Phakic IOLs an effective option for high myopes

They can offer good quality of vision to patients seeking a vision correction alternative.

Tina Geis

Robert K. Maloney

When glasses or contact lenses fail, primary care eye doctors often offer LASIK as an alternative. However, LASIK is not optimal for some patients, such as those with a high degree of nearsightedness. For these patients, the primary care doctor has another tool in his or her armamentarium: a phakic IOL, known colloquially as an implantable contact lens.

Case presentation

J.T. presented to us complaining of contact lens intolerance. She was highly myopic and had worn soft contact lenses for 20 years. She practiced good lens hygiene and followed a daily wear routine, but her wear time had been reduced to about 8 hours per day. Her optometrist had noticed increasing corneal neovascularization associated with decreasing wear time and increasing discomfort with the lenses. She hated wearing her thick spectacles. Her doctor referred her for a refractive surgery consultation.

On examination, the patient had a refraction of -8.50 D -1.00 D x 178 OD and -9.00 D -0.75 D x 005 OS. Best-corrected vision was 20/20 in each eye. Slit lamp examination revealed neovascularization 360 degrees in both eyes that was most prominent superiorly, extending 2 mm into the cornea. Corneal thickness was 520 µm in the right eye and 523 µm in the left eye. The corneal topographies were normal.

A Staar ICL in a patient’s eye. The pupil has been dilated so the outline of the lens is visible (arrows). The central optical zone (arrowheads) is supported by two plate haptics that tuck behind the iris and rest in the ciliary sulcus. There is typically 500 µm between the crystalline lens and the ICL. This lack of contact minimizes the risk of cataract. Because the lens is foldable, it is easy to insert through a small incision and easy to remove if necessary. Images: Maloney RK

The patient underwent implantation of the Staar Implantable Collamer Lens phakic IOL (Staar Surgical, Monrovia, Calif.) bilaterally, with prophylactic peripheral iridotomy performed preoperatively. The Staar ICL was placed behind the iris, in front of the crystalline lens.

On postoperative day 1, uncorrected vision was 20/25 OD and 20/20+ OS. At 1 month postoperatively, uncorrected vision in the right eye was 20/20 with a refraction of +0.50 D -0.75 D x 175 and 20/15 in the left eye with a refraction of +0.50 D -0.50 D x 010. Both eyes were quiet with the lens in stable position.

Choosing a procedure

This patient came to us hoping to have LASIK. However, the corneal thickness of 525 µg was too thin to safely perform LASIK for her degree of myopia. Photorefractive keratectomy was considered; it is not subject to the corneal thickness limitation of LASIK because there is no flap. However, PRK (and also LASIK) can result in a decrease in quality of vision and significant night-time glare in high myopes.

Verisyse lens. The Verisyse lens is visible in front of the iris in this undilated patient. The Verisyse lens has two haptics that clip onto a knuckle of peripheral iris. Because the lens is clipped to the peripheral iris, the patient can be dilated widely to allow for fundus examination. The lens is not foldable and must be inserted through a 6-mm incision. The suture closing the incision is visible here superiorly.

A phakic IOL was the optimal procedure for this patient. Highly myopic patients are more likely to have 20/20 visual acuity, better night vision, less glare and greater quality of vision with a phakic IOL than with laser refractive surgery. This is particularly important in people who do a lot of driving at night or who require acute vision for their profession, such as artists, videographers and radiologists. A phakic IOL is also removable, in contrast to LASIK, in which corneal tissue cannot be replaced.

Choosing a phakic IOL

The two types of phakic IOLs available in the United States are the Staar ICL and the Verisyse lens (Abbott Medical Optics, Santa Ana, Calif.).

The Staar lens is foldable and can be inserted through a small 2.8-mm incision. This has several advantages. First, the surgical procedure is quick because no sutures are required. Second, recovery of vision is fast because the wound stabilizes rapidly in the absence of sutures. Third, the ICL is not visible to the naked eye.

Disadvantages of the ICL include the limited range of powers, with a maximum power of -16 D, and an increased incidence of cataract formation because of the ICL’s position behind the iris (in contact with the crystalline lens peripherally). This can lead to mild anterior subcapsular opacities that, on occasion, can progress to a cataract. Fortunately, cataract surgery is not a problem in patients with the ICL because the ICL is easily removed through the cataract incision.

The Verisyse lens is a nonfoldable lens, 6 mm in diameter, which lies in the anterior chamber and attaches to the peripheral iris by two clips. This lens does not appear to accelerate the development of cataracts because it is separated from the crystalline lens by the patient’s iris.

However, because it is not foldable, it must be inserted through a 6-mm incision that is sutured. This results in a prolonged recovery, usually with induction of significant astigmatism from the sutures until they are removed 6 weeks postoperatively. This prolonged period of blurry vision is challenging for the patient. Because of this difference, we often perform bilateral ICL implantation at the same surgical sitting, but perform the Verisyse lens implants 6 weeks apart.

The Verisyse lens has a greater range of powers, up to -20 D. It is visible to the naked eye because it is in front of the iris, but it is only visible on close inspection.

Astigmatism correction

Neither of the IOLs on the market currently can correct astigmatism. We normally correct astigmatism, when present, with a LASIK procedure performed postoperatively, typically 3 months after the implantable lens surgery. Staar has developed a toric version of the ICL for which U.S. Food and Drug Administration approval may come soon.

Our preference is to use the Staar ICL in most patients, with the Verisyse lens reserved for patients between -16 D and -20 D of myopia and those who do not dilate well enough to insert the ICL behind the iris.

Postoperative care

Postoperatively, we prescribe a fluoroquinolone antibiotic and a topical corticosteroid for 1 week.

The case presented here illustrates why phakic IOLs are an excellent option for patients with high myopia. Phakic IOLs offer better quality of vision and accurate corrections to patients outside the optimal range of LASIK.

• Tina Geis, OD, specializes in the preoperative evaluation and postoperative care of patients at Maloney Vision Institute. She can be reached at Maloney Vision Institute, 19021 Wilshire Blvd. #900, Los Angeles, CA 90024; (310) 208-3937; fax: (310) 208-0169; drgeis@maloneyvision.com; www.maloneyvision.com.
• Robert K. Maloney, MD, can also be reached at Maloney Vision Institute; info@maloneyvision.com.
• Disclosures: Dr. Geis has no direct financial interest in the products mentioned in this article, nor is she a paid consultant for any companies mentioned. Dr. Maloney has no direct financial interest in the products mentioned in this article. He is a consultant for AMO.