Murat M. Kus

Nonmechanical corneal trephination with the excimer laser improves outcome after penetrating keratoplasty1

OBJECTIVE To assess the impact of nonmechanical trephination on the outcome after penetrating keratoplasty (PK). DESIGN Prospective, randomized, cross-sectional, clinical, single-center study. PATIENTS A total of 179 eyes of 76 females and 103 males, mean age at the time of surgery 50.6 +/- 18.5 (range, 15-83) years. Inclusion criteria were (1) time interval from October 1992 to December 1997; (2) one surgeon (GOHN); (3) primary central PK; (4) Fuchs dystrophy (diameter, 7.5 mm) or keratoconus (diameter, 8.0 mm); (5) graft oversize, 0.1 mm; (6) no previous intraocular surgery; and (7) 16-bite double-running diagonal suture. INTERVENTION In a randomized fashion, eyes were assigned either to trephination with the 193-nm Meditec excimer laser (manually guided beam in patients, automated rotation device of artificial anterior chamber in donors) along metal masks with eight orientation teeth/notches (EXCIMER: 53 keratoconus, 35 Fuchs dystrophy; mean follow-up, 37 +/- 16 months) or with a hand-held motor trephine (Microkeratron; Geuder) ( CONTROL 53 keratoconus, 38 Fuchs dystrophy; mean follow-up, 38 +/- 14 months). Subjective refractometry (trial glasses), standard keratometry (Zeiss), and corneal topography analysis (TMS-1; Tomey) were performed before surgery, before removal of the first suture (15.2 +/- 4.2 months), and after removal of the second suture (21.4 +/- 5.6 months). MAIN OUTCOME MEASURES Keratometric and topographic net astigmatism as well as refractive cylinder; keratometric and topographic central power; best-corrected visual acuity (VA); surface regularity index (SRI), surface asymmetry index (SAI), and potential visual acuity (PVA) of the TMS-1. RESULTS Before suture removal, mean refractive/keratometric/topographic astigmatism did not differ significantly between EXCIMER (2.5 +/- 1.8 diopters [D]/3.4 +/- 2.8 D/4.7 +/- 3.1 D) and CONTROL groups (3.0 +/- 1.8 D/3.7 +/- 2.4 D/4.3 +/- 2.1 D). After suture removal, respective values were significantly lower in the EXCIMER group (2.8 +/- 2.0 D/3.0 +/- 2.1 D/3.8 +/- 2.6 D) than in the CONTROL group (4.2 +/- 2.4 D/6.1 +/- 2.7 D/6.7 +/- 3.1 D) (P < 0.0009). In the EXCIMER versus CONTROL group, mean VA increased from 20/100 versus 20/111 (P > 0.05) before surgery, to 20/31 versus 20/38 before (P = 0.001) and to 20/28 versus 20/39 (P < 0.00001) after suture removal. Mean spherical equivalent was significantly less myopic in the EXCIMER group before (-0.9 +/- 3.6 D vs. -2.6 +/- 3.4 D) (P = 0.01) and after suture removal (-1.4 +/- 3.1 D vs. -2.4 +/- 3.5 D) (P = 0.02). Mean SRI (P = 0.04) and PVA (P = 0.007) were significantly more favorable in the EXCIMER versus CONTROL group after suture removal (0.91 +/- 0.45 and 0.82 +/- 0.15 vs. 1.05 +/- 0.46 and 0.73 +/- 0.18). CONCLUSIONS Postkeratoplasty results seem to be superior using nonmechanical excimer laser trephination. Thus, this methodology is recommended as the procedure of first choice in avascular corneal pathologies requiring PK.

Evaluation of corneal flap dimensions and cut quality using the Automated Corneal Shaper microkeratome.

PURPOSE To evaluate flap dimensions and cut deterioration with repeated blade use in an automated microkeratome. METHODS The Automated Corneal Shaper (Chiron-Adatomed, Munich, Germany), 160-microm plate attached, was used to make a corneal flap in 90 pig cadaver eyes, reusing blades up to five times. Flap diameter was measured by planimetry and thickness was calculated by ultrasound pachymetry. Scanning electron microscopy of stromal beds and blade cutting edges was performed to assess cut deterioration after repeated blade use. RESULTS Mean flap central thickness was 125 +/- 32 microm. Mean vertical flap diameter was 7.6 +/- 0.4 mm. No correlation was found between thickness and diameter (r = 0.15, P = .45). Progressive thinning of the flap was observed in the direction of the flap hinge. Smooth cuts (using new blades) with periodic chatter lines at the keratectomy edge and in the stromal bed were observed with scanning electron microscopy. Increasing tissue remnants on the stromal bed and decreasing cut quality occurred with repeated blade use. Blades showed larger tissue remnants, nicks, and even folds on the cutting edge proportional to the number of times blades were used. CONCLUSION Satisfactory cut quality and reproducibility were obtained after a single use of stainless steel blades in the Automated Corneal Shaper microkeratome. Cut quality was degraded dramatically by repeated use of blades.

Evaluation of corneal flap dimensions and cut quality using a manually guided microkeratome.

BACKGROUND To evaluate reproducibility of corneal flap dimensions and cut quality with repeated blade use with a manually guided microkeratome in pig eyes. METHODS Corneal flaps were created using a manually guided microkeratome (Model One, Moria) with an intended 130-microns cut depth in 130 enucleated pig eyes. Flap thickness was calculated by pachymetry and diameter was estimated by means of applanation lenses compared to planimetry. Histology and scanning electron microscopy of samples and blades were performed to evaluate the keratectomy surface and blade cutting edge after repeated use of the blades. RESULTS Mean flap central thickness was 135 microns (SD, 37 microns). The mean diameter of 8.4 mm (SD, 0.4 mm) correlated significantly (P < .001) to the intended diameter (r = .79). Mean difference from the intended diameter was 0.8 mm (SD, 0.3 mm; range, 0.04 to 1.4 mm). Scanning electron microscopy showed even and smooth cuts with chatter lines at the keratectomy edge using new blades. After repeated blade use, increasing cut irregularity, folds, and tissue remnants on the corneal bed surface, and nicks and tissue remnants at the cutting edge of the blades were observed. CONCLUSION Reproducible flap dimensions were obtained using the Moria One microkeratome on pig eyes. The cut surface was regular and smooth with a new blade, but surface quality deteriorated considerably after repeated use of the same blade.

Orientation teeth in non-mechanical laser corneal trephination for penetrating keratoplasty: 2.94 µm Er:YAG v 193 nm ArF excimer laser

BACKGROUND/AIMS “Orientation teeth” at the donor trephination margin and correspondent “notches” at the host margin facilitate graft orientation and avoid “horizontal torsion” induced by asymmetric suture placement. In this study the quality and reproducibility of these structures created by non-mechanical laser corneal trephination were compared using two laser emissions. METHODS The procedure was performed in 20 enucleated pigs’ eyes using open metal masks with eight “orientation teeth/notches” (0.3 × 0.15 mm, base × height), an automated globe rotation device, and either a 193 nm ArF excimer laser or a Q switched 2.94 μm Er:YAG laser. “Teeth/notches” were analysed by planimetry and scanning electron microscopy (SEM). RESULTS Mean size was 0.30 (0.027) × 0.16 (0.017) mm for “teeth” and 0.30 (0.035) × 0.15 (0.021) mm for “notches” (excimer), and 0.31 (0.022) × 0.16 (0.015) mm and 0.30 (0.031) × 0.14 (0.021) mm respectively (Er:YAG). Overall, variability of notches was higher than that of teeth. By SEM, comparable cut regularity and sustained ablation profile were observed with both lasers. However, the corneal surface at the cut edge appeared slightly elevated (⩽35 μm) in the Er:YAG group. CONCLUSION Orientation teeth/notches resembling those obtained with the excimer laser can be created using the Q switched Er:YAG laser, with potential advantages of lower costs, convenient equipment size, and solid state safety.

Endothelium and pachymetry of clear corneal grafts 15 to 33 years after penetrating keratoplasty

PURPOSE To evaluate long-term endothelial cell count and thickness of clear corneal grafts after penetrating keratoplasty. METHODS Specular microscopy and ultrasonic pachymetry were performed in 20 eyes (14 eyes that were keratoconus, three aphakic/pseudophakic bullous keratopathy, one Fuchs dystrophy, one had herpetic keratitis, and one avascular scar after injury) of 18 patients (mean age +/- SD 58+/-15 years; range, 34 to 82 years) with a mean follow-up of 22+/-6 years (range, 15 to 33 years). RESULTS Mean endothelial cell count was 808+/-194 cells per mm2 (range, 575 to 1243 cells/mm2), and thickness was 608+/-75 microm (range, 430 to 751 microm). Endothelial cell count was neither correlated with thickness (P = .25, r2 = .08) nor with follow-up interval (P = .31, r2 = .028). We observed predominantly enlarged endothelial cells and mild polymegethism. No graft rejections were recorded. CONCLUSION Despite a reduced cell density, the dehydration function of the endothelium may still be sufficient in corneal grafts up to 33 years after penetrating keratoplasty.

Graft endothelium and thickness after penetrating keratoplasty, comparing mechanical and excimer laser trephination: a prospective randomised study.

Abstract Purpose: To assess the impact of nonmechanical trephination on the graft endothelium and thickness after penetrating keratoplasty (PK). Methods: Inclusion criteria for this prospective, randomised, cross-sectional, clinical study were: (1) Treatment between October 1992 and December 1997; (2) one surgeon (G.O.H.N.); (3) primary central PK; (4) Fuchs’ dystrophy (diameter 7.5/7.6 mm) or keratoconus (diameter 8.0/8.1 mm); (5) graft oversize 0.1 mm; (6) no previous intraocular surgery; (7) 16-bite double-running diagonal suture. In 179 patients (mean age 51±18 years), PK was performed using either the 193-nm Meditec MEL60 excimer laser (”Excimer”) along metal masks with eight ”orientation teeth/notches” (53 keratoconus, 35 Fuchs’ dystrophy) or motor trephination with the Mikrokeratron (Geuder) (”Control”: 53 keratoconus, 38 Fuchs’ dystrophy). For donor trephination from the epithelial side an artificial anterior chamber was used in both groups. In 27% of the excimer and 29% of the control group a triple procedure was performed. Specular microscopy (EM-1000, Tomey) and pachymetry (SP-2000, Tomey) were performed before removal of the first suture (0.4±0.2 years postoperatively), before (1.1±0.4 years) and after (1.7±0.6 years) removal of the second suture but before any additional surgical intervention. Results: Endothelial cell count: Neither ”two-sutures-in” (1953±426/1804±385 cells/mm2, p=0.13), ”one-suture-in” (1629±439/1765±440 cells/mm2, p=0.27), nor ”all-sutures-out” (1259±493/1294±532 cells/mm2, p=0.83) differed significantly between Excimer and Control. Graft thickness: Neither ”two-sutures-in” (527±58/524±16 µm, p=0.89), ”one-suture-in” (537±72/551±40 µm, p=0.86), nor ”all-sutures-out” (576±53/565±62 µm, p=0.38) differed significantly between Excimer and Control. Cell count and corneal thickness were not significantly different comparing Fuchs’ dystrophy and keratoconus or comparing PK only and triple procedures. Graft thickness and endothelial cell count correlated highly significantly inversely with ”all sutures out” (P<0.0001). Conclusions: Excimer laser trephination from the epithelial side using an artificial anterior chamber in donors seems to have no disadvantages concerning the graft endothelium after PK. Endothelial cell loss was not increased in eyes with Fuchs’ dystrophy compared with keratoconus or after triple procedures compared with PK only.

Reproduzierbarkeit und Validität eines neuen automatisierten Verfahrens der spiegelmikroskopischen Hornhautendothelanalyse

Ziel dieser prospektiven Studie war die Prüfung der Reproduzierbarkeit eines automatisierten Verfahrens der Hornhautendothelanalyse und die Beurteilung seiner Validität im Vergleich zu einer Standardmethode.Personen und Methoden: Verwendet wurde ein Kontaktspiegelmikroskop mit integrierter Videokamera (Tomey EM-1000) und ein Computer (IBM kompatibler PC, 486DX33) mit zugehöriger Software (Tomey EM-1100, Version 0.94). Grundprinzip des Verfahrens ist die direkte Überführung eines Videoendothelbilds (Fläche: 0,312 mm2) in ein digitalisiertes Computerbild und dessen automatisierte Prozessierung unter Umgehung einer Filmvorlage. Die Methode wurde bei 67 Probanden mit unauffälliger Hornhaut (Alter: 30,9±8,6 Jahre) angewendet. Bei 42 Normalprobanden wurde die Zelldichte 3mal von demselben Untersucher (Retest-Stabilität), bei 25 Probanden je 1mal von 3 verschiedenen Untersuchern (Objektivität) bestimmt. Festgehalten wurden der nach Analyse des Rohbilds vom Rechner ermittelte Zelldichtewert sowie ein 2. Wert nach Korrektur des prozessierten Bilds durch den Untersucher. Zusätzlich wurde die Endothelzelldichte anhand von Photographien (Spiegelmikroskop Bio Optics LSM 2000 A) in Fixed-frame-Technik durch manuelles Auszählen ermittelt (Validität).Ergebnisse: Bezüglich der korrigierten Zelldichtewerte waren sowohl die Reteststabilität (Reliabilitätskoeffizient r = 0,943) als auch die Objektivität (r = 0,904) hoch. Die Werte der automatisierten Methode (2415±214 Zellen/mm2) und nach manuellem Auszählen (2431±228 Zellen/mm2) waren nicht signifikant verschieden (p = 0,898). Die mittlere Abweichung betrug 3,3±2,4%, wobei keine systematische Abweichung in eine Richtung vorlag. Die unkorrigierten Zelldichtewerte (2252±190 Zellen/mm2) lagen im Mittel um 7,2±2,6% unter den korrigierten. Bezüglich der unkorrigierten Werte waren die Reteststabilität (r = 0,856) und die Objektivität (r = 0,737) zufriedenstellend. Der unkorrigierte Wert war gegenüber dem durch manuelles Auszählen ermittelten Wert signifikant erniedrigt (p<0,001).Schlußfolgerung: Das getestete Endothelanalyseverfahren liefert bei normaler Hornhaut schnell zuverlässige und reproduzierbare Ergebnisse, vorausgesetzt, daß vom Korrekturmodus der Software Gebrauch gemacht wird.Purpose: This prospective study was designed to test the reproducibility of a new automated technique for analyzing the corneal endothelium and to assess the validity of the technique by comparing it with a standard method.Subjects and methods: We used a contact specular microscope combined with a video camera (Tomey EM-1000) and a computer (IBM compatible PC, 486DX33) with suitable software (Tomey EM-1100, version 0.94). Video images of the corneal endothelium (area: 0.312 mm2) were passed directly into the computer input by means of a frame grabber and were automatically processed. The area to be analyzed could be varied by location and size (5580 – 135,150 µm2), depending on the quality of the image. Healthy corneas of 67 volunteers (age: 30.9±8.6 years) were examined. One examiner measured cell density three times in each of 42 eyes (retest-stability); three different examiners made one measurement in each of 25 eyes (objectivity). We evaluated the cell density determined by the computer after automated analysis and assessed the corrected cell density. This second result was obtained after the examiner had corrected the processed image by drawing in cell boundaries that the computer had not recognized or erasing cell boundaries the computer had sketched in by mistake. Additionally, a photograph of the corneal endothelium (specular microscope Bio Optics LSM 2000 A) was obtained from 40 volunteers to be used for manual cell counting applying a ,,fixed-frame`` technique (validity).Results: The corrected values showed a high retest-stability (reliability coefficient r = 0.943) and a high objectivity (r = 0.904). The values obtained by the automated method (2415±214 cells/mm2) did not differ significantly from those obtained by manual cell counting (2431±228 cells /mm2) (P = 0.898). The uncorrected values (2252±190 cells/mm2) were on average 7.2±2.6% lower than the corrected ones (177±69 cells/mm2). Retest-stability (r = 0.856) and objectivity (r = 0.737) of the uncorrected values were satisfactory. The uncorrected value was significantly lower than the value of manual cell counting (P<0.001). The size of the analyzed area (range 12,750 – 84,708 µm2; average 31,438±10,655 µm2) had no significant effect on cell density (Spearmans correlation coefficient k = –0.150, P = 0.093).Conclusion: The automated method for analyzing the corneal endothelium quickly produces valid, reproducible results in normal corneas, provided that the correction mode of the software is applied.

Phototherapeutische Kera-tektomie bei rezidivierender Erosio corneae (e-PTK) Bericht über 116 konsekutive Eingriffe

ZusammenfassungHintergrund und Ziele. Patienten mit rezidivierender Erosio corneae können wegen zum Teil exzessiver Schmerzen psychisch und sozial stark belastet sein. Bei Versagen konservativer Therapien wurden konventionelle operative Eingriffe, wie etwa die Hornhautstichelung, vorgeschlagen. Ziel dieser Studie war es, die morphologischen und funktionellen Ergebnisse der minimalinvasiven “Excimerlaser Phototherapeutischen Keratektomie” bei rezidivierender Erosio corneae (e-PTK) unter Berücksichtigung der kumulierten Rezidivrate zu analysieren. Patienten und Methoden. Im Zeitraum von 07/1990 bis 01/2001 wurden im Rahmen einer Singlecenterstudie 116 e-PTKs bei rezidivierender Erosio corneae in der Regel in der Akutphase durchgeführt. Extern war bei 15 Augen eine erfolglose PTK vorausgegangen. Ursachen der Erosio waren 80-mal ein Trauma, 14-mal eine Cogan-Epitheldystrophie, 2-mal eine Keratopathia bullosa, 20-mal war eine Ursache nicht eruierbar. Hierbei wurden 99-mal im manuell geführten Fleckprofil (Pulsenergie um 10 mJ, Repetitionsrate 2/s bzw. 3/s, 66–330 Pulse) und 17-mal im Scanning-Slit-Verfahren (intendierte Ablation pro Scan 1 μm, Repetitionsrate 20/s, 447–1.017 Pulse) Laserpulse defokussiert nach großflächiger Abrasio corneae überlappend appliziert. Ergebnisse. Bis zum vollständigen Epithelschluss dauerte es im Mittel 2,3±1,3 (Median 2) Tage. Die Beobachtungsdauer betrug im Mittel 2,2±1,6, maximal 5,6 Jahre. Der bestkorrigierte Visus stieg von 0,6±0,4 präoperativ auf 0,9±0,3 postoperativ an. Die keratometrische zentrale Brechkraft blieb konstant (präoperativ 43,0±2,2 D, postoperativ 43,3±1,9 D). Der mediane keratometrische Astigmatismus blieb konstant bei 1,0 D. Bei 2 Patienten wurde in der Lernphase iatrogen ein nicht komplett reversibler irregulärer Astigmatismus von mehr als 2 D induziert. Das sphärische Äquivalent blieb annähernd konstant (−1,0±3,3 D präoperativ, −1,1±3,4 D postoperativ). Bei 9 Patienten (7,8%) trat nach 2–24 (im Mittel 8±6) Monaten ein Rezidiv auf. Die kumulierte 1-Jahres-Rezidivrate betrug 6,5%, die 2-Jahres-Rezidivrate 11,5%, die 3-, 4-, und 5-Jahres-Rezidivrate betrug 13,6%. Schlussfolgerungen. Bei rezidivierender Erosio corneae lässt sich mit der e-PTK bei niedriger Pulsenergie und Pulszahl ein schneller und zumeist dauerhafter Epithelschluss erzielen. Auch nach großflächiger Entfernung des lockeren Epithels kommt es nur extrem selten zu einer Refraktionsänderung oder gar der Induktion eines irregulären Astigmatismus mit Visusverlust.AbstractBackground and aims. Patients with recurrent corneal erosion syndrome can suffer both psychologically and socially due to excessive pain. After the failure of conservative treatment, conventional surgical interventions, such as anterior stromal puncture have been suggested. The purpose of this study was to assess the morphological and functional results of minimally invasive excimer laser phototherapeutic keratectomy (e-PTK) for treatment of recurrent corneal erosion syndrome and in particular, to evaluate the cumulative recurrence rate. Patients and methods. Between July 1990 and January 2001, 116 e-PTKs have been performed mostly in the acute stage of the disease in this single center study. In 15 eyes an unsuccessful PTK had previously been performed elsewhere. Reasons for the erosion included trauma (n=80), Cogans epithelial dystrophy (n=14), bullous keratopathy (n=2), and in 20 cases no cause could be detected. A manually guided spot profile was applied in 99 cases (pulse energy 10 mJ, repetition rate 2/s or 3/s, 66–330 pulses). In 17 cases a scanning slit procedure was applied (intended ablation per scan 1 μm, repetition rate 20/s, 447–1,017 pulses). The broad deepithelialisation of Bowmans layer was treated with defocussed overlapping laser pulses. Results. Complete epithelial closure was achieved after an average of 2.3±1.3 (median 2) days, the mean follow-up was 2.2±1.6 years with a maximum of 5.6 years. Best corrected visual acuity increased from 0.6±0.4 preoperatively to 0.9±0.3 postoperatively. The keratometric central power remained constant (preoperative 43.0±2.2 D (diopters), postoperative 43.3±1.9 D). The median keratometric astigmatism remained constant at 1.0 D. Only in 2 patients was an iatrogenic, not completely reversible irregular astigmatism of more than 2 D induced during the learning curve. The spherical equivalent did not change significantly (−1.0±3.3 D preop., −1.1±3.4 D postop.). In 9 eyes (7.8%) a recurrent epithelial defect occurred after 2–24 (average 8±6) months. The cumulative 1-year recurrence rate was 6.5%, the 2-year recurrence rate was 11.5%, the 3-, 4-, and 5-year recurrence rates were all 13.6%. Conclusions. For recurrent corneal erosion syndrome, e-PTK performed with low pulse energy and low number of pulses can be considered an effective treatment modality to achieve a fast and mostly durable epithelial closure. Even after broad removal of the loose epithelium, change of refraction or induction of an irregular astigmatism with visual loss seems to be the exception.

Elliptical nonmechanical corneal trephination: intraoperative complications and long-term outcome of 42 consecutive excimer laser penetrating keratoplasties.

Purpose: To assess intraoperative complications and long-term outcome of elliptical excimer laser trephination for penetrating keratoplasties (EELPKs) performed at the Friedrich-Alexander University of Erlangen, between 1989 and 2002. Methods: This was a retrospective, longitudinal, single-center, clinical, interventional case series. Forty-two eyes (14 Fuchs dystrophy, 11 corneal ulcer, 7 aphakic/pseudophakic bullous keratopathy, 9 corneal scars, 1 keratotorus) after EELPK were observed. Trephination was performed with a 193-nm Meditec excimer laser along metal masks with 0-8 orientation teeth/notches. Horizontal/vertical graft diameters ranged from 7.0/6.0 to 8.0/7.0 mm, and 12 to 24 interrupted sutures were used. Simultaneously, 11 eyes (26.2%) underwent cataract surgery, 3 (7.1%) underwent intraocular lens (IOL) exchange, and 1 (2.4%) underwent secondary IOL implantation. The main outcome measures included intraoperative complications, immune reactions, and final astigmatism/visual acuity at the end of follow-up. Results: During surgery, 4 (9.5%) recipients had iris bleedings, and 10 (23.8%) ring-shaped superficial corneal thermal donor damages were detected. One (2.4%) immunologic graft rejection was seen in Fuchs dystrophy, and 3 (7.1%) in corneal ulcers occurred during follow-up (4.7 ± 3.2 years). At the end of follow-up, corrected visual acuity (0.1/0.4; P < 0.001) and keratometric astigmatism (2.3 D/4.7 D, P = 0.001) increased significantly. Conclusions: In EELPK, intraoperative disadvantages, such as the need for interrupted sutures and a tendency toward higher and more irregular astigmatism, may be expected. This study does not have the power to statistically confirm the tendency of EELPK toward a lower rate of immunologic graft rejections after normal-risk keratoplasty. However, EELPK may have advantages in deep or perforated elliptically shaped corneal ulcers (such as in acanthamoeba keratitis).

[Phototherapeutic keratectomy for recurrent corneal erosion syndrome (e-PTK). Report on 116 consecutive interventions].

ZusammenfassungHintergrund und Ziele. Patienten mit rezidivierender Erosio corneae können wegen zum Teil exzessiver Schmerzen psychisch und sozial stark belastet sein. Bei Versagen konservativer Therapien wurden konventionelle operative Eingriffe, wie etwa die Hornhautstichelung, vorgeschlagen. Ziel dieser Studie war es, die morphologischen und funktionellen Ergebnisse der minimalinvasiven “Excimerlaser Phototherapeutischen Keratektomie” bei rezidivierender Erosio corneae (e-PTK) unter Berücksichtigung der kumulierten Rezidivrate zu analysieren. Patienten und Methoden. Im Zeitraum von 07/1990 bis 01/2001 wurden im Rahmen einer Singlecenterstudie 116 e-PTKs bei rezidivierender Erosio corneae in der Regel in der Akutphase durchgeführt. Extern war bei 15 Augen eine erfolglose PTK vorausgegangen. Ursachen der Erosio waren 80-mal ein Trauma, 14-mal eine Cogan-Epitheldystrophie, 2-mal eine Keratopathia bullosa, 20-mal war eine Ursache nicht eruierbar. Hierbei wurden 99-mal im manuell geführten Fleckprofil (Pulsenergie um 10 mJ, Repetitionsrate 2/s bzw. 3/s, 66–330 Pulse) und 17-mal im Scanning-Slit-Verfahren (intendierte Ablation pro Scan 1 μm, Repetitionsrate 20/s, 447–1.017 Pulse) Laserpulse defokussiert nach großflächiger Abrasio corneae überlappend appliziert. Ergebnisse. Bis zum vollständigen Epithelschluss dauerte es im Mittel 2,3±1,3 (Median 2) Tage. Die Beobachtungsdauer betrug im Mittel 2,2±1,6, maximal 5,6 Jahre. Der bestkorrigierte Visus stieg von 0,6±0,4 präoperativ auf 0,9±0,3 postoperativ an. Die keratometrische zentrale Brechkraft blieb konstant (präoperativ 43,0±2,2 D, postoperativ 43,3±1,9 D). Der mediane keratometrische Astigmatismus blieb konstant bei 1,0 D. Bei 2 Patienten wurde in der Lernphase iatrogen ein nicht komplett reversibler irregulärer Astigmatismus von mehr als 2 D induziert. Das sphärische Äquivalent blieb annähernd konstant (−1,0±3,3 D präoperativ, −1,1±3,4 D postoperativ). Bei 9 Patienten (7,8%) trat nach 2–24 (im Mittel 8±6) Monaten ein Rezidiv auf. Die kumulierte 1-Jahres-Rezidivrate betrug 6,5%, die 2-Jahres-Rezidivrate 11,5%, die 3-, 4-, und 5-Jahres-Rezidivrate betrug 13,6%. Schlussfolgerungen. Bei rezidivierender Erosio corneae lässt sich mit der e-PTK bei niedriger Pulsenergie und Pulszahl ein schneller und zumeist dauerhafter Epithelschluss erzielen. Auch nach großflächiger Entfernung des lockeren Epithels kommt es nur extrem selten zu einer Refraktionsänderung oder gar der Induktion eines irregulären Astigmatismus mit Visusverlust.AbstractBackground and aims. Patients with recurrent corneal erosion syndrome can suffer both psychologically and socially due to excessive pain. After the failure of conservative treatment, conventional surgical interventions, such as anterior stromal puncture have been suggested. The purpose of this study was to assess the morphological and functional results of minimally invasive excimer laser phototherapeutic keratectomy (e-PTK) for treatment of recurrent corneal erosion syndrome and in particular, to evaluate the cumulative recurrence rate. Patients and methods. Between July 1990 and January 2001, 116 e-PTKs have been performed mostly in the acute stage of the disease in this single center study. In 15 eyes an unsuccessful PTK had previously been performed elsewhere. Reasons for the erosion included trauma (n=80), Cogans epithelial dystrophy (n=14), bullous keratopathy (n=2), and in 20 cases no cause could be detected. A manually guided spot profile was applied in 99 cases (pulse energy 10 mJ, repetition rate 2/s or 3/s, 66–330 pulses). In 17 cases a scanning slit procedure was applied (intended ablation per scan 1 μm, repetition rate 20/s, 447–1,017 pulses). The broad deepithelialisation of Bowmans layer was treated with defocussed overlapping laser pulses. Results. Complete epithelial closure was achieved after an average of 2.3±1.3 (median 2) days, the mean follow-up was 2.2±1.6 years with a maximum of 5.6 years. Best corrected visual acuity increased from 0.6±0.4 preoperatively to 0.9±0.3 postoperatively. The keratometric central power remained constant (preoperative 43.0±2.2 D (diopters), postoperative 43.3±1.9 D). The median keratometric astigmatism remained constant at 1.0 D. Only in 2 patients was an iatrogenic, not completely reversible irregular astigmatism of more than 2 D induced during the learning curve. The spherical equivalent did not change significantly (−1.0±3.3 D preop., −1.1±3.4 D postop.). In 9 eyes (7.8%) a recurrent epithelial defect occurred after 2–24 (average 8±6) months. The cumulative 1-year recurrence rate was 6.5%, the 2-year recurrence rate was 11.5%, the 3-, 4-, and 5-year recurrence rates were all 13.6%. Conclusions. For recurrent corneal erosion syndrome, e-PTK performed with low pulse energy and low number of pulses can be considered an effective treatment modality to achieve a fast and mostly durable epithelial closure. Even after broad removal of the loose epithelium, change of refraction or induction of an irregular astigmatism with visual loss seems to be the exception.