Full-Thickness Astigmatic Keratotomy Combined With Small-Incision Lenticule Extraction to Treat High-Level and Mixed Astigmatism

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1 CLINICAL SCIENCE Full-Thickness Astigmatic Keratotomy Combined With Small-Incision Lenticule Extraction to Treat High-Level and Mixed Astigmatism Bu Ki Kim, MD, MS,* Su Joung Mun, MD, PhD,* Dae Gyu Lee, MD, PhD,* Jae Ryun Kim, MD, MS, Hyun Seung Kim, MD, PhD, and Young Taek Chung, MD, PhD* Purpose: To explore the clinical effects of combined full-thickness astigmatic keratotomy and small-incision lenticule extraction (SMILE) in patients who are inoperable using SMILE alone. Methods: We included 13 eyes of 9 patients with high-level or mixed astigmatism who underwent full-thickness astigmatic keratotomy followed by SMILE (secondarily) to correct the residual refractive error. Results: Six months after SMILE, the spherical equivalent was reduced from D to D (P, 0.001), and the astigmatism was reduced from D to D (P, 0.001). The uncorrected and corrected (CDVA) distance visual acuities improved from to (P, 0.001) and from to (P = 0.002), respectively. The CDVA improved by 1 or 2 Snellen lines in 8 cases (61.5%), and there was no loss in CDVA. All procedures were completed without intraoperative or postoperative complications. Conclusions: This combined procedure was effective and safe for the treatment of high-level or mixed astigmatism. Key Words: small-incision lenticule extraction, SMILE, astigmatic keratotomy, astigmatism, high astigmatism (Cornea 2015;34: ) Small incision lenticule extraction (SMILE) is a relatively new technique for correcting myopia and myopic astigmatism. SMILE was first described by Sekundo et al 1 and Shah et al 2 in In this procedure, a lenticule is removed through a small incision (2 4-mm long) using a VisuMax (Carl Zeiss Meditec, Jena, Germany) femtosecond laser, without flap Received for publication March 5, 2015; revision received July 21, 2015; accepted July 23, Published online ahead of print September 29, From the *Onnuri Smile Eye Clinic, Hyobong Building, 9F 1, Gangnam-daero 65 gil, Seocho-gu, Seoul, Korea; and St. Mary s Hospital, Department of Ophthalmology and Visual Science, College of Medicine, The Catholic University of Korea, Seoul, Korea. The authors have no funding or conflicts of interest to disclose. Reprints: Hyun Seung Kim, MD, PhD, St. Mary s Hospital, Department of Ophthalmology and Visual Science, College of Medicine, The Catholic University of Korea, 90-1 Hyehwa-dong, Jongno-gu, Seoul, South Korea ( sara514@catholic.ac.kr). Wolters Kluwer Health, Inc. All rights reserved. creation, thus avoiding potential side effects such as dry eye syndrome, ectasia, and traumatic flap detachment. 3 5 Recent evidence suggests that the procedure affords excellent clinical outcomes, and is safe, effective, and predictable. 2,6 Currently, however, SMILE is limited to a refractive correction of up to 10 diopters (D) for myopia, 5 D for astigmatism, and 10 D for the sum of myopia and astigmatism. 1 Astigmatic keratotomy is effective in correcting astigmatism; in this technique, an incision is made over a steep axis to flatten the cornea. 7 It is possible to reduce astigmatism without altering the spherical equivalent. 7 Using this procedure, it is possible to perform surgeries on patients with high level or mixed astigmatism. In this study, we review the feasibility and outcomes of SMILE after full-thickness astigmatic keratotomy in patients who were inoperable with SMILE alone, as the sum of the spherical and cylindrical refractions exceeded 10 D, the cylindrical refraction exceeded 5 D, or mixed astigmatism was present. METHODS We enrolled 13 eyes from 9 patients with high-level or mixed astigmatism, who were treated with SMILE after full-thickness astigmatic keratotomy at the Onnuri Eye Clinic, Jeonju, Korea, from June 2013 to May SMILE was performed 2 months after astigmatic keratotomy, when the refraction was stable for 4 weeks. The patients were monitored for 6 months. This study was approved by the Internal Regulatory Board of Yeouido St. Mary s Hospital, Seoul, Korea. All patients signed the informed consent, which was in accordance with the tenets of the Declaration of Helsinki. Preoperative Assessment Patients underwent preoperative examination and were measured for uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest and cycloplegic refraction, and intraocular pressure tonometric data (CT-80; Topcon, Japan). Patients also underwent slitlamp microscopic examination, fundus examination, autokeratometry (KR-8900; Topcon, Japan), specular microscopy (noncom Robo-ca; Konan Medical, Japan), topography (Orbscan IIz; Bausch & Lomb), and corneal thickness measurements (Galilei; Ziemer Ophthalmic Systems, Port, Switzerland) Cornea Volume 34, Number 12, December 2015

2 Cornea Volume 34, Number 12, December 2015 SMILE to Treat High-Level and Mixed Astigmatism Astigmatic Keratotomy The steepest axis was considered when planning for surgery. After eyes were anesthetized with 0.5% proparacaine HCl (Alcaine; Alcon), the 0-, 90-, and 180-degree axes were marked on the limbus using a 26-G needle visible in the sitting position, with the aid of a slit lamp. After scrubbing the skin and eyelids with povidone iodine, the eyes were anesthetized with 0.5% proparacaine HCl, and an eyelid speculum was used to keep the eye open in the recumbent position. Rings were marked with a ring marker that featured cross wires (7.5 mm) and gentian violet. The 0-, 90-, and 180- degree axes were marked on the ring markings using a surgical marking pen. Next, the quadrant that included the steep axis was divided into 3 sections, and the axis of the steep meridians was marked. A beveled full-thickness incision was made using a 2.8-mm keratome at 0, 0.5, 1.0, or 1.5 mm from the posterior ring marking, and the incision tunnel made was 1.5 mm in length. The incision was widened using a wider keratome (4.1 or 5.7 mm) depending on the magnitude of astigmatism. After checking for leakage with a Weck-Cel sponge, a mixture of cefazolin, prednisolone, and lidocaine was injected subconjunctivally near the incision (Fig. 1). We used 1 superior incision to treat the undercorrection of astigmatism. When astigmatism was too undercorrected to perform SMILE, an inferior incision was made to reinforce the same method. Small-Incision Lenticule Extraction A VisuMax 500-kHz femtosecond laser was used for SMILE surgery. The eyes were anesthetized with 0.5% proparacaine HCl eye drops 2 to 3 minutes before surgery. After scrubbing the skin and eyelids with povidone iodine, the patient was draped with sterile drapes and an eyelid speculum was used to keep the eye open. The patient was positioned under the curved contact glass of a femtosecond laser. The patient was asked to look at a fixation beam, and the patient s eye was adjusted to the contact glass interface at the center of treatment, which is relative to the pupil center. Once appropriate centration was achieved, suction was applied to the contact glass. Only an S-size treatment pack ( contact glass ) was used. We used a 500-kHz, cut energy index, 36 pulsed femtosecond laser and a 4.5-mm spot spacing. First, the back of the intrastromal lenticule was created by photodisruption from the periphery to the center, and then the lenticule front was created from the center to the periphery, and an incision tunnel was located at the 11 o clock position. The lenticule diameter was 6.0 to 6.8 mm and the cap diameter was 1.0 mm larger than the lenticule diameter. The incision was 2-mm long. The intended cap thickness was 100 to 110 mm. After laser treatment, a thin blunt spatula was inserted through the incision to break the remaining tissue bridges and loosen the stromal lenticule, which was removed using McPherson forceps (M. Blum design; Geuder, Heidelberg, Germany). After removing the FIGURE 1. A, Corneal marking using a ring marker with cross wires (7.5 mm). B, Markings at 3, 9, and 12 o clock with a marking pen. C, Beveled, full-thickness corneal incision with a 2.8-mm blade. D, Extension of the corneal incision with a wider blade. The long tunnel can be seen. E, Checking for leakage with a Weck-Cel sponge. Wolters Kluwer Health, Inc. All rights reserved

3 Kim et al Cornea Volume 34, Number 12, December 2015 lenticule, the stromal pocket was flushed with balanced salt solution (BSS; Alcon). After surgery, all patients were treated with 0.5% moxifloxacin (Vigamox; Alcon) for 5 days, 0.1% fluorometholone (Ocumetholone; Samil, Korea) for 2 weeks, and preservative-free hyaluronic acid lubricating drops (Hyalein Mini 0.1%; Santen, Japan) for at least 2 weeks. Outcome Measures The patients were evaluated 1 day, 1 week, and 1, 3, and 6 months after surgery. At each visit, the UDVA and CDVA were measured; manifest refraction, slit-lamp examination, keratometry, and corneal topography were performed, and complications were assessed. Vector Analyses of Astigmatism The method reported by Kaye et al 8 was used for vector analyses of astigmatism. K 2 ¼ K 3 cos2 ðb 2 uþ 2 K 1 cos2 ðb 2 aþ 2b ¼ tan 2 1 K1 sin2a 2 K 3 sin2u ; K 1 cos2a 2 K 3 cos2u where K 1 is the preoperative astigmatism at angle a, K 2 the surgical effect at angle b, and K 3 the postoperative astigmatism at angle u. Statistical Analyses Statistical analyses were performed using SPSS version 18 (SPSS, Chicago, IL). Graphics were generated using Microsoft Excel 2013 (Microsoft Corporation, Redmond, WA). All values are given as means 6 SDs. Statistical analyses of visual acuity used logarithms of the minimum angle of resolution (). A P of less than 0.05 was considered to indicate statistical significance. RESULTS Study Population This study included 13 eyes of 9 patients: 6 women and 3 men. Their mean age was (range, 20 39) years. Table 1 summarizes patient characteristics. Five eyes of 4 patients had myopia with high-level astigmatism such that the sum of the spherical and cylindrical refraction exceeded 10 D; 7 eyes of 5 patients had high-level astigmatism (over 5 D); and 3 eyes of 3 patients had mixed astigmatism. Efficacy The mean UDVA improved from to , 2 months after astigmatic keratotomy (P = 0.183), and to , 6 months after SMILE (P = 0.002). The effect of the combined procedure was significant (P, 0.001). The efficacy index (mean postoperative UDVA/mean preoperative CDVA) was Figure 2 shows the changes in the spherical equivalents and astigmatism after the combined procedure. No significant change in the spherical equivalent was evident 2 months after astigmatic keratotomy (P = 0.147), but the astigmatism reduced from D to D, 2 months after keratotomy (P, 0.001). Six months after SMILE, the spherical equivalent reduced to D (P, 0.001) and the astigmatism to D (P, 0.001). We found that 62.7% of astigmatism was removed 2 months after astigmatic keratotomy and 95.9% at 6 months after SMILE. Predictability We found that the spherical equivalents of 84.6% of eyes that were treated with the combined procedure, were within 60.5 D, and that, 6 months after astigmatic keratotomy and SMILE, all eyes were within 61.0 D. Stability The postoperative spherical equivalent was D at 1 week, D at 1 month, D at 3 months, and D at 6 months. There was no significant change up to 6 months postoperatively (P = 0.544). Safety and Complications Of all eyes, 38.5% had an unchanged CDVA, 38.5% had gained one line, and 23.0% had gained 2 lines. There was no loss in CDVA. The mean CDVA improved from to (P = 0.002). No complication, such as wound leakage, endophthalmitis, retinal detachment, epithelial ingrowth, keratitis, or ectasia, was observed during the follow-up. Also, there was no significant change in the endothelial cell number (P = 0.894). Figure 3 shows a typical example of the combined procedure of full-thickness astigmatic keratotomy and SMILE. DISCUSSION Laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) precisely correct the spherical equivalents of highly astigmatic eyes, but lead to astigmatic undercorrection. 9 Although many reports have shown that SMILE yields good results when used to correct myopic astigmatism, 1,2,6 SMILE is of limited utility when high-level astigmatism is present. Currently, VisuMax use is restricted to less than 10 D of myopia, 5 D of astigmatism, and 10 D of the sum of myopia and astigmatism, 1 and cannot correct hyperopia. Astigmatic keratotomy is effective for the correction of naturally occurring astigmatism, and any residual astigmatism present in patients who have undergone PKP, lensectomy, or LASIK The procedure does not give rise to ectasia or irregular astigmatism because no keratectomy is performed, and treatment is confined to the peripheral cornea. 12 When we considered these facts, we hypothesized that it should be possible to reduce astigmatism with astigmatic keratotomy, at which point the myopia would increase by as much as half of the reduction in astigmatism so that an eye Wolters Kluwer Health, Inc. All rights reserved.

4 Cornea Volume 34, Number 12, December 2015 SMILE to Treat High-Level and Mixed Astigmatism TABLE 1. Patient Demographics and Postoperative Results Age/ Sex UDVA, Preoperative 2 Months After Astigmatic Keratotomy 6 Months After SMILE CDVA, Refraction, degrees UDVA, CDVA, Refraction, degrees UDVA, CDVA, Refraction, degrees 1 23/F to to to /F to to to /F to to to to to to /F to to to /M to to to /M to to to /M to to to to to /F to to to to to to /F to to to to to with astigmatism exceeding 5 D, or myopic astigmatism (the sum of myopia and astigmatism exceeding 10 D), would be subsequently operable; we could correct the residual astigmatism and myopia with SMILE. Patients with mixed astigmatism could be treated the same way. In general, astigmatic keratotomy involves the creation of a partial-thickness corneal incision perpendicular to the steep meridian of the corneal astigmatism, using a diamond knife. 13,14 However, manual astigmatic keratotomy is less reliable and predictable for astigmatic reduction and associated complications, such as endophthalmitis and retinal detachment To improve the accuracy and reproducibility of the incision depth and length, several authors have reported positive results when astigmatic keratotomy features either a Hanna arcitome or a femtosecond laser. 10,18 We use manual incision, but each full-thickness incision is made with a uniform keratome to avoid inaccuracies in depth and length. We achieved 62.7% reduction in astigmatism after astigmatic keratotomy, which exceeds the 55%, 47%, and 36% reductions reported by Hoffart et al, 19 Buzzonetti et al, 20 and Kumar et al, 21 respectively. We suggest that this is because the cited studies used partial-thickness incisions, and we used full-thickness incisions. Cleary et al 10 reported that beveled, femtosecond laser astigmatic keratotomy yielded better results than those achieved using a perpendicular incision; the beveled incision allows the anterior cornea to slide forward in relation to the posterior cornea, and the realigned stroma heals without wound gaping or formation of an epithelial plug. We also sought to render beveled keratotomy to produce a long incision tunnel and prevent wound leakage or regression. We did not note any complication, such as endophthalmitis or retinal detachment, after astigmatic keratotomy. One of the biggest concerns with astigmatic keratotomy is the variety in the nomogram. We have developed a nomogram for beveled, full-thickness astigmatic keratotomy, which others are welcome to use (Table 2). Age was not included in the nomogram, which may reduce the precision. Also, the amount of corrected astigmatism depends on the incision length and the diameter of the optic zone. Therefore, the greater the astigmatism, the lower the reliability of the procedure. However, these do not pose problems because residual astigmatism can subsequently be corrected with SMILE. FIGURE 2. Changes in spherical equivalent (A) and astigmatism (B) after astigmatic keratotomy and SMILE. Wolters Kluwer Health, Inc. All rights reserved

5 Kim et al Cornea Volume 34, Number 12, December 2015 FIGURE 3. In a typical case, beveled, 5.7-mm-long, full-thickness astigmatic keratotomy was performed on the right eye at the 11:30 o clock position. A, The incision is seen in a slit-lamp photograph taken 1 month postoperatively. B, The beveled fullthickness incision is faintly seen on anterior segment OCT. C, Preoperatively, K max was 45.9 D and K min 42.7 D by topography, and refraction was to degrees. D, After astigmatic keratotomy, K max was 45.1 D, K min 44.6 D, and refraction to degrees. E, After SMILE, K max was 39.4 D, K min 38.2 D, and refraction to 0. Despite the fact that the flattening of the incised meridian almost equals the steepening of the opposite meridian after astigmatic keratotomy, because we incised only superiorly instead of paired incisions if undercorrection was not too much, there can be concerns about change in spherical equivalent and induction of irregular astigmatism. 7,22 Also, there were some cases of change in spherical equivalent or irregular astigmatism. However, these did not cause clinical problem after SMILE. It is difficult to correct high-level astigmatism with LASIK or PRK alone, so combined procedures have been performed, such as an astigmatic keratotomy with PRK 23 or astigmatic keratotomy with LASIK. 15 Good results were TABLE 2. Nomogram of the Beveled, Full-Thickness Astigmatic Keratotomy Distance From Corneal Marking, mm Incision Width, mm Corrected Astigmatism, D obtained in terms of safety, efficacy, and predictability. We obtained excellent results for refractive change and visual acuity. In our study, the mean spherical equivalent was D, the mean astigmatism D, and the spherical equivalent of all cases within 61.0 D. We used SMILE as the second procedure. In this manner, we avoided the corneal haze and regression, which are common after PRK, and dry eye syndrome, ectasia, and traumatic loosened flaps that are common after LASIK. 15,23 Several studies have shown that refractive accuracy, dry eye, contrast, and induced aberrations were less problematic after SMILE than LA- SIK. 24,25 This is very valuable for the quality of vision and patient satisfaction. In addition, because SMILE preserves the anterior segment of the cornea that possesses greater biomechanical strength than posterior segments, it is thought to have strong mechanical stability compared to LASIK or PRK as the second procedure after full-thickness astigmatic keratotomy. 26 Recently, there have been studies on toric ICL that reported good results in correction of high astigmatism, 27,28 but have some limitations in comparison to our combined procedure. Most importantly, axis rotation can occur after surgery, resulting in undercorrection of astigmatism. Kamiya et al 27 reported 8% of eyes required ICL repositioning because of axis rotation by 10 or more. There is also the possibility of inaccuracy in predictability because of corneal astigmatism changes due to corneal incision during surgery. In addition, patients sometimes should wait several weeks for toric ICL manufacture. Our combined procedure does not have these Wolters Kluwer Health, Inc. All rights reserved.

6 Cornea Volume 34, Number 12, December 2015 SMILE to Treat High-Level and Mixed Astigmatism concerns and other ICL-related complications, such as endothelial cell loss, cataract formation, and pupillary block. One important aspect of the combined technique is its safety. Usually, combined procedures are associated with few or no complications. 15 Nevertheless, complications such as perforation, epithelial ingrowth, and interface haze remain of concern. As intraocular pressure rises during SMILE, complications associated with wound dehiscence are potentially serious when performing SMILE after astigmatic keratotomy. To avoid this problem, we waited 2 months after keratotomy before performing SMILE, and we did not encounter any case of wound dehiscence during or after SMILE. In addition, we noted no intraoperative or postoperative complications. Also, there could be concerns about gas break along the keratome incision, and we ve had some cases of gas trapped at the keratome incision during SMILE after full-thickness astigmatic keratotomy. However, even in those cases, there was no case of bubbles in the anterior chamber, and the dissection was conducted completely without any difficulties. In conclusion, our data indicate that the combination of astigmatic keratotomy and SMILE is effective and appears to be safe. However, larger studies with longer follow-up period are required to test the limitations of the combined procedure because 6 months of follow-up might not be enough due to the regression of astigmatism. REFERENCES 1. Sekundo W, Kunert KS, Blum M. Small incision corneal refractive surgery using the small incision lenticule extraction (SMILE) procedure for the correction of myopia and myopic astigmatism: results of a 6 month prospective study. Br J Ophthalmol. 2011;95: Shah R, Shah S, Sengupta S. 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Three-year follow-up of posterior chamber phakic intraocular lens implantation for moderate to high myopic astigmatism. PLoS One. 2013;8:e Sari ES, Pinero DP, Kubaloglu A, et al. Toric implantable collamer lens for moderate to high myopic astigmatism: 3-year follow-up. Graefes Arch Clin Exp Ophthalmol. 2013;251: Wolters Kluwer Health, Inc. All rights reserved