Published on July 27th, 2012 | by Chris Knobbe, MD0
Refractive Lens Exchange (RLE) And Intraocular Lens Implants
Intraocular lens implant for presbyopia
Refractive lens exchange (RLE) is a procedure that should be reserved specifically for individuals that are significantly presbyopic (bifocal and reading glasses dependent), who are at least 40 to 50 years of age, and in whom other less invasive procedures (such as LASIK, Epi-LASIK, IntraLASIK, phakic IOLs, and conductive keratoplasty) do not fully meet the individual’s needs. If you are above the age of 55 or 60, you should strongly consider RLE due to increasing presbyopia.
Refractive lens exchange is a potential option for presbyopic patients who have refractive error including hyperopia (farsightedness) of +1.0 diopter and greater and myopia (nearsightedness) of –1.0 to about –8.0 diopters. In my opinion, for those individuals who are over the age of 40 and have refractive error greater than or equal to +4.0 diopters of hyperopia, Refractive lens exchange is by far the best refractive surgical option. If you have more than –8.0 or –9.0 diopters of myopia, RLE may not be your best option due to increased risk of retinal detachment in axially long eyes following RLE or cataract surgery. However, if you’re about 60 years of age or higher, and cataract surgery is relatively imminent anyway, then RLE may still be your best option even if you’re a high myope, that is, above –8.0 or –9.0 diopters.
In the refractive surgery armamentarium, refractive lens exchange is a fairly aggressive procedure with greater potential risks than most other refractive surgical procedures today. However, there are many, many instances where it is not only a viable option but perhaps the best option. If you choose RLE, I implore you to find a highly experienced and successful cataract surgeon.
Refractive lens exchange is essentially the same as cataract surgery, but by its very definition, includes the removal of a clear natural lens as opposed to a cataract. If a natural lens is cloudy, it is a cataract, and removal of same with a lens implant would be called “cataract surgery with an intraocular lens implant“. This procedure has more inherent risks than corneal refractive procedures because the lens of the eye is located behind the iris (behind the pupil as well) and thus, removal of the lens and replacement with an artificial implant becomes intraocular surgery. The only other refractive surgical procedure discussed in this website that requires intraocular surgery is implantation of a phakic intraocular lens (IOL), i.e., the Verisyse™ IOL or the Visian ICL™. However, the latter procedure poses substantially less risk than RLE because the natural lens of the eye is not removed.
So why would one choose Refractive lense exchange? First of all, as I’ve mentioned, it is generally only an option for the presbyopic. All of the other refractive surgical procedures (e.g., LASIK, Epi-LASIK, IntraLASIK, CK, and Phakic IOL’s such as the Verisyse™ IOL and Visian ICL™) cannot directly address the loss of near reading type vision that we experience with aging. RLE does!
How is this possible, you ask? Because when a cataract/refractive surgeon removes the natural lens of the eye, it is possible to implant an IOL that provides both near and distance vision without spectacles. This is only possible by implanting an “accommodating IOL” or a multifocal IOL. Now, to be sure, RLE does not require implantation of either of these types of lenses, but this is the only option that would generally allow distance and near vision simultaneously. Many patients might choose to have a monofocal IOL implanted, for perceived visual benefit and/or reduced risk.
Let’s take a look at the refractive lens exchange procedure
Refractive lens exchange is performed using a microincisional procedure.
To the patient, this means minimal discomfort during or after surgery, a more speedy recovery of vision, and reduced risk of induced astigmatism. This also generally means less dependence on glasses afterwards.
Using the illustrations below, I’ve detailed the major steps of RLE using a microincisional procedure, phacoemulsification (ultrasonic lens removal), and a foldable lens implant that is injected into the eye using a lens implant injector. The procedure demonstrates basic principles only. Eye surgeons use many variations of the general theme, even from one case to another, depending on their own surgical preferences.
The most commonly used RLE incision is about 3 millimeters in size – just about one-eighth of an inch! Because of the careful construction of this incision and its small size, the incision is generally self-sealing. This translates to a “no-stitch” type operation.
Phacoemulsification is the aspect of the procedure in which ultrasonic vibrations are used to break the natural lens into smaller fragments. These fragments are then aspirated from the eye using the same instrumentation.
Lens Cortex Removal
Once the denser nucleus has been removed, the softer peripheral cortex is removed with the assistance of an irrigation/aspiration handpiece. The backside (posterior) aspect of the capsule is left intact when possible to help support the lens (IOL) implant.
In the next step, the surgeon gains access to the natural lens by creating an opening in the capsule, which is the ultra-thin membrane (about 4 thousandths of a millimeter thick) that surrounds the natural lens. The surgeon must manipulate instruments inside the anterior chamber, a space that is only about 1/8th of an inch deep.
The surgeon may elect to create grooves in the natural lens, and subsequently break the lens into smaller pieces using the phacoemulsification tip and a second instrument passed through a smaller “side-port” incision.
This lateral view of the IOL implant shows the lens within the “capsular bag,” which is the desired location. This position is the same as that of the natural lens (or cataract, when present) of the eye and, therefore, is generally well tolerated and also provides the most optimal visual results. At this stage, the cataract operation with IOL implantation is complete.
Potential Risks and Complications of Refractive lens exchange
Today, cataract surgery is one of the most successful procedures in all of medicine. Refractive lens exchange should enjoy the same or perhaps even greater success, given that the procedures are practically identical. However, complications will still occasionally occur and may range from devastating visual loss to minor inflammation in the eye. In general, the risk of severe visual loss is very rare, but may occur (as with virtually any procedure) as a result of infection or bleeding inside the eye, or even retinal detachment, the latter of which may occur months or years after a perfectly successful RLE procedure. Most complications are minor, such as swelling of the cornea or retina, increased pressure in the eye, and droopy eyelid. These complications nearly always resolve with medications and continued healing time.