EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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EW CORNEA 62 October 2014 by Michelle Dalton EyeWorld Contributing Writer Silicone oil in anterior segment surgeries? S ilicone oil has been evalu- ated and used for decades in various retinal surgeries, most notably pars plana vitrectomy, to help avoid serious complications. In 1965, Levenson et al. experimented with a thin intracorneal layer of silicone with the hope that it would "serve as a barrier to the passage of fluid through the cornea from the ante- rior chamber in the presence of an injured or diseased endothelium." 1 According to Ioannis Pallikaris, MD, the outcomes of that experi- ment were "not truly encouraging." Dr. Pallikaris, Institute of Vision & Optics, University of Crete, Greece, explained that after silicone oil was injected into the stroma of rabbit and dog corneas, there was no tissue reaction, and the silicone served as a barrier to the spread of the edema. But several months later the researchers found anterior stromal atrophy—a crater-like defect covered with epithelium, he said during a presentation at the 2014 ASCRS•ASOA Symposium & Congress 2 and published in Cornea. 3 "But we thought we'd retry using oil in the anterior chamber," Prof. Pallikaris said. "The idea to in- troduce silicone oil into the cornea resulted after observing post retinal detachment eyes [that] were treated with silicone oil. In some cases silicone entered the anterior cham- ber, clearing edematous corneas." Most anterior segment surgeons are aware that silicone oil can dam- age endothelial cells when found in the anterior chamber, said William Trattler, MD, in practice at Center for Excellence in Eye Care, Miami. George D. Kymionis, MD, PhD, from Prof. Pallikaris' group, picked up on the idea that while silicone oil in the anterior chamber damages endothelial cells, the corneas remained thin and clear as long as the silicone oil remained in the an- terior chamber against the cornea. 4 "The placement of silicone oil within a pocket in the cornea has the potential, based on findings from this paper, to treat conditions like bullous keratopathy. This tech- nology is very exciting," Dr. Trattler said. Dr. Trattler said bullous ker- atopathy can often be the result of multiple surgeries or surgery in advanced cataracts where stress and trauma from the surgery itself causes the disorder. In those situations, Descemet's stripping endothelial keratoplasty (DSEK) "is a very safe, easy pro- cedure for corneal surgery when people have good visual potential," Dr. Trattler said. "But Prof. Pallikaris' technique offers an alternative for people who have poor visual poten- tial where they're not likely going to be good candidates for corneal transplants or DSEK." He added that the procedure may not produce visual gains but may reduce pain and discomfort. Prof. Pallikaris said femtosecond lasers allow for "precise intracorneal pocket creation that would im- prove the outcomes of this surgical approach. The main advantage that femtosecond lasers offered was the limited and well-controlled pocket creation allowing for corneal nutrition peripherally to the silicone meniscus and thereby avoid- ing possible corneal complications (such as band keratopathy) due to suboptimal nutrition." The new technique Prof. Pallikaris created a pocket with the femtosecond laser sim- ilar to those created for use with intracorneal inlays. His group used the lamellar keratoplasty treatment • Production instrument for simple and fast testing of IOL batches • Imaging technique close to real conditions • Measurement of all types of IOLs: including multifocal diffractive, trifocal, toric lenses and others • Measurement parameters: Power, Add power, Cylinder, MTF, toric marks, radius of curvature, through focus scans, energy distribution and others • In air or in situ conditions according to ISO 11979 standard • Traceability to international standard NPL and NIST IOL Testing Fast and Automated OptiSpheric ® IOL PRO 2 is the most comprehensive measurement system for any types of IOLs in production. AZ2 OS IOL PRO 2 254 x 165 mm_print 21.08.14 18:00 Seite 1