The adjustable refractive surgery concept (ARS)

The primary goal of refractive surgery is the smallest residual refractive error and preserved contrast sensitivity with the same visual capacity under bright and dim illumination. Corneal refractive surgery cannot correct very high ametopias; from -10 to -14 D is the limit of myopia correction in the cornea and from +4 to +6 D, the limit of hyperopia correction. Intraocular refractive surgery (both lens extraction with intraocular lens [IOL] and phakic IOL surgery) is a better option for high corrections. Improvements in biometry or lens capacity calculations and measurements and nomograms for phakic IOL power calculation have diminished, but not eliminated, the residual refractive error in most cases. Several corneal refractive surgery techniques have been previously used to refine the final refraction after intraocular refractive surgery, such as radial keratotomy, arcuate and transverse keratotomy, and photorefractive keratectomy (PRK).1,2 Since March 1994, we have been using laser in situ keratomileusis (LASIK) to correct residual ametropia after intraocular surgery, especially after lens surgery with IOL implantation, penetrating keratoplasty, pars plana vitrectomy, PRK, radial and arcuate transverse keratotomy, and phakic IOL implantation.3 Reviewing these last four year’s experience, almost two-thirds of our very high ametropic patients treated with intraocular surgery were referred for LASIK surgery as a second step. There are several potential complications related to the increase of intraocular pressure (IOP) with the microkeratome suction ring during the LASIK procedure in a pseudophakic eye. Some vitreoretinal specialists think that the pressure from the suction is even more dangerous for high myopic eyes when they are pseudophakic. There may be risk of endothelial-IOL touch during the pass of the microkeratome, especially with angle or iris supported IOLs. This has led us to the practical concept of Adjustable Refractive Surgery (ARS).4 In high myopic and hyperopic candidates for intraocular surgery with lens extraction and IOL implantation, or those with phakic IOL implantation, we may perform the lamellar cut at the time of the first surgery. After our retrobulbar block or under topical anesthesia (15% of our intraocular cases), we first make an anterior corneal flap with the microkeratome. Once we think the flap is adhered (between 30 and 120 seconds), we proceed with the intraocular surgery in our standard way. Between 2 and 4 months after the intraocular surgery (depending on the incision size and location, we may need to wait longer), we can easily adjust the final refraction with LASIK (by lifting the flap and doing the ablation with the excimer laser, as with retreatment after previous LASIK. This approach avoids possible risks related to the microkeratome use in eyes that contain an IOL. It also is a procedure simpler to perform for surgeons only partially trained in lamellar surgery, who have access to an excimer laser and have experience with PRK. Although refractive predictability in IOL implantation in phakic and aphakic eyes will be better in the near future, I think Adjustable Refractive Surgery will still be useful in those patients with high ametropias. In these cases, we need to use both intraocular and corneal procedures to correct the error completely, as Roberto Zaldivar described using the term, bioptics. Adjustable Refractive Surgery avoids smaller diameter ablation zones, thicker IOLs with potentially greater optical aberrations, and also allows treatment of patients whose ametropia is outside the range of LASIK, PRK, or IOLs alone.