Phakic IOLs (Implantable Lenses)
Phakic IOLs (intraocular lenses) are an alternative to LASIK and PRK eye surgery for correcting moderate to severe myopia (nearsightedness), and in some cases produce better and more predictable vision outcomes than laser refractive surgery.
Phakic IOLs are clear implantable lenses that are surgically placed either between the cornea and the iris (the colored portion of your eye) or just behind the iris, without removing your natural lens. Phakic lenses enable light to focus properly on the retina for clearer vision without corrective eyewear.
Implantable lenses function like contact lenses to correct nearsightedness. The difference is that phakic IOLs work from within your eye instead of sitting on the surface of your eye.
Also, phakic IOLs offer a permanent correction of myopia, unless the lens is surgically removed.
Unlike contact lenses, you can't feel a phakic intraocular lens in your eye (much like you don't feel a dental filling for a cavity) and, apart from regular eye exams, phakic IOLs typically do not require any maintenance.
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Two FDA-approved phakic IOLs currently are available in the United States. Your eye surgeon will recommend the most appropriate implantable lens for you.
- Visian ICL. The Visian ICL (Implantable Collamer Lens) marketed by Staar Surgical is a posterior chamber phakic IOL, meaning it is positioned behind the iris and in front of your natural lens. It received FDA approval in 2005 for correcting nearsightedness ranging from -3.00 to -20.00 D.
Because the Visian ICL is placed behind the iris, it is undetectable to the naked eye and can only be seen through a microscope.
The Visian ICL is made of a soft, biocompatible collagen copolymer. Due to its flexibilty, the lens is able to be folded during implantation, allowing for a much smaller surgical incision.
- Verisyse. The Verisyse (Abbott Medical Optics) is an anterior chamber phakic IOL, meaning it is positioned in front of the iris. In 2004, the Verisyse phakic IOL received FDA approval for correcting moderate to severe nearsightedness within the range of -5.00 to -20.00 diopters (D).
The Verisyse lens is made of medical-grade plastic (polymethylmethacrylate, or PMMA) and is rigid in form. In Europe, it is approved and marketed under the trade name Artisan.
Verisyse IOLs typically aren't noticeable in the eye, though you may see the lens if you look closely in the mirror.
The Visian ICL (Implantable Collamer Lens).
The Visian ICL and Verisyse phakic IOL are FDA approved to correct myopia (nearsightedness) only. Clinical trials for both lenses are continuing for potential FDA approval for treating hyperopia (farsightedness). A toric version of the Visian ICL is being studied for correcting astigmatism as well as nearsightedness.
Also pending FDA approval is the AcrySof Cachet angle-supported phakic IOL (Alcon). The Cachet is a soft acrylic lens positioned in front of the iris and secured in the angle of the anterior chamber of the eye where the cornea and iris meet.
Ongoing clinical trials of the AcrySof Cachet in the United States, Canada and Europe have shown promising results.
The Cachet IOL has been approved for use in Europe since 2008, and according to a presentation at a 2012 international refractive surgery symposium in Rome, the procedure has yielded excellent visual outcomes and few complications over a 5-year study period.
Clinical studies show mean refraction improved from -10.00 D to -0.25 D (which has remained stable over the five years of follow-up), and more than 96 percent of patients were satisfied with the results of the Cachet IOL procedure at one and five years after surgery.
Phakic IOLs vs. LASIK Eye Surgery
LASIK, which uses a computer-controlled laser to reshape the cornea, is the most popular refractive surgery to correct myopia, hyperopia and astigmatism, in part due to continual technological advancements such as wavefront custom LASIK and femtosecond laser technology.
Not everyone is a candidate for LASIK, though. Contraindications to LASIK surgery include: a very high degree of nearsightedness (usually more than -8.00 D); having a cornea that is too thin or irregular in shape; eye conditions such as keratoconus; and chronic dry eyes.
For many people who are outside the treatment range of LASIK, phakic intraocular lenses can produce excellent results.
A 2010 study that evaluated LASIK versus phakic IOL surgery for the correction of -6.00 to -20.00 D of myopia revealed that the two procedures produced essentially equal odds of attaining 20/20 vision without corrective lenses one year after surgery.
The study also found that patients who underwent phakic IOL implantation had better contrast sensitivity and were more satisfied with their outcome than LASIK patients. Neither technique caused significant complications that permanently affected vision.
"Our findings suggest phakic IOLs are safer than excimer laser surgery for correcting moderate to high levels of short-sightedness," said lead author Allon Barsam, MD, of the Moorfields Eye Hospital NHS Foundation Trust in London.
The cost of phakic IOLs also should be taken into consideration; implantable lenses typically are somewhat higher than the cost of LASIK. If your surgeon recommends a phakic IOL over LASIK, it may be prudent to not let cost cloud your decision to follow your surgeon's advice.
After a thorough eye exam and health evaluation, your eye surgeon will advise on the best type of surgery for you.
Phakic IOLs: What to Expect
Before. If you wear contact lenses, you should stop wearing them at least one week before your pre-operative eye exam and/or consultation. Contacts can alter the shape of your cornea and therefore make your refractive error reading less accurate.
A week or two before your phakic IOL surgery, your eye surgeon may perform a laser iridotomy on each eye to prepare your eye for lens implantation. An iridotomy creates a small opening at the outer edge of your iris, allowing fluid to circulate and helps to prevent a possible increase of intraocular pressure after phakic IOL surgery.
The iridotomy procedure typically is performed in-office and is relatively quick, taking only a few minutes for each eye. It is important that you follow your surgeon's instructions after the procedure to minimize any possible complications.
Some surgeons have incorporated the iridotomy procedure on the same day as the phakic IOL surgery.
Insertion of the Verisyse phakic IOL.
During. Numbing eye drops are first applied to your eye to alleviate any discomfort during the procedure. Your doctor may also give you some medication to help you relax.
An instrument called a lid speculum is used to keep your eyelids open and a tiny incision is made in the cornea. The incision length for a Verisyse lens is around 6 mm; the Visian ICL incision is as little as 3.2 mm due to the flexible and foldable material of the lens.
With the Verisyse, the lens is positioned in the anterior eye chamber behind the cornea and attached to the front of the iris. Tiny dissolvable stitches often are used to close the wound and an eye shield is placed over your eye.
The Visian ICL is positioned in the posterior chamber of the eye behind the iris and pupil and in front of your natural lens. Once inserted, the artificial lens unfolds to its full width and typically does not require any stitches. An eye shield is then placed over your eye which needs to be worn for a day or two after the procedure.
The phakic IOL procedure typically takes 10 to 30 minutes and is performed on an outpatient basis, although you will need to organize someone to drive you home after surgery. Your doctor will prescribe antibiotic and anti-inflammatory drops for you to use at home.
After. Most people notice improved vision immediately following the phakic IOL procedure, but vision may be hazy or blurry with an increased sensitivity to light for the first few days. For some people, it can take two to four weeks for their vision to stabilize.
Vision with the Visian ICL tends to stabilize in about 1 to 7 days, which can be quicker than with the Verisyse lens.
There typically is minimal discomfort after phakic IOL surgery but you may have a mild scratching sensation, like something is in your eye. If required, your doctor can prescribe medication to make you more comfortable during the first few days following surgery.
You will need to return for a follow-up visit with your doctor the next day. It's essential that you follow your eye surgeon's post-operative instructions carefully and attend frequent check-ups to help avoid any complications.
Refrain from rubbing or squeezing your eye, lifting heavy objects and participating in strenuous activities until your eye has completely healed, which could take several weeks.
Most people can return to work and resume driving within a couple of days, once you are given the okay from your doctor.
Risks and Complications
As with any type of surgical procedure, phakic IOL surgery has certain risks. Fortunately, these risks are low. Possible short-term and long-term complications of phakic IOL surgery include:
- Retinal detachment, a serious and sight-threatening emergency situation.
- Glaucoma, increased eye pressure that can damage the eye's optic nerve and cause permanent vision loss.
- Loss of cells in the thin layer inside the cornea (endothelium) that could cause corneal edema and progressive clouding of vision (your doctor will measure your endothelial cell count at regular intervals).
- Inflammation or infection of the eye.
- Distorted vision such as halos or glare, especially while driving at night, and blurry vision.
- Cataracts, a clouding of your natural lens which can eventually cause blindness if left untreated.
- Distortion of the pupil, which increases the potential for glare and blurry vision.
Phakic IOL Vision Outcomes
In a study of 3-year outcomes of the FDA clinical trial of the Verisyse lens, 84 percent of patients achieved uncorrected vision of 20/40 or better, which is the legal limit for driving without prescription eyewear in most states. And 31 percent achieved uncorrected vision of 20/20 or better.
These are the results of a comparative study of the Visian ICL and Verisyse.
In FDA trials of the posterior chamber Visian ICL, 81 percent of patients achieved uncorrected visual acuity of 20/40 or better.
Forty-one percent attained uncorrected vision of 20/20 or better.
Patient satisfaction with the quality of vision with both types of phakic IOLs was generally high.
Some patients, particularly those with very severe myopia, elect to undergo LASIK as a follow-up to further improve vision after phakic IOL surgery.
Phakic IOLs are an effective option for people with moderate to severe nearsightedness who fall outside the treatment range of LASIK. When considering implantable lenses or any refractive surgery be sure to discuss all the benefits and risks with your eye surgeon.
Excimer laser refractive surgery versus phakic intraocular lenses for the correction of moderate to high myopia. The Cochrane Library. May 2010.
Phakic intraocular lens implantation for the correction of myopia: a report by the American Academy of Ophthalmology. Ophthalmology. November 2009.
About the Author: Brian Boxer Wachler, MD, is an ophthalmologist and refractive surgeon at the Boxer Wachler Vision Institute in Beverly Hills, Calif. He has pioneered treatments for keratoconus, participated in many FDA clinical trials for new refractive surgery technologies and written several books. He is a member of All About Vision's editorial advisory board.
Aimee Surtenich also contributed to this article.
[Page updated May 2014]