Eyeworld

71 EW RESIDENTS June 2017 refractive surgery. J Cataract Refract Surg. 2011;37:1394–1402. 6.Cha D, et al. New axis-marking method for a toric intraocular lens: mapping method. J Refract Surg. 2011;27:375–379. 7. Popp N, et al. Evaluation of 4 corneal astig- matic marking methods. J Cataract Refract Surg. 2012;38:2094–2099. 8.Carey PJ, et al. Assessment of toric intraoc- ular lens alignment by a refractive power/cor- neal analyzer system and slitlamp observation. J Cataract Refract Surg. 2010;36:222–229. 9. Elhofi AH, et al. Comparison between digital and manual marking for toric intraocular lens- es: A randomized trial. Medicine (Baltimore). 2015;94:e1618. Contact information Hwang: hwangt@ohsu.edu would be interesting in the future to compare advanced technology forms of imaging with manual mapping or slit lamp marking methods. It is also important to note that at least one other study comparing a digital toric marker, using a three-dimen- sional computer guided visualization system with intraoperative registra- tion of limbal vessels, did not find any significant difference between this digital and more conventional manual methods. 9 The VERION toric system has been previously evaluated with similar results as demonstrated in this study. A randomized study by Elhofi at al. compared the VERION system to a pendulum-attached marker at the slit lamp in 60 eyes of 60 patients. They found that using the VERION resulted in significantly less toric misalignment compared to manual marking (2.4±1.96 degrees vs. 4.33±2.72 degrees, p=0.003), 9 but similar to the study by Webers et al., there was no significant difference in uncorrected distance visual acuity between the two groups (0.12±0.12 logMAR versus 0.18±0.14 logMAR, p=0.399). Elhofi et al. used a dif- ferent brand intraocular lens, the Tecnis toric IOL (Johnson & Johnson Vision, Santa Ana, California), and still achieved similar results. It should be noted that there are some important differences between the present study and previously conducted studies. A considerable advantage in the design of the current study is the ability to dis- tinguish between surgical misalign- ment of the toric IOL and rotational drift, which occurs postoperatively. In the previously published stud- ies, misalignment was measured several weeks after surgery rather than immediately postoperatively, making true misalignment indistin- guishable from possible rotation of the IOL in the early postoperative period. Webers et al. conducted an immediate postoperative measure- ment at 1 hour after surgery, as well as measurements of alignment at 1 week, 1 month, and 3 months post- operatively. These later alignment measurements could depend more on subsequent rotation than initial alignment. Another notable differ- ence between the Weber et al. study and the other VERION papers is the technique used to assess postopera- tive IOL position. Many of the other studies recorded final toric IOL axis by assessing its orientation as viewed at the slit lamp. Webers et al. instead created an overlay between pre- and postoperative VERION images to eliminate cyclotorsion and differ- ences in head position, which may have improved the accuracy of their results. As with any study, sources of potential bias should be considered. Given the inability to mask the two surgeons to the procedure being per- formed, it is impossible to complete- ly exclude surgeon bias. It is feasible that in one group, the surgeons were more careful to remove remaining viscoelastic at the end of the case, spent more time aligning the lens, or even more carefully counseled the patient on postoperative activity. It is interesting to note that there was a higher rate of rotation reported in the manual group (85%) when com- pared to the VERION group (75%). It is unclear why initial marking with different methods would relate to later lens rotation, and therefore this may suggest other differences in the surgeries between these two groups. Although some of the variables introduced by an unmasked sur- geon would be difficult to measure or eliminate, efforts to standardize these would be beneficial to the study's validity, especially in light of known industry funding. In conclusion, misalignment and rotation of toric IOLs remain a challenge for cataract surgeons. The VERION Image Guided System aims to make the process of toric IOL alignment more accurate and poten- tially offers a way to limit sources of error. Webers et al. demonstrate improvement in toric alignment with the VERION compared to a manual method. However, this did not lead to significant improvement in uncorrected refractive error or residual astigmatism. Further work is needed to address the use of this system. Some factors that would be interesting to explore with the various marking systems include op- erating room time, use in different magnitudes of astigmatic correc- tion, patient experience, and cost. The VERION system may limit the human error of preoperative manual marking, but it remains to be seen whether this translates to a mean- ingful clinical advantage in everyday settings. EW References 1.Shimizu K, et al. Toric intraocular lenses: correcting astigmatism while controlling axis shift. J Cataract Refract Surg. 1994;20:523– 526. 2.Thulasi P, et al. Intraocular lens alignment methods. Curr Opin Ophthalmol. 2016;27:65– 75. 3.www.myalcon.com/products/surgical/veri- on-guided-system/. Accessed April 30, 2017. 4.Webers V, et al. A randomized controlled trial of an image-guided system versus manual marking in the alignment of toric intraocular lenses in cataract surgery. J Cataract Refract Surg. 2017;43(6). Article in press 5.Visser N, et al. Accuracy of toric intra- ocular lens implantation in cataract and A randomized controlled trial of an image-guided system versus manual marking in the alignment of toric intraocular lenses in cataract surgery Valentijn S.C. Webers, MD, Noel J.C. Bauer, MD, PhD, Nienke Visser, MD, Tos T.J.M. Berendschot, PhD, Frank J.H.M. van den Biggelaar, PhD, Rudy M.M.A. Nuijts, MD, PhD J Cataract Refract Surg. 2017;43(6). Article in press Purpose: To compare the accuracy in toric IOL alignment using the VERION Image Guided System versus a conventional manual ink-marking procedure. Setting: University Eye Clinic Maastricht, the Netherlands. Design: Prospective randomized clinical trial. Methods: A total of thirty-six eyes (24 patients) with regular corneal astigmatism of at least 1.25 diopters, which required cataract surgery and toric IOL implantation (AcrySof SN6AT3-T9), were randomly assigned to either the VERION group or the manual marking group. The primary outcome was the alignment of the toric IOL, by using pre- and postoperative images immediately after surgery. Secondary outcome measures were residual astigmatism, uncorrected distance visual acuity (UDVA), and complication profile. Results: The mean toric IOL misalignment was significantly less in the VERION group compared to the manual group both 1 hour (1.3 ± 1.6º vs. 2.8 ± 1.8º, p=.02) and 3 months postoperatively (1.7 ± 1.5º vs. 3.1 ± 2.1º, p<.05). The mean residual refractive cylinder was –0.36 ± 0.32 D and –0.47 ± 0.28 D for the VERION and manual group (p>.05), respectively. UDVA was 0.03 ± 0.10 logMAR in the VERION group versus 0.04 ± 0.09 logMAR in the manual group (both p>.05). No intraoperative complications occurred during any of the surgeries. Conclusions: This study showed significantly less misalignment using digital marking when compared with manual marking. However, this did not result in a better UDVA or lower residual refractive astigmatism.

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