Phakic (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 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 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 typically do not require any maintenance.
Phakic IOL Types
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 flexibility, the lens can be folded during implantation, requiring only a small 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 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.
Vision with the Visian ICL tends to stabilize in about one to seven days, which can be quicker than with the Verisyse lens.
Keratoconus treatment with Phakic IOLs
Keratoconus commonly presents during patients’ second decade of life, with a gradual progression in most eyes. In such cases, phakic IOLs can provide fast rehabilitation and a wide range of correction of stable refractive error, including myopia and compound myopic astigmatism.
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.
Reference:
https://www.allaboutvision.com/visionsurgery/implantable-lenses.htm
http://www.keratoconus.com/10.html
https://crstodayeurope.com/articles/2010-jul/refractive-iols-in-patients-with-keratoconus/
