EyeWorld Asia-Pacific September 2012 Issue

24 EWAP CAtArACt/IOL September 2012 Bag-in-the-lens technique goes toric by Enette Ngoei EyeWorld Contributing Editor EyeWorld checks in on new developments with the technique that prevents PCO F ollowing the success of the bag-in-the-lens (BIL) technique in preventing posterior capsular opacification (PCO) with the BIL IOL, its inventor Marie-Jose Tassignon, MD, ophthalmology department, Antwerp University Hospital, and faculty of medicine, Antwerp University, Belgium, developed a sphero-toric BIL IOL. Clinical results of the lens were published in the Journal of Cataract & Refractive Surgery. According to the study, spherotoric BIL IOL implantation yielded outcomes similar to those with other spherotoric IOLs, even in eyes with ocular comorbidity or irregular astigmatism up to 15 degrees. Led by Dr. Tassignon, researchers at the Antwerp University Hospital enrolled 52 consecutive eyes of 35 patients with cataract and corneal astigmatism ranging from 0.9- 6.19 D. Spherotoric BIL IOLs were implanted. The IOLs were centered based on the patient’s pupillary entrance using Purkinje reflexes of the surgical microscope light, the authors wrote. The toric power was between 1-8 D. One third of eyes had an additional ocular comorbidity (including amblyopia) that could influence the clinical outcomes; 5.2% had an irregular astigmatism up to 15 degrees. According to the report, 12 eyes had high myopia (axial length [AL] >26 mm) and five eyes had high hyperopia (AL <21 mm). The mean pre-op corrected distance visual acuity was 0.58±0.25. Post-op, the uncorrected distance visual acuity (UDVA) was 0.5 or better in 92% of eyes, the mean UDVA was 0.85±0.21 D, the mean magnitude of error was 0.05±0.49 D, and the mean angle of error was 0.29±0.89 degrees. Astigmatism correction was successful in 82% of eyes, the study said. A toric bag-in-the-lens implant Source: Marie-Jose Tassignon, MD, PhD A natural progression Having already developed a lens that does not have PCO as it is not dependent on the healing process of the capsular bag and its final position in the eye always remains stable, it was obvious that designing a toric model of the lens was the next step, Dr. Tassignon said. The BIL technique does not position the lens within the capsular bag but instead positions the capsular bag within the lens in a groove that surrounds the periphery of the BIL lens optic, she explained. The BIL lens is anteriorly positioned with a one-sided toric element, Dr. Tassignon said, because the closer the toric element is to the cornea, the better the correction. “The more you put it backwards, the higher the astigmatism will be to get the same effect of correction,” she said. The way the BIL lenses are implanted allows surgeons to make adjustments in case that is necessary, which may be an important offering, like in the case of marking the cornea, which depends on the position of the toric element within the eye. At present, marking the cornea is still a bit of an approximation, and if the axis of the toric element is misaligned even 10 degrees, there will be an immediate decrease of the toric effect of 33%, Dr. Tassignon noted. This ability to position the lens in various ways could be useful in alignment, which is also important because the anatomy of the eye is such that the lens is not necessarily aligned with the cornea, she said. When a lens is implanted within the capsular bag, that element will not necessarily be aligned with the corneal structure, and the vertex of the astigmatism may not necessarily be in the same vertex of the cornea, Dr. Tassignon said. The new lens has been introduced in Belgium for approval, and initial clinical studies are proving that it works and has good results. The fact that the lens can be easily reoriented even a year post-op in the case of a misalignment makes it ready to go, she said. There are few side effects with this lens as well, Dr. Tassignon said. The most important side effect is the capture of the iris in the immediate post-op period, which may happen, but it can be avoided by following the procedure precisely and by keeping the iris closed for the first 3 days post-op, which is not a problem if there are no complications, she said. Inflammatory reactions following surgery even in babies and children are very low, she said, because there is no contact with the biomaterial and the lens epithelial cells of the capsular bag since the capsular bag is completely closed and without any contact with the IOL unless at the level of the lens groove, which is minimal compared to the classical implantation method. With the capsular bag intact, you have very clear eyes immediately after surgery even in eyes with uveitis, she said. Other factors to consider While positive results have made the technique appealing, the main barrier to entry with the BIL technique is that the lens requires a very accurate approach to cataract surgery, Dr. Tassignon said. continued on page 29