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

Purpose: To assess the impact of nonmechanical trephination on the graft en dothelium and thickness after penetrating keratoplasty CPK). Methods: Inclu sion criteria for this prospective, randomised, cross-sectional, clinical s tudy were: (1) Treatment between October 1992 and December 1997; (2) one su rgeon (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 su ture. In 179 patients (mean age 51+/-18 years), PK was performed using eith er the 193-nm Meditec MEL60 excimer laser ("Excimer") along metal masks wit h eight "orientation teeth/notches" (53 keratoconus, 35 Fuchs' dystrophy) o r motor trephination with the Mikrokeratron (Geuder) ("Control": 53 keratoc onus, 38 Fuchs' dystrophy). For donor trephination from the epithelial side an artificial anterior chamber was used in both groups. In 27% of the exci mer 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), befo re (1.1+/-0.4 years) and after (1.7+/-0.6 years) removal of the second sutu re but before any additional surgical intervention. Results: Endothelial ce ll count: Neither "two-sutures-in" (1953+/-426+/-1804+/-385 cells/mm(2), p= 0.13), "one-suture-in" (1629+/-439/1765+/-440 cells/mm(2), p=0.27), nor "al l-sutures-out" (1259+/-393/1294+/-532 cells/mm(2), p=0.83) differed signifi cantly between Excimer and Control. Graft thickness: Neither "two-sutures-i n" (527+/-58/524+/-16 mum, p=0.89), "one-suture-in" (537+/-72/551+/-40 mum, p=0.86), nor "all-sutures-out" (576+/-53/565+/-62 mum, p=0.38) differed si gnificantly between Excimer and Control. Cell count and corneal thickness w ere 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 s ide using an artificial anterior chamber in donors seems to have no disadva ntages concerning the graft endothelium after PK. Endothelial cell loss was not increased in eyes with Fuchs' dystrophy compared with keratoconus or a fter triple procedures compared with PK only.