Purchase this article with an account.
Y. Qian, W. J. Dupps, Jr., D. J. Covert, S. B. Koenig, D. M. Meisler; Graft Thickness Profile and Refractive Shift After Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK). Invest. Ophthalmol. Vis. Sci. 2007;48(13):4717.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To evaluate donor corneal thickness profiles using very high frequency arc-scanning ultrasound (VHF US) after Descemet’s stripping automated endothelial keratoplasty (DSAEK) and to relate shape to postoperative refractive change.
VHF US corneal imaging (Artemis II, Ultralink LLC, St. Petersburg, FL) was performed at 9 postoperative visits in 7 patients enrolled in a prospective IRB-approved study of DSAEK. Donor lenticles were procured with either a 300-um LSK (n=4 patients) or CB (n=3) microkeratome (Moria, Antony, FR). Six meridional VHF US arc scans were obtained at visits ranging from 1 week to 12 months after surgery, and the ArtPro v1.50 software package was used to construct maps of total corneal, epithelial, host and donor thickness profiles. A rectangular region 2mm in height and spanning 40 0.1mm intervals along the horizontal meridian was defined for graft thickness profile analysis. Each profile was fit by a quadratic regression and the second order coefficient representing the bulk curvature of the graft was extracted.
Mean central graft thicknesses derived from Artemis images across all postoperative visits ranged from 137 to 407 um. Donor lenticles were clearly thicker in the periphery in 5 out of 7 patients. In the group with the largest hyperopic shifts (+2.50D, n=3 at 6 months postop), a strong negative lens effect was predicted by the curvature coefficient (mean +22.72, range +4.95 to +45.17) and unequivocal U-shaped thickness plots. In the group with minimal refractive shifts (+0.50 to -0.50D, n=3), the coefficients were more neutral (mean +7.28, range +2.01 to +13.82). Two of these patients had U-shaped plots. The lone patient who experienced a myopic shift (-1.00D) also had the only negative (myopically-biased) curvature coefficient (-0.643).
Transplanted donor lenticles typically exhibited nonuniform thicknesses and an overall posterior convex meniscus shape. This morphology favors a decrease in the radius of curvature of the posterior cornea, which together with increased postoperative corneal thickness could cause a hyperopic shift based on optic principles. The shape of the graft may be related to current microkeratome-based techniques for procuring the donor cornea. Measurement of graft and host deturgescence over time could facilitate studies of refractive error and optimization of graft preparation methods.
This PDF is available to Subscribers Only