98th Annual Meeting DOG 2000

V 35

Intraocular pressure after penetrating keratoplasty for keratoconus and Fuchs' dystrophy – comparison of mechanical and laser trephination

B. Seitz, A. Langenbucher, N. X. Nguyen, M. Küchle, G. O. H. Naumann

Background and Purpose: In the literature the incidence of "secondary glaucoma" after penetrating keratoplasty (PK) is reported to range from 10% to 35%. The purpose of this study was to assess the impact of the trephination method on the intraocular pressure (IOP) after PK in a positively selected group of patients.

Patients and Methods: Inclusion criteria for this prospective, randomized, cross-sectional, clinical study were: (1) One surgeon (G.O.H.N.), (2) Primary central PK, (3) Fuchs' dystrophy (7.5/7.6 mm) or keratoconus (8.0/8.1 mm), (4) 16-bite double running diagonal suture. Exclusion criteria were: (1) Previous intraocular surgery, (2) Preoperative glaucoma, (3) Postoperative trauma or endophthalmitis. In 170 patients (mean age 51 ± 18 years), PK was performed using either the 193-nm Meditec excimer laser (EXCIMER) along metal masks with eight "orientation teeth/notches" (50 keratoconus, 32 Fuchs') or motor trephination with the Mikrokeratron (Geuder, Germany) (CONTROL: 53 keratoconus, 35 Fuchs'). In 27% of EXCIMER and 29% of CONTROL a triple procedure was performed. The perioperative systemic acetazolamide application and the postoperative topical steroid therapy were standardized.

Results: In the EXCIMER group the maximal IOP during the first week after PK was 15.7 ± 3.6 (7% > 21, max. 28) mmHg, in the CONTROL group it was 16.2± 3.5 (7% > 21, max. 30) mmHg. During the follow-up of 3.3± 1.4 or 3.5± 1.2 years, respectively, an IOP > 21 mmHg and/or application of topical antiglaucomatous medication was documented in 9% of EXCIMER and 15% of CONTROL (p = 0.32), or in 15% of Fuchs' dystrophy and 11% of keratoconus (p = 0.41). The individually maximal IOP during the entire follow-up was 16.6 ± 3.5 (12 to 38) mmHg in the EXCIMER group and it was 17.2± 3.2 (12 to 30) mmHg in the CONTROL group. The IOP elevation started on average 3.7± 2.8 months (1 week to 9 months) post PK and ended on average 6.5± 3.1 months (6 weeks to 12 months) post PK. Only in one patient after triple procedure in Fuchs' dystrophy the elevated IOP lasted from 32 months post PK until the end of follow-up. However, neither in this nor in any of the other patients, a glaucomatous optic disc atrophy developed.

Conclusions: In eyes with keratoconus and Fuchs' dystrophy without previous surgery, rarely a temporary "secondary ocular hypertension after PK" occurs without detectable impact of the trephination method. With a standardized surgical technique and an uncomplicated postoperative course, the development of a secondary glaucoma seems to be the exception.

Department of Ophthalmology, University of Erlangen-Nürnberg, Schwabachanlage 6, D-91054 Erlangen