NOV 2013

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

Issue link: https://digital.eyeworld.org/i/220233

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Page 30 of 122

28 EW REFRACTIVE SURGERY November 2013 Advances in nomogram and surgical technique for the Ferrara Ring by Leonardo Torquetti, MD, PhD T he Ferrara intrastromal corneal ring segments (ICRS, Ferrara Ophthalmics, Belo Horizonte, Brazil) have been implanted for keratoconus treatment since 1996. From that time to now several advances have been made to provide better outcomes to patients, with more safety and predictability of results. The main contributing factors to the improved efficacy and safety of the technique are the new nomograms and the laser-assisted surgical technique. The nomogram The nomogram has evolved as the knowledge of the predictability of results has grown. Initially, surgeons implanted a pair of symmetrical segments in every case. The incision was always placed on the steep meridian to take advantage of the coupling effect achieved by the rings. In the first generation of the nomogram (1997–2002), only the grade of keratoconus was considered for the ring selection, which means that in keratoconus grade I, the most suitable Ferrara Ring for im- plantation was that of 150 µm and in keratoconus grade IV, the most appropriate ring was 350 µm. At this time the incidence of segment extrusion was relatively high as in keratoconus grade IV the cornea is usually very thin and the thick ring segment sometimes was not properly fitted into the corneal stroma. The second generation of the nomogram (2002–2006) considered the refraction for the ICRS selection, besides the distribution of the ectasia area on the cornea. Therefore, as the spherical equivalent increased, the selected ring thickness also increased. However, in many keratoconus cases the myopia and astigmatism was not caused by the ectasia itself but by an increase in the axial length of the eye (axial myopia). In these cases, an overcorrection by implanting a thick ring segment in a keratoconus in which a thinner segment was indicated was observed. In the third generation (2002– 2009) of the nomogram, the segment selection depended on the corneal thickness, the amount of topographic corneal astigmatism Q change according to the Ferrara Ring thickness continued on page 31 Study: Punctal plugs might assist after LASIK with dry eye management The use of punctal plugs following refractive surgery could help with dry eye management, according to Abdullah Alfawaz, MD, and colleagues. "Punctal plug insertion after LASIK surgeries may minimize the need for frequent lubricant application and hence improve patient satisfaction," Dr. Alfawaz and colleagues said in the study. In the randomized clinical trial at a tertiary eyecare center in Riyadh, Saudi Arabia, 78 eyes of 39 patients underwent LASIK for myopia in both eyes. A lower punctal occlusion was implanted in one eye with the other eye acting as a control. The subject and control eyes received the same postoperative medications except for lubricant duration—the punctal occlusion eye received it four times per day for one week, while the control eye received it four times per day for six months. Patients were evaluated at one week and two and six months postoperatively for dry eye symptoms. In Ocular Surface Disease Index scores, eyes with punctal plugs scored better at all follow-up visits, with statistically significant differences between both eyes. "At the final follow-up visit, the percentage of normal eyes was higher in eyes with punctal plugs for all ocular surface parameters (Schirmer 1 test, 94.9%; tear breakup time, 77.8%; punctate epithelial keratitis score, 71.8%) compared to eyes without occlusion (Schirmer 1 test, 92.3%; tear breakup time, 58.3%; punctate epithelial keratitis score, 53.8%); however, such differences were not statistically significant," Dr. Alfawaz and colleagues said. The study is published ahead of print in Current Eye Research. Tunnel creation using the femtosecond laser Two Ferrara Rings symmetrically implanted by femtosecond laser Source (all): Leonardo Torquetti, MD, PhD

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