A cost-saving, picture-assisted method for toric intraocular lens alignment versus manual self-leveling marking via RoboMarker

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Roessler, Randolf A. Widder This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4274131/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 14 Mar, 2025 Read the published version in International Ophthalmology → Version 1 posted 9 You are reading this latest preprint version Abstract Purpose: To determine the accuracy of two axis-marking methods for toric intraocular lens (IOL) implantation, one picture-assisted approach based on scleral vessel vectors, and the other based on a self-leveling device for manual marking. Methods: This retrospective single-center study involved 60 eyes of 51 participants, who underwent phacoemulsification with toric IOL implantation. In all eyes, preoperative markings were made in a seated position both manually via a self-leveling corneal marker (RoboMarker), and digitally on slit-lamp photographs, defining scleral vessels as landmarks, aiding to find the correct intraoperative orientation for an angular graduation instrument. The axis of IOL alignment at the end of surgery was determined from high resolution, intraoperative footage from a microscope-integrated camera and the axis-marking error served as an outcome measurement for both marking techniques. The endpoint was the alignment of the lens at the end of surgery. Results: The average axis-marking error was 2.5 ±1.9 degrees for picture-assisted marking, which was significantly less than that of the self-leveling corneal marker, being 5.4 ±4.4 degrees. Conclusion: Our results indicate that scleral vessel vector marking leads to highly accurate toric IOL alignments, while being an inexpensive technique, as solely a slit-lamp camera is required for preoperative preparation. Figures Figure 1 Figure 2 Figure 3 INTRODUCTION For three decades, toric intraocular lenses (IOL) have been an asset in cataract surgery to minimize astigmatism, which promotes independence from corrective devices.[ 1 ] During this time, multiple approaches have been introduced to pursue the most accurate alignment possible, as it is known that misalignment diminishes the correcting power of the toric IOL and therefore increases residual cylinder.[ 2 ] Taking posture-induced cyclotorsion into account, transferring the target axis from the upright on the supine position has been the common objective of numerous marking techniques.[ 1 ] Manual marking devices, such as the bubble marker, the pendulum marker, tonometer-based markers and slit-beam marking commonly aim at a transfer of the horizontal meridian, at which the respective 0° and 180° markings of an angular graduation instrument can be aligned to during surgery. As a final step of this 3-step procedure, the target-axis is delineated at the instrument.[ 3 , 4 ] Manual 1-step approaches, marking the target-axis directly using a slit-beam, have been described as well.[ 5 ] More recently, in the digital age, smartphone-based tools have been introduced, such as the toriCAM (Graham D. Barrett, Perth, Australia). The application relies on built-in gyroscopes and accelerometers of contemporary smartphones to create both a horizontal meridian and rotational deviation to the defined target axis. [ 6 ] Within the last decade, a large magnitude of image-guided methods has become available. Computer-assisted alignment systems such as Verion (Alcon Inc., Fort Worth, TX, USA), Callisto (Carl Zeiss Meditec AG, Jena, Germany) and True Vision (True Vision Systems, Goleta, CA, USA) create a preoperative reference image with the delineated target axis, which serves as an overlay on the live-image of the microscope.[ 7 – 10 ] Another approach utilizes intraoperative wavefront-aberrometry to determine the residual refractive error in real-time as a result of a misaligned toric IOL.[ 11 ] Two of those systems currently in use are ORA (Alcon Inc., Fort Worth, TX, USA) and Holos (Clarity Medical Systems, Pleasanton, CA, USA). As the majority of the aforementioned approaches requires costly hard- and software as well as an adequate infrastructure, we were eager to investigate the accuracy of two simple axis-marking methods, one being a scleral vessel vector guided 3-step procedure and the other being a manual self-leveling corneal marker for 1-step marking. Therefore, we compared axis-marking errors among the two groups at the end of surgery. METHODS Study design and patients This single-center retrospective study was based on the data acquired from our Department of Ophthalmology. The retrospective study protocol and data accumulation were conducted with the approval of the Institutional Review Board. All tenets of the Declaration of Helsinki have been regarded. We reviewed our database and identified all patients who received phacoemulsification with toric IOL implantation from 2020 to 2022 and, during preoperative preparation, underwent both marking techniques on the same day of surgery, which will be described in the following. Biometry was carried out using the IOL Master 700 (Carl Zeiss Meditec AG, Jena, Germany) and irregular astigmatism, as well as corneal pathologies were excluded via the Pentacam HR topographer (Oculus AG, Wetzlar, Germany). The two study lenses used were AT TORBI 709 (Carl Zeiss Meditec AG, Jena, Germany) and LENTIS Comfort Toric LS-313 MF15 (Teleon Surgical BV, Spankeren, Netherlands). Surgery was carried out by a single surgeon. Self-leveling corneal marking Prior to surgery, corneal markings were made in a seated position using the RoboMarker Corneal Marking System (Surgilum, Wilmington, NC, USA). The handheld device combines ball-bearings and a dual-pendulum weight system to maintain the chosen axis degree of the movable tip, regardless of the axis the handpiece is held in (Fig. 1 ). After the application of numbing drops (Proparakain-POS 0,5%, Ursapharm, Saarbrücken, Germany) the patient was instructed to maintain an upright seated position, while fixating on the integrated fixation light. By holding the device in a horizontal plane and gently applying coaxial pressure and with both pre-inked marking horns touching the ocular surface synchronically, two markings were made on the peripheral cornea. The disposable tip was then discarded. Scleral vessel vector marking On the same day of surgery, the patient was seated infront of a slit-lamp with an integrated imaging module (IM900, Haag-Streit AG, Koenitz, Switzerland). The patient was instructed to fixate on a distant target in horizontal height with the fellow eye. Then, a photograph was made with special respect of scleral vessels. If unsure, whether the targeted vessels were either conjunctival or scleral, the eye was given numbing drops (Proparakain-POS 0,5%, Ursapharm, Saarbrücken, Germany) and movability of the vessel, which would indicate conjunctival origin, was assessed using a cotton swab. The image was then edited via the EyeSuite software (Version 9.1.0.0, Haag-Streit AG, Koenitz, Switzerland). A circular angle overlay was superimposed on the photograph and centered on the pupillary center, with a diameter of the largest white-to-white distance. Remarkable configurations of scleral vessels, for example crossing or angulation, were assessed by a single examiner and a vector was drawn from the center of the overlay, resulting in an axis degree. A minimum of three vectors to three respective landmarks was required for each image, before a colored printout was made (Fig. 2 ). Surgical technique Firstly, guided by the printout of the slit-lamp photograph, the marked configurations of scleral vessels were relocated in the supine position of the patient, and marked with an ink augmented 27 gauge cannula (Sterimedix, Redditch, UK). This was done in case a conjunctival chemosis occurs which might make the relocation of the respective vessels difficult. Secondly, taking these landmarks into account, an angular graduation instrument (Mendez ring, Geuder AG, Heidelberg, Germany) was put on the eye aligned concordantly to the respective axis degrees at the corneal limbus (Fig. 3 ). Thirdly, the target axis was determined and marked with the ink augmented cannula applying gentle pressure, so that the markings could be relocated in case the ink gets blurred. Cataract surgery was performed through a standard 2.5 mm clear cornea incision and two paracenteses in the peripheral cornea, at a 90° angle to the tunnel. Capsular rhexis was performed manually aiming at a 5 mm rhexis. After bimanual phacoemulsification with posterior chamber and viscoelastic free in-the-bag IOL implantation, the lens was rotated in the target axis with the respective irrigation- and aspiration cannula. Outcome measurement The axis of IOL alignment at the end of surgery was considered as the outcome measurement for picture-assisted marking and was determined from high resolution stills of intraoperative footage obtained by a microscope (OPMI Lumera T, Carl Zeiss Meditec AG, Jena, Germany) integrated camera (IMAGE1 S H3-M Coview, Karl Storz AG, Tuttlingen Germany). This intraoperative image also shows the previous corneal markings of the RoboMarker device. The target axis was marked on the preoperative slit-lamp photograph, using a digital protractor overlay, being congruent to the circular angle overlay. Then, the intraoperative image was rotated until the respective 0° and 180° determined by the Mendez ring were set in a horizontal plane. This rotated image was regarded as equivalent to an upright seated position and therefore served as an overlay for the preoperative image. The axis-marking error of both picture-assisted and self-leveling corneal marking could now be delineated by the digital protractor, which was superimposed on both images on a PowerPoint sheet (Version 15.27, Microsoft Corp. Redmond, WA, USA). Statistical analyses We performed the statistical analyses using SPSS (Version 24.0, IBM Corp., Armonk, NY, USA) and the statistical programming language R V3.2.2 (R Foundation for Statistical Computing, Vienna, Austria). Axis-marking errors among the two marking groups were compared via Wilcoxon signed rank test. The threshold for statistical significance was defined as p < 0.05. RESULTS The average axis-marking error was 2.5 ± 1.9 degrees (range 0–7 degrees) for picture-assisted marking. For the self-leveling corneal marker, the average axis-marking error was 5.4 ± 4.4 degrees (range 0–21 degrees) (Table). The Wilcoxon test determined a significant difference between the two marking techniques (p < 0.001). Table. Comparison of axis-marking error between the investigated marking methods Scleral vessel vector marking RoboMarker device Axis-marking error (°) 2.5 ± 1.9 5.4 ± 4.4 Range of error (°) 0 to 7 0 to 21 DISCUSSION The aim of this study was the comparative evaluation of the two marking techniques at the end of surgery. Therefore further parameters, such as pre- and postoperative astigmatism, the type of intraocular lens used and rotational stability, were no subject to this investigation. We found that our picture-assisted, scleral vessel vector guided approach, is not inferior but leads to more accurate toric IOL alignments, when compared to a manual self-leveling device for 1-step marking. The average axis-marking error of this technique is comparable to that of commercially available image-guided systems. Webers et al. reported a respective average axis-marking error of 1.3 ± 1.6 degrees for Verion, Mayer et al. a value of 2.0 ± 1.9 degrees for Callisto and Montes de Oca et al. a value of 3.0 ± 2.5 degrees for True Vision. All of those studies drew a comparison to a bubble-based, reference marker for 3-step manual marking, the average axis-marking error ranged from 2.8 ± 1.8 degrees to 3.4 ± 2.4 degrees.[ 7 , 9 , 10 ] As manual marking commonly involves a 3-step procedure and each step can be prone to errors, investigations on its accuracy tend to heterogeneous results. Visser et al. investigated the average axis marking-errors for each of these steps and reported a mean error of 2.4 ± 0.8 degrees for horizontal axis marking, 3.3 ± 2.0 degrees for alignment axis marking, and 2.6 ± 2.6 degrees for intraoperative lens alignment with a cumulated value of 4.9 ± 2.1 degrees. Popp et al. evaluated the accuracy of a variety of approaches for the first step of horizontal axis marking, involving the pendulum marker, slit-beam marking, the bubble marker and a tonometer-based marker. The average axis-marking errors were 1.8 ± 2.2 degrees, 2.3 ± 1.8 degrees, 2.9 ± 1.9 degrees, and 4.7 ± 2.9 degrees, respectively. Whereas 1-step approaches, marking the target-axis directly, have been described, the authors did not provide information on the respective average axis-marking error.[ 5 , 12 – 15 ] In respect to the aforementioned studies on manual 3-step marking methods, one might find our results of the RoboMarker strikingly inferior. To the best of our knowledge there has to date no data on the self-leveling corneal marker been published. As advised by the manufacturer, it is crucial that the device is held in a horizontal plane when used. Furthermore, we have made the experience that pressure has to be applied absolutely coaxially, so that both inked marking horns will have synchronic contact to the ocular surface. If one horn touches the cornea first, the sensitive tip will naturally tilt and the subsequent horn will make an erratic second mark, which will ultimately result in an inaccurate axis-marking altogether. Taking these pitfalls into account, it might take a certain learning curve to solidify the handling of the marker, if the aforementioned issues are avoidable at all. Moreover, we regard further studies on the RoboMarker to be necessary to evaluate its efficiency. Also, it could be considered to equip the device with one single marking horn to avoid tilting. Considering scleral vessels as reference points is an approach that was also pursued in a study by Gerding et al., who followed the spatial relationship of these landmark structures to the target-axis. However, the endpoint of their study was pre- and postoperative astigmatism, the respective average axis-marking error at the end of surgery was not investigated in particular.[ 16 ] While we took scleral vessels into account for defining vectors aiding to find the correct intraoperative orientation for the Mendez ring, Cha et al. utilized the distance of scleral vessel landmarks to both axis-marking points, those being defined as the two crossing-points between the target-axis and a reference circle, centered on the cornea. The authors compared the resulting mean marking error to a 3-step procedure augmented either via bubble marker and slit-beam marking and reported superior results for their own method. They delivered a value of 2.3 ± 1.1 degrees, being comparable to the average axis-marking error of our picture-assisted technique.[ 17 ] As conjunctival vessels have a high mobility and therefore are influenced by gravity in a greater extent, their configuration in an upright position and in a supine position might vary. Therefore, it is of critical importance that solely scleral vessels are used for this technique. As with every other marking technique, one might argue that our method is prone to malfixation of the patient, because it does rely on slit-lamp photographs essentially. We acknowledge this potential drawback and were eager to equalize this uncertain variable as much as possible by taking multiple images and by instructing the patient thoroughly. However, it is to be considered that our results on the average axis-marking error are notably comparable with those of previous studies on image-guided methods, using assets such as eye-tracking.[ 7 , 9 , 10 ] The limitations of our study include its limited sample size and the retrospective study design. According to our results, we could validate that scleral vessel vector marking, when compared to a manual 1-step corneal marker, leads to superior accuracy of toric IOL alignment. Our technique is simple and can widely be used, as solely a slit-lamp camera is required for preoperative preparation. As far as availability of a camera and a color printer is given, our approach turned out as inexpensive, as follow-up costs are rather low. An image editing software is helpful for axis-marking, albeit optional as it is possible to delineate axes manually on the printout using a protractor. The merit of our method is the independency of marking from subsequent surgery. The surgeon is not obliged to carry out the marking preoperatively by him-/herself as the preparation of the marked picture is delegable to the assisting staff. Extensive instructions are not required for this procedure. Declarations Authors’ contributions: All authors contributed to the study conception and design. Material preparation and data collection was performed by Randolf A. Widder and David Kiessling, statistical analysis was performed by David Kiessling. The first draft of the manuscript was written by Randolf A. Widder and David Kiessling, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Funding: none Compliance with ethical standards Conflict of interest: David Kiessling: none, Gernot F. Roessler: none, Randolf A. Widder: none Ethical approval: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional review board as well as the 1964 Helsinki declaration and its later amendments or comparable ethical standards. TheInstitutional Review Board (Ethik und Kommission Klinische Studien, Dernbacher Gruppe Katharina Kasper, Germany) approved the study. Consent to publish: For this type of study (anonymized data, retrospective analysis), formal consent is not required. References Visser N, Bauer NJ, Nuijts RM (2013) Toric intraocular lenses: historical overview, patient selection, IOL calculation, surgical techniques, clinical outcomes, and complications. J Cataract Refract Surg. 39(4): 624-37. DOI: 10.1016/j.jcrs.2013.02.020. Ma JJK, Tseng SS (2008) Simple method for accurate alignment in toric phakic and aphakic intraocular lens implantation. J Cataract Refract Surg. 34(10): 1631-1636. DOI: 10.1016/j.jcrs.2008.04.041. Popp N, Hirnschall N, Maedel S, Findl O (2012) Evaluation of 4 corneal astigmatic marking methods. J Cataract Refract Surg. 38(12): 2094-9. DOI: 10.1016/j.jcrs.2012.07.039. Visser N, Berendschot TT, Bauer NJ, Jurich J, Kersting O, Nuijts RM (2011) Accuracy of toric intraocular lens implantation in cataract and refractive surgery. J Cataract Refract Surg. 37(8): 1394-402. DOI: 10.1016/j.jcrs.2011.02.024. Packer M (2010) Effect of intraoperative aberrometry on the rate of postoperative enhancement: retrospective study. J Cataract Refract Surg. 36(5): 747-55. DOI: 10.1016/j.jcrs.2009.11.029. Pallas A, Yeo TK, Trevenen M, Barrett G (2018) Evaluation of the Accuracy of Two Marking Methods and the Novel toriCAM Application for Toric Intraocular Lens Alignment. J Refract Surg. 34(3): 150-155. DOI: 10.3928/1081597x-20180115-03. Webers VSC, Bauer NJC, Visser N, Berendschot TTJM, van den Biggelaar FJHM, Nuijts RMMA (2017) Image-guided system versus manual marking for toric intraocular lens alignment in cataract surgery. J Cataract Refract Surg. 43(6): 781-788. DOI: 10.1016/j.jcrs.2017.03.041. Varsits RM, Hirnschall N, Döller B, Findl O (2019) Evaluation of an intraoperative toric intraocular lens alignment system using an image-guided system. J Cataract Refract Surg. 45(9): 1234-1238. DOI: 10.1016/j.jcrs.2019.04.009. Montes de Oca I, Kim EJ, Wang L, Weikert MP, Khandelwal SS, Al-Mohtaseb Z, Koch DD (2016) Accuracy of toric intraocular lens axis alignment using a 3-dimensional computer-guided visualization system. J Cataract Refract Surg. 42(4): 550-5. DOI: 10.1016/j.jcrs.2015.12.052. Mayer WJ, Kreutzer T, Dirisamer M, Kern C, Kortuem K, Vounotrypidis E, Priglinger S, Kook D (2017) Comparison of visual outcomes, alignment accuracy, and surgical time between 2 methods of corneal marking for toric intraocular lens implantation. J Cataract Refract Surg. 43(10): 1281-1286. DOI: 10.1016/j.jcrs.2017.07.030. Krueger RR, Shea W, Zhou Y, Osher R, Slade SG, Chang DF (2013) Intraoperative, real-time aberrometry during refractive cataract surgery with a sequentially shifting wavefront device. J Refract Surg. 29(9): 630-5. DOI: 10.3928/1081597x-20130819-04. Dick HB, Krummenauer F, Tröber L (2006) [Compensation of corneal astigmatism with toric intraocular lens: results of a multicentre study]. Klin Monbl Augenheilkd. 223(7): 593-608. DOI: 10.1055/s-2006-926652. Zuberbuhler B, Signer T, Gale R, Haefliger E (2008) Rotational stability of the AcrySof SA60TT toric intraocular lenses: a cohort study. BMC Ophthalmol. 8: 8. DOI: 10.1186/1471-2415-8-8. Hoffmann PC, Auel S, Hütz WW (2011) Results of higher power toric intraocular lens implantation. J Cataract Refract Surg. 37(8): 1411-8. DOI: 10.1016/j.jcrs.2011.02.028. Tassignon MJ, Gobin L, Mathysen D, Van Looveren J (2011) Clinical results after spherotoric intraocular lens implantation using the bag-in-the-lens technique. J Cataract Refract Surg. 37(5): 830-4. DOI: 10.1016/j.jcrs.2010.12.042. Gerding H, Somfai G, Langenegger M (2019) A Simple, Inexpensive, and Precise Photographic Method for Intraoperative Toric IOL Alignment. Klinische Monatsblätter für Augenheilkunde. 236(04): 391-397. DOI: 10.1055/a-0861-9601. Cha D, Kang SY, Kim SH, Song JS, Kim HM (2011) New axis-marking method for a toric intraocular lens: mapping method. J Refract Surg. 27(5): 375-9. DOI: 10.3928/1081597x-20101005-01. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 14 Mar, 2025 Read the published version in International Ophthalmology → Version 1 posted Editorial decision: Revision requested 11 Dec, 2024 Reviews received at journal 09 Dec, 2024 Reviewers agreed at journal 09 Dec, 2024 Reviews received at journal 21 Jul, 2024 Reviewers agreed at journal 25 Jun, 2024 Reviewers invited by journal 20 Jun, 2024 Editor assigned by journal 17 Apr, 2024 Submission checks completed at journal 16 Apr, 2024 First submitted to journal 16 Apr, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4274131","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":292311527,"identity":"0cd86134-f9af-4171-82b6-d07659af4351","order_by":0,"name":"David Kiessling","email":"","orcid":"","institution":"St. Martinus-Krankenhaus","correspondingAuthor":false,"prefix":"","firstName":"David","middleName":"","lastName":"Kiessling","suffix":""},{"id":292311528,"identity":"6fb60cb1-2e4d-43e4-964f-490a109c200f","order_by":1,"name":"Gernot F. Roessler","email":"","orcid":"","institution":"St. Martinus-Krankenhaus","correspondingAuthor":false,"prefix":"","firstName":"Gernot","middleName":"F.","lastName":"Roessler","suffix":""},{"id":292311529,"identity":"983126c0-285a-4472-bbe7-d433b8491b5f","order_by":2,"name":"Randolf A. Widder","email":"data:image/png;base64,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","orcid":"","institution":"St. Martinus-Krankenhaus","correspondingAuthor":true,"prefix":"","firstName":"Randolf","middleName":"A.","lastName":"Widder","suffix":""}],"badges":[],"createdAt":"2024-04-16 07:42:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4274131/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4274131/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10792-025-03479-5","type":"published","date":"2025-03-14T15:58:54+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":55324570,"identity":"00f7df5d-22cb-4b6b-b4ff-729b1e1e0abd","added_by":"auto","created_at":"2024-04-25 16:50:52","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":4493,"visible":true,"origin":"","legend":"\u003cp\u003eThe commercially available RoboMarker device.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4274131/v1/d4c725beefc57ea862b2c717.png"},{"id":55324571,"identity":"2d1eed08-99d1-45c6-b758-1d4e1fd1a752","added_by":"auto","created_at":"2024-04-25 16:50:52","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":4493,"visible":true,"origin":"","legend":"\u003cp\u003eScleral vessel vectors on the preoperative slit-lamp photograph.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4274131/v1/1c1e334842c61a69523c9300.png"},{"id":55324572,"identity":"dd4f8c6c-141b-4a78-9426-6f886a9078a1","added_by":"auto","created_at":"2024-04-25 16:50:52","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1333626,"visible":true,"origin":"","legend":"\u003cp\u003eA Mendez ring\u003cstrong\u003e \u003c/strong\u003eis put on the eye aligned concordantly to the landmark axis degrees at the corneal limbus and the target axis is marked with an ink augmented cannula.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4274131/v1/0c263dcb623b8ac2bde265ad.png"},{"id":78689147,"identity":"e048bf31-f978-4895-b81b-67cabbdb7e5c","added_by":"auto","created_at":"2025-03-17 16:11:53","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2242936,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4274131/v1/01651094-2edc-4194-bb50-ce8f069b6ef8.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"A cost-saving, picture-assisted method for toric intraocular lens alignment versus manual self-leveling marking via RoboMarker","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eFor three decades, toric intraocular lenses (IOL) have been an asset in cataract surgery to minimize astigmatism, which promotes independence from corrective devices.[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eDuring this time, multiple approaches have been introduced to pursue the most accurate alignment possible, as it is known that misalignment diminishes the correcting power of the toric IOL and therefore increases residual cylinder.[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eTaking posture-induced cyclotorsion into account, transferring the target axis from the upright on the supine position has been the common objective of numerous marking techniques.[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eManual marking devices, such as the bubble marker, the pendulum marker, tonometer-based markers and slit-beam marking commonly aim at a transfer of the horizontal meridian, at which the respective 0\u0026deg; and 180\u0026deg; markings of an angular graduation instrument can be aligned to during surgery. As a final step of this 3-step procedure, the target-axis is delineated at the instrument.[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] Manual 1-step approaches, marking the target-axis directly using a slit-beam, have been described as well.[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eMore recently, in the digital age, smartphone-based tools have been introduced, such as the toriCAM (Graham D. Barrett, Perth, Australia). The application relies on built-in gyroscopes and accelerometers of contemporary smartphones to create both a horizontal meridian and rotational deviation to the defined target axis. [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eWithin the last decade, a large magnitude of image-guided methods has become available. Computer-assisted alignment systems such as Verion (Alcon Inc., Fort Worth, TX, USA), Callisto (Carl Zeiss Meditec AG, Jena, Germany) and True Vision (True Vision Systems, Goleta, CA, USA) create a preoperative reference image with the delineated target axis, which serves as an overlay on the live-image of the microscope.[\u003cspan additionalcitationids=\"CR8 CR9\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eAnother approach utilizes intraoperative wavefront-aberrometry to determine the residual refractive error in real-time as a result of a misaligned toric IOL.[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] Two of those systems currently in use are ORA (Alcon Inc., Fort Worth, TX, USA) and Holos (Clarity Medical Systems, Pleasanton, CA, USA).\u003c/p\u003e \u003cp\u003eAs the majority of the aforementioned approaches requires costly hard- and software as well as an adequate infrastructure, we were eager to investigate the accuracy of two simple axis-marking methods, one being a scleral vessel vector guided 3-step procedure and the other being a manual self-leveling corneal marker for 1-step marking. Therefore, we compared axis-marking errors among the two groups at the end of surgery.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design and patients\u003c/h2\u003e \u003cp\u003eThis single-center retrospective study was based on the data acquired from our Department of Ophthalmology. The retrospective study protocol and data accumulation were conducted with the approval of the Institutional Review Board. All tenets of the Declaration of Helsinki have been regarded. We reviewed our database and identified all patients who received phacoemulsification with toric IOL implantation from 2020 to 2022 and, during preoperative preparation, underwent both marking techniques on the same day of surgery, which will be described in the following.\u003c/p\u003e \u003cp\u003eBiometry was carried out using the IOL Master 700 (Carl Zeiss Meditec AG, Jena, Germany) and irregular astigmatism, as well as corneal pathologies were excluded via the Pentacam HR topographer (Oculus AG, Wetzlar, Germany).\u003c/p\u003e \u003cp\u003eThe two study lenses used were AT TORBI 709 (Carl Zeiss Meditec AG, Jena, Germany) and LENTIS Comfort Toric LS-313 MF15 (Teleon Surgical BV, Spankeren, Netherlands). Surgery was carried out by a single surgeon.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eSelf-leveling corneal marking\u003c/h2\u003e \u003cp\u003ePrior to surgery, corneal markings were made in a seated position using the RoboMarker Corneal Marking System (Surgilum, Wilmington, NC, USA). The handheld device combines ball-bearings and a dual-pendulum weight system to maintain the chosen axis degree of the movable tip, regardless of the axis the handpiece is held in (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). After the application of numbing drops (Proparakain-POS 0,5%, Ursapharm, Saarbr\u0026uuml;cken, Germany) the patient was instructed to maintain an upright seated position, while fixating on the integrated fixation light. By holding the device in a horizontal plane and gently applying coaxial pressure and with both pre-inked marking horns touching the ocular surface synchronically, two markings were made on the peripheral cornea. The disposable tip was then discarded.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eScleral vessel vector marking\u003c/h2\u003e \u003cp\u003eOn the same day of surgery, the patient was seated infront of a slit-lamp with an integrated imaging module (IM900, Haag-Streit AG, Koenitz, Switzerland). The patient was instructed to fixate on a distant target in horizontal height with the fellow eye. Then, a photograph was made with special respect of scleral vessels. If unsure, whether the targeted vessels were either conjunctival or scleral, the eye was given numbing drops (Proparakain-POS 0,5%, Ursapharm, Saarbr\u0026uuml;cken, Germany) and movability of the vessel, which would indicate conjunctival origin, was assessed using a cotton swab.\u003c/p\u003e \u003cp\u003eThe image was then edited via the EyeSuite software (Version 9.1.0.0, Haag-Streit AG, Koenitz, Switzerland). A circular angle overlay was superimposed on the photograph and centered on the pupillary center, with a diameter of the largest white-to-white distance. Remarkable configurations of scleral vessels, for example crossing or angulation, were assessed by a single examiner and a vector was drawn from the center of the overlay, resulting in an axis degree. A minimum of three vectors to three respective landmarks was required for each image, before a colored printout was made (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eSurgical technique\u003c/h2\u003e \u003cp\u003eFirstly, guided by the printout of the slit-lamp photograph, the marked configurations of scleral vessels were relocated in the supine position of the patient, and marked with an ink augmented 27 gauge cannula (Sterimedix, Redditch, UK). This was done in case a conjunctival chemosis occurs which might make the relocation of the respective vessels difficult.\u003c/p\u003e \u003cp\u003eSecondly, taking these landmarks into account, an angular graduation instrument (Mendez ring, Geuder AG, Heidelberg, Germany) was put on the eye aligned concordantly to the respective axis degrees at the corneal limbus (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Thirdly, the target axis was determined and marked with the ink augmented cannula applying gentle pressure, so that the markings could be relocated in case the ink gets blurred.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eCataract surgery was performed through a standard 2.5 mm clear cornea incision and two paracenteses in the peripheral cornea, at a 90\u0026deg; angle to the tunnel. Capsular rhexis was performed manually aiming at a 5 mm rhexis.\u003c/p\u003e \u003cp\u003eAfter bimanual phacoemulsification with posterior chamber and viscoelastic free in-the-bag IOL implantation, the lens was rotated in the target axis with the respective irrigation- and aspiration cannula.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eOutcome measurement\u003c/h2\u003e \u003cp\u003eThe axis of IOL alignment at the end of surgery was considered as the outcome measurement for picture-assisted marking and was determined from high resolution stills of intraoperative footage obtained by a microscope (OPMI Lumera T, Carl Zeiss Meditec AG, Jena, Germany) integrated camera (IMAGE1 S H3-M Coview, Karl Storz AG, Tuttlingen Germany). This intraoperative image also shows the previous corneal markings of the RoboMarker device.\u003c/p\u003e \u003cp\u003eThe target axis was marked on the preoperative slit-lamp photograph, using a digital protractor overlay, being congruent to the circular angle overlay. Then, the intraoperative image was rotated until the respective 0\u0026deg; and 180\u0026deg; determined by the Mendez ring were set in a horizontal plane. This rotated image was regarded as equivalent to an upright seated position and therefore served as an overlay for the preoperative image. The axis-marking error of both picture-assisted and self-leveling corneal marking could now be delineated by the digital protractor, which was superimposed on both images on a PowerPoint sheet (Version 15.27, Microsoft Corp. Redmond, WA, USA).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analyses\u003c/h2\u003e \u003cp\u003eWe performed the statistical analyses using SPSS (Version 24.0, IBM Corp., Armonk, NY, USA) and the statistical programming language R V3.2.2 (R Foundation for Statistical Computing, Vienna, Austria). Axis-marking errors among the two marking groups were compared via Wilcoxon signed rank test. The threshold for statistical significance was defined as p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eThe average axis-marking error was 2.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9 degrees (range 0\u0026ndash;7 degrees) for picture-assisted marking. For the self-leveling corneal marker, the average axis-marking error was 5.4\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4 degrees (range 0\u0026ndash;21 degrees) (Table). The Wilcoxon test determined a significant difference between the two marking techniques (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e \u003cp\u003e \u003cb\u003eTable.\u003c/b\u003e Comparison of axis-marking error between the investigated marking methods\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eScleral vessel vector marking\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRoboMarker device\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAxis-marking error (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.4\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRange of error (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 to 7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 to 21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThe aim of this study was the comparative evaluation of the two marking techniques at the end of surgery. Therefore further parameters, such as pre- and postoperative astigmatism, the type of intraocular lens used and rotational stability, were no subject to this investigation.\u003c/p\u003e \u003cp\u003eWe found that our picture-assisted, scleral vessel vector guided approach, is not inferior but leads to more accurate toric IOL alignments, when compared to a manual self-leveling device for 1-step marking.\u003c/p\u003e \u003cp\u003eThe average axis-marking error of this technique is comparable to that of commercially available image-guided systems. Webers et al. reported a respective average axis-marking error of 1.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.6 degrees for Verion, Mayer et al. a value of 2.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9 degrees for Callisto and Montes de Oca et al. a value of 3.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5 degrees for True Vision. All of those studies drew a comparison to a bubble-based, reference marker for 3-step manual marking, the average axis-marking error ranged from 2.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8 degrees to 3.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4 degrees.[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eAs manual marking commonly involves a 3-step procedure and each step can be prone to errors, investigations on its accuracy tend to heterogeneous results. Visser et al. investigated the average axis marking-errors for each of these steps and reported a mean error of 2.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8 degrees for horizontal axis marking, 3.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.0 degrees for alignment axis marking, and 2.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6 degrees for intraoperative lens alignment with a cumulated value of 4.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 degrees.\u003c/p\u003e \u003cp\u003ePopp et al. evaluated the accuracy of a variety of approaches for the first step of horizontal axis marking, involving the pendulum marker, slit-beam marking, the bubble marker and a tonometer-based marker. The average axis-marking errors were 1.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2 degrees, 2.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8 degrees, 2.9\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9 degrees, and 4.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9 degrees, respectively.\u003c/p\u003e \u003cp\u003eWhereas 1-step approaches, marking the target-axis directly, have been described, the authors did not provide information on the respective average axis-marking error.[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIn respect to the aforementioned studies on manual 3-step marking methods, one might find our results of the RoboMarker strikingly inferior. To the best of our knowledge there has to date no data on the self-leveling corneal marker been published. As advised by the manufacturer, it is crucial that the device is held in a horizontal plane when used.\u003c/p\u003e \u003cp\u003eFurthermore, we have made the experience that pressure has to be applied absolutely coaxially, so that both inked marking horns will have synchronic contact to the ocular surface. If one horn touches the cornea first, the sensitive tip will naturally tilt and the subsequent horn will make an erratic second mark, which will ultimately result in an inaccurate axis-marking altogether. Taking these pitfalls into account, it might take a certain learning curve to solidify the handling of the marker, if the aforementioned issues are avoidable at all. Moreover, we regard further studies on the RoboMarker to be necessary to evaluate its efficiency. Also, it could be considered to equip the device with one single marking horn to avoid tilting.\u003c/p\u003e \u003cp\u003eConsidering scleral vessels as reference points is an approach that was also pursued in a study by Gerding et al., who followed the spatial relationship of these landmark structures to the target-axis. However, the endpoint of their study was pre- and postoperative astigmatism, the respective average axis-marking error at the end of surgery was not investigated in particular.[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eWhile we took scleral vessels into account for defining vectors aiding to find the correct intraoperative orientation for the Mendez ring, Cha et al. utilized the distance of scleral vessel landmarks to both axis-marking points, those being defined as the two crossing-points between the target-axis and a reference circle, centered on the cornea.\u003c/p\u003e \u003cp\u003eThe authors compared the resulting mean marking error to a 3-step procedure augmented either via bubble marker and slit-beam marking and reported superior results for their own method. They delivered a value of 2.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.1 degrees, being comparable to the average axis-marking error of our picture-assisted technique.[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eAs conjunctival vessels have a high mobility and therefore are influenced by gravity in a greater extent, their configuration in an upright position and in a supine position might vary. Therefore, it is of critical importance that solely scleral vessels are used for this technique.\u003c/p\u003e \u003cp\u003eAs with every other marking technique, one might argue that our method is prone to malfixation of the patient, because it does rely on slit-lamp photographs essentially. We acknowledge this potential drawback and were eager to equalize this uncertain variable as much as possible by taking multiple images and by instructing the patient thoroughly.\u003c/p\u003e \u003cp\u003eHowever, it is to be considered that our results on the average axis-marking error are notably comparable with those of previous studies on image-guided methods, using assets such as eye-tracking.[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eThe limitations of our study include its limited sample size and the retrospective study design.\u003c/p\u003e \u003cp\u003eAccording to our results, we could validate that scleral vessel vector marking, when compared to a manual 1-step corneal marker, leads to superior accuracy of toric IOL alignment. Our technique is simple and can widely be used, as solely a slit-lamp camera is required for preoperative preparation. As far as availability of a camera and a color printer is given, our approach turned out as inexpensive, as follow-up costs are rather low.\u003c/p\u003e \u003cp\u003eAn image editing software is helpful for axis-marking, albeit optional as it is possible to delineate axes manually on the printout using a protractor.\u003c/p\u003e \u003cp\u003eThe merit of our method is the independency of marking from subsequent surgery. The surgeon is not obliged to carry out the marking preoperatively by him-/herself as the preparation of the marked picture is delegable to the assisting staff. Extensive instructions are not required for this procedure.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthors’ contributions:\u0026nbsp;\u003c/strong\u003eAll authors contributed to the study conception and design. Material preparation and data collection was performed by Randolf A. Widder and David Kiessling, statistical analysis was performed by David Kiessling. The first draft of the manuscript was written by Randolf A. Widder and David Kiessling, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e none\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompliance with ethical standards\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest:\u003c/strong\u003e David Kiessling: none, Gernot F. Roessler: none, Randolf A. Widder: none\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval:\u003c/strong\u003e All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional review board as well as the 1964 Helsinki declaration and its later amendments or comparable ethical standards. TheInstitutional Review Board (Ethik und Kommission Klinische Studien, Dernbacher Gruppe Katharina Kasper, Germany) approved the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to publish:\u0026nbsp;\u003c/strong\u003eFor this type of study (anonymized data, retrospective analysis), formal consent is not required.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eVisser N, Bauer NJ, Nuijts RM (2013) Toric intraocular lenses: historical overview, patient selection, IOL calculation, surgical techniques, clinical outcomes, and complications. J Cataract Refract Surg. 39(4): 624-37. DOI: 10.1016/j.jcrs.2013.02.020.\u003c/li\u003e\n\u003cli\u003eMa JJK, Tseng SS (2008) Simple method for accurate alignment in toric phakic and aphakic intraocular lens implantation. J Cataract Refract Surg. 34(10): 1631-1636. DOI: 10.1016/j.jcrs.2008.04.041.\u003c/li\u003e\n\u003cli\u003ePopp N, Hirnschall N, Maedel S, Findl O (2012) Evaluation of 4 corneal astigmatic marking methods. J Cataract Refract Surg. 38(12): 2094-9. DOI: 10.1016/j.jcrs.2012.07.039.\u003c/li\u003e\n\u003cli\u003eVisser N, Berendschot TT, Bauer NJ, Jurich J, Kersting O, Nuijts RM (2011) Accuracy of toric intraocular lens implantation in cataract and refractive surgery. J Cataract Refract Surg. 37(8): 1394-402. DOI: 10.1016/j.jcrs.2011.02.024.\u003c/li\u003e\n\u003cli\u003ePacker M (2010) Effect of intraoperative aberrometry on the rate of postoperative enhancement: retrospective study. J Cataract Refract Surg. 36(5): 747-55. DOI: 10.1016/j.jcrs.2009.11.029.\u003c/li\u003e\n\u003cli\u003ePallas A, Yeo TK, Trevenen M, Barrett G (2018) Evaluation of the Accuracy of Two Marking Methods and the Novel toriCAM Application for Toric Intraocular Lens Alignment. J Refract Surg. 34(3): 150-155. DOI: 10.3928/1081597x-20180115-03.\u003c/li\u003e\n\u003cli\u003eWebers VSC, Bauer NJC, Visser N, Berendschot TTJM, van den Biggelaar FJHM, Nuijts RMMA (2017) Image-guided system versus manual marking for toric intraocular lens alignment in cataract surgery. J Cataract Refract Surg. 43(6): 781-788. DOI: 10.1016/j.jcrs.2017.03.041.\u003c/li\u003e\n\u003cli\u003eVarsits RM, Hirnschall N, D\u0026ouml;ller B, Findl O (2019) Evaluation of an intraoperative toric intraocular lens alignment system using an image-guided system. J Cataract Refract Surg. 45(9): 1234-1238. DOI: 10.1016/j.jcrs.2019.04.009.\u003c/li\u003e\n\u003cli\u003eMontes de Oca I, Kim EJ, Wang L, Weikert MP, Khandelwal SS, Al-Mohtaseb Z, Koch DD (2016) Accuracy of toric intraocular lens axis alignment using a 3-dimensional computer-guided visualization system. J Cataract Refract Surg. 42(4): 550-5. DOI: 10.1016/j.jcrs.2015.12.052.\u003c/li\u003e\n\u003cli\u003eMayer WJ, Kreutzer T, Dirisamer M, Kern C, Kortuem K, Vounotrypidis E, Priglinger S, Kook D (2017) Comparison of visual outcomes, alignment accuracy, and surgical time between 2 methods of corneal marking for toric intraocular lens implantation. J Cataract Refract Surg. 43(10): 1281-1286. DOI: 10.1016/j.jcrs.2017.07.030.\u003c/li\u003e\n\u003cli\u003eKrueger RR, Shea W, Zhou Y, Osher R, Slade SG, Chang DF (2013) Intraoperative, real-time aberrometry during refractive cataract surgery with a sequentially shifting wavefront device. J Refract Surg. 29(9): 630-5. DOI: 10.3928/1081597x-20130819-04.\u003c/li\u003e\n\u003cli\u003eDick HB, Krummenauer F, Tr\u0026ouml;ber L (2006) [Compensation of corneal astigmatism with toric intraocular lens: results of a multicentre study]. Klin Monbl Augenheilkd. 223(7): 593-608. DOI: 10.1055/s-2006-926652.\u003c/li\u003e\n\u003cli\u003eZuberbuhler B, Signer T, Gale R, Haefliger E (2008) Rotational stability of the AcrySof SA60TT toric intraocular lenses: a cohort study. BMC Ophthalmol. 8: 8. DOI: 10.1186/1471-2415-8-8.\u003c/li\u003e\n\u003cli\u003eHoffmann PC, Auel S, H\u0026uuml;tz WW (2011) Results of higher power toric intraocular lens implantation. J Cataract Refract Surg. 37(8): 1411-8. DOI: 10.1016/j.jcrs.2011.02.028.\u003c/li\u003e\n\u003cli\u003eTassignon MJ, Gobin L, Mathysen D, Van Looveren J (2011) Clinical results after spherotoric intraocular lens implantation using the bag-in-the-lens technique. J Cataract Refract Surg. 37(5): 830-4. DOI: 10.1016/j.jcrs.2010.12.042.\u003c/li\u003e\n\u003cli\u003eGerding H, Somfai G, Langenegger M (2019) A Simple, Inexpensive, and Precise Photographic Method for Intraoperative Toric IOL Alignment. Klinische Monatsbl\u0026auml;tter f\u0026uuml;r Augenheilkunde. 236(04): 391-397. DOI: 10.1055/a-0861-9601.\u003c/li\u003e\n\u003cli\u003eCha D, Kang SY, Kim SH, Song JS, Kim HM (2011) New axis-marking method for a toric intraocular lens: mapping method. J Refract Surg. 27(5): 375-9. DOI: 10.3928/1081597x-20101005-01.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"international-ophthalmology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"inte","sideBox":"Learn more about [International Ophthalmology](https://www.springer.com/journal/10792)","snPcode":"10792","submissionUrl":"https://submission.nature.com/new-submission/10792/3","title":"International Ophthalmology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-4274131/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4274131/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cu\u003ePurpose:\u003c/u\u003e To determine the accuracy of two axis-marking methods for toric intraocular lens (IOL) implantation, one picture-assisted approach based on scleral vessel vectors, and the other based on a self-leveling device for manual marking.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eMethods:\u003c/u\u003e This retrospective single-center study involved 60 eyes of 51 participants, who underwent phacoemulsification with toric IOL implantation. In all eyes, preoperative markings were made in a seated position both manually via a self-leveling corneal marker (RoboMarker), and digitally on slit-lamp photographs, defining scleral vessels as landmarks, aiding to find the correct intraoperative orientation for an angular graduation instrument.\u003c/p\u003e\n\u003cp\u003eThe axis of IOL alignment at the end of surgery was determined from high resolution, intraoperative footage from a microscope-integrated camera and the axis-marking error served as an outcome measurement for both marking techniques. The endpoint was the alignment of the lens at the end of surgery.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eResults:\u003c/u\u003e The average axis-marking error was 2.5 ±1.9 degrees for picture-assisted marking, which was significantly less than that of the self-leveling corneal marker, being 5.4 ±4.4 degrees.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eConclusion:\u003c/u\u003e Our results indicate that scleral vessel vector marking leads to highly accurate toric IOL alignments, while being an inexpensive technique, as solely a slit-lamp camera is required for preoperative preparation.\u003c/p\u003e","manuscriptTitle":"A cost-saving, picture-assisted method for toric intraocular lens alignment versus manual self-leveling marking via RoboMarker","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-25 16:50:47","doi":"10.21203/rs.3.rs-4274131/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-12-11T10:33:10+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-12-09T13:16:39+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"204310813259750950838486597909376009926","date":"2024-12-09T11:37:06+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-21T20:57:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"313072151245110698650043797559532227949","date":"2024-06-25T12:46:15+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-06-20T09:13:38+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-04-17T07:38:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-04-16T17:18:01+00:00","index":"","fulltext":""},{"type":"submitted","content":"International Ophthalmology","date":"2024-04-16T07:39:55+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"international-ophthalmology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"inte","sideBox":"Learn more about [International Ophthalmology](https://www.springer.com/journal/10792)","snPcode":"10792","submissionUrl":"https://submission.nature.com/new-submission/10792/3","title":"International Ophthalmology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"77e0dbcd-eba5-4ad8-bc1a-37b46b747832","owner":[],"postedDate":"April 25th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-03-17T16:05:53+00:00","versionOfRecord":{"articleIdentity":"rs-4274131","link":"https://doi.org/10.1007/s10792-025-03479-5","journal":{"identity":"international-ophthalmology","isVorOnly":false,"title":"International Ophthalmology"},"publishedOn":"2025-03-14 15:58:54","publishedOnDateReadable":"March 14th, 2025"},"versionCreatedAt":"2024-04-25 16:50:47","video":"","vorDoi":"10.1007/s10792-025-03479-5","vorDoiUrl":"https://doi.org/10.1007/s10792-025-03479-5","workflowStages":[]},"version":"v1","identity":"rs-4274131","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4274131","identity":"rs-4274131","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}