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

• Published in: Ophthalmology (Rochester, Minn.) Vol. 106; no. 6; pp. 1156 - 1165
• Main Authors: Seitz, Berthold, Langenbucher, Achim, Kus, Murat M, Küchle, Michael, Naumann, Gottfried O.H
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.1999
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Astigmatism - prevention & control; Cornea - surgery; Corneal Diseases - surgery; Corneal Topography; Cross-Sectional Studies; Double-Blind Method; Female; Humans; Keratoplasty, Penetrating - methods; Lasers, Excimer; Male; Middle Aged; Photorefractive Keratectomy; Prospective Studies; Refraction, Ocular; Tissue Donors; Treatment Outcome; Visual Acuity
• ISSN: 0161-6420; 1549-4713
• DOI: 10.1016/S0161-6420(99)90265-8

To assess the impact of nonmechanical trephination on the outcome after penetrating keratoplasty (PK). Prospective, randomized, cross-sectional, clinical, single-center study. 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. 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). 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. 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). 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.