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 corneal 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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 339-345 |
| Number of pages | 7 |
| Journal | Graefe's Archive for Clinical and Experimental Ophthalmology |
| Volume | 238 |
| Issue number | 4 |
| State | Published - Apr 2000 |
| Externally published | Yes |
Fingerprint
ASJC Scopus subject areas
- Ophthalmology
Cite this
Thermal load of laser aperture masks in nonmechanical trephination for penetrating keratoplasty with the Er : YAG laser: Comparison between stainless steel and ceramic masks. / Langenbucher, Achim; Küchle, Michael; Seitz, Berthold; Kus, M. Murat; Behrens, Ashley; Weimel, Erich; Naumann, Gottfried O H.
In: Graefe's Archive for Clinical and Experimental Ophthalmology, Vol. 238, No. 4, 04.2000, p. 339-345.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Thermal load of laser aperture masks in nonmechanical trephination for penetrating keratoplasty with the Er
T2 - YAG laser: Comparison between stainless steel and ceramic masks
AU - Langenbucher, Achim
AU - Küchle, Michael
AU - Seitz, Berthold
AU - Kus, M. Murat
AU - Behrens, Ashley
AU - Weimel, Erich
AU - Naumann, Gottfried O H
PY - 2000/4
Y1 - 2000/4
N2 - 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 corneal 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.
AB - 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 corneal 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.
UR - http://www.scopus.com/inward/record.url?scp=0342313582&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0342313582&partnerID=8YFLogxK
M3 - Article
C2 - 10853934
AN - SCOPUS:0342313582
VL - 238
SP - 339
EP - 345
JO - Albrecht von Graefes Archiv für Klinische und Experimentelle Ophthalmologie
JF - Albrecht von Graefes Archiv für Klinische und Experimentelle Ophthalmologie
SN - 0721-832X
IS - 4
ER -