LAUSR

T he Visian ICL (STAAR Surgical, Monrovia, CA, USA) might have advantages over other add-on intraocular lenses (IOLs), since the anteriorly vaulting shape prevents the attachment of the two IOLs, since the thickness is far thinner than other IOLs, and since the material is made from hydroxyethyl methacrylate and collagen collamer. Until now, there have been several studies on piggyback ICL implantation for the management of pseudophakic ametropia, but all studies were conducted in a single institution with a relatively small sample size (Chiou et al. 2001; Hsuan et al. 2002; Kojima et al. 2010; Eissa 2017; Eissa et al. 2017). Herein, we report the outcomes of piggyback ICL implantation in eyes having pseudophakic ametropia, conducted as a collaborative work of the Japan ICL Study Group. The protocol was registered with the University Hospital Medical Information Network Clinical Trial Registry (000029258) and was approved by the Institutional Review Board at Kitasato University. Thirty-five eyes of 28 consecutive patients [10 of men and 25 of women, mean age standard deviation, 61.4 11.7 years, spherical equivalent, 2.79 4.08 dioptre (D)] who underwent ICL implantation as a piggyback IOL at five major institutions (Kitasato University Hospital, Sanno Hospital, Kobe Kanagawa Eye Clinic, Nagoya Eye Clinic, and Sato Eye Clinic) between 2007 and 2017 were enrolled. We performed standard ICL implantation (Kojima et al. 2010). The toric and non-toric ICLs were implanted in 26 and nine eyes, respectively. Preoperatively, 1 day, 1 week, and at 1, 3, 6 and 12 months postoperatively, we assessed uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction and the vault (from the ICL to the IOL). The target refraction was emmetropia or a similar refraction to that of the fellow eye to accomplish isometropia, which was individually determined with visual simulation. The detailed breakdown of the ICL version was V3 (four eyes), V4b (21 eyes) and V4c (KS-AP, 10 eyes). The number of eyes at each follow-up examination was 30 eyes at 1 week, 28 eyes at 3 months, 20 eyes at 6 months and 16 eyes at 1 year, postoperatively. The visual and refractive outcomes were summarized in Figure 1. The logarithm of the minimal angle of resolution (logMAR) CDVA significantly improved from 0.02 0.25 preoperatively to 0.04 0.23 postoperatively (Wilcoxon signed rank test, P = 0.002). Eighteen eyes (51%) showed no change in CDVA, 12 eyes (34%) gained 1 line, three eyes (9%) and two eyes (6%) lost one line. LogMAR UDVA also significantly improved from 0.77 0.42 preoperatively to 0.24 0.38 postoperatively (P < 0.001). In 21 eyes that the target refraction was emmetropia, 66% and 89% of eyes had UDVA of 20/20 or better and 20/40 or better, respectively. About 66% and 91% were within 0.5 and 1.0 D of the attempted correction, respectively. Changes in manifest refraction from 1 day postoperatively to the final follow-up were 0.07 0.77 D. The ICL vault was 1.44 0.35 mm. Of the 35 eyes, one eye (3%) developed a considerable ICL dislocation, possiblydue to zonularweakness after primary cataract surgery. In this eye, the ICL was extracted, and subsequent LASIK was performed. Another one eye (3%) developed posterior capsule opacification of the primary IOL requiring a Nd-YAG capsulotomy. No interlenticular opacification, significant intraocular pressure rise (>21 mmHg), pupillary block, iritis, cystoid macular oedema or other vision-threatening complications occurred. It should be noted that peripheral iridectomy or laser iridotomy was necessary only for conventional ICL (V3 and V4b) implantation, in order to prevent the occurrence of pupillary block. Although the ICL vault is high for phakic patients, it is clinically acceptable in terms of the safety, because the anterior chamber is deep in pseudophakic eyes. A further study is necessary to develop the ICL sizing nomogram in IOL-implanted eyes. In summary, our multicenter study showed that the piggyback ICL performed was good in all measures of the safety, efficacy, predictability and stability, suggesting that secondary ICL implantation as a piggyback IOL is a feasible surgical option for the management of pseudophakic ametropia.