Photorefractive keratectomy for astigmatism. Initial clinical results
P. J. McDonnell, H. Moreira, T. N. Clapham, J. D'Arcy and C. R. Munnerlyn
Doheny Eye Institute, Los Angeles, CA 90033.
Excimer laser photorefractive keratectomy, developed to perform radially
symmetric ablations to correct myopic or hyperopic refractive errors, was
used to perform toric ablations designed to correct cylindrical errors. An
expanding slit was used to flatten the cornea in the steep meridian. Four
contact lens-intolerant patients underwent this procedure for correction of
astigmatism (two patients after penetrating keratoplasty, one patient after
corneal ulcer, and one patient with naturally occurring high astigmatism).
In each patient, surgery reduced the regular component of the astigmatism;
residual irregular astigmatism limited spectacle-corrected acuity in one
patient. All patients experienced a shift in spherical equivalent toward
hyperopia. Toric ablations with the excimer laser appear to represent a
promising strategy for the correction of compound myopic astigmatism that
does not rely on creation of deep corneal incisions, excisions, or
compression sutures.
