The regularity of laser keratectomy depth in nonmechanical trephination for penetrating keratoplasty.

Abstract

BACKGROUND AND OBJECTIVES:

To study the regularity of laser keratectomy depth in nonmechanical trephination for penetrating keratoplasty (PK) and to assess its implications on astigmatism and visual acuity (VA).

PATIENTS AND METHODS:

In this retrospective clinicopathologic study, the authors enrolled 26 women and 32 men (mean age 54 +/- 20 years) with either keratoconus (n = 27) or Fuchs' dystrophy (n = 31), who underwent excimer laser (193 nm) trephination using a manually guided beam. Donor cornea trephination was performed using an artificial anterior chamber and either an automated rotation device (n = 27) or a manually guided beam (n = 31). The minimum residual corneal thickness (MRCT) and the random residual corneal thickness (RRCT), requiring division with scissors in excised patient buttons or corneoscleral donor rims, were assessed in a masked fashion using histologic sections. The postkeratoplasty keratometric net astigmatism, the subjective cylinder, and the VA were evaluated before and after suture removal.

RESULTS:

In patients with keratoconus, the mean MRCT (13% +/- 14%) and RRCT (38% +/- 20%) were significantly higher than in the patients with Fuchs' dystrophy (7% +/- 11% and 26% +/- 15%, respectively) (P < .01). When an automated rotation device for trephination of the donor cornea was used, the mean MRCT (2% +/- 4%) and RRCT (14% +/- 11%) were significantly smaller than when a manually guided laser beam was employed (15% +/- 12% and 38% +/- 15%, respectively) (P < .001). After suture removal, the VA increased significantly with automated trephination (P = .04), but not with manually guided trephination of the donor cornea (P = .24). However, after a mean follow-up of 30 +/- 8 months, the differences in the mean keratometric astigmatism, refractive cylinder, and VA after automated trephination (3.0 D, 2.6 D, 20/29, respectively) compared with those after manually guided trephination of the donor cornea (4.3 D, 3.9 D, 20/33, respectively) did not reach statistical significance.

CONCLUSIONS:

The regularity of donor trephination depth can be significantly improved by using an automated rotation device instead of a manually guided beam. Although residual postkeratoplasty astigmatism was not directly related to trephination depth, the improvement of the functional results after suture removal seems to be promoted by automated trephination.

• Authors: B Seitz, A Langenbucher, S Fischer, M M Kus, E Vilchis, G O Naumann
• Journal: Ophthalmic surgery and lasers (Ophthalmic Surg Lasers) Vol. 29 Issue 1 Pg. 33-42 (Jan 1998) ISSN: 1082-3069 [Print] United States
• PMID: 9474598 (Publication Type: Comparative Study, Journal Article)

Topics

• Astigmatism (etiology, pathology)
• Cornea (surgery)
• Female
• Follow-Up Studies
• Fuchs' Endothelial Dystrophy (pathology, surgery)
• Humans
• Keratoconus (surgery)
• Keratoplasty, Penetrating (adverse effects, methods)
• Laser Therapy (instrumentation, methods)
• Male
• Middle Aged
• Postoperative Complications (etiology)
• Refraction, Ocular
• Retrospective Studies
• Suture Techniques
• Tissue Donors
• Treatment Outcome
• Visual Acuity