Relationship between preoperative aberrations and postoperative refractive error in enhancement of previous laser in situ keratomileusis with the LADARVision system
Accepted 15 April 2008.
Purpose
To identify factors leading to inaccuracy of spherical correction in wavefront-guided enhancement treatments.
Setting
Department of Ophthalmology, University of California, Irvine, California, USA.
Methods
This retrospective outcomes analysis comprised 23 eyes (20 patients) having wavefront-guided flap-lift (19 eyes) or photorefractive keratectomy (4 eyes) enhancements after conventional non-wavefront-guided laser in situ keratomileusis (LASIK) for correction of residual myopia with a minimum follow-up of 1 month. Main outcomes measures were changes in lower-order aberrations and higher-order aberrations (HOAs) related to predictability of the refractive outcome.
Results
The enhancement procedures reduced HOAs. Because of a hyperopic shift, however, uncorrected visual acuity (UCVA) improved 2 or more Snellen lines in 3 of 9 eyes (33.3%) treated without a surgeon offset compared with 9 of 14 (64.3%) when a surgeon offset was incorporated into the treatment plan. The quantitative amount of preoperative HOAs correlated with the amount of hyperopic shift, particularly strongly for spherical aberration (r2 = 0.446, P = .0005). The amount of hyperopic shift was related in a linear manner to the amount of HOAs (for spherical aberrations, Y = 1.31X − 0.30, where Y is the postoperative manifest refraction spherical equivalent and X is the wavefront error in microns root mean square).
Conclusions
Wavefront-guided enhancements can reduce levels of HOAs. Although UCVA improved in many patients, some with high levels of preenhancement spherical aberration had worse UCVA. Adjusting the nomogram for the amount of preenhancement HOAs may improve the accuracy of the lower-order correction in wavefront-guided enhancements.
From the Department of Ophthalmology (Steinert), University of California, Irvine, California, and the Center for Eye Research and Education (Fynn-Thompson), Ophthalmic Consultants of Boston, Boston, Massachusetts, USA
Corresponding author: Roger F. Steinert, MD, Department of Ophthalmology, University of California, Irvine, 118 Med Surge I, Irvine, California 92697-4375, USA.
Neither author has a financial or proprietary interest in any material or method mentioned.
Supported in part by a departmental challenge grant from Research to Prevent Blindness, New York, New York, to the Department of Ophthalmology, University of California Irvine, California, USA.
ABSTRACT