Bruchs membrane opening-MRA surpasses other parameters in diagnostic power for glaucoma.

The use of Bruch's membrane opening-based optical coherence tomography of the optic nerve head for glaucoma detection in microdiscs

Purpose To assess the performance of Bruchs membrane opening (BMO)-based spectral domain optical coherence tomography (SD-OCT) of the optic nerve head for glaucoma detection in microdiscs in comparison with confocal scanning laser tomography (CSLT). Design Retrospective cohort study. Methods 82 eyes of 82 patients with disc size <1.63 mm2 underwent SD-OCT and CSLT measurements, visual field testing and clinical examination. BMO-based minimal rim width (BMO-MRW), retinal nerve fibre layer thickness (RNFLT) in SD-OCT and rim area measured in CSLT were compared and correlated with visual field defects. Results 51 patients with glaucoma, 11 patients with ocular hypertension (OHT) and 20 healthy controls had a mean disc area of 1.36±0.19 mm2 in CSLT, and BMO area was 1.45±0.22 mm2 (r=0.17; p=0.12). In patients with glaucoma, visual field mean defect was −7.5±6.7 dB. Global BMO-MRW correlated better with visual field function (Spearmans r=0.65; p<0.001) than RNFLT (r=0.58; p≤0.001) and CSLT rim area (r=0.47; p=0.004). BMO-MRW significantly deteriorated with progressive visual field loss (p<0.001). In receiver operating characteristic analysis, sensitivity of BMO-MRW was 68.6% at 95% specificity (area under curve (AUC)=0.87), similar to sensitivity of RNFLT (66.4%; AUC=0.81). Performance of CSLT rim area was significantly worse (AUC=0.70, p=0.008). In healthy controls, mean BMO-MRW was 344.3±64.1 µm, mean RNFLT 78.0±11.3 µm and CSLT mean rim area 1.07±0.18 mm2. Conclusions In small optic discs, BMO-MRW and peripapillary RNFLT (OCT) have similar sensitivity to discriminate patients with glaucoma from normal controls; both exceed CSLT rim area in diagnostic power. In glaucomatous patients, BMO-MRW correlates strongest with visual field function.

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.

Effects of short inter-stimulus intervals on olfactory and trigeminal event-related potentials

Conclusion: Chemosensory event-related potentials (CSERPs) were identified in all measurements using the 20 s and the 10 s inter-stimulus interval (ISI) protocol, reducing the recording time to 75% or 57% compared with the standard protocol. A possible explanation for the rising CSERP amplitudes by shortening the ISI in CO2 stimulation is due to a phenomenon known as trigeminal sensitization during repeated stimulation. Objectives: CSERPs are influenced by the ISI. The aim of this study was to evaluate the changes in CSERPs by decreasing the ISI from 30 s to 20 s or 10 s, respectively. Subjects and methods: Ten normosmic healthy subjects participated this study. Phenyl ethyl alcohol (PEA), hydrogen sulphide (H2S) and carbon dioxide (CO2) were used in CSERP measurements with different ISI protocols (30 s (standard), 20 s and 10 s). Amplitudes and latencies of ISI protocols were submitted to ANOVA for repeated measurements and t tests for paired samples. Results: The amplitudes of CSERPs with PEA and H2S stimuli were decreasing with shortening the ISI significantly. In contrast, the highest amplitudes of trigeminal CSERPs were recorded with the 10 s ISI protocol with CO2. The ANOVA revealed a significantly different effect of shortening the ISI on CSERPs on the right and the left side.

[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.