EyeWorld Asia-Pacific June 2020 Issue

EWAP JUNE 2020 43 CORNEA That being said, there are reports v Ã}wV>Ì>âi >vÌiÀ VÀÃÃ} when laser was done concurrently, so there are many docs who recommend laser afterward only. With EBK and avoiding the removal of more than xä ù v ÌÃÃÕi ÜÌÌi >ÃiÀ] Ì>Ì>Ã not been my experience though.” An emerging refractive therapy Dr. Hersh described another technique that he’s working on Ì LiiwÌ iÀ>ÌVÕÃ «>ÌiÌÃ refractively. It’s called corneal tissue addition for keratoconus, or CTAK. He said it uses preserved corneal tissue that is cut into customized shapes with a femtosecond laser. “Depending on the location of the cone and thickness of the cornea, we are implanting preserved corneal tissue to preserve corneal topography and thicken the cornea,” he said. About 10 patients have been treated with this technique so far and “it’s looking very promising,” Dr. Hersh said. º/i LiiwÌ v Ì>Ì Ã ÞÕ V> make different sizes and shapes, customized for the patient,” he said. EWAP References 1. Hersh PS, et al. Corneal crosslinking and intracorneal ring segments for keratoconus: A randomized study of concurrent versus sequential surgery. J Cataract Refract Surg. 2019;45:830–839. 2. Nguyen N, et al. Incidence and associations of intracorneal ring segment explantation. J Cataract Refract Surg. 2019;45:153–158. Editors’ note: Dr. Hersh is in practice at CLEI Center for Keratoconus, The Cornea & Laser Eye Institute, Hersh Vision Group, Teaneck, New Jersey, and has relevant interests with Avedro (acquired by Glaukos), Lions Vision Gift, and Addition Technology. Dr. Loden practices at Loden Vision, Nashville, Tennessee. Dr. Rebenitsch practices at ClearSight Center, Oklahoma City, Oklahoma. Dr. Loden and &T 4GDGPKVUEJ FGENCTGF PQ TGNGXCPV ƂPCPEKCN interests. Do Hyung Lee, MD, PhD Professor, Department of Ophthalmology, Ilsan Paik Hospital, Inje University 2240 Daewha, Ilsan, Koyang, Kyunggyi, South Korea eyedr0823@hotmail.com ASIA-PACIFIC PERSPECTIVES I read the article with great interest. Nobody doubts that the treatment of KCN such as corneal collagen crosslinking and intrastromal corneal ring segment (ICRS) implantation is challenging. It is true that these treatments are effective in terms of vision and keratometric value. However, the topographic w`}Ã >` >LiÀÀiÌiÀ Û>ÕiÃ >Ài Ì >Ü>ÞÃ VÃÃÌiÌ >` «>ÌÌiÀÃ v >Ài `ÛiÀÃi >} `Û`Õ>Ã° />Ì½Ã ÜÞ Ì Ã ÛiÀÞ `vwVÕÌ Ì «Ài`VÌ Ìi ÃÕÀ}V> ÀiÃÕÌÃ vÀ i>V«>ÌiÌ° Many researchers consider corrected distant visual acuity (CDVA) to be an important parameter to evaluate the success of surgery. However, I found that some KCN patients can read Snellen chart letters better than normal patients despite very high corneal higher-order aberrations (HOAs). From this perspective, I believe in addition to CDVA, functional vision should also be evaluated. The repeatability of keratometric values and HOAs is not always certain in even moderate KCNs. These limitations cause many to perform ICRS implantation. However, although the company provides surgical guidelines, the actual surgical procedures depend on surgeons’ experience. Ìi «>ÃÌ]>Ûi iÝ«iÀiVi` >Þ V>ÃiÃ ÜÌ`ÃVÀi«>ViÃ LiÌÜii Ì«}À>«V w`}Ã >` symptoms after surgery. Recent study combining ICRS implantation and corneal collagen crosslinking with meta-analysis suggests that both procedures used simultaneously may provide better outcomes than staged techniques for improving the corneal shape. 1 However, as they mentioned, 12 months follow-up is too short to draw concrete conclusions. We need more discussions and exchange case results to improve surgical outcomes. In this article, all three ophthalmologists supported crosslinking combined with topography- guided PRK. Some authors reported the usefulness of combined therapy with crosslinking, ICRS, and topography guided or wavefront guided PRK. 2–4 Unfortunately, I do not have any experience with Ì«}À>«Þ}Õ`i` >L>Ì y>ÌÌi} Vi ÜÌiÃÃ Ì> xä >L>Ì >` Ü>ÛivÀÌ}Õ`i` ablation decreasing very high HOAs in KCN. Most have reported effective and safe results. However, we need more, longer-term follow-up studies in cases such as iatrogenic ectasia. Recently, He et al. reported that t he combined surgery of ICRS, CXL, and ICL implantation had Ã}wV>ÌÞ «ÀÛi` ÛÃÕ> >VÕÌÞ] "ƂÃ] >` VÀi> Ã>«i >` «ÃÌ Ƃ- iVÌ>Ã>° 5 Based on my experience, the reduction of high regular astigmatism and spherical error is also an important factor in improving vision in KCN patients. As of now, we cannot say for certain who are the best candidates, which procedure is most effective, and how the combination therapy should be performed for KCN patients. Despite these limitations, the reason why I try to perform combined therapy is I agree with Dr. Loden’s comments: waiting to show progression is dereliction of duty. References 1. Hashemi H, et al. Appropriate Sequence of Combined Intracorneal Ring Implantation and Corneal Collagen Cross- Linking in Keratoconus: A Systematic Review and Meta-Analysis. Cornea . 2018;37:1601-1607. 2. Iovieno A, et al. Intracorneal ring segments implantation followed by same-day photorefractive keratectomy and corneal collagen cross-linking in keratoconus. J Refract Surg . 2011;27:915-8. 3. Elbaz U, et al. Accelerated versus standard corneal collagen crosslinking combined with same day phototherapeutic keratectomy and single intrastromal ring segment implantation for keratoconus. Br J Ophthalmol . 2015; 99:155-9. 4. Lee H, et al. Visual rehabilitation in moderate keratoconus: combined corneal wavefront-guided transepithelial «ÌÀivÀ>VÌÛi iÀ>ÌiVÌÞ >`}yÕiVi >VViiÀ>Ìi` VÀi> V>}i VÀÃÃ} >vÌiÀ ÌÀ>VÀi> À} segment implantation. BMC Ophthalmology . 2017; 17:270 5. He C, et al. Three-Step Treatment of Keratoconus and Post-LASIK Ectasia: Implantation of ICRS, Corneal Cross- linking, and Implantation of Toric Posterior Chamber Phakic IOLs. J Refract Surg . 2020;36:104-109. 'FKVQTUo PQVG &T .GG FGENCTGF PQ TGNGXCPV ƂPCPEKCN KPVGTGUVU