In the mid-1950s, phakic intraocular lenses (PIOLs) were first implanted to correct myopia; unfortunately, this yielded poor results. In the last decade, refinements in manufacturing and surgical techniques have led to a proliferation of safe and effective PIOL designs.
There are several advantages of PIOL implantation over corneal refractive surgery such as LASIK. These implants provide a high quality of vision largely because of the absence of the induced optical aberrations that accompany corneal refractive surgery. The fact that these lenses are removable allows the eye to be restored to essentially its original configuration if the PIOL must be removed. In addition, if an inaccurate refractive outcome is achieved, the PIOL can be exchanged. Implantation of PIOLs also preserves normal corneal aspheric contours. The PIOL does not alter corneal shape, whereas corneal refractive surgery converts the cornea from its normal prolate to an abnormal oblate shape in treating myopia, and creates paracentral flattening for the treatment of hyperopia, both of which can induce optical aberrations. Finally, PIOL implantation leaves the corneal thickness unchanged; excimer laser corneal surgery thins the cornea, and if the thinning is excessive, corneal steepening and ectasia may occur over time.
Two trends are certain regarding PIOLs. First, the lenses will become more popular and will be used to treat lower degrees of ametropia, especially when surgeons realize that they can come to one operating room and do cataract surgery and PIOL implantation with the same staff and equipment. Surgeons will not have to concern themselves with the changing environment of excimer lasers, microkeratomes, and laser centers. Second, designs of PIOLs will change and improve, especially designs of toric lenses, and possibly multifocal lenses, as well as lenses with adjustable/interchangeable optics.
Although we have no doubts concerning these trends, one of the big questions remains: Is it better to implant PIOLs in the anterior chamber or the the posterior chamber? There have been and continue to be many debates on this matter. Recently, a group of surgeons assembled at the AAO meeting in New Orleans, Louisiana, for a discussion-turned-debate on implanting anterior chamber PIOLs versus posterior chamber PIOLs. The following pages serve as an excerpt of this dialogue.
George O. Waring, III, MD, FACS, FRCOphth, is Professor of Ophthalmology and Director of Refractive Surgery at Emory University, Atlanta, Georgia. He is a consultant for Bausch & Lomb and Nidek, Inc. Dr. Waring may be reached at 678-222-5102; georgewaring@emoryvision.com
