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One-year results of European multicentre study confirm safety and efficacy of ‘floating' refractive implant
The one-year results of an 11-centre European trial indicate that the Phakic Refractive Lens (PRL™, Ciba Vision / Med-ennium) offers a safe and effective new option for the correction of myopia, Bo Philipson MD, PhD told the XXI Congress of the ESCRS Among 186 myopic patients who underwent implantation of the lens for myopia ranging from –3.5 D to -20.0 D (mean: -13.3 D), mean postoperative UCVA after one year was 0.74 – or roughly the same as the mean preoperative best corrected acuity (0.73). Furthermore, mean BCVA improved to 0.94 and 80% of patients gained at least one line of vision, while half of patients gained two or more lines. In addition, 68% of eyes were within 0.5 D of intended refraction and almost 90% were within 1.0 D. "The 12-month results of the PRL European Clinical Trial are promising. Efficacy and safety of the PRL procedure in the treatment of myopia and hyperopia seem to be confirmed." IOL floats without fixationThe PRL is a non-fixated one-piece "floating" posterior chamber IOL. It is made of a hydrophobic silicone material with a lower specific gravity than water. It also has a high refractive index and is very thin as a result. The curvature of its posterior surface corresponds to the anterior surface of the crystalline lens. Its haptics rest on the zonules. The aim of the IOL's design is to prevent it touching the crystalline lens. The refractive IOL has an optic diameter of 4.5 to 5.0mm and an overall length of 10.8mm, or 11.3mm in the myopic model and 10.6mm on the hyperopic model. The refractive range of the myopic implant is -3.0 D to –20.0 D and that of the hyperopic design is +3.0 D to +15.0 D. Both are available in increments of 0.5 D. Dr Philipson said that he implants the lens through a 2.8 - 3.0 mm incision using a 1.5 mm forceps. He uses a viscoelastic of medium viscosity in order to maintain the anterior chamber and protect the corneal endothelium. High viscosity viscoelastics make manipulation of the lens more difficult, he noted. When inserting the lens, he grasps the entire IOL with the end of the forceps and pushes it through the incision. When he has it about 75% inserted, he re-grasps the lens and inserts it the rest of the way into the anterior chamber. He than manipulates the lens with a second instrument placed through a side port incision. Once he has the edge of the lens under the well-dilated iris, he rotates it into place.
Bo Philipson MD, PhD
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While he did not present data from hyperopic eyes entered into the study so far, Dr Philipson said their early results have not been as favourable as they have been in myopic eyes. He attributed the less promising results to the difficulty of obtaining accurate refractions in such individuals.The overall complications for both hyperopes and myopes included three instances of traumatic cataract and one case of luxation of the PRL into the vitreous body. A total of six eyes underwent explantation of the lens. The reasons included overcorrection in two hyperopes, luxation into the vitreous in a myopic patient, iridocyclitis in a hyperopic patient, and traumatic cataract in a hyperopic patient. Other complications included PRL rotation, which occurred in three percent of eyes. In addition, transient corneal oedema occurred in 27.6% of eyes during the first postoperative day. Transient increases of IOP to greater than 25 mmHg occurred in 5.5% during the early postoperative period, which probably resulted from incomplete removal of the viscoelastic. 
"Some of the viscoelastic material inevitably remains inside the eye because unlike cataract surgery you can only irrigate it you cannot aspirate it. It's also important to perform an iridectomy to avoid blocking the pupil." Optical complications included glare in 13.0%, halos in 29.3%, and difficulty in driving at night in 13.5%. Dr Philipson noted that most patients learn to disregard the optical phenomena over time. Endothelial cell loss was low, averaging at 6.3% after one year. Dr Philipson noted that he does not use the special injector for the lens because he found that it made it more difficult to insure that the lens was right side up. He concluded, however, that a newer version of the lens on which the two sides are clearly marked might make the injector a more attractive option.