Article
Phakic IOLs address challenge of treating broad range of refractive errors
Phakic IOLs are viable alternatives for treating high refractive errors.
Take-home message: Phakic IOLs are viable alternatives for treating high refractive errors. The technology provides good predictability and stable results, and has good safety profiles.
By Lynda Charters; Reviewed by Allon Barsam, MBBS, FRCOphth
London-Patients who undergo implantation of phakic IOLs to correct high refractive errors can gain a number of benefits from this type of surgery. Namely, some preserved accommodation and use of surgery that most cataract and refractive surgeons find familiar, said Allon Barsam, MBBS, FRCOphth.
In addition, the phakic IOL procedure is reversible, there is lower risk of a retinal detachment compared with that associated with refractive lens exchange, the natural corneal shape is preserved, and patients with ocular surface disease are candidates for the surgery.
This is in contrast to PRK and LASIK, which are limited in the degree of refractive errors that are correctable and have lower predictability and stability levels in patients with high myopia, said Dr. Barsam, a consultant in cornea, cataract, and refractive surgery, L&D University Hospital, UCL Partners, London.
However, as with all good things, complications are possible with phakic IOL implantation, such as development of cataracts, endothelial cell loss, development of glaucoma, iris atrophy associated with the claw configuration, and traumatic dislocation, he noted.
Dr. Barsam and colleagues compared the outcomes achieved with phakic IOLs with excimer laser procedures in studies that were published during the past 10 years.
He reported that 12 months postoperatively there was no difference between the two surgeries in the percentages of patients with an uncorrected distance visual acuity (UNVA) of 20/20 or better.
The investigators also reported that the phakic IOL procedure was safer for correcting moderate to high myopia with less loss of the final best spectacle-corrected visual acuity.
Finally, patients who underwent phakic IOL implantation had better contrast sensitivity than those who underwent excimer laser surgery for moderate to high myopia and the patient satisfaction levels were higher after phakic IOL procedures compared with excimer laser procedures, Dr. Barsam noted.
Available phakic IOLs
Three types of phakic IOLs are currently available-namely, those implanted into the posterior chamber in front of the crystalline lens, and two types of anterior chamber phakic IOLs (those that are iris fixated and those that are angle supported).
The Implantable Collamer Lens (ICL) (Visian ICL, STAAR Surgical) is the only such lens that the FDA has approved to correct myopia. It is indicated for implantation in patients who are between the ages of 21 and 45 years to correct myopia ranging from 3 to 20 D with a maximal level of 2.5 D of astigmatism, and the anterior chamber aqueous depth must exceed 2.8 mm. In Europe, surgeons can correct from +21.00 D of hyperopia to -23.0 D of myopia in patients with up to 6 D of cylinder.
“The 3-year outcomes with this lens in 526 eyes of 294 patients were excellent, with 60% of patients achieving an UCVA of 20/20 or better and 95% achieved 20/40 or better,” Dr. Barsam said. “The lens has good predictability and low complications rates.”
The Verisyse phakic IOL (manufactured by Ophtec and referred to as Verisyse in the United States and Artisan in Europe) is an iris claw-fixated phakic IOL that can correct from -5 to -20 D of myopia with 2.5 D of astigmatism and higher degrees of myopia, hyperopia, and astigmatism in Europe. A potential concern with this lens is the endothelial cellular loss over time compared with the ICL.
The AcrySof Cachet phakic IOL (Alcon Laboratories) has now been removed from the market.
Recent developments
A few improvements in phakic IOL technology have been introduced.
A newer ICL model is the V4c, which has an artificial port in the center of the lens optic that eliminates the need for a preoperative peripheral laser iridotomy and might decrease the risks of glaucoma and cataract development, Dr. Barsam explained.
“This lens is very encouraging,” he noted, but pointed out that it has not yet received FDA approval.
A toric ICL and the toric Artisan are currently yielding excellent results. Dr. Barsam likes these lenses for patients who have more than 1.5 D of refractive astigmatism.
In addition, these lenses can be used to treat keratoconus and astigmatism that develops after a corneal graft procedure.
Novel posterior chamber phakic technology (IPCL phakic IOL, Care Group India) to correct presbyopia and myopia and astigmatism has also been recently introduced. The lens provides near additions ranging from +1.5 to +3.5 D that can be customized to the patient’s degree of accommodation.
“It is an interesting lens because it is a presbyopic ICL that is a reversible solution for presbyopia in patients aged 40 to 55 years who have not yet developed cataracts,” Dr. Barsam said. “There are no long-term results with this lens regarding safety and efficacy.”
Allon Barsam, MBBS, FRCOphth
This article was adapted from Dr. Barsam’s presentation at Refractive Surgery Subspecialty Day during the 2015 meeting of the American Academy of Ophthalmology. Dr. Barsam has no financial interest in the subject matter.
