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PubMed2004

[Long-term results of penetrating keratoplasty with different trephine systems -- a clinical investigation from the university eye hospital of halle/saale and the eye clinic of the helios hospital aue].

BACKGROUND: The results of penetrating keratoplasty in two centres for cornea transplantation were investigated with regard to the following parameters: the trephine system used, the origin of the donor cornea, the influence on the postoperative astigmatism and other aspects. PATIENTS AND METHODS: The retrospective clinical investigation reports about the results of 186 patients with penetrating keratoplasty from the University Eye Hospital of Halle and 204 patients from the Eye Clinic of the Helios hospital Aue. RESULTS: Three trephine systems have been used: the Hessburg-Barron trephine, the guided trephine system (GTS) and the Asmotom device. There were no significant differences between them concerning visual acuity after 12 months postoperatively. The results were highly significantly better (p = 0.003 Halle; p = 0.001 Aue) when using larger diameters of the trephine (7.5 mm and 8.0 mm). The origin of the donor cornea ("fresh" cornea from a deceased subject or organ cultivated cornea from a cornea bank) had no influence on visual outcome after twelve months (p > 0.8). There were less wound dehiscences using the double running suture in comparison with other techniques (p = 0.05). The removal of suturing material was not effective in reducing postoperative astigmatism (p > 0.11). There was no increase in astigmatism when leaving the sutures in situ (p > 0.25). CONCLUSIONS: Generally, each of the three trephine systems can be recommended for clinical use. The trephination should be done with trephine diameters of 7.5 mm or 8.0 mm. A timely operation guarantees better visual acuity at one year postoperatively.

Adolescent↗
PubMed1997

Keratometric results of penetrating keratoplasty with the Hessburg-Barron and Hanna trephine systems using a standard double-running suture technique.

PURPOSE: To compare final, sutures-out, keratometric results of penetrating keratoplasty using two different suction trephine systems and a standard double-running suture technique. METHODS: Keratometric data after final suture removal were compared retrospectively for three groups of transplants: Group 1, 7.50-mm Hessburg-Barron recipient trephine and 7.70-mm modified Lieberman donor punch (n = 70); Group 2, 7.50-mm Hessburg-Barron recipient trephine and 8.00-mm modified Lieberman donor punch (n = 18); Group 3, 7.50-mm Hanna recipient trephine and 7.75-mm Hanna donor punch (n = 68). RESULTS: Final average keratometry was 46.7 +/- 2.4 D (mean +/- SD, diopters), and final median keratometric astigmatism was 4.6 D (2.6-7.4 D, interquartile range), with no significant difference between groups. Final average keratometry values increased from preoperative values by 3.3 +/- 2.7 D. The correlation between preoperative average keratometry values and final values was low (rs = 0.2; p = 0.07). Average keratometry values increased by 2.3 D (median) after 10/ 0 suture removal (p < 0.0001) and by 0.2 D (median) after 11/0 suture removal (p = 0.09), with no significant difference between groups. There was a negative correlation between donor age and overall change in average keratometry (rs = -0.3; p = 0.002). Visual acuity improved by a median of 5 lines, with no significant difference between trephine systems. CONCLUSIONS: There was no statistically significant difference in keratometric results using these two suction trephines with a standard suture technique. Final graft curvature was greater with both suction trephines compared with previously published results of transplants using hand-held trephines with the same suture technique.

Aged↗
PubMed1981

Emergency twist drill trephination.

We have used the rapid progression of post-traumatic uncal herniation in spite of intensive medical therapy as the indication for twist drill trephination in the emergency department. During a 54-month period, 51 trephinations were performed on 41 patients. The trephine was placed through the temporal bone ipsilateral to the dilated pupil, and the dura mater was opened to allow partial evacuation of the hematoma. All patients subsequently underwent craniotomy, autopsy, and/or cerebral computed tomography (CT). The trephination was diagnostically accurate for the absence or presence of an extracerebral hematoma in 42 of 51 trephinations (82%). In 6 of these cases the dilated pupil responded to partial hematoma evacuation by decreasing in size. In 3 of the 6 there was a marked overall improvement in neurological status subsequent to trephination. These 3 patients later recovered to an independent functional state. Only 23 of these 41 patients (56%) with herniation profiles actually had significant extracerebral hematomas. This fact emphasizes the inadvisability of taking this type of patient directly to the operating room without a diagnostic study. A rapidly performed CT scan is the obvious first choice. However, if there is any delay in obtaining this study or when uncal herniation occurs rapidly, a twist drill trephination can be of value in diagnosing the absence or presence of a treatable extracerebral hematoma. There were no complications related to this procedure in this group.

Adult↗
PubMed2000

Thermal load of laser aperture masks in nonmechanical trephination for penetrating keratoplasty with the Er:YAG laser: comparison between stainless steel and ceramic masks.

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-microm 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.

Animals↗
PubMed1981

[The relationship between pressure regulation and anatomic localization as well as trephine sites in goniotrepanation. A prospective study].

Long-term regulation of IOP after trephining procedures was studied in 65 eyes with regard to the anatomical localization of the trephine hole. The observation period ranged between six and 39 months. The anatomical localization had no statistically significant influence on long-term pressure regulation after surgery, nor on the immediate postoperative situation. It was clinically impossible to localize the trephine within the trabecular area including Schlemm's canal with a high degree of accuracy. The use of larger-diameter trephines did not increase the probability of striking Schlemm's canal. With larger-diameter trephines the immediate effect on IOP was more pronounced, but the long-term IOP response was poorer. The absence of a filtering bleb or the development of a large filtering bleb was significantly more often associated with poor regulation of IOP in the long term. Where the trephine was positioned closer to the sclera, the incidence of choroidal detachment was higher. The diameter of the trephine had no effect on the occurrence of postoperatively flat chambers or choroidal detachments. Nor did the anatomical localization influence the incidence of postoperatively flat chambers.

Adult↗
PubMed2001

Effect of apical trephination on postoperative pain and swelling in symptomatic necrotic teeth.

The purpose of this prospective, randomized, blinded study was to determine the effect of apical trephination on postoperative pain and swelling in symptomatic necrotic teeth. Fifty emergency patients participated, and each had a clinical diagnosis of a symptomatic necrotic tooth with associated periapical radiolucency. After endodontic treatment, patients randomly received either an apical trephination or mock trephination procedure. The trephination procedure used a Stabident perforator to provide an initial opening in the cortical bone that was enlarged with files (#25 through #120) and an endodontic spoon. Postoperatively, each patient received: ibuprofen; acetaminophen with codeine (30 mg); and a 7-day diary to record pain, percussion pain, swelling, and number and type of pain medication taken. Results demonstrated the use of an apical trephination procedure did not significantly (p > 0.05) reduce pain, percussion pain, swelling, or number of ibuprofen tablets taken in symptomatic necrotic teeth with periapical radiolucencies. The trephination procedure did significantly (p < 0.05) reduce the use of acetaminophen with codeine overall for the 7 days. In conclusion, because there was not a significant reduction in pain, percussion pain, or swelling we cannot recommend the routine use of an apical trephination procedure, as used in this study, in symptomatic necrotic teeth with radiolucencies.

Acetaminophen↗
PubMed1989

Preclinical evaluation of a new donor corneal trephination system.

A new corneal trephination system developed by the University of Minnesota, Department of Ophthalmology and Vision Care/3M features a corneal holder that orients and stabilizes the donor cornea during storage, transportation, and trephination. A gravity corneal punch, and disposable trephine and cutting block minimize corneal button irregularities that in other devices may contribute to postoperative astigmatism. This new system was compared with the Iowa Press by evaluating trephinated corneas on the basis of profile projectors. Buttons trephined from 10 pairs of human corneas stored in (CSM) preservation solution at 4 degrees C were evaluated by measuring diameters and edge angles and correlating them with the trephine size used. In contrast with the Iowa Press, this new system produces corneal buttons that are consistently circular, parallel-edged, and identical in size to the trephine used.

Analysis of Variance↗
PubMedDate not supplied

The theoretical effect of trephine tilt on postkeratoplasty astigmatism.

Most corneal surgeons use a free-hand technique to perform trephination. Of the factors thought to be associated with postkeratoplasty astigmatism, surgeons agree that the process of trephination has the greatest effect on astigmatism. We describe the use of a new trephine that, while affixed to the donor and/or recipient by suction, applanates the cornea to eliminate the oblique incision and undercutting that occur with currently available suction trephines. By mathematical analysis we demonstrate that a 5 degrees to 10 degrees tilt of the trephine can induce significant astigmatism. In theory, the use of the guided trephine system described here will eliminate this complication. This new instrument should be capable of producing identical incisions in the donor and recipient, thereby allowing easier wound coaptation with sutures. This new technology has the potential to eliminate trephination errors as a major cause of postkeratoplasty astigmatism.

Astigmatism↗
PubMedDate not supplied

Endothelial damage by the corneal Hessburg-Barron vacuum trephine.

BACKGROUND: Tissue damage in corneal transplantation procedures was previously assessed in comparative pilot studies using vacuum-assisted metal blade trephines and a noncontact hydrogen fluoride laser trephine system. With the laser, endothelial damage was less than 20 x 30 microns at the edge of the posterior corneal perforation. METHODS: In this study, a second generation vacuum-assisted Hessburg-Barron trephine was evaluated in full-thickness penetrating trephination performed in 16 rabbit eyes and eight fresh human donor eyes. RESULTS: We found a relatively large, 150-micrometer wide, annular zone of endothelial damage on the recipient cornea located 1.25 mm away from the trephined opening. Our study demonstrates that endothelial damage is linked to the instrument's vacuum fixation ring. CONCLUSION: With this trephine, endothelial damage may be avoided by using partial-depth trephination, filling the anterior chamber with viscoelastic and completing the procedure using a metal blade or diamond knife.

Animals↗
PubMed1988

Excimer laser trephination in penetrating keratoplasty. Morphologic features and wound healing.

The imprecision of trephination of donor and recipient corneas is a major factor in post-keratoplasty astigmatism. In order to improve the quality of trephination, the authors developed a rotating slit delivery system for noncontact penetrating keratoplasty trephination using the excimer laser at 193 nm. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and light microscopy (LM) demonstrated the superior quality of excimer-cut buttons and recipient beds as compared with those obtained by free hand and suction trephines in human cadaver and rabbit eyes. The laser trephined more regularly and precisely without distortion of corneal topography and with less damage to adjacent corneal tissue. The authors morphologically examined wound healing at 6 hours, 12 hours, 3 days, 5 days, 2 weeks, 2 months, and 3 months after penetrating keratoplasty with laser and mechanical trephination in an animal autograft model. The laser did not cause any adverse alteration of wound healing processes including cellular migration, proliferation, and production of new tissue.

Animals↗
PubMed1994

The influence of the cutting procedure on the loss of corneal endothelial cells of the recipient eye in mechanically guided trephination.

BACKGROUND: Excessive damage to the endothelial monolayer during corneal trephination may contribute to transplant failure. For this reason, we performed several trephining experiments to determine the influence of various cutting conditions (sharpness, rotation rate, and cutting power) on the endothelial damage in the recipient bed. METHODS: A mechanically guided motor trephine (Mikro-Keratron) was used for cutting experiments in fresh, enucleated porcine eyes. Eight different, reproducible combinations of cutting conditions were applied, and ten epithelial, full-thickness trephinations were performed for each combination. The endothelial defect was measured with a light microscope (60 x). In addition, the bend radii of the porcine cornea were measured. RESULTS: The mechanically guided Mikro-Keratron used with a sharp blade, high rotation rate (840 rev/min), and moderate cutting power (49 mN) caused a 31-micron-wide band of damaged endothelium in the recipient bed. Decrease of the rotation rate to 30 rev/min resulted in an increase of the endothelial defect to 168%. A cutting power of 392 mN combined with a rotation rate of 840 rev/min increased the defect to 126%. The system allowed full-thickness 360 degrees trephination. The corneal bend radii in porcine eyes measured 8.28 mm horizontally and 8.20 mm vertically. CONCLUSION: Our preliminary results indicate that the mechanically guided motor trephine, used under optimal conditions, is a suitable cutting device and may improve the outcome of penetrating keratoplasty; however, further investigation of this new approach is necessary.

Animals↗
PubMed1998

Blood-aqueous barrier after mechanical or nonmechanical excimer laser trephination in penetrating keratoplasty.

PURPOSE: To analyze whether nonmechanical trephination with an excimer laser influences post-operative blood-aqueous barrier breakdown after penetrating keratoplasty. METHODS: Patients undergoing penetrating keratoplasty for keratoconus or Fuchs dystrophy were prospectively randomly assigned to trephination by either excimer laser or conventional mechanical handheld motorized trephine. All surgery was performed by one surgeon, and preoperative, intraoperative, and postoperative treatment was identical in both groups. Aqueous flare was quantitatively determined postoperatively in a masked fashion by laser flare-cell meter. For statistical analysis, the nonparametric Wilcoxon-Mann-Whitney test was used. RESULTS: A total of 52 eyes of 52 patients were examined (Fuchs dystrophy, 10; keratoconus, 42). During the early postoperative period (days 3 to 9), eyes that had undergone nonmechanical excimer laser trephination (25/52) showed significantly (P < .005) lower flare values than did eyes that had undergone mechanical trephination (27/ 52). In both groups, flare values returned to normal levels by 6 weeks postoperatively. CONCLUSION: Early postoperative blood-aqueous barrier breakdown is less pronounced after penetrating keratoplasty with nonmechanical excimer laser trephination.

Adolescent↗
PubMed1996

A comparison of pulpectomy alone versus pulpectomy with trephination for the relief of pain.

Patients who when initially seen have pain of endodontic origin have a higher incidence of posttreatment pain than those who are pain-free pretreatment. The purpose of this study was to compare two methods of treatment--pulpectomy alone or pulpectomy with trephination--for the reduction of posttreatment pain in patients presenting with acute periradicular pain of pulpal origin. Seventeen patients with pretreatment pain were studied. Eleven received a pulpectomy to the radiographically determined working length. Six patients received a pulpectomy and trephination using a #4 round bur through a vertical incision. Visual analog scales were used preoperatively to measure pain intensity and unpleasantness, and postoperatively to measure intensity, unpleasantness, and pain relief at 4, 8, 16, 24, 48, 72, and 96 h. Analysis of preoperative data showed no difference between control and experimental groups. Posttreatment, at 4 h, the trephination group reported significantly more pain intensity and unpleasantness and less pain relief than the control group. Pulpectomy alone provided significantly better postoperative pain relief at 4 h compared with pulpectomy with trephination. At no time interval did the trephination group have less pain than the group without trephination.

Decompression, Surgical↗
PubMed1989

Effect of recipient-donor trephine size disparity on refractive error in keratoconus.

A retrospective study was performed to evaluate the effect of recipient-donor trephine disparity on refractive error and corneal curvature post-suture removal in keratoconus. A double running suture technique was used and donor corneas were trephined from the endothelial side. When keratoconus patients with 0.25-mm larger donor than recipient trephines were compared with keratoconus patients with the same size recipient and donor trephines, a statistically significant increase in the mean keratometer value (45.4 and 43.8 diopters [D], respectively; P = 0.03) and increase in myopic spherical equivalent (-3.5 and -1.8 D, respectively; P = 0.03) was found. When keratoconus patients were compared with phakic Fuchs' dystrophy patients (both groups had 0.25-mm oversize donor trephines), the keratoconus group had a statistically significantly higher myopic spherical equivalent (-3.5 and -1.4 D, respectively; P = 0.03) despite only a 0.7-D difference in mean keratometer value which was not statistically significant (45.4 and 44.7 D, respectively). This study supports the hypothesis that the degree of post-penetrating keratoplasty myopia in patients with keratoconus can be decreased by reducing recipient-donor trephine disparity.

Corneal Dystrophies, Hereditary↗
PubMed2000

Lens opacities after nonmechanical versus mechanical corneal trephination for keratoplasty in keratoconus.

PURPOSE: To compare the lens opacity formation after penetrating keratoplasty (PKP) using nonmechanical excimer laser corneal trephination and mechanical motor trephination. SETTTING: University Eye Clinic, University of Erlangen-Nürnberg, 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). CONCLUSIONS: In addition to its optical advantages, nonmechanical corneal trephination appears to have no adverse impact on cataract formation after PKP for keratoconus.

Adolescent↗
PubMed2000

Effect of trephination on postoperative pain and swelling in symptomatic necrotic teeth.

OBJECTIVE: The purpose of this prospective, randomized, blinded study was to determine the effect of trephination on postoperative pain and swelling in symptomatic necrotic teeth. STUDY DESIGN: Fifty emergency patients participated, and each had a clinical diagnosis of a symptomatic necrotic tooth with associated periapical radiolucency. After endodontic treatment, patients randomly received either a trephination or mock trephination procedure. The trephination procedure used an intraosseous perforator to provide an initial opening in the cortical bone that was enlarged with files (No. 25 through No. 70) and an endodontic spoon. After surgery, each patient received ibuprofen; acetaminophen with codeine (30 mg); and a 7-day diary to record pain, percussion pain, swelling, and number and type of pain medication taken. RESULTS: The majority of patients with symptomatic necrotic teeth had significant postoperative pain and required analgesics to manage this pain. The use of a trephination procedure with an intraosseous perforator, files, and a spoon excavator did not significantly reduce pain, percussion pain, swelling, or the number of analgesic medications taken in symptomatic necrotic teeth with periapical radiolucencies (P >.05). CONCLUSION: We cannot recommend the routine use of a trephination procedure, as used in this study, for relief of pain in symptomatic necrotic teeth with radiolucencies.

Adult↗
PubMed2002

Corneal neovascularization after nonmechanical versus mechanical corneal trephination for non-high-risk keratoplasty.

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 x100) 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 test. RESULTS: Corneal neovascularization within the first postoperative year was lower in the nonmechanical [73 of 152 (48%)] compared with mechanical trephination group [24 of 32 (75%); p< 0.01; Mann-Whitney 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.

Aged↗
PubMed2003

Q-Switched 2.94-microm Er:YAG laser trephination with convergent and divergent cut angles for penetrating keratoplasty.

PURPOSE: To study the morphologic properties of perpendicular (P), convergent (C), and divergent (D) cut angles using different speeds of rotations during donor and recipient nonmechanical trephination for experimental penetrating keratoplasty. METHODS: With a Q-switched 2.94-microm Er:YAG laser corneal trephination was performed in 150 enucleated porcine eyes using ceramic open masks with 8 "orientation teeth/notches" and an automated globe rotation device allowing different cut angles [0 degree (P), 10 and 20 degrees (C and D)] toward the optical axis and variation of the rotation speed [3, 7, and 11 rotations per minute (rpm)]. The regularity of the cut (I, regular; II, slightly irregular; III, irregular) was assessed by light microscopy. The area of thermal damage and the number and size of "spikes" in the stroma at the superficial, intermediate and deep level of the excision were analyzed using digital images and the Optimas image processing software. RESULTS: The regularity of the cut was classified as I in 42%/22% of donor/recipient and as II in 41%/56%, respectively. The thermal damage was least expressed with D20 degree cut angle and donor mask (P < 0.01). With all cut angles and speeds of rotation, thermal damage at the deep level of excision was significantly smaller (P < 0.01). With different speeds of donor rotations, the thermal damage showed no significant difference. With recipient trephination, the thermal damage at the deep level was greatest with 7 rpm (P < 0.01). The number and size of spikes of thermal damage with donor and recipient masks were significantly smaller in the deep stroma (P < 0.01). CONCLUSIONS: Q-switched Er:YAG laser trephination with appropriate settings results in low thermal damage zones at the cut margin. Different cut angles and speeds of trephination may affect the cut performance and quality of the excision. In our study, low rotation speed and divergent donor cut angles showed the best results. The cut quality and the small thermal damage with the Q-switched 2.94-microm Er:YAG laser seem to be tolerable for corneal trephination. Therefore, this modality may be a low-cost, easy-to-handle alternative for nonmechanical corneal transplantation in humans.

Cornea↗