Phakic Intraocular Lenses.
The implantation of artificial intraocular lenses (IOLs) in the eye has been a part of cataract surgery for many years. However, it is only relatively recently that trials have begun in the United States for approval of IOLs developed for person who are phakic, that is, still have their natural lens intact. Several of these trials are nearing completion, with some of them closed to further participants, and FDA approval of one or more of these types of lenses is anticipated in the next six months to two years. Until then, this surgery is available in the United States with participation in the trials that are still open or through travel overseas.
Several companies have developed phakic intraocular lenses that treat nearsightedness, farsightedness, and astigmatism. IOLs that treat astigmatism are known as toric lenses. The lenses from the different companies differ in their placement within the eye but all are implanted without removal of the patient's natural lens. Because there are some differences, a patient should select the lens to be implanted, then find a doctor working with that lens. But no matter what lens is selected, all phakic IOLs have proven particularly effective in treating severe nearsightedness and severe farsightedness -- conditions that are not well treated using other refractive surgeries such as LASIK.
With all the lenses, once implanted they cannot be felt in the eye, and there is no maintenance of the lens. If the eye happens to change after implantation, this can be corrected with glasses, removal of the lenses entirely, or replacement of the lenses with a new prescription. Because of the cost of the surgery, doctors make sure that the eye has stabilized for at least six months at its current prescription before performing the implantation surgery.
What are the most
common benefits of this surgery?
What will happen at the initial consultation?
How is the procedure performed?
How long does the surgery take?
Where will the procedure be performed?
How much pain is there?
What can I expect after the procedure?
What is the recovery period like?
What is the long-term outcome like for most people?
Ideal Candidate
Other important information
Risks and Limitations
By implanting a lens in the eye, the need for glasses or contact lenses is eliminated. Implanted lenses provide a highly predictable alteration in vision, unlike other refractive surgeries that rely on the healing process to result in the final refractive state. Phakic IOLs almost always meet or exceed the best vision achievable using eyeglasses or contacts, a final result not always achieved with LASIK or other surgeries. Because of the stability of the artificial lens, the results do not regress over time, as is sometimes seen with LASIK and LTK. For several types of lenses, the surgical process is closely related to cataract surgery, so with only minor adjustments many, many surgeons are experienced in the implant procedure. Additionally, this surgery keeps the cornea and lens in its natural state, allowing the process to be reversed if necessary.
One of the most significant benefits of this surgery is the ability to treat with equal efficiency mild to severe nearsightedness and farsightedness, even to a refractive error that requires correction in the 10 to 20 diopter range. This is beyond what is recommended for treatment using LASIK or other laser based surgeries.
What will happen at the initial consultation?
At the initial consultation you will be carefully tested to determine the refractive errors in your eye so that the surgeon can select the lens needed to correct the problems. If astigmatism is present, very careful measurements will need to be taken because the toric lenses used to correct this type of error are custom made to the exact characteristics of the eye. The doctor will also perform a complete physical to determine if you have pre-existing medical conditions that will make the surgery more difficult. Because different lenses are at different stages in the approval process, it may be possible that the trial for treatment of the exact error present in your eye will not be possible because the trial is accepting no new patients. Treatment with the lens of choice could still occur with travel and treatment outside the United States or by waiting for the approval of the lens by the FDA.
How is the procedure performed?
For several of the lens types, such as the implantable contact lens (ICL) of Staar Surgical; the silicone lens of International Vision, Inc.; and the NuVita lens of Bausch and Lomb; the implantation procedure is the same as for cataract surgery. Anesthetic drops are placed in the eye. Then a small incision of about 3 millimeters is made where the cornea and the white of the eye (sclera) meet. Unlike cataract surgery, portions of the lens are not removed at this time. Instead, the artificial intraocular lens is folded and placed within the posterior chamber of the eye, behind the iris and the natural lens. This placement has been associated with an increase in developments of cataracts, although changes in the surgical procedure is thought to now increase aqueous flow between the implanted lens and the natural lens, which is expected to reduce cataract formation.
One type of lens, the Artisan lens developed by Ophtec, Inc., is placed in the anterior chamber, in front of the iris and the natural lens. This placement requires a procedure that differs from cataract surgery in that three small incisions are made and involves the use of specially developed placement tools. The extra incisions and special placement allow the lens to be anchored to the eye using tissue in the iris. This has proven well tolerated during over 20 years of use in Europe and in the current U.S. trial, and is very effective in fixing the lens in place. There are no indications that anterior chamber placement effects cataract development.
How long does the surgery take?
For all types of lenses, the procedure is done on an outpatient basis and takes about 30 minutes. Patients can go home after a short wait to check for complications.
Where will the procedure be performed?
The procedure can be performed in a surgery suite of an ophthalmologist's office or a minor surgery room of a hospital.
How much pain is there?
Local anesthesia, often administered as eyedrops at the beginning of the procedure, takes care of the any pain due to forming the incision and implanting the intraocular lens (IOL). There may be minor pain during the healing process, but it should be relieved by non-prescription drugs such as acetaminophen or aspirin.
What can I expect after the procedure?
You will need someone to drive you home after the procedure. Post-operative care often includes the use of eye drops, wearing of glasses or shields, the use of over-the-counter pain medication to control any residual twinges.
What is the recovery period like?
Recovery is generally short, with full healing occurring within one or two months of the surgery. Most patients have noticeable improvement in their vision from the day of surgery onward, with the best vision achieved somewhere about 24 to 48 hours after the procedure.
What is the long-term outcome like for most people?
Phakic intraocular lenses generally provide excellent correction of even severe myopia (nearsightedness) or hyperopia (farsightedness). In a recent study with the STAAR lens, 87% of patients were corrected to 20/20 or better. However, it should be noted that the STAAR lens trial is currently closed for patients with myopia, although they are still enrolling patients with hyperopia. So if you are nearsighted and want to use a STAAR lens, you will have to wait until the lens is approved or travel overseas for implantation. The STAAR lens has also been associated with a 10% development of cataracts, but new surgical placement techniques are expected to reduce this complication.
Ideal Candidate:
Because these lenses are still experimental, they are best considered by someone whose nearsightedness or farsightedness is so severe that other approved procedures are not recommended. However, other advantages of the surgery, such as correction stability and reversibility could make this procedure attractive to persons with less severe vision problems. The ideal candidate for this type of surgery would also have to met the requirements to participate in the FDA trial for the lens of interest, where details can be obtained by calling a participating doctor.
Other important information
Here are some details about the different lens that may help make choosing a lens easier. A major difference between the lenses is the material that they are made of. The STAAR lens is fabricated from a unique collagen/HEMA (a type of plastic) copolymer that seems to be well tolerated in the body. The IVI lens is made of silicone, a material with a long history of use in body implants that is known to not change over time. The Artisan lens by Ophtec is made of PMMA, a plastic used for implants for many years, and is manufactured using a special technique that makes it especially strong and smooth.
The lenses can also differ in shape. Three of the lenses -- the STAAR lens, the IVI lens, and the Artisan lens -- are of a shape known as plate haptic. They are rectangular in shape, with a round lens structure in the center. The NuVita lens is a second type, called a looped lens, where the circular lens has attached tensioned string-like "loops" that hold the lens in place after placement. Although the looped lens is very popular as an IOL shape for cataract surgery, this phakic lens is currently only available overseas and no FDA trial in the United States is in progress.
Ienhance will provide further information on credentialed and trained physicians for these procedures as they receive FDA approvals for the US.
Risks and Limitations:
One significant risk associated with phakic intraocular lenses is adverse reaction of eye tissue to the implant. This can be seen as development of a cataract (adverse reaction by lens), thinning of the corneal tissue (adverse reaction by the cornea), or inflammation of the iris (adverse reaction by the iris). Although each of these conditions occurs very infrequently, they are occasionally seen in association with the lens implants. Different lenses incurred these complications with different frequency due to placement. For example, a trial of the STAAR lens saw an approximately 10% incidence of cataracts, but new placement surgical procedures is believed to have corrected this problem. It is important for you to understand the specific eye tissue reaction problems that occur with the type of lens you are considering.
Because the eye is being opened for the implant, internal eye infections are a risk. Although very infrequent, they are quite serious and can result in loss of the eye. This is another risk that should be discussed with your doctor prior to the procedure.
Another risk that is unique to implants is the possibility of the lens shifting from its proper position after implantation. Because the different lenses have different means of anchoring the lens in place within the eye, there are different frequencies of this occurring. Although with all lenses the chance of misalignment is low, it does happen and should be considered.
