Regularizing Highly Aberrated Corneas Before Cataract Surgery: The Role Of Sequential Custom Therapeutic Keratectomy

Cataract surgery increasingly resembles refractive surgery, with patients asking for a high level of postoperative vision quality, possibly with great freedom from spectacle correction. Anterior corneal surface regularity is the main refractive element in the ocular optical system. Irregularities induced by previous refractive surgery, corneal dystrophies or degenerations, as well as by corneal infections or trauma, induce high order aberrations that can not be amended by any type of intraocular lens implanted after cataract surgery. Sequential Custom Therapeutic Keratectomy (SCTK) provides an efficient tool for improving the optical quality of these highly aberrated corneas.

Department of Ophthalmology, Humanitas Research Hospital, Rozzano – Milano, Italy

We retrospectively evaluated 63 eyes with highly aberrated corneas requiring cataract surgery for senile lens opacity.  Anterior corneal high aberrations (spherical aberration, coma, trefoil) were due to previous myopic refractive surgery (RK, PRK), corneal infections (herpetic, EKC), corneal dystrophies (Reis-Bucklers, GCD1, MDFP), corneal degeneration (Salzmann) or trauma.    SCTK - a sequence of custom therapeutic excimer laser keratectomies and step-by-step intraoperative corneal topography monitoring of results - was performed to decrease corneal aberrations. After postoperative corneal surface stability was achieved, cataract surgery was performed. IOL power calculation targeted emmetropia or residual myopia for useful reading vision.

Comparative evaluation of corneal HOAs between preoperative and final results showed a significant de[1]crease in spherical aberration (P = .004) and coma (P = .035). Spherical error increased significantly after SCTK for the treatment of previous myopic refractive surgery eyes, and was corrected by adequate IOL calculation.

Optical aberrations induced by corneal surface irregularity decrease vision in a way not correctable with spectacles or IOL implantation. They certainly hinder implantation of premium IOLs. SCTK is a powerful tool for the reduction of anterior corneal irregularities in highly aberrated corneas, providing a regular ocular optical system that best exploits cataract correction with IOL implantation.