EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/220233
November 2013 EW REFRACTIVE SURGERY 31 Advances continued from page 28 (simK), and the distribution of the ectasia area on the cornea. The Ferrara Ring implantation can be considered an orthopedic procedure and the refraction is not important on this nomogram. For symmetric bowtie patterns of keratoconus, two equal segments are selected. For peripheral, oval cones, the most common form type, asymmetrical segments are selected. It is important to note that the ring segment thickness cannot exceed 50% of the thickness of the cornea on the track of the ring. The drawback of this nomogram was that different corneas can have the same topographic astigmatism, for example, one patient with keratometry (K) values of 45.00 x 50.00 D and another one with K values of 50.00 x 55.00 D have the same topographic astigmatism. Therefore, for these two completely different corneas, the surgical plan based on this nomogram would be the same, which showed to be inadequate. The fourth generation (2009– 2013) of the nomogram needed to overcome the failures of the previous versions to provide better and more reliable outcomes. The actual nomogram is based on the corneal asphericity (Q), which is a concept related to the shape of the cornea. The asphericity can vary from oblate (where the center of the cornea is flatter than the periphery) to prolate (where the center of the cornea is steeper than the periphery). The normal cornea is mildly prolate and in keratoconus the cornea is usually hyperprolate. The most accepted Q value is about –0.23±0.08, which is the target postoperative Q value after Ferrara Ring implantation. As the amount of Q change after each ICRS thickness implantation has been described, we can easily choose a segment or pair of segments that could change the preoperative Q value to the target postoperative value (–0.23). The nomogram based on cornea asphericity showed to be more reliable as we treat the corneal deformity, regardless of the refraction and topographic astigmatism. The clinical results show that using this nomogram we can implant less tissue in the cornea stroma to achieve the same or better results than were obtained in the past. of femtosecond lasers the number of laser-assisted surgeries has dramatically increased. The main advantages of the femtosecond-assisted ICRS implantation are the symmetry of segments, uniform tunnel depth, and the short learning curve. Many surgeons abandoned the technique because of the steep learning curve of the manual technique. The femtosecond laser made the surgery much easier to perform, which led to an increase in the number of surgeons performing the procedure. However, once the manual technique is mastered, after the learning curve, the clinical outcomes are very similar to the laser-assisted surgery. In summary, the evolution of the nomogram and laser-assisted THINK ENERGY REDUCTION "With the LENSAR Laser, I've experienced a signifcant reduction in phaco energy, and in some cases I've needed no ultrasound energy at all. More importantly, I've seen a reduction in infusion volume and surgical time, resulting in much quieter postoperative eyes." surgery are the main milestones in the Ferrara Ring implantation, which makes the procedure safer, effective, and reproducible. EW Editors' note: Dr. Torquetti has financial interests with Ferrara Ophthalmics. Contact information Torquetti: leotorquetti@gmail.com At LENSAR™, we're always thinking ahead. That's why we designed the LENSAR Laser System with phaco energy reduction in mind. By combining superior imaging of the anterior segment, precise laser placement, and effcient lenticular fragmentation, the LENSAR Laser allows for a reduction in phaco time and up to 100% reduction in phaco energy.1 This ultimately provides patients with a higher level of safety and you with greater peace of mind. The LENSAR Laser System. Designed for energy reduction, designed for you. Learn more at LENSAR.com – Jonathan Solomon, MD Surgical technique The most widely used surgical technique for the Ferrara Ring implantation used to be the manual (or mechanical). With the recent advent Scan to learn about LENSAR at AAO 2013