Multivariate model of refractive shift in Descemet-stripping automated endothelial keratoplasty.
OBJECTIVE
To relate in situ graft shape in Descemet-stripping automated endothelial keratoplasty (DSAEK) to surgically induced refractive error.


METHODS
Academic eye institute.


METHODS
High frequency arc-scanning ultrasound was performed in 7 patients enrolled in a prospective study of microkeratome-assisted endothelial keratoplasty approved by the Investigative Review Board. A region of interest spanning the horizontal meridian was defined for analysis of epithelial, host, graft, and total corneal thicknesses. Graft thickness profiles were fit by quadratic polynomials where the 2nd-order coefficients represent the posterior corneal curvature contributed by the graft. The curvature coefficient and central graft thickness were analyzed as predictors of induced refractive error.


RESULTS
At final follow-up (mean 5.9 months +/- 3.2 [SD]), 3 patients had a hyperopic shift (+2.50 diopters [D] each), 3 had insignificant (< 0.50 D) refractive shifts, and 1 had a myopic shift. In the group with hyperopic shift, a negative lens effect was predicted by positive curvature coefficients, representing grafts that were thinner centrally than peripherally (mean +22.72 microm/mm(2); range +4.95 to +45.17 microm/mm(2)). In the group with minimal refractive shift, coefficients were less positive (mean +7.28 microm/mm(2); range +2.01 to +13.82 microm/mm(2)). The patient with a myopic shift (-1.00 D) had the only negative curvature coefficient (-0.64 microm/mm(2)). In a 2-predictor model of refractive shift, central graft thickness and the curvature coefficient together accounted for 86% of the variance in the refractive response to DSAEK (P = .025).


CONCLUSIONS
Nonuniform thickness profiles and variable central graft thicknesses both contribute to refractive shift after DSAEK.
Dupps
William J
WJ
Cole Eye Insitute, Cleveland Clinic, 9500 Euclid Avenue/i-32, Cleveland, OH 44195, USA. bjdupps@sbcglobal.net
Qian
Ying
Y
Meisler
David M
DM
D003315:Cornea / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003317:Corneal Dystrophies, Hereditary / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D016039:Corneal Transplantation; D003886:Descemet Membrane / Q000601:surgery*; D004728:Endothelium, Corneal / Q000637:transplantation*; D005500:Follow-Up Studies; D006801:Humans; D015233:Models, Statistical; D015999:Multivariate Analysis; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D012030:Refractive Errors / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D014463:Ultrasonography; D014792:Visual Acuity / Q000502:physiology