Korean J Ophthalmol.  2013 Oct;27(5):322-330. 10.3341/kjo.2013.27.5.322.

Comparison of Clinical Outcomes of Same-size Grafting between Deep Anterior Lamellar Keratoplasty and Penetrating Keratoplasty for Keratoconus

• Oh BL
• Kim MK
• Wee WR

• KMID: 1707285
• DOI: http://doi.org/10.3341/kjo.2013.27.5.322

Abstract

PURPOSE
To compare the clinical outcomes between deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) with same-size grafts in patients with keratoconus.
METHODS
Medical records of 16 eyes from 15 patients treated from June 2005 through April 2011 were retrospectively reviewed. Patients with contact lens intolerance or who were poor candidates for contact lens fitting due to advanced cone underwent keratoplasty. The transplantations consisted of 11 DALK and 5 PKP with same-size grafting for keratoconus. Best-corrected visual acuity (BCVA), refractive error, corneal topographic profiling, and clinical course were compared between DALK and PKP groups.
RESULTS
The follow-up period was 30 +/- 17 months in the DALK group and 45 +/- 20 months in the PKP group (p = 0.145). At final follow-up, the DALK and PKP groups achieved a BCVA (logarithm of the minimum angle of resolution) of 0.34 and 0.52, respectively (p = 0.980). Postoperative refractive error and mean simulated keratometric index showed myopic astigmatism in both groups without any statistical difference. Corneal irregularity index measured at 5 mm in the DALK group was less than that of the PKP group at 1-year follow-up (p = 0.021); however, at final follow-up, there was no longer a statistically significant difference. Endothelial cell counts were lower in the PKP group than in the DALK group at final follow-up (p = 0.021).
CONCLUSIONS
The optical outcomes of DALK with same-size grafts for keratoconus are comparable to those of PKP. Endothelial cell counts are more stable in DALK compared to PKP.

Keyword

Corneal transplantation; Keratoconus; Penetrating keratoplasty

MeSH Terms

Adult
Cornea/pathology/surgery
Corneal Topography
Female
Follow-Up Studies
Humans
Keratoconus/pathology/physiopathology/*surgery
Keratoplasty, Penetrating/*methods
Male
*Refraction, Ocular
Retrospective Studies
Time Factors
Tissue and Organ Harvesting/*methods
Treatment Outcome

Figure

• 

  Fig. 1 The change in (A) spherical equivalent, (B) astigmatism, (C) 3-mm zone irregular astigmatism, and (D) 5-mm zone irregular astigmatism at 1-year and final follow-up after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) with same-size donor graft. (A) Postoperative spherical equivalent refractive error was not different between DALK and PKP groups. (B) The incidence of astigmatism was not different between DALK and PKP groups for all follow-up periods. (C) Corneal irregularity indices measuring 3 mm were similar in DALK and PKP groups at all follow-up periods. (D) 5-mm corneal irregularity indices were less in the DALK group than in the PKP group at 1-year follow-up; however, there was only marginal significance at final follow-up (p = 0.084). Solid arrow: mean time of final suture removal in the PKP group. *Statistically significant (p < 0.05, Mann-Whitney test). (*) Marginal significance (0.05 < p < 0.10, Mann-Whitney test).

• 

  Fig. 2 (A) Illustration of the equilibrium of forces acting on the graft. Tensile forces of the peripheral recipient cornea act downward and counteract the 2 upward forces provided by the pressure of the aqueous humor and the pushing force of the recipient bed against the graft. (B) Illustration of a flattened recipient bed when the stiffness of the residual recipient bed decreases (for example, in a thinner residual bed). The graft exerts effective compressive force on the recipient bed, which flattens easily, resulting in flattening of the graft. (C) Illustration of a steepened graft when the stiffness of the residual recipient bed increases (for example, in a thicker residual bed) and stiffness of the peripheral corneal decreases (for example, in the thinner peripheral cornea seen in advanced keratoconus cases). The residual cornea would resist the flattening force exerting downward pressure, resulting in steepening of the graft.

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