Long-term follow-up of Intraocular pressure after penetrating keratoplasty for keratoconus and Fuchs' dystrophy -: Comparison of mechanical and excimer laser trephination

Purpose. In the literature, the incidence of secondary glaucoma after penetrating keratoplasty (PK) is reported to range from 10% to 42%, depending on the diagnosis and the complexity of surgery. The purpose of this study was to assess the impact of the trephination method and simultaneous cataract surgery on the early and long-term intraocular pressure (IOP) after PK in eyes without previous surgery and glaucoma. Methods. Inclusion criteria for this prospective, randomized, longitudinal 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), and (4) 16-bite double running diagonal suture. Exclusion criteria were (1) previous intraocular surgery, (2) preoperative glaucoma. and (3) postoperative trauma or endophthalmitis. In 170 patients (mean age, 51 18 years), PK was performed with use of either a 193-nm excimer laser (Excimer patients) along metal masks with eight orientation teeth/notches (50 keratoconus, 32 Fuchs') or motor trephination (Control patients; 53 keratoconus, 35 Fuchs'). In 27% of Excimer patients and 29% of Control patients a triple procedure was performed. The perioperative systemic acetazolamide application and the postoperative topical steroid therapy were standardized. Results. Maximal IOP during the first week after PK was 15.7+/-3.6 mm Hg (7%>21; maximum, 28) in the Excimer group and 16.2+/-3.5 mm Hg (7%>21; maximum, 30) in the Control group. During a mean follow-up of 3.4+/-1.3 years (maximal, 6.0), an IOP p >21 mm Hg and/or application of topical antiglaucomatous medication was documented in 9% of Excimer patients versus 15% of Control patients (p=0.32), in 15% of Fuchs' dystrophy versus 11% of keratoconus cases (p=0.41), and in 11% of PK-only versus 15% of triple-procedure cases (p=0.68). The IOP elevation started an average of 3.7+/-2.8 months (1 week to 9 months) after PK and ended an average of 6.5+/-3.1 months (6 weeks to 12 months) after PK. Mean maximal IOP during follow-up was 16.6+/-3.5 min Hg (12-38) in the Excimer group and 17.2+/-3.2 mm Hg (12-30) in the Control group. Only one patient, who had undergone a triple procedure for Fuchs' dystrophy and had an elevated IOP, needed topical medication, from 32 months after PK to the end of follow-up, Glaucomatous optic disc damage was clinically detected in none of the patients. Conclusions. Temporary secondary ocular hypertension after, PK is rare in eyes with keratoconus or Fuchs' dystrophy without previous surgery. There was no detectable impact from the trephination method, the diagnosis, or simultaneous cataract surgery. With meticulous microsurgical technique, careful suturing, and peripheral iridotomy the development of secondary glaucoma with disc cupping seems to be the exception.