Nonmechanical corneal trephination with the excimer laser improves outcome after penetrating keratoplasty.
OBJECTIVE
To assess the impact of nonmechanical trephination on the outcome after penetrating keratoplasty (PK).


METHODS
Prospective, randomized, cross-sectional, clinical, single-center study.


METHODS
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.


METHODS
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) (


METHODS
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).


METHODS
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.
Seitz
B
B
Department of Ophthalmology, University of Erlangen-Nürnberg, Erlangen, Germany. berthold.seitz@augen.med.uni-erlangen.de
Langenbucher
A
A
Kus
M M
MM
Küchle
M
M
Naumann
G O
GO
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000517:prevention & control; D003315:Cornea / Q000601:surgery*; D003316:Corneal Diseases / Q000601:surgery*; D019781:Corneal Topography; D003430:Cross-Sectional Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D015948:Keratoplasty, Penetrating / Q000379:methods*; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D018903:Photorefractive Keratectomy; D011446:Prospective Studies; D012029:Refraction, Ocular; D014019:Tissue Donors; D016896:Treatment Outcome; D014792:Visual Acuity