EyeWorld Asia-Pacific March 2011 Issue

23 EW REFRACTIVE March 2011 Resolving residual refractive error by Matt Young EyeWorld Contributing Editor TICL an option for piggyback IOL implantation P atients with residual refractive error after cataract surgery have several options for visual improvement. Ophthalmologists can now add the Visian TICL (STAAR Surgical, Monrovia, Calif., USA/Nidau, Switzerland) to that list of options, according to promising results suggesting that the TICL, a toric posterior chamber phakic IOL, can work well as a piggyback lens to correct residual astigmatism. “Piggyback insertion of a toric ICL [implantable contact lens] appears to be effective and predictable in correcting refractive error in pseudophakic eyes,” according to lead study author Takashi Kojima, MD, Department of Ophthalmology, Social Insurance Chukyo Hospital, Nagoya, Japan. Dr. Kojima refers to the TICL as an “ICL” since the TICL is the toric version of the Visian ICL (STAAR Surgical). The study was published online in May in the Journal of Refractive Surgery, and its authors note that it is the first report evaluating TICL implantation for pseudophakic eyes. One thing to keep in mind: The possibility of pupillary block after TICL implantation, which did occur in this series in one case, does necessitate use of iridectomies. That’s piggyback ICL, not IOL Dr. Kojima analyzed eight eyes of five patients that previously underwent cataract surgery and subsequently underwent piggyback TICL implantation for correction of refractive error. “At 6 months postoperatively, the ICL was well centered in all eyes, and no inflammation was observed under slit-lamp examination,” Dr. Kojima reported. “All eight (100%) eyes were corrected within ±0.50 D of attempted mean spherical equivalent refraction. Manifest refractive astigmatism was corrected within ±0.50 D in five (62.5%) eyes and ±1.00 D in seven (87.5%) eyes.” Specifically, pre-op manifest refractive sphere was –3.06±3.75 D. That improved to 0.06±0.90 D at six months post-op. Pre-op manifest refractive astigmatism was –2.63±0.76 D, improving to –0.72±0.65 D post-op. “A slight decrease in endothelial cell density was noted during 6-month follow-up, and a minimum clinical effect on corneal endothelial cell was confirmed,” Dr. Kojima noted. “Considering the risk of corneal endothelial cell loss in IOL exchange surgery, ICL implantation was considered safe.” Vault was found to be high in six eyes (75%), but further inspection determined that the angle was open, “and no abnormalities such as peripheral iris synechia were apparent”, Dr. Kojima noted. The fact that there is vault is also helpful in some respects. “The ICL was designed not to touch the crystalline lens, and therefore the ICL creates a vault,” Dr. Kojima noted. “We speculated that the stable anterior vault may contribute to achieving stable refraction. In our study, refractive sphere and astigmatism were stable during the 6 months following surgery.” Avoidance of contact with the crystalline lens has other advantages over traditional piggyback IOLs, which could lead to interlenticular opacities and hyperopic shift because of the proximity of two IOL optics, Dr. Kojima noted. One eye did experience papillary block one day after surgery and was resolved by laser iridectomy. “Although the posterior chamber is wide in the pseudophakic eye, the possibility of pupillary block remains,” Dr. Kojima reported. “To avoid this complication, sufficient peripheral iridectomy or laser iridotomy should be performed before or during surgery.” Dr. Kojima acknowledged that other options for residual refractive error after cataract surgery, such as LASIK, could be considered. “The advantage of LASIK is that it can correct not only spherical and astigmatic error, but also higher order aberrations and irregular astigmatism using wavefront or topography-guided technology,” Dr. Kojima noted. “Another advantage is that LASIK does not affect corneal endothelial cell count. However, a thin and/or abnormal cornea is a contraindication for LASIK, and postoperative dry eye can affect visual function.” Audrey R. Talley-Rostov, MD, Northwest Eye Surgeons, Seattle, Wash., USA, said she does not believe making piggyback use of an ICL is appropriate. “In terms of piggybacks, there are IOLs on the market and IOLs coming out in the future that are made for that use,” Dr. Talley-Rostov said. “The Visian toric ICL Source: STAAR Surgical collamer ICL is not made to be a piggyback IOL per se.” Although Dr. Talley-Rostov added that she would have to dig deeper into the study to comment further, she did mention that STAAR makes a variety of lenses that are perfectly suitable as piggyback IOLs. “There are low- powered IOLs on the market,” Dr. Talley-Rostov said. So, she said, it’s hard to imagine using the TICL as a piggyback lens when STAAR “makes a lovely sulcus IOL”. EW Editors’ note: Dr. Kojima has no financial interests related to this study. Dr. Talley-Rostov has no financial interests related to her comments. Contact information Kojima: +81 52 691 7151 , tkojkoj@mac.com Talley-Rostov: atalleyrostov@nweyes.com Tel: +65 64936953 Fax: +65 64936955