For patients who have high degrees of nearsightedness (myopia) or farsightedness (hyperopia), it is sometimes possible to implant a lens in the eye to correct the refractive error. A phakic intraocular lens (PIOL), sometimes referred to as an implanted contact lens, can be inserted through small incisions in the cornea and placed in front of the natural lens. This will allow patients who are not yet presbyopic (i.e., whose reading vision has not yet begun to deteriorate, as tends to happen to people in their early forties) to retain their normal focusing ability for reading vision.
Once implanted in the eye, the foldable lens expands to its full size. The procedure is minimally invasive, thus reducing induced astigmatism and recovery time. The lens may be implanted either in front of or behind the iris, and it works with the eye’s natural lens to correct refractive errors. While phakic lenses are intended to be permanent, these lenses can be removed if necessary.
Currently, all FDA-approved intraocular lenses (IOLs) are for the correction of nearsightedness. Phakic intraocular lenses are thin and made of plastic or silicone. The term phakic means to implant a lens into the eye without removing the eye’s natural lens. In effect, the lens becomes an internal contact lens. Phakic intraocular lenses (PIOL) are different from intraocular lenses (IOL) that are implanted after cataract surgery. During cataract surgery, the natural lens is removed and replaced with an IOL; during implantation of the PIOL, the natural lens remains in place.
What Are The Various Types of Phakic Intraocular Lenses?
Currently, two implantable lenses have been approved by the FDA and are available in the United States: Verisyse and Visian ICL.
The Verisyse Lens (also known as the Artisan lens outside of the US) is manufactured by Abbott Medical Optics of Santa Ana, California. This lens has been designed for implantation in front of the iris and clips onto the iris.
This allows the lens to remain centered in the eye without the possibility of rotation or movement. The Versyse lens comes in two sizes and is used to correct high amounts of myopia (nearsightedness). It is available in one-diopter increments, which enables it to treat myopia ranging from 5 to 23 diopters.
The Visian ICL (implantable collamer lens) was created by Staar Surgical of Monrovia, California. Available since 2005, this lens is made partly from collagen, a biocompatible material. This lens has been designed for implantation behind the iris.
This lens is US FDA approved to correct myopia ranging from 3 to 15 diopters, and to reduce myopia to more manageable levels for patients with 15 to 20 diopters of myopia. Staar Surgical also has Visian Toric ICL that can correct 1 to 6 diopters of astigmatism in patients who have up to 18 diopters of myopia.
The Visian Toric ICL and the Visian ICL for the correction of hyperopia (farsightedness) are currently not available in United States, although the Visian Toric ICL is currently being reviewed by the US FDA.
Am I A Phakic Intraocular Lens Candidate?
Implantable contact lenses are usually recommended for patients whose visual correction is outside the range that can be treated with LASIK surgery, or have other factors, such as thin corneas, that make it impossible to perform LASIK safely. Patients who are poor candidates for PIOLs are those with more than 2 diopters of astigmatism, or those who have a history of recurrent ocular inflammation; a history of retinal detachment; cataract or glaucoma; or have good vision in only one eye (for example, those who suffer from amblyopia, also known as lazy eye).
Phakic Intraocular Lens Surgery
Before surgery for phakic intraocular lenses can begin, you will need to complete a thorough eye examination to ensure you are a good candidate for implants. Your eye doctor will take measurements of your pupils, measure the distance between your cornea and iris, and count your endothelial cells (the cells located on the back of the cornea responsible for keeping your cornea clear).
Typically, your eye doctor will inquire about your medical and family history, medications you are taking, any allergies you may have, and any other medical conditions you have which may suggest that PIOLs are not the best solution for you. Unlike other types of refractive surgeries, there is much preparation before phakic intraocular lens surgery. If this surgery is going to be performed, you may first need to undergo a procedure called laser iridotomy. This procedure prepares the eyes for implantation of the phakic lens and is done approximately two to three weeks before surgery. During laser iridotomy a laser is used to create a small hole on the outer edge of the iris (the colored part of the eye). This procedure takes only a few minutes, and it is necessary to prevent fluid and pressure build-up in the eye after the PIOL is implanted. Steroid eye drops may be prescribed afterward to reduce inflammation.
Complications rarely arise from this procedure, but possible complications may include an increase in eye pressure, cataract caused by the laser, injury to the cornea, or an iritis (inflammation in the anterior chamber of the eye). After an iridotomy, those who wear contact lenses are asked to stop wearing them. Some patients are asked to temporarily refrain from taking their normal medications. Some patients are given antibiotic and/or anti-inflammatory eye drops in the days prior to surgery.
For phakic intraocular lens surgery, transportation will need to arranged. Most people are asked not to eat or drink anything after midnight the night before surgery. Phakic intraocular lens surgery usually begins with the eye doctor administering drops to the eye that is receiving the implant. In some cases, oral sedatives are used to relax anxious patients. Anesthetic will then be administered.
Once you are relaxed and numb, the area around your eye is cleaned and a lid speculum is put in place to prevent the eyes from blinking. To begin phakic intraocular lens surgery, one or two small incisions will be made in the cornea. A lubricant is then placed in the eye to protect the back of the cornea while the phakic lenses are inserted. This is removed prior to completion of the procedure. The phakic lens is then inserted through the incision and positioned in the eye. The Verisyse PIOL requires tiny sutures to close the incisions whereas the Visian ICL typically does not. The eye is then covered with a patch or shield. This procedure usually takes 15–30 minutes.
After Phakic Intraocular Lens Surgery
Following surgery, you will be placed in a recovery room to be monitored for a few hours. You will then be prescribed antibiotic and anti-inflammatory eye drops to be used at home. An Implant Identification Card is given to you for safekeeping. These cards are to be shown to all other eye care professionals in the future. After a few hours, you will be allowed to go home and rest for the remainder of the day. The day after surgery the patch or shield is removed and the condition of the eye is assessed. Typically, it is during this appointment that the eye doctor instructs you on how to use the eye drops that will be prescribed; you will need to take these for a few weeks following surgery.
In general, it takes approximately two to four weeks for vision to stabilize. Your eye doctor will determine how many follow-up appointments are necessary, depending on your overall condition and response to the surgery. Most people see their doctor several times within the first month following surgery and only a few times in the next several months after that. Annual visits are required following this surgery.
Additional tips for a healthy and speedy recovery following phakic intraocular lens surgery include:
- Use the prescribed medications as directed
- Avoid touching or rubbing your eyes
- Wash your hands before using your eye drops
- Avoid getting water into your eyes until your doctor gives the okay
- Avoid lifting heavy objects and bending from the waist to pick something up
- Expect about two months of healing time
- Complications of Phakic Intraocular Lenses
- Phakic intraocular lenses carry long-term risks that will need to be monitored for the rest of your life. Despite the excellent outcomes in most cases, complications are sometimes associated with phakic intraocular lens implants.
In some studies a small percentage of patients developed cataracts shortly after implantation of the lens. There is also a small risk of endophthalmitis (infection inside the eye). This rare complication could lead to complete loss of vision. Endothelial cell loss is also a concern with some lens designs, and this is being studied rigorously. Additional complications that may arise include:
- Sensitivity to light, especially during the initial days and weeks following surgery
- Floating spots or blank spots may develop
- Vision loss
- Development of glare, haloes, or double vision
- Blurry vision
- Additional eye surgery to reposition, replace, or remove the phakic lens may be necessary
- Removal of phakic lenses may result in permanent vision loss
- Elevated Intraocular pressure may develop
- Cornea may become cloudy
- Cataracts may develop
- Severe inflammation, bleeding, or pain may occur
- Although long-term data is not available, several studies conducted in recent years suggest phakic intraocular lenses provide clearer vision and better contrast sensitivity when compared to LASIK surgery.
In an FDA clinical trial, 92 percent of the 662 people who received the Verisyse lens had 20/40 or better vision. Another FDA study concluded 95 percent of 294 myopic patients who received the Visian ICL implant had 20/40 or better vision.
Advantages of Phakic Intraocular Lenses
Although there are risks associated with this type of surgery, there are also many advantages:
- Only takes a few minutes to complete each eye
- The lenses are removable in case complications arise
- The lenses are extremely thin, resilient, and flexible
- Reduced risk of haloes and other distortions as compared to LASIK
- The lenses are designed to correct all types of refractive errors, although they are currently only approved for myopia (nearsightedness) in the United States
- Surgery is relatively inexpensive compared to other types of refractive surgery
- Surgery is done out-patient
- Unlike regular contact lenses, you cannot feel the lenses in your eye
- The lenses require no maintenance or cleaning
- PIOLs can potentially improve vision better than LASIK in some cases