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Achim Langenbucher - One of the best experts on this subject based on the ideXlab platform.

  • comparison of excimer laser versus femtosecond laser assisted Trephination in penetrating keratoplasty a retrospective study
    Advances in Therapy, 2019
    Co-Authors: Nora Szentmary, Achim Langenbucher, Gabor Toth, Elina Akhmedova, M Elhusseiny, Berthold Seitz
    Abstract:

    To compare the impact of non-mechanical excimer-assisted (EXCIMER) and femtosecond laser-assisted (FEMTO) Trephination on outcomes after penetrating keratoplasty (PK). In this retrospective study, 68 eyes from 23 females and 45 males (mean age at time of surgery, 53.3 ± 19.8 years) were included. Inclusion criteria were one surgeon (BS), primary central PK, Fuchs’ dystrophy (FUCHS) or keratoconus (KC), no previous intraocular surgery, graft oversize 0.1 mm and 16-bite double running suture. Trephination was performed using a manually guided 193-nm Zeiss Meditec MEL70 excimer laser (EXCIMER group: 18 FUCHS, 17 KC) or 60-kHz IntraLase™ femtosecond laser (FEMTO group: 16 FUCHS, 17 KC). Subjective refractometry (trial glasses) and corneal topography analysis (Pentacam HR; Casia SS-1000 AS-OCT; TMS-5) were performed preoperatively, before removal of the first suture (11.4 ± 1.9 months) and after removal of the second suture (22.6 ± 3.8 months). Before suture removal, mean refractive/AS-OCT topographic astigmatism did not differ significantly between EXCIMER and FEMTO. After suture removal, mean refractive/Pentacam/AS-OCT topographic astigmatism was significantly higher in the FEMTO (6.2 ± 2.9 D/7.1 ± 3.2 D/7.4 ± 3.3 D) than in the EXCIMER patients (4.3 ± 3.0 D/4.4 ± 3.1 D/4.0 ± 2.9 D) (p ≤ 0.005). Mean corrected distance visual acuity increased from 0.22 and 0.23 preoperatively to 0.55 and 0.53 before or 0.7 and 0.6 after suture removal in the EXCIMER and FEMTO groups, respectively. Differences between EXCIMER and FEMTO were only pronounced in the KC subgroup. Non-mechanical EXCIMER Trephination seems to have advantages regarding postoperative corneal astigmatism and visual acuity compared with FEMTO Trephination, especially in KC. A bigger sample size and longer follow-up are needed to evaluate the long-term impact of EXCIMER and FEMTO Trephination on postoperative topographic and visual outcomes.

  • Development of Endothelial Cell Density after Penetrating Keratoplasty in Patients with Fuchs Dystrophy or Keratoconus - Comparison of Excimer Laser and Mechanical Trephination
    Klinische Monatsblatter fur Augenheilkunde, 2017
    Co-Authors: M. Schumacher, Achim Langenbucher, B Seitz
    Abstract:

    Purpose The aim of this retrospective study was to compare the development of endothelial cell density (ECD) after penetrating keratoplasty (PKP) in patients with Fuchs dystrophy (FD), keratoconus (KC) or "other diagnoses" (OD), depending on the type of Trephination. Patients and Methods In 104 eyes with Fuchs dystrophy, keratoconus or "other diagnoses", the ECD after PKP using either excimer laser (EXC) or mechanical Trephination (MECH) was registered after 1.5, 6, 12, 18 and 24 months. With linear and exponential regression models, the endothelial cell loss (ECL) was determined as absolute and percentage cell loss per year. Results For the entire group of patients, ECD was significantly higher after EXC-PKP during the full range of follow-up (except 6 months). With a linear regression model, there was no significant difference in the absolute ECL per year (p = 0.084), but with an exponential regression model, there was a significant difference in the percentage ECL per year (p = 0.021) in favour of EXC Trephination. For keratoconus (n = 33), except for the 24-month-follow-up (p = 0.035), ECD was not significantly different on the basis of EXC vs. MECH. With a linear regression model, there was a significant difference in the absolute ECL per year (p = 0.015) in favour of EXC-Trephination, but with an exponential regression model there was no significant difference in the percentage ECL per year (p = 0.088) between the two types of threphination. In patients with FUCHS (n = 35) - except for the 6-week-follow-up (p = 0.024) - ECD was not significantly different for EXC vs. MECH. With linear/exponential regression model, the ECL per year was not significantly different in favour of any type of Trephination (p = 0.287/p = 0.121). In patients with OD (n = 36), ECD was not significantly different for EXC vs. MECH. With a linear/exponential regression model, the ECL per year was not significantly different in favour of any type of Trephination (p = 0.494/p = 0.787). Conclusion During the first 24 months after PKP, a significantly higher ECD and a significantly lower percentage of ECL per year was observed after EXC Trephination for the entire group of patients. For the different diagnostic groups KC, FD and OD, no significant difference in ECD or ECL loss was noticed over a range of follow-up intervals. This may most likely be attributed to the small number of patients in the three subgroups.

  • Development of Endothelial Cell Density after Penetrating Keratoplasty in Patients with Fuchs Dystrophy or Keratoconus - Comparison of Excimer Laser and Mechanical Trephination
    Klinische Monatsblatter fur Augenheilkunde, 2017
    Co-Authors: M. Schumacher, Achim Langenbucher, B Seitz
    Abstract:

    Purpose The aim of this retrospective study was to compare the development of endothelial cell density (ECD) after penetrating keratoplasty (PKP) in patients with Fuchs dystrophy (FD), keratoconus (KC) or "other diagnoses" (OD), depending on the type of Trephination. Patients and Methods In 104 eyes with Fuchs dystrophy, keratoconus or "other diagnoses", the ECD after PKP using either excimer laser (EXC) or mechanical Trephination (MECH) was registered after 1.5, 6, 12, 18 and 24 months. With linear and exponential regression models, the endothelial cell loss (ECL) was determined as absolute and percentage cell loss per year. Results For the entire group of patients, ECD was significantly higher after EXC-PKP during the full range of follow-up (except 6 months). With a linear regression model, there was no significant difference in the absolute ECL per year (p = 0.084), but with an exponential regression model, there was a significant difference in the percentage ECL per year (p = 0.021) in favour of EXC Trephination. For keratoconus (n = 33), except for the 24-month-follow-up (p = 0.035), ECD was not significantly different on the basis of EXC vs. MECH. With a linear regression model, there was a significant difference in the absolute ECL per year (p = 0.015) in favour of EXC-Trephination, but with an exponential regression model there was no significant difference in the percentage ECL per year (p = 0.088) between the two types of threphination. In patients with FUCHS (n = 35) - except for the 6-week-follow-up (p = 0.024) - ECD was not significantly different for EXC vs. MECH. With linear/exponential regression model, the ECL per year was not significantly different in favour of any type of Trephination (p = 0.287/p = 0.121). In patients with OD (n = 36), ECD was not significantly different for EXC vs. MECH. With a linear/exponential regression model, the ECL per year was not significantly different in favour of any type of Trephination (p = 0.494/p = 0.787). Conclusion During the first 24 months after PKP, a significantly higher ECD and a significantly lower percentage of ECL per year was observed after EXC Trephination for the entire group of patients. For the different diagnostic groups KC, FD and OD, no significant difference in ECD or ECL loss was noticed over a range of follow-up intervals. This may most likely be attributed to the small number of patients in the three subgroups.

  • Immune reactions following excimer laser and femtosecond laser-assisted penetrating keratoplasty
    Klinische Monatsblatter fur Augenheilkunde, 2013
    Co-Authors: Nora Szentmary, M. El-husseiny, S Goebels, Achim Langenbucher, B Seitz
    Abstract:

    In 10-20 % of conventional keratoplasties immunological graft reactions (TPR) occur, which may lead to endothelial cell loss and irreversible transplant rejection. Beside the optical advantages of non-mechanical excimer laser Trephination, it does not seem to have immunological disadvantages (13.9 % TPR in keratoconus, 2.9 % in Fuchs' dystrophy after 3 years). The femtosecond laser-assisted keratoplasty has visual and refractive outcomes similar to conventional Trephination. However, the "mushroom-shaped" Trephination seems to have immunological disadvantages (21.8 % TPR in keratoconus after 14 months) and "top hat-shaped" keratoplasties seem to have no immunological disadvantages (6.6 % TPR in Fuchs' dystrophy after 14 months).

  • intra individual variability of penetrating keratoplasty outcome after excimer laser versus motorized corneal Trephination
    Journal of Refractive Surgery, 2006
    Co-Authors: Nora Szentmary, Achim Langenbucher, Gottfried O. H. Naumann, Berthold Seitz
    Abstract:

    PURPOSE: To assess the intra-individual variability of outcomes after penetrating keratoplasty by comparing mechanical and nonmechanical corneal Trephination. METHODS: Fifteen patients (30 eyes, 16 with keratoconus and 14 with Fuchs' dystrophy; median age at penetrating keratoplasty 56.3/53.5 years) were assessed whose Trephination was performed using a motor trephine in one eye and the 193-nm excimer laser (MEL 60, Carl Zeiss-Meditec) in the other eye by one experienced surgeon. Subjective refractometry, standard keratometry, and corneal topography were used to assess best spectacle-corrected visual acuity (BSCVA); spherical equivalent refraction; keratometric and topographic central corneal power; refractive, keratometric, and topographic astigmatism; surface regularity index; surface asymmetry index; and potential visual acuity preoperatively, before first suture removal (at 1 year), and at last available follow-up after final suture removal but before additional surgery (1.3 and 1.9 years, respectively). RESULTS: Before first suture removal BSCVA was significantly higher (0.7 vs 0.5; P=.008) after excimer laser Trephination. At the end of follow-up, refractive/ keratometric/topographic astigmatism (2.20/2.10/2.40 diopters [D] vs 5.00/6.00/7.10 D) and surface regularity index (0.8 vs 1.1) were significantly lower (P=.02, P=.005, P=.01, and P=.03, respectively) and potential visual acuity was significantly higher (0.9/0.6; P=.02) after excimer laser Trephination. CONCLUSIONS: During long-term follow-up, all-sutures-out postkeratoplasty astigmatism and surface regularity are superior in the eye where nonmechanical excimer laser was applied in contrast to the fellow eye with motor Trephination in the same individual.

Berthold Seitz - One of the best experts on this subject based on the ideXlab platform.

  • Excimerlaser-gestützte DALK: Ein Fallbericht aus dem Homburger Keratokonus Center (HKC)
    Der Ophthalmologe, 2021
    Co-Authors: Loay Daas, Loïc Hamon, Navid Ardjomand, Tarek Safi, Berthold Seitz
    Abstract:

    Indications The aim of excimer laser-assisted deep anterior lamellar keratoplasty (excimer-DALK) is, as in mechanical DALK, the treatment of keratectasia (keratoconus and pellucid marginal degeneration), stromal scars or stromal corneal dystrophy. A prerequisite for surgery is the absence of (pre‑) Descemet’s scars and an intact endothelium. Surgical technique After excimer laser-assisted Trephination to 80% of the corneal thickness at the Trephination site, intrastromal air injection (so-called big bubble) and lamellar corneal preparation, a lamellar anterior transplantation of the endothelium-free donor tissue is performed. The technique combines the advantages of DALK and excimer laser Trephination. We describe the steps of an excimer-DALK from the Homburg Keratoconus Center (HKC). Conclusion Excimer-DALK is a viable treatment option for patients with intact endothelium. In cases of intraoperative perforation, conversion to excimer-perforating keratoplasty (PKP) with all the advantages of excimer laser Trephination remains feasible. Indikationen Ziel der Excimerlaser-gestützten DALK (Excimer-DALK) ist, wie bei der mechanischen DALK, die Behandlung von Keratektasien (Keratokonus und pellucide marginale Degeneration), stromalen Narben oder stromalen Hornhautdystrophien. Voraussetzung für die Operation ist die Abwesenheit von (prä)descemetalen Narben sowie ein gesundes Endothel. Operationstechnik Nach der Excimerlaser-gestützten Trepanation auf 80 % der kornealen Dicke an der Trepanationsstelle, einer intrastromalen Lufteingabe (sog. „Big-Bubble“) sowie einer lamellären Hornhautpräparation erfolgt eine lamelläre anteriore Transplantation des endothelfreien Spendergewebes. Diese Technik kombiniert die Vorteile einer DALK und einer Excimerlaser-Trepanation. Wir beschreiben die Schritte einer Excimer-DALK aus unserem Homburger Keratokonus Center (HKC). Schlussfolgerungen Die Excimer-DALK stellt bei Patienten mit gutem Endothel eine gute Behandlungsmöglichkeit dar. Bei einer intraoperativen Perforation bleibt die Möglichkeit einer sog. Konversion zur Excimer-PKP mit allen Vorteilen der Excimerlaser-Trepanation.

  • comparison of excimer laser versus femtosecond laser assisted Trephination in penetrating keratoplasty a retrospective study
    Advances in Therapy, 2019
    Co-Authors: Nora Szentmary, Achim Langenbucher, Gabor Toth, Elina Akhmedova, M Elhusseiny, Berthold Seitz
    Abstract:

    To compare the impact of non-mechanical excimer-assisted (EXCIMER) and femtosecond laser-assisted (FEMTO) Trephination on outcomes after penetrating keratoplasty (PK). In this retrospective study, 68 eyes from 23 females and 45 males (mean age at time of surgery, 53.3 ± 19.8 years) were included. Inclusion criteria were one surgeon (BS), primary central PK, Fuchs’ dystrophy (FUCHS) or keratoconus (KC), no previous intraocular surgery, graft oversize 0.1 mm and 16-bite double running suture. Trephination was performed using a manually guided 193-nm Zeiss Meditec MEL70 excimer laser (EXCIMER group: 18 FUCHS, 17 KC) or 60-kHz IntraLase™ femtosecond laser (FEMTO group: 16 FUCHS, 17 KC). Subjective refractometry (trial glasses) and corneal topography analysis (Pentacam HR; Casia SS-1000 AS-OCT; TMS-5) were performed preoperatively, before removal of the first suture (11.4 ± 1.9 months) and after removal of the second suture (22.6 ± 3.8 months). Before suture removal, mean refractive/AS-OCT topographic astigmatism did not differ significantly between EXCIMER and FEMTO. After suture removal, mean refractive/Pentacam/AS-OCT topographic astigmatism was significantly higher in the FEMTO (6.2 ± 2.9 D/7.1 ± 3.2 D/7.4 ± 3.3 D) than in the EXCIMER patients (4.3 ± 3.0 D/4.4 ± 3.1 D/4.0 ± 2.9 D) (p ≤ 0.005). Mean corrected distance visual acuity increased from 0.22 and 0.23 preoperatively to 0.55 and 0.53 before or 0.7 and 0.6 after suture removal in the EXCIMER and FEMTO groups, respectively. Differences between EXCIMER and FEMTO were only pronounced in the KC subgroup. Non-mechanical EXCIMER Trephination seems to have advantages regarding postoperative corneal astigmatism and visual acuity compared with FEMTO Trephination, especially in KC. A bigger sample size and longer follow-up are needed to evaluate the long-term impact of EXCIMER and FEMTO Trephination on postoperative topographic and visual outcomes.

  • intra individual variability of penetrating keratoplasty outcome after excimer laser versus motorized corneal Trephination
    Journal of Refractive Surgery, 2006
    Co-Authors: Nora Szentmary, Achim Langenbucher, Gottfried O. H. Naumann, Berthold Seitz
    Abstract:

    PURPOSE: To assess the intra-individual variability of outcomes after penetrating keratoplasty by comparing mechanical and nonmechanical corneal Trephination. METHODS: Fifteen patients (30 eyes, 16 with keratoconus and 14 with Fuchs' dystrophy; median age at penetrating keratoplasty 56.3/53.5 years) were assessed whose Trephination was performed using a motor trephine in one eye and the 193-nm excimer laser (MEL 60, Carl Zeiss-Meditec) in the other eye by one experienced surgeon. Subjective refractometry, standard keratometry, and corneal topography were used to assess best spectacle-corrected visual acuity (BSCVA); spherical equivalent refraction; keratometric and topographic central corneal power; refractive, keratometric, and topographic astigmatism; surface regularity index; surface asymmetry index; and potential visual acuity preoperatively, before first suture removal (at 1 year), and at last available follow-up after final suture removal but before additional surgery (1.3 and 1.9 years, respectively). RESULTS: Before first suture removal BSCVA was significantly higher (0.7 vs 0.5; P=.008) after excimer laser Trephination. At the end of follow-up, refractive/ keratometric/topographic astigmatism (2.20/2.10/2.40 diopters [D] vs 5.00/6.00/7.10 D) and surface regularity index (0.8 vs 1.1) were significantly lower (P=.02, P=.005, P=.01, and P=.03, respectively) and potential visual acuity was significantly higher (0.9/0.6; P=.02) after excimer laser Trephination. CONCLUSIONS: During long-term follow-up, all-sutures-out postkeratoplasty astigmatism and surface regularity are superior in the eye where nonmechanical excimer laser was applied in contrast to the fellow eye with motor Trephination in the same individual.

  • inverse mushroom shaped nonmechanical penetrating keratoplasty using a femtosecond laser
    American Journal of Ophthalmology, 2005
    Co-Authors: Berthold Seitz, Gottfried O. H. Naumann, H Brunner, Arne Viestenz, Carmen Hofmannrummelt, Ursula Schlotzerschrehardt, Achim Langenbucher
    Abstract:

    Purpose To demonstrate the feasibility of an inverse mushroom-shaped nonmechanical corneal Trephination using a femtosecond laser in a noncontact manner. Design Experimental study. Methods In this laboratory study, 10 polymethylmethacrylate (PMMA) blocks and 20 porcine corneas were treated with an industrial femtosecond laser source. The Trephination profile consisted of (1) a 7- or 6-mm diameter cylinder from the anterior chamber, (2) an intermediate horizontal connecting plane, and (3) a concentric 5- or 4-mm diameter cylinder upwards. Results Applying appropriate combinations of pulse energy and spacing, Trephination took less than 60 seconds. In porcine eyes, light microscopy displayed Trephination edges delineated by partly confluent gas bubbles (10–40 μm) with tissue bridges in between. By TEM, the cut edges were lined by a delicate, electron-dense layer (5–40 nm). Conclusions Femtosecond laser technology seems to offer a promising approach towards minimally invasive self-sealing “no-stitch keratoplasty.”

  • Predictive donor factors for chronic endothelial cell loss after nonmechanical penetrating keratoplasty in a regression model
    Graefe's Archive for Clinical and Experimental Ophthalmology, 2003
    Co-Authors: Achim Langenbucher, Nhung X. Nguyen, Berthold Seitz
    Abstract:

    Purpose To assess the diagnosis-based impact of donor parameters and Trephination diameter as predictive factors on corneal endothelial cell density with an exponential regression model after nonmechanical penetrating keratoplasty (PK). Methods Six hundred thirty-one eyes [291 keratoconus (group I, Trephination diameter 8.0 mm); 202 Fuchs’ dystrophies (group II, Trephination diameter 7.5 mm)—84 PK only (IIa) and 118 triple procedures (IIb); and 138 pseudophakic bullous keratopathies (group III, Trephination diameter 6.5–8.0 mm)] were included in this retrospective study. The time course of the endothelial cell density (specular microscope EM 1100, Tomey, Erlangen) after PK was assessed. Endothelial cell density was analyzed in a longitudinal manner considering at least three valid postoperative cell counts (follow-up 29±17 months) with an exponential regression model (minimizing the residuum between observed and predicted endothelial cell count). The following potentially predictive parameters were assessed: donor age (DA), post-mortem time (PM), storage time (ST) and Trephination diameter (group III). Results In the exponential regression model endothelial cell count decreased in I/II/III by 3.1±24.2% / 12.6±20.2% (IIa: 8.9±17.3%, IIb: 14.8±22.0%) / 18.7±27.3% annually. PM ( P =0.16 / P =0.10 / P =0.25) and DA ( P =0.20, / P =0.12 / P =0.16) did not correlate with the cell loss, but ST ( P =0.04 / P =0.04 / P =0.02) showed a mild correlation, especially in short-term-stored corneas. In group III the Trephination diameter ( P =0.01) correlated inversely with the cell loss. Between short-term-preserved and organ-cultured donor corneas there was no statistically significant difference in the cell loss in any group. Conclusions The post-mortem time and the donor age is not associated with a chronic endothelial cell loss after keratoplasty, whereas a long storage time may exaggerate the endothelial cell loss. Between short-term-preserved and organ-cultured donor corneas there was no difference in the time gradient. In bullous keratopathy patients a larger Trephination size reduces the chronic endothelial cell loss.

Gottfried O. H. Naumann - One of the best experts on this subject based on the ideXlab platform.

  • intra individual variability of penetrating keratoplasty outcome after excimer laser versus motorized corneal Trephination
    Journal of Refractive Surgery, 2006
    Co-Authors: Nora Szentmary, Achim Langenbucher, Gottfried O. H. Naumann, Berthold Seitz
    Abstract:

    PURPOSE: To assess the intra-individual variability of outcomes after penetrating keratoplasty by comparing mechanical and nonmechanical corneal Trephination. METHODS: Fifteen patients (30 eyes, 16 with keratoconus and 14 with Fuchs' dystrophy; median age at penetrating keratoplasty 56.3/53.5 years) were assessed whose Trephination was performed using a motor trephine in one eye and the 193-nm excimer laser (MEL 60, Carl Zeiss-Meditec) in the other eye by one experienced surgeon. Subjective refractometry, standard keratometry, and corneal topography were used to assess best spectacle-corrected visual acuity (BSCVA); spherical equivalent refraction; keratometric and topographic central corneal power; refractive, keratometric, and topographic astigmatism; surface regularity index; surface asymmetry index; and potential visual acuity preoperatively, before first suture removal (at 1 year), and at last available follow-up after final suture removal but before additional surgery (1.3 and 1.9 years, respectively). RESULTS: Before first suture removal BSCVA was significantly higher (0.7 vs 0.5; P=.008) after excimer laser Trephination. At the end of follow-up, refractive/ keratometric/topographic astigmatism (2.20/2.10/2.40 diopters [D] vs 5.00/6.00/7.10 D) and surface regularity index (0.8 vs 1.1) were significantly lower (P=.02, P=.005, P=.01, and P=.03, respectively) and potential visual acuity was significantly higher (0.9/0.6; P=.02) after excimer laser Trephination. CONCLUSIONS: During long-term follow-up, all-sutures-out postkeratoplasty astigmatism and surface regularity are superior in the eye where nonmechanical excimer laser was applied in contrast to the fellow eye with motor Trephination in the same individual.

  • inverse mushroom shaped nonmechanical penetrating keratoplasty using a femtosecond laser
    American Journal of Ophthalmology, 2005
    Co-Authors: Berthold Seitz, Gottfried O. H. Naumann, H Brunner, Arne Viestenz, Carmen Hofmannrummelt, Ursula Schlotzerschrehardt, Achim Langenbucher
    Abstract:

    Purpose To demonstrate the feasibility of an inverse mushroom-shaped nonmechanical corneal Trephination using a femtosecond laser in a noncontact manner. Design Experimental study. Methods In this laboratory study, 10 polymethylmethacrylate (PMMA) blocks and 20 porcine corneas were treated with an industrial femtosecond laser source. The Trephination profile consisted of (1) a 7- or 6-mm diameter cylinder from the anterior chamber, (2) an intermediate horizontal connecting plane, and (3) a concentric 5- or 4-mm diameter cylinder upwards. Results Applying appropriate combinations of pulse energy and spacing, Trephination took less than 60 seconds. In porcine eyes, light microscopy displayed Trephination edges delineated by partly confluent gas bubbles (10–40 μm) with tissue bridges in between. By TEM, the cut edges were lined by a delicate, electron-dense layer (5–40 nm). Conclusions Femtosecond laser technology seems to offer a promising approach towards minimally invasive self-sealing “no-stitch keratoplasty.”

  • immunological graft reactions after penetrating keratoplasty a prospective randomized trial comparing corneal excimer laser and motor Trephination
    Klinische Monatsblatter Fur Augenheilkunde, 2001
    Co-Authors: B Seitz, Achim Langenbucher, Michael Kuchle, Alexios Diamantis, Claus Cursiefen, Gottfried O. H. Naumann
    Abstract:

    BACKGROUND AND PURPOSE Nonmechanical Trephination has been established as an advantageous procedure in penetrating keratoplasty (PK) for avascular corneal diseases and has been performed successfully in more than 1000 eyes at our institution. The purpose of this study was to compare incidence, type and reversibility of immunological graft reactions after mechanical and nonmechanical Trephination for PK. PATIENTS AND METHODS As part of a prospective randomized clinical trial 179 eyes of 76 females and 103 males were included, that had primary central PK without previous intraocular surgery between 10/1992 and 12/1997 for Fuchs' dystrophy (diameter 7.5 mm, n=73) or keratoconus (8.0 mm, n=106). The recipient and donor Trephinations were performed from the epithelial side using either a motor trephine (Microkeratron, Geuder, n=91) or an 193-nm excimer laser (MEL60, Aesculap-Meditec, 1.5 x 1.5 mm spot mode, 16 - 24 mJ/pulse, repetition rate 25/s) along round metal masks with 8 "orientation teeth/notches" (n=88). As a routine, donor oversize was 0.1 mm. 128 patients (72 %) had PK only, 51 patients had simultaneous cataract extraction and PC-IOL implantation (triple procedure). Wound closure was achieved using a 16-bite double running diagonal suture by one surgeon (G.O.H.N.). In 53 % of procedures short-term-preserved donor tissue, in 47 % organ-cultured tissue was used. The mean patient/donor age was 51 +/- 17/57 +/- 19 years with nonmechanical Trephination and 50 +/- 19/58 +/- 20 years with mechanical Trephination. Incidence, type and reversibility of endothelial immunologic graft reactions were recorded continuously by clinical follow-up in an outpatient service with cornea specialization (after 6 weeks, then every 3 months until after suture removal, then every half year). RESULTS During a mean follow-up of 40 +/- 15 months, 7.3 % of eyes developed an immunological endothelial graft reaction. Acute diffuse (5.6 %) were more frequent than chronic focal reactions (1.7 %). Only 1.7 % of grafts became irreversibly cloudy. More than 80 % of all graft reactions occurred later than one year (on average 23 +/- 13 months) after PK. Neither incidence (p=0.82, Chi square test) nor cumulative 3-year-rate of immunological graft reactions (p=0.91, LogRank test) differed significantly comparing nonmechanical (6.8 % or 7.3 %) and mechanical (7.7 % or 5.6 %) Trephination. In eyes with keratoconus (6.6 %, 16 +/- 8 months) graft reactions did not occur more frequently (p=0.68) but earlier (p=0.02) than in eyes with Fuchs' dystrophy (8.2 %, 31 +/- 11 months). Donor age, post-mortem-time and preservation period did not significantly affect the rate of graft reactions in our study setting. CONCLUSIONS Besides well-established optical advantages, nonmechanical Trephination using the excimer laser seems to have no immunologic drawbacks in contrast to conventional mechanical Trephination. Donor parameters appear to have no major impact on the incidence of graft reactions after non-high-risk PK. Rather, an adequate postoperative therapy with topical steroids, an informed patients' compliance, a consequent long-term follow-up in a clinical out-patient service with corneal specialization and a good education of and cooperation with the referring ophthalmologists are of utmost importance for the clear corneal graft in the long run.

  • lens opacities after nonmechanical versus mechanical corneal Trephination for keratoplasty in keratoconus
    Journal of Cataract and Refractive Surgery, 2000
    Co-Authors: Ashley Behrens, Achim Langenbucher, B Seitz, Murat M. Kus, Michael Kuchle, Gottfried O. H. Naumann
    Abstract:

    Abstract Purpose To compare the lens opacity formation after penetrating keratoplasty (PKP) using nonmechanical excimer laser corneal Trephination and mechanical motor Trephination. Setting University Eye Clinic, University of Erlangen-Nurnberg, Erlangen, Germany. Methods Ninety-six patients with keratoconus (96 eyes) and clear crystalline lenses were randomly assigned to the nonmechanical Trephination (NMT) group (n = 46; 35 men; mean age 38.2 years ± 10.8 [SD]) or the mechanical Trephination (MT) group (n = 50; 35 men; mean age 34.4 ± 9.0 years). Suturing and postoperative treatment were identical. Dilated pupil biomicroscopy and slitlamp lens photography were performed preoperatively and postoperatively at 3 month intervals. Opacities were identified as cortical, nuclear, and posterior subcapsular and graded from 1 (mild) to 3 (severe). Results Mean follow-up in the NMT/MT group was 3.2 ± 1.3 years/3.4 ± 1.1 years. Overall, incident opacities appeared in 23.9%/32.0% of eyes (4.3%/6.0% cortical; 19.6%/26.0% posterior subcapsular; 0%/0% nuclear) ( P = .833). All cortical opacities in both groups were grade 1; posterior subcapsular opacities were grade 1 in 66.6%/61.5% of eyes and grade 2 in 22.2%/30.8% of eyes. One patient in each group presented grade 3 posterior subcapsular opacities. No differences between Trephination methods were seen in a 5 year Kaplan–Meier cumulative risk of lens opacity formation ( P = .763 cortical, P = .530 posterior subcapsular). Conclusion In addition to its optical advantages, nonmechanical corneal Trephination appears to have no adverse impact on cataract formation after PKP for keratoconus.

  • thermal load of laser aperture masks in nonmechanical Trephination for penetrating keratoplasty with the er yag laser comparison between stainless steel and ceramic masks
    Graefes Archive for Clinical and Experimental Ophthalmology, 2000
    Co-Authors: Achim Langenbucher, B Seitz, Murat M. Kus, Michael Kuchle, Ashley Behrens, Erich Weimel, Gottfried O. H. Naumann
    Abstract:

    Purpose: Thermal effects on the laser aperture mask may play a major role in the thermal loading of the cornea during nonmechanical Trephination in penetrating keratoplasty. The purpose of this study was to assess the temperature increase on the laser mask using the 2.94-µm Er:YAG laser in order to find suitable parameters for avoidance of thermal damage to the cornea. Methods: Thermal load measurements were performed on donor (7.5 mm Trephination diameter, 0.7 mm thickness, central hole 3.0 mm) and recipient (7.5 mm Trephination diameter, 0.7 mm thickness, outer diameter 13.0 mm) aperture masks. The masks were either mounted on a thermal isolator or fixed directly on porcine corneal samples. Temperature increase was measured either under static conditions in the ablation area (setup 1) and at the opposite side of the mask (setup 2) or in the ablation area under dynamic conditions, rotating the whole globe to simulate a constant Trephination speed with the mask positioned directly on a porcine cornea (setup 3). We used the NWL Er:YAG solid-state laser in a 1.3-mm free-running spot mode focused on the Trephination margin (half of the beam on the mask and half of it on the cornea) with a pulse energy of 200 or 400 mJ and 18CrNi10 stainless steel versus three different types of ceramic masks (silicium carbide, silicium nitrite, aluminum oxide). Temperature was assessed using an infrared pyrometer with automatic data acquisition software for a personal computer. Results: Overall, the temperature rise ranged between 43.6 K (metal donor mask at the Trephination area with 400 mJ pulse energy) and 3.3 K (silicium carbide recipient mask at the opposite side of the mask with 200 mJ pulse energy). With all setups and both energy levels, the heating of the metal mask was significantly higher (P<0.02) than the heating of the three types of ceramic masks. The silicium carbide masks revealed the lowest temperature rise. Comparing the three setups, the temperature rise was maximal under static conditions in the ablation area and minimal at the opposite side, with the dynamic setup ranging in between. Temperature rise was significantly greater (P<0.04) in donor masks than in recipient masks for each mask material and both energy levels. Conclusion: The physical characteristics of silicium carbide masks seem superior to those of metal masks with regard to minimizing the thermal load of the epithelium or superficial stroma during Er:YAG laser Trephination of the cornea for penetrating keratoplasty.

B Seitz - One of the best experts on this subject based on the ideXlab platform.

  • Development of Endothelial Cell Density after Penetrating Keratoplasty in Patients with Fuchs Dystrophy or Keratoconus - Comparison of Excimer Laser and Mechanical Trephination
    Klinische Monatsblatter fur Augenheilkunde, 2017
    Co-Authors: M. Schumacher, Achim Langenbucher, B Seitz
    Abstract:

    Purpose The aim of this retrospective study was to compare the development of endothelial cell density (ECD) after penetrating keratoplasty (PKP) in patients with Fuchs dystrophy (FD), keratoconus (KC) or "other diagnoses" (OD), depending on the type of Trephination. Patients and Methods In 104 eyes with Fuchs dystrophy, keratoconus or "other diagnoses", the ECD after PKP using either excimer laser (EXC) or mechanical Trephination (MECH) was registered after 1.5, 6, 12, 18 and 24 months. With linear and exponential regression models, the endothelial cell loss (ECL) was determined as absolute and percentage cell loss per year. Results For the entire group of patients, ECD was significantly higher after EXC-PKP during the full range of follow-up (except 6 months). With a linear regression model, there was no significant difference in the absolute ECL per year (p = 0.084), but with an exponential regression model, there was a significant difference in the percentage ECL per year (p = 0.021) in favour of EXC Trephination. For keratoconus (n = 33), except for the 24-month-follow-up (p = 0.035), ECD was not significantly different on the basis of EXC vs. MECH. With a linear regression model, there was a significant difference in the absolute ECL per year (p = 0.015) in favour of EXC-Trephination, but with an exponential regression model there was no significant difference in the percentage ECL per year (p = 0.088) between the two types of threphination. In patients with FUCHS (n = 35) - except for the 6-week-follow-up (p = 0.024) - ECD was not significantly different for EXC vs. MECH. With linear/exponential regression model, the ECL per year was not significantly different in favour of any type of Trephination (p = 0.287/p = 0.121). In patients with OD (n = 36), ECD was not significantly different for EXC vs. MECH. With a linear/exponential regression model, the ECL per year was not significantly different in favour of any type of Trephination (p = 0.494/p = 0.787). Conclusion During the first 24 months after PKP, a significantly higher ECD and a significantly lower percentage of ECL per year was observed after EXC Trephination for the entire group of patients. For the different diagnostic groups KC, FD and OD, no significant difference in ECD or ECL loss was noticed over a range of follow-up intervals. This may most likely be attributed to the small number of patients in the three subgroups.

  • Development of Endothelial Cell Density after Penetrating Keratoplasty in Patients with Fuchs Dystrophy or Keratoconus - Comparison of Excimer Laser and Mechanical Trephination
    Klinische Monatsblatter fur Augenheilkunde, 2017
    Co-Authors: M. Schumacher, Achim Langenbucher, B Seitz
    Abstract:

    Purpose The aim of this retrospective study was to compare the development of endothelial cell density (ECD) after penetrating keratoplasty (PKP) in patients with Fuchs dystrophy (FD), keratoconus (KC) or "other diagnoses" (OD), depending on the type of Trephination. Patients and Methods In 104 eyes with Fuchs dystrophy, keratoconus or "other diagnoses", the ECD after PKP using either excimer laser (EXC) or mechanical Trephination (MECH) was registered after 1.5, 6, 12, 18 and 24 months. With linear and exponential regression models, the endothelial cell loss (ECL) was determined as absolute and percentage cell loss per year. Results For the entire group of patients, ECD was significantly higher after EXC-PKP during the full range of follow-up (except 6 months). With a linear regression model, there was no significant difference in the absolute ECL per year (p = 0.084), but with an exponential regression model, there was a significant difference in the percentage ECL per year (p = 0.021) in favour of EXC Trephination. For keratoconus (n = 33), except for the 24-month-follow-up (p = 0.035), ECD was not significantly different on the basis of EXC vs. MECH. With a linear regression model, there was a significant difference in the absolute ECL per year (p = 0.015) in favour of EXC-Trephination, but with an exponential regression model there was no significant difference in the percentage ECL per year (p = 0.088) between the two types of threphination. In patients with FUCHS (n = 35) - except for the 6-week-follow-up (p = 0.024) - ECD was not significantly different for EXC vs. MECH. With linear/exponential regression model, the ECL per year was not significantly different in favour of any type of Trephination (p = 0.287/p = 0.121). In patients with OD (n = 36), ECD was not significantly different for EXC vs. MECH. With a linear/exponential regression model, the ECL per year was not significantly different in favour of any type of Trephination (p = 0.494/p = 0.787). Conclusion During the first 24 months after PKP, a significantly higher ECD and a significantly lower percentage of ECL per year was observed after EXC Trephination for the entire group of patients. For the different diagnostic groups KC, FD and OD, no significant difference in ECD or ECL loss was noticed over a range of follow-up intervals. This may most likely be attributed to the small number of patients in the three subgroups.

  • Immune reactions following excimer laser and femtosecond laser-assisted penetrating keratoplasty
    Klinische Monatsblatter fur Augenheilkunde, 2013
    Co-Authors: Nora Szentmary, M. El-husseiny, S Goebels, Achim Langenbucher, B Seitz
    Abstract:

    In 10-20 % of conventional keratoplasties immunological graft reactions (TPR) occur, which may lead to endothelial cell loss and irreversible transplant rejection. Beside the optical advantages of non-mechanical excimer laser Trephination, it does not seem to have immunological disadvantages (13.9 % TPR in keratoconus, 2.9 % in Fuchs' dystrophy after 3 years). The femtosecond laser-assisted keratoplasty has visual and refractive outcomes similar to conventional Trephination. However, the "mushroom-shaped" Trephination seems to have immunological disadvantages (21.8 % TPR in keratoconus after 14 months) and "top hat-shaped" keratoplasties seem to have no immunological disadvantages (6.6 % TPR in Fuchs' dystrophy after 14 months).

  • corneal neovascularization after nonmechanical versus mechanical corneal Trephination for non high risk keratoplasty
    Cornea, 2002
    Co-Authors: Claus Cursiefen, Achim Langenbucher, B Seitz, Nhung X. Nguyen, Peter Martus, Michael Kuchle
    Abstract:

    Purpose. To analyze the influence of mechanical versus nonmechanical Trephination of donor and host corneas on superficial, peripheral corneal neovascularization occurring after non-high-risk keratoplasty. Methods. Patients of the prospective Erlangen non-high-risk keratoplasty study with standardized corneal photographs taken preoperatively and 1 year later were analyzed (n = 184). Slides of these photographs were projected (magnification ×100) and corneal vessels graded in a standardized semiquantitative fashion into five categories with regard to limbus, sutures, and host-graft junction in each of 12 corneal sectors. Degree (total increase of grades in the 12 sectors) and maximal extent of corneal neovascularization (maximal centripetal extension of blood vessels) were analyzed. In 32 patients mechanical (17%) and in 152 nonmechanical Trephination of host and donor tissue was performed (193-nm excimer laser, 83%). Statistical analysis was done using Fisher's exact and Mann-Whitney U test. Results. Corneal neovascularization within the first postoperative year was lower in in the nonmechanical [73 of 152 (48%)] compared with mechanical Trephination group [24 of 32 (75%); p < 0.01; Mann-Whitney U test]. Maximal extent of neovascularization (i.e., vessels reaching the interface or growing beyond) was not yet significantly different between nonmechanical (8%) and mechanical (17%) Trephination (p = 0.074). Conclusions. Nonmechanical Trephination using the 193-nm excimer laser in non-high-risk keratoplasties might reduce corneal neovascularization occurring within the first postoperative year. This indicates that in the non-high-risk setting, development of postoperative corneal neovascularization may be affected by the Trephination technique and subsequent wound-healing response.

  • immunological graft reactions after penetrating keratoplasty a prospective randomized trial comparing corneal excimer laser and motor Trephination
    Klinische Monatsblatter Fur Augenheilkunde, 2001
    Co-Authors: B Seitz, Achim Langenbucher, Michael Kuchle, Alexios Diamantis, Claus Cursiefen, Gottfried O. H. Naumann
    Abstract:

    BACKGROUND AND PURPOSE Nonmechanical Trephination has been established as an advantageous procedure in penetrating keratoplasty (PK) for avascular corneal diseases and has been performed successfully in more than 1000 eyes at our institution. The purpose of this study was to compare incidence, type and reversibility of immunological graft reactions after mechanical and nonmechanical Trephination for PK. PATIENTS AND METHODS As part of a prospective randomized clinical trial 179 eyes of 76 females and 103 males were included, that had primary central PK without previous intraocular surgery between 10/1992 and 12/1997 for Fuchs' dystrophy (diameter 7.5 mm, n=73) or keratoconus (8.0 mm, n=106). The recipient and donor Trephinations were performed from the epithelial side using either a motor trephine (Microkeratron, Geuder, n=91) or an 193-nm excimer laser (MEL60, Aesculap-Meditec, 1.5 x 1.5 mm spot mode, 16 - 24 mJ/pulse, repetition rate 25/s) along round metal masks with 8 "orientation teeth/notches" (n=88). As a routine, donor oversize was 0.1 mm. 128 patients (72 %) had PK only, 51 patients had simultaneous cataract extraction and PC-IOL implantation (triple procedure). Wound closure was achieved using a 16-bite double running diagonal suture by one surgeon (G.O.H.N.). In 53 % of procedures short-term-preserved donor tissue, in 47 % organ-cultured tissue was used. The mean patient/donor age was 51 +/- 17/57 +/- 19 years with nonmechanical Trephination and 50 +/- 19/58 +/- 20 years with mechanical Trephination. Incidence, type and reversibility of endothelial immunologic graft reactions were recorded continuously by clinical follow-up in an outpatient service with cornea specialization (after 6 weeks, then every 3 months until after suture removal, then every half year). RESULTS During a mean follow-up of 40 +/- 15 months, 7.3 % of eyes developed an immunological endothelial graft reaction. Acute diffuse (5.6 %) were more frequent than chronic focal reactions (1.7 %). Only 1.7 % of grafts became irreversibly cloudy. More than 80 % of all graft reactions occurred later than one year (on average 23 +/- 13 months) after PK. Neither incidence (p=0.82, Chi square test) nor cumulative 3-year-rate of immunological graft reactions (p=0.91, LogRank test) differed significantly comparing nonmechanical (6.8 % or 7.3 %) and mechanical (7.7 % or 5.6 %) Trephination. In eyes with keratoconus (6.6 %, 16 +/- 8 months) graft reactions did not occur more frequently (p=0.68) but earlier (p=0.02) than in eyes with Fuchs' dystrophy (8.2 %, 31 +/- 11 months). Donor age, post-mortem-time and preservation period did not significantly affect the rate of graft reactions in our study setting. CONCLUSIONS Besides well-established optical advantages, nonmechanical Trephination using the excimer laser seems to have no immunologic drawbacks in contrast to conventional mechanical Trephination. Donor parameters appear to have no major impact on the incidence of graft reactions after non-high-risk PK. Rather, an adequate postoperative therapy with topical steroids, an informed patients' compliance, a consequent long-term follow-up in a clinical out-patient service with corneal specialization and a good education of and cooperation with the referring ophthalmologists are of utmost importance for the clear corneal graft in the long run.

Michael Kuchle - One of the best experts on this subject based on the ideXlab platform.

  • corneal neovascularization after nonmechanical versus mechanical corneal Trephination for non high risk keratoplasty
    Cornea, 2002
    Co-Authors: Claus Cursiefen, Achim Langenbucher, B Seitz, Nhung X. Nguyen, Peter Martus, Michael Kuchle
    Abstract:

    Purpose. To analyze the influence of mechanical versus nonmechanical Trephination of donor and host corneas on superficial, peripheral corneal neovascularization occurring after non-high-risk keratoplasty. Methods. Patients of the prospective Erlangen non-high-risk keratoplasty study with standardized corneal photographs taken preoperatively and 1 year later were analyzed (n = 184). Slides of these photographs were projected (magnification ×100) and corneal vessels graded in a standardized semiquantitative fashion into five categories with regard to limbus, sutures, and host-graft junction in each of 12 corneal sectors. Degree (total increase of grades in the 12 sectors) and maximal extent of corneal neovascularization (maximal centripetal extension of blood vessels) were analyzed. In 32 patients mechanical (17%) and in 152 nonmechanical Trephination of host and donor tissue was performed (193-nm excimer laser, 83%). Statistical analysis was done using Fisher's exact and Mann-Whitney U test. Results. Corneal neovascularization within the first postoperative year was lower in in the nonmechanical [73 of 152 (48%)] compared with mechanical Trephination group [24 of 32 (75%); p < 0.01; Mann-Whitney U test]. Maximal extent of neovascularization (i.e., vessels reaching the interface or growing beyond) was not yet significantly different between nonmechanical (8%) and mechanical (17%) Trephination (p = 0.074). Conclusions. Nonmechanical Trephination using the 193-nm excimer laser in non-high-risk keratoplasties might reduce corneal neovascularization occurring within the first postoperative year. This indicates that in the non-high-risk setting, development of postoperative corneal neovascularization may be affected by the Trephination technique and subsequent wound-healing response.

  • immunological graft reactions after penetrating keratoplasty a prospective randomized trial comparing corneal excimer laser and motor Trephination
    Klinische Monatsblatter Fur Augenheilkunde, 2001
    Co-Authors: B Seitz, Achim Langenbucher, Michael Kuchle, Alexios Diamantis, Claus Cursiefen, Gottfried O. H. Naumann
    Abstract:

    BACKGROUND AND PURPOSE Nonmechanical Trephination has been established as an advantageous procedure in penetrating keratoplasty (PK) for avascular corneal diseases and has been performed successfully in more than 1000 eyes at our institution. The purpose of this study was to compare incidence, type and reversibility of immunological graft reactions after mechanical and nonmechanical Trephination for PK. PATIENTS AND METHODS As part of a prospective randomized clinical trial 179 eyes of 76 females and 103 males were included, that had primary central PK without previous intraocular surgery between 10/1992 and 12/1997 for Fuchs' dystrophy (diameter 7.5 mm, n=73) or keratoconus (8.0 mm, n=106). The recipient and donor Trephinations were performed from the epithelial side using either a motor trephine (Microkeratron, Geuder, n=91) or an 193-nm excimer laser (MEL60, Aesculap-Meditec, 1.5 x 1.5 mm spot mode, 16 - 24 mJ/pulse, repetition rate 25/s) along round metal masks with 8 "orientation teeth/notches" (n=88). As a routine, donor oversize was 0.1 mm. 128 patients (72 %) had PK only, 51 patients had simultaneous cataract extraction and PC-IOL implantation (triple procedure). Wound closure was achieved using a 16-bite double running diagonal suture by one surgeon (G.O.H.N.). In 53 % of procedures short-term-preserved donor tissue, in 47 % organ-cultured tissue was used. The mean patient/donor age was 51 +/- 17/57 +/- 19 years with nonmechanical Trephination and 50 +/- 19/58 +/- 20 years with mechanical Trephination. Incidence, type and reversibility of endothelial immunologic graft reactions were recorded continuously by clinical follow-up in an outpatient service with cornea specialization (after 6 weeks, then every 3 months until after suture removal, then every half year). RESULTS During a mean follow-up of 40 +/- 15 months, 7.3 % of eyes developed an immunological endothelial graft reaction. Acute diffuse (5.6 %) were more frequent than chronic focal reactions (1.7 %). Only 1.7 % of grafts became irreversibly cloudy. More than 80 % of all graft reactions occurred later than one year (on average 23 +/- 13 months) after PK. Neither incidence (p=0.82, Chi square test) nor cumulative 3-year-rate of immunological graft reactions (p=0.91, LogRank test) differed significantly comparing nonmechanical (6.8 % or 7.3 %) and mechanical (7.7 % or 5.6 %) Trephination. In eyes with keratoconus (6.6 %, 16 +/- 8 months) graft reactions did not occur more frequently (p=0.68) but earlier (p=0.02) than in eyes with Fuchs' dystrophy (8.2 %, 31 +/- 11 months). Donor age, post-mortem-time and preservation period did not significantly affect the rate of graft reactions in our study setting. CONCLUSIONS Besides well-established optical advantages, nonmechanical Trephination using the excimer laser seems to have no immunologic drawbacks in contrast to conventional mechanical Trephination. Donor parameters appear to have no major impact on the incidence of graft reactions after non-high-risk PK. Rather, an adequate postoperative therapy with topical steroids, an informed patients' compliance, a consequent long-term follow-up in a clinical out-patient service with corneal specialization and a good education of and cooperation with the referring ophthalmologists are of utmost importance for the clear corneal graft in the long run.

  • lens opacities after nonmechanical versus mechanical corneal Trephination for keratoplasty in keratoconus
    Journal of Cataract and Refractive Surgery, 2000
    Co-Authors: Ashley Behrens, Achim Langenbucher, B Seitz, Murat M. Kus, Michael Kuchle, Gottfried O. H. Naumann
    Abstract:

    Abstract Purpose To compare the lens opacity formation after penetrating keratoplasty (PKP) using nonmechanical excimer laser corneal Trephination and mechanical motor Trephination. Setting University Eye Clinic, University of Erlangen-Nurnberg, Erlangen, Germany. Methods Ninety-six patients with keratoconus (96 eyes) and clear crystalline lenses were randomly assigned to the nonmechanical Trephination (NMT) group (n = 46; 35 men; mean age 38.2 years ± 10.8 [SD]) or the mechanical Trephination (MT) group (n = 50; 35 men; mean age 34.4 ± 9.0 years). Suturing and postoperative treatment were identical. Dilated pupil biomicroscopy and slitlamp lens photography were performed preoperatively and postoperatively at 3 month intervals. Opacities were identified as cortical, nuclear, and posterior subcapsular and graded from 1 (mild) to 3 (severe). Results Mean follow-up in the NMT/MT group was 3.2 ± 1.3 years/3.4 ± 1.1 years. Overall, incident opacities appeared in 23.9%/32.0% of eyes (4.3%/6.0% cortical; 19.6%/26.0% posterior subcapsular; 0%/0% nuclear) ( P = .833). All cortical opacities in both groups were grade 1; posterior subcapsular opacities were grade 1 in 66.6%/61.5% of eyes and grade 2 in 22.2%/30.8% of eyes. One patient in each group presented grade 3 posterior subcapsular opacities. No differences between Trephination methods were seen in a 5 year Kaplan–Meier cumulative risk of lens opacity formation ( P = .763 cortical, P = .530 posterior subcapsular). Conclusion In addition to its optical advantages, nonmechanical corneal Trephination appears to have no adverse impact on cataract formation after PKP for keratoconus.

  • thermal load of laser aperture masks in nonmechanical Trephination for penetrating keratoplasty with the er yag laser comparison between stainless steel and ceramic masks
    Graefes Archive for Clinical and Experimental Ophthalmology, 2000
    Co-Authors: Achim Langenbucher, B Seitz, Murat M. Kus, Michael Kuchle, Ashley Behrens, Erich Weimel, Gottfried O. H. Naumann
    Abstract:

    Purpose: Thermal effects on the laser aperture mask may play a major role in the thermal loading of the cornea during nonmechanical Trephination in penetrating keratoplasty. The purpose of this study was to assess the temperature increase on the laser mask using the 2.94-µm Er:YAG laser in order to find suitable parameters for avoidance of thermal damage to the cornea. Methods: Thermal load measurements were performed on donor (7.5 mm Trephination diameter, 0.7 mm thickness, central hole 3.0 mm) and recipient (7.5 mm Trephination diameter, 0.7 mm thickness, outer diameter 13.0 mm) aperture masks. The masks were either mounted on a thermal isolator or fixed directly on porcine corneal samples. Temperature increase was measured either under static conditions in the ablation area (setup 1) and at the opposite side of the mask (setup 2) or in the ablation area under dynamic conditions, rotating the whole globe to simulate a constant Trephination speed with the mask positioned directly on a porcine cornea (setup 3). We used the NWL Er:YAG solid-state laser in a 1.3-mm free-running spot mode focused on the Trephination margin (half of the beam on the mask and half of it on the cornea) with a pulse energy of 200 or 400 mJ and 18CrNi10 stainless steel versus three different types of ceramic masks (silicium carbide, silicium nitrite, aluminum oxide). Temperature was assessed using an infrared pyrometer with automatic data acquisition software for a personal computer. Results: Overall, the temperature rise ranged between 43.6 K (metal donor mask at the Trephination area with 400 mJ pulse energy) and 3.3 K (silicium carbide recipient mask at the opposite side of the mask with 200 mJ pulse energy). With all setups and both energy levels, the heating of the metal mask was significantly higher (P<0.02) than the heating of the three types of ceramic masks. The silicium carbide masks revealed the lowest temperature rise. Comparing the three setups, the temperature rise was maximal under static conditions in the ablation area and minimal at the opposite side, with the dynamic setup ranging in between. Temperature rise was significantly greater (P<0.04) in donor masks than in recipient masks for each mask material and both energy levels. Conclusion: The physical characteristics of silicium carbide masks seem superior to those of metal masks with regard to minimizing the thermal load of the epithelium or superficial stroma during Er:YAG laser Trephination of the cornea for penetrating keratoplasty.

  • stromal thermal effects induced by nonmechanical 2 94 µm erbium yag laser corneal Trephination
    Archives of Ophthalmology, 1998
    Co-Authors: Ashley Behrens, Achim Langenbucher, B Seitz, Murat M. Kus, Michael Kuchle, Ursula Schlotzerschrehardt, Thomas Amann, C Rummelt, Gottfried O. H. Naumann
    Abstract:

    Objective: To determine stromal thermal changes after erbium (Er):YAG laser corneal Trephination with the use of 2 open masks. Methods: Corneal Trephination was performed in 89 enucleated pig eyes with an Er:YAG laser (400microsecond pulse duration), 4 open masks (2 metallic and 2 ceramic) for both donors and recipients, and an automated globe rotation device. Different combinations of laser settings were used: pulse energy, 100, 200, and 400 mJ; repetition rate, 2 and 5 Hz; and spot size, 1.3 and 3.2 mm. Thermal effects in corneal stroma and regularity of the cut edges were quantitatively assessed by light microscopy, transmission and scanning electron microscopy. Results: Best regularity and minimal thermal effects of the cut were observed with the use of ceramic masks at 200 mJ, 2 Hz, and 3.2-mm spot size, with middepth thermal changes of 18 ± 2 µm. Effects increased with cut depth and were lower in donor corneas and with the use of ceramic masks (P,.001). Regularity of the cut was higher in the donors (P = .05) with lower repetition rates (P,.001). Conclusions: Even with the “free-running” Er:YAG laser mode, features of the Trephination cut resembling those created by the 193-nm excimer laser along metal mask were achieved. Ceramic masks may be more suitable than metal masks. The Er:YAG laser seems to have the potential to be a compact and low-cost alternative in nonmechanical Trephination for penetrating keratoplasty. Clinical Relevance: Thermal effects after corneal Trephination with the free-running Er:YAG laser (2.94 mm) are limited and predictable.

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