Eyeworld

EW CATARACT 74 March 2018 Presentation spotlight by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer New study reveals the benefits of iris claw IOLs for myopia more than –9 D compared to LASEK M any factors contrib- ute to choosing an iris claw lens over a surface ablation procedure for the treatment of high myopia, most importantly corneal thickness and anterior chamber depth. A new trial that compared the implantation of the Artiflex myopia model 401 iris claw IOL (Ophtec, Groningen, the Netherlands) with laser-assisted subepithelial keratectomy (LASEK) for the correction of eyes with high myopia found that both techniques were comparable in terms of visual and refractive outcomes, as well as predictability and stability after a 2-year follow-up period. So which do physicians choose? According to Mi Hyun Cheon, MD, Hanbit Eye Clinic, Jeonju, South Korea, who presented the study at the XXXV Congress of the ESCRS, the Arti- flex iris claw lens showed definite advantages in terms of small main incision size, less induced corneal astigmatism, and quicker visual recovery than LASEK. Trial setup The non-randomized clinical trial included 80 eyes of 40 patients (20 male patients and 20 female patients) who underwent pIOL implantation of an Artiflex myopia model 401 iris claw IOL in one eye (group 1) and LASEK in the contra- lateral eye (group 2) from January 2014 to December 2015 in Hanbit Eye Clinic. The mean patient age was 23.79 ± 5.98 years. All of the patients had stable refraction over a 12-month peri- od prior to surgery. Patients who received iris claw phakic IOLs had a manifest refraction spherical equivalent (MRSE) of greater than or equal to –9.0 D, an anterior cham- ber depth (ACD) of 3.0 mm or more, an epithelial cell density (ECD) greater than 2800 cells/mm 2 , and insufficient corneal thickness for laser surgery. LASEK patients had an MRSE below –9.0 D, an ACD smaller than 3.0 mm, a residual stromal bed thickness of more than 380 µm, and did not want to undergo intraocular surgery if possible. Patients were excluded from the study if they had underlying ocular disease such as anterior or posterior uveitis, any form of cataract, glau- coma, pre-existing retinal problems, or previous ocular surgery; in the case of iris disease like iris atrophy, adhesion, NVI, or aniridia; with ab- normal pupil function; and if they presented with systemic diseases such as collagen vascular diseases, atopic dermatitis, or diabetes. The MRSE remained stable throughout the follow-up period in both groups, and there was no myopic regression. The preoperative pIOL MRSE was –7.89 ± 1.22 D. At the 12-month follow-up visit, it was –0.01 ± 0.13 D, and at 24 months it was –0.02 ± 0.13 D (P<.001). In the LASEK group, preoperative MRSE was –7.04 ± 1.18 D. At 12 months it was –0.07 ± 0.14 D, and at 24 months it was –0.08 ± 0.17 D (P<.001). Approximately 90% of the pIOL group and 83% of the LASEK group had an uncorrected visual acuity (UCVA) of 20/20 or better during the follow-up period. The UCVA in the pIOL group stayed steady at 1-, 3-, 6-, 12-, and 24-month con- trols, from logMAR 0.02 ± 0.05 at 1 month to logMAR 0.00 ± 0.02 at the 24-month control visit (P=.101). Similarly, UCVA in the LASEK group went from logMAR 0.07 ± 0.10 at 1 month to logMAR 0.02 ± 0.05 at 24 months (P=.001). The mean preoperative endo- thelial cell density (ECD) was similar in both groups. The pIOL group had 3252.31 ± 214.25 cells/mm 2 preop- eratively. At 12 months postopera- tively it was 3186.62 ± 185.23 cells/ mm 2 . This reflected a mean cell loss of 65.89 ± 154.26 cells/ mm 2 , which corresponded to a 2.02% endothelial density loss (P=.004). The LASEK group had a mean cell loss of 28.24 ± 98.97 cells/mm 2 , which corresponded to a 0.88% loss (P=.072). "No significant differences were found between the two groups within the follow-up period in cell density or percentage of endothelial cell loss," Dr. Cheon said. "I think the results suggest that the endothe- lial cell's changes are due to intraop- erative damage rather than the lens itself." The mean percentage of hex- agonal cells over 2 years in the two groups was stable throughout the follow-up period. The mean coef- ficient of variation (CV) was about 29 in both groups preoperatively. There was no statistically significant change in CV in either group at any time during the follow-up period. There were no significant differences in ACD or critical edge distance, both nasally and tempo- rally, in either group throughout the follow-up period. "The most relevant factor for endothelial cell damage is the distance between the periphery of the optic and the en- dothelium," Dr. Cheon. "It depends on the optic power or the lens, the depth of the anterior chamber, and the size of the optic. This required a precise preoperative examination to determine viability of the Artiflex." Dr. Cheon noted an increasing trend for total higher order aberra- tions (HOA) in the LASEK group, as was expected after surface ablation procedures. HOA was 0.40 ± 0.15 µm compared to 0.55 ± 0.22 µm postoperatively (P=.050). Horizontal coma was –0.04 ± 0.14 µm preop- eratively compared to 0.10 ± 0.13 µm after surgery (P=.006), and the spherical aberration was 0.27 ± 0.08 µm preoperatively compared to 0.55 ± 0.21 µm after surgery (P<.001) in the LASEK group. Iris claw or LASEK? The refractive correction of high myopia includes a number of treatment options. Among the more popular are cornea based surgery such as PRK, LASIK, and SMILE; lenticular based surgeries includ- ing phakic IOLs like ICL and the Artiflex; and clear lens extraction. A combined approach (bioptics) maxi- mizes the benefits of laser treatment with pIOL implantation. The Artiflex myopia PIOL model 401 is made of polysiloxane, and the haptics are PMMA. The device has Comparing iris claw IOLs and LASEK for treating high myopia Dr. Cheon compared the refractive outcomes in paired eyes of iris claw pIOL and LASEK in high myopic patients. Source: Mi Hyun Cheon, MD

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