Drill-and-Prechop Technique: Modification of the Drill-and-Crack Technique for Mature Cataracts

Drill-and-Prechop Technique: Modification of the Drill-and-Crack Technique for Mature Cataracts | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Drill-and-Prechop Technique: Modification of the Drill-and-Crack Technique for Mature Cataracts Mao Xu, Yongjun Qi, Yongde Weng, Yang Yang, Jianhua Deng, Wanjun Liu, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1836018/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 8 You are reading this latest preprint version Abstract Background :There are some techniques for disassembly of hard nuclear.It is challenging in hard cataract surgery through microincision.The classic chop or prechop techniques often do not succeed,resulting in incomplete nuclear segmentation.The authors describe a new chop technique for removing hard nucleus cataracts in coaxial microincisional cataract surgery. Methods :We have termed this new technique“drill and prechop”.We create a deep hole (drill) in the central nucleus with the phaco tip and divide the nucleus (prechop) with the Nagahara chopper and the modified capsulorhexis forceps inside the hole.The chopper and the modified capsulorhexis forceps are spread apart laterally after they approach at the center of the nucleus, to create a complete fracture across the entire nucleus.Since January 2022, we have completed 27 eyes of 25 patients with hard nucleus cataract using this technique. Result s:Complete segmentation of the hard nuclear into two hemispheres was implemented with this drill and prechop technique in all cases.The phaco time and energy decreased significantly.No intraoperative complication such as iris injury, anterior capsule tears, zonulysis, or posterior capsule rupture with vitreous loss occurred during surgery. Conclusions :This technique simplifies the previous prechop techniques especially for hard nucleus in microincisional cataract surgery. The technique is efficient, safe and simple.Even inexperienced surgeons are able to quickly master this technique. Chop Microincision Phacoemulsification Prechop Hard nucleus Teaching phaco Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Background Phacoemulsification of mature cataracts is more widely performed than extracapsular cataract extraction even in the Chinese rural population. However, it has always been a challenge to perform coaxial microincision phacoemulsification of hard cataracts. The absence of a protective epinuclear layer, the paucity of cortex, the fragility of the capsule, and the laxity of the zonules increase the risk of injury to the supportive structures of the lens during surgery[ 1 ]. Many techniques for hard cataracts have been described: step-by-step chop in situ[ 2 ], crater-and-chop technique[ 3 ], drill and chop[ 4 ], multilevel chop technique[ 5 ], terminal chop[ 1 ], consecutive drilling combined with phaco chop[ 6 ], and rotary chop[ 17 ]. To minimize the ultrasound energy in phacoemulsification, many prechop techniques have been described[ 6 – 11 ]. However, they require additional special instruments or the additional expensive femtosecond-laser platform. Some manual prechop techniques could not easily complete segmentation of the dense nuclear into two hemispheres. We introduce a modification of the drill-and-crack technique introduced by Hwang HS et al.[ 13 ] that can be used safely and effectively to remove hard nucleus. With our technique, the very hard nucleus can be split through the posterior plate without stress to zonular fibres. We propose that this alternative technique is smooth, safe, and effective, with a short learning curve and excellent early postoperative visual outcomes. Methods No additional equipment is required for this technique compared with traditional phaco beyond a capsulorhexis forceps (Mingren, Suzhou, China, patent no: ZL201520078867.9, Fig.1). It has a sharp triangular forceps head looking like the bow of a warship when it closes. Our video example uses a megaTRON S4 System (Geuder, Heidelberg, Germany) with the following parameters: longitudinal phaco at 60% power in continuous mode, 90-cm bottle height, 350 mmHg of vacuum, and 30 cc/min of aspiration flow. Surgical technique All coaxial microincisional cataract surgery (coaxial MICS) is performed under topical anaesthesia through a clear corneal incision with a side port. The size of main incision is 2.2 mm. After a continuous curvilinear capsulorhexis is made, the exposed phaco tip is extended to about 1.5–2.0mm and then inserted into the anterior chamber with the bevel down. The superficial cortex are removed. With the phaco tip bevel down facing the nucleus, a deep, narrow hole is made by embedding the phaco tip near the geometric centre of the endonucleus (Fig.2). The angle of drilling is approximately 60°, and the depth is approximately two-thirds depth of the anteroposterior lens thickness, which can be measured by placing the phaco tip with a known diameter. When the entire exposed phaco tip has been embedded in the nucleus, it is removed and sodium hyaluronate is injected into the anterior chamber. The long Nagahara chopper is introduced into the anterior chamber through the paracentesis. The nucleus is gently engaged by the capsulorhexis forceps at the anterior pole, followed by a slight pull toward the main incision. Simultaneously, the chopper is slid under the capsule and rotated so the blade is perpendicular to the equator of the nucleus, resting at 5 o'clock in the bag, maintaining the chopper tip toward the hole. By this time, the capsulorhexis forceps has been repositioned and inserted into the hole. The Nagahara chopper and the capsulorhexis forceps are kept in apposition at the same radial meridian. The chopper is pulled obliquely up toward the centre along the lens fibre, while the capsulorhexis forceps is pushed slightly obliquely down to provide a counterforce (Fig. 3–4). Once they meet, the capsulorhexis forceps is unfolded slightly and two instruments are gently separated laterally so the nucleus will be split completely into two hemispheres (Fig. 5). The hemispheres are rotated by the chopper and divided into quadrants. Each fragment is then aspirated and emulsified within the capsular bag. The main operation steps are shown in the operation screenshot (Fig. 6–8). Patients The drill and prechop technique has been adopted in 27 eyes of 25 patients with cataract harder than nuclear opalescence 4 on the Lens Opacities Classification System III scale with a hard nucleus in the past 6 months. All patients signed an informed consent for participation in this study. All patients were treated in accordance with compliance guidelines outlined by the Declaration of Helsinki. Results Since January 2022, we have completed 27 eyes of 25 patients using this technique. The postoperative visual acuity was significantly improved.We found that the intraoperative phaco time and energy decreased.No intraoperative complication such as iris injury, anterior capsule tears, zonulysis, or posterior capsule rupture with vitreous loss occurred during surgery. Discussion Complete splitting of the nucleus into two hemispheres is an essential step in accomplishing uneventful coaxial microincision phacoemulsification of mature cataracts. Endothelial cell loss was initially increased in MICS, especially in eyes with increased nuclear density because of increased cumulative dissipated energy, aspiration time, and volume of balanced salt solution used[ 14 ]. Some advanced phacoemulsification techniques may also decrease energy use. However, the techniques including various prechop techniques quite often does not succeed, resulting in incomplete nuclear segmentation and intact posterior plate, or the prechoppers are too wide to be used in MICS. The consecutive drilling combined with phaco chop technique introduced by Chen D et al.[ 6 ] to remove hard cataracts in MICS involves 3–4 holes consecutively drilled into the endonucleus. The nucleus is deeply impaled with the last drilling and firmly engaged with high vacuum, and then chopped with chopper centripetally from the lens equator. The chopper and phaco tip are spread apart laterally after they approach at the centre of the nucleus. It combines the advantages of phaco-chop and phaco-drill[ 15 ]. Rotary chop introduced by Ifantides C et al.[ 17 ] created two or more partial thickness pilot holes around the periphery of the nucleus by the phaco tip. Then, tackle the nucleus with the chopper and phaco tip in two holes in a meridian. At least two holes need to be created in the technique. Moreover, drilling holes with high ultrasound energy may increase the risk of complications such as corneal burn and corneal endothelial damage in mature cataracts in MICS. The drill-and-crack technique, introduced by Hwang HS et al.[ 13 ] involves a deep hole in the central nucleus with the phaco tip and divides the nucleus with the prechopper inside the hole. Different from the consecutive drilling combined with the phaco chop technique[ 6 ] and rotary chop[ 17 ], it only drills one deep, narrow hole near the geometric centre of the endonucleus which could decrease the ultrasound energy. It offers easy and effective nuclear disassembly in patients with a hard nucleus cataract. However, it needs an Akahoshi prechopper[ 7 , 9 ] which is not applicable to MICS. We adopted the drill-and-prechop idea from the drill-and-crack technique[ 13 ] and the cystotome-assisted prechop technique[ 16 ]. After digging a narrow, deep hole near the centre of the endonucleus, we used the Nagaharra chopper and the modified capsulorhexis forceps to split the nucleus. It can be considered a prechop technique. No phaco energy is wasted in the prechop procedure. We made a new capsulorhexis forceps which can perform the capsulorhexis and prechop. The modified capsulorhexis forceps (Fig. 1 ) has a sharp triangular forceps head similar to a bow of a warship when it closes. Because of this feature, the nucleus is easily split into two unconnected hemispheres. In the cystotome-assisted prechop technique[ 16 ], after the capsulorhexis, the surgeon-bent cystotome is inserted into the lens while the Nagahara chopper is set around the lens equator. The cystotome and the chopper are then brought together in the centre to create a bisecting crack in the nucleus, dividing it into two hemispheres. The nuclear opalescence 3 nucleus are easy to split, but when splitting the nuclear opalescence 4 or 5 nucleus, the nucleus may rotate or cannot completely split the posterior plate. We replace the cystotome with our modified capsulorhexis forceps to do the prechop. When we firstly dig a hole in the endonucleus, the hardest part of the nucleus was wrecked. Then the counterforce of the chopper and the capsulorhexis forceps can totally split the nucleus. We performed the bisection without hydrodissection. Xu Chen et al.[ 16 ] made the point that after hydrodissection, the endonucleus may be rotatable, which makes holding and bisecting it difficult or impossible in the manual prechop technique. The surgeon can also choose to perform additional hydrodissection after the nucleus bisection procedure. Then, the hemispheres are rotated by the chopper and divided into quadrants. Conclusions In summary, this technique could simplify the previous prechop techniques especially in MICS. It reduces the use of ultrasonic energy and the damage to corneal endothelial cells. It does not need additional instruments and it is easy to learn. It is an efficient, safe, simple, and swift procedure for full-thickness nuclear segmentation, giving consistent results, especially in hard mature cataracts. It will be helpful to experienced and inexperienced surgeons. Abbreviations MICS:microincisional cataract surgery Declarations Ethics approval and consent to participate All procedures followed the tenets of the Declaration of Helsinki. This study obtained approval from the ethical committee of Guangdong Hospital of Traditional Chinese Medicine.We have obtained signed informed consent for participation in this study and consent to publish from each participant to report individual patient data. Consent for publication Not Applicable. Availability of data and materials Data are available upon request due to concerns about potential breach of confidentiality.The dataset is only available upon request to qualified researchers. Please contact the first author, Dr. Mao Xu, for access to the data set. Competing interests The authors declare that they have no competing interests. Funding. No funding or sponsorship was received for this study or publication of this article. Authors’contributions MX and YDW designed the study, acquired the data,MX wrote the paper, YY and JHD helped acquire the data and conceived of the reported analyses, WJL,TM and XXY supervised patients and helped acquire the data, YJQ sanctioned the study and edited the paper. All authors viewed and approved the final manuscript and had the opportunity to comment on earlier drafts. Acknowledgements Not Applicable. References Prasad R, Badhani A, Dogra GB. Terminal chop: New technique for full thickness nuclear segmentation in mature hard cataract. Indian J Ophthalmol. 2017;65:1415–18. Vasavada A, Singh R. Step-by-step chop in situ and separation of very dense cataracts. J Cataract Refract Surg 1998;24:156–159. Vanathi M, Vajpayee RB, Tandon R, et al. Crater-and-chop technique for phacoemulsification of hard cataracts. J Cataract Refract Surg.2001;27:659–61. Kim DY, Jang JH. Drill and chop: modified vertical chop technique for hard cataract. Ophthalmic Surg Lasers Imaging. 2012;43:169–72. Vasavada AR, Raj SM. Multilevel chop technique. J Cataract Refract Surg. 2011; 37:2092–2094. Chen D, Tang Q, Yu F, et al. Consecutive drilling combined with phaco chop for full thickness segmentation of very hard nucleus in coaxial microincisional cataract surgery[J]. BMC Ophthalmol. 2019,19(1). Akahoshi T. Phaco prechop: manual nucleofracture prior to phacoemulsification. Operative Tech Cataract Refract Surg 1998;1:69–91. Henriques JS, Alio JL, Akahoshi T, et al. Prechopping surgical techniques. Tech Ophthalmol 2009;7:139–145. Akahoshi T. Phaco prechop: mechanical nucleofracture prior to phacoemulsification. In: Yuan J-Q, Lim ASM, eds, The Frontier of Ophthalmology in the 21st Century. Tianjin, China, Tianjin Science and Technology Press, 2001;288–322. Bhatti SS. Description of surgical technique: the Bhatti modification for small-incision cataract surgery of the Akahoshi prechop technique. Indian J Ophthalmol 2009;57:31–33. Berger A, Contin IN, Nicoletti G, et al. Middle prechop: fracturing the middle portion of the nucleus. J Cataract Refract Surg 2012;38:564–567. Moshirfar M, Churgin DS, Hsu M. Femtosecond laser-assisted cataract surgery: a current review. Middle East Afr J Ophthalmol 2011;18:285–291. Hwang HS, Kim EC, Kim MS. Drill-and-crack technique for nuclear disassembly of hard nucleus. J Cataract Refract Surg. 2010;36:1627–30. Mahdy MAS, Eid MZ, Mohammed MA-B, et al. Relationship between endothelial cell loss and microcoaxial phacoemulsification parameters in noncomplicated cataract surgery. Clin Ophthalmol 2012;6:503–510. Joo C-K, Kim YH. Phacoemulsification with a bevel-down phaco tip: phaco-drill. J Cataract Refract Surg 1997;23:1149–1152. Chen X, Liu B, Xiao Y, et al. Cystotome-assisted prechop technique [J]. J Cataract Refract Surg. 2015; 41(1): 9–13. Ifantides C, Sieck EG, Christopher KL. Rotary chop: A new technique for teaching chop and tackling mature cataracts[J]. Ophthalmol Ther, 2020; 9:321–327. Additional Declarations No competing interests reported. Supplementary Files drillandprechopvideoBMC.mp4 Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Major revision 15 Sep, 2022 Reviews received at journal 13 Aug, 2022 Reviewers agreed at journal 13 Aug, 2022 Reviewers invited by journal 13 Aug, 2022 Editor assigned by journal 13 Aug, 2022 Editor invited by journal 14 Jul, 2022 Submission checks completed at journal 14 Jul, 2022 First submitted to journal 07 Jul, 2022 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-1836018","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":121109483,"identity":"2cdd0fa5-a5f0-4281-856a-96a6c97d7eec","order_by":0,"name":"Mao Xu","email":"","orcid":"","institution":"Guangzhou University of Chinese Medicine","correspondingAuthor":false,"prefix":"","firstName":"Mao","middleName":"","lastName":"Xu","suffix":""},{"id":121109484,"identity":"1a4bf9b4-ba11-42f9-963d-b3d7ea18e96d","order_by":1,"name":"Yongjun 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Medicine,Zhuhai","correspondingAuthor":false,"prefix":"","firstName":"Ting","middleName":"","lastName":"Mo","suffix":""},{"id":121109490,"identity":"5152178a-9f22-44af-81b9-a09ac86a3c34","order_by":7,"name":"Xiangxiang Ye","email":"","orcid":"","institution":"Guangdong Hospital of Traditional Chinese Medicine,Zhuhai","correspondingAuthor":false,"prefix":"","firstName":"Xiangxiang","middleName":"","lastName":"Ye","suffix":""}],"badges":[],"createdAt":"2022-07-07 15:44:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-1836018/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-1836018/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":24221430,"identity":"84b816e5-90b6-4c13-8abf-088db063c4e4","added_by":"auto","created_at":"2022-07-22 21:07:35","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":842277,"visible":true,"origin":"","legend":"\u003cp\u003eThe sharp triangular forceps head of the modified capsulorhexis forceps.\u003c/p\u003e","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-1836018/v1/8afb1649fa45ef231e8e263d.png"},{"id":24221434,"identity":"a2a7428d-9775-4a14-9254-6b0851589f97","added_by":"auto","created_at":"2022-07-22 21:07:35","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1505804,"visible":true,"origin":"","legend":"\u003cp\u003eWith the phaco tip bevel down, facing the nucleus, a deep, narrow hole is made by embedding the phaco tip near the geometric centre of the endonucleus.\u003c/p\u003e","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-1836018/v1/e101672c9de46d7a803f49c6.png"},{"id":24221562,"identity":"00672880-e4dc-428c-8f12-b55e5d3fee93","added_by":"auto","created_at":"2022-07-22 21:12:35","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1236478,"visible":true,"origin":"","legend":"\u003cp\u003e The chopper is slid under the capsule and rotated resting at 5 o'clock in the bag, maintaining the chopper tip toward the hole. The capsulorhexis forceps was inserted into the hole. The chopper is pulled obliquely up toward the centre along the lens fibre, while the capsulorhexis forceps is pushed slightly obliquely down to provide a counterforce.\u003c/p\u003e","description":"","filename":"Fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-1836018/v1/4e15f40dbb724ad25763c345.png"},{"id":24221431,"identity":"ea77b9e8-3f96-424e-be83-a8c7fd706304","added_by":"auto","created_at":"2022-07-22 21:07:35","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":2042532,"visible":true,"origin":"","legend":"\u003cp\u003eThe chopper is slid under the capsule and rotated resting at 5 o'clock in the bag, maintaining the chopper tip toward the hole. The capsulorhexis forceps was inserted into the hole. The chopper is pulled obliquely up toward the centre along the lens fibre, while the capsulorhexis forceps is pushed slightly obliquely down to provide a counterforce.\u003c/p\u003e","description":"","filename":"Fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-1836018/v1/17da90537d9b70d9d361b50b.png"},{"id":24221432,"identity":"de173714-fb4b-4c2d-917b-170611e88dfc","added_by":"auto","created_at":"2022-07-22 21:07:35","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1936828,"visible":true,"origin":"","legend":"\u003cp\u003eThe nucleus will be split completely into two hemispheres.\u003c/p\u003e","description":"","filename":"Fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-1836018/v1/de23180a664a61da838796be.png"},{"id":24221433,"identity":"93575490-421d-4091-82bc-9a0a73cb002e","added_by":"auto","created_at":"2022-07-22 21:07:35","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":4851155,"visible":true,"origin":"","legend":"\u003cp\u003eThe main operation steps are shown in the operation screenshot.\u003c/p\u003e","description":"","filename":"fig6.png","url":"https://assets-eu.researchsquare.com/files/rs-1836018/v1/348414b009125d1ea81471be.png"},{"id":24221661,"identity":"b09cb946-a264-40f4-b8c1-baf7ca87b8ae","added_by":"auto","created_at":"2022-07-22 21:17:36","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":4858690,"visible":true,"origin":"","legend":"\u003cp\u003eThe main operation steps are shown in the operation screenshot.\u003c/p\u003e","description":"","filename":"fig7.png","url":"https://assets-eu.researchsquare.com/files/rs-1836018/v1/337fd20d43aa1ccd8a115b5a.png"},{"id":24221437,"identity":"f5ce2a4d-5d6d-4540-a253-cf9bc9889d12","added_by":"auto","created_at":"2022-07-22 21:07:35","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":4666752,"visible":true,"origin":"","legend":"\u003cp\u003eThe main operation steps are shown in the operation screenshot.\u003c/p\u003e","description":"","filename":"fig8.png","url":"https://assets-eu.researchsquare.com/files/rs-1836018/v1/3c3cbaeabecbcbd530a953b1.png"},{"id":24221662,"identity":"5ceff22c-544e-4547-9c0a-15892c49ceba","added_by":"auto","created_at":"2022-07-22 21:17:38","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":237293,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1836018/v1/be0a0acc-5e22-4e72-91b6-f0865427756b.pdf"},{"id":24221438,"identity":"88de15e4-4294-46f2-873d-39b3c31ca150","added_by":"auto","created_at":"2022-07-22 21:07:38","extension":"mp4","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":79517243,"visible":true,"origin":"","legend":"","description":"","filename":"drillandprechopvideoBMC.mp4","url":"https://assets-eu.researchsquare.com/files/rs-1836018/v1/db17e9e1218965cfa95ff1a9.mp4"}],"financialInterests":"No competing interests reported.","formattedTitle":"Drill-and-Prechop Technique: Modification of the Drill-and-Crack Technique for Mature Cataracts","fulltext":[{"header":"Background","content":"\u003cp\u003ePhacoemulsification of mature cataracts is more widely performed than extracapsular cataract extraction even in the Chinese rural population. However, it has always been a challenge to perform coaxial microincision phacoemulsification of hard cataracts. The absence of a protective epinuclear layer, the paucity of cortex, the fragility of the capsule, and the laxity of the zonules increase the risk of injury to the supportive structures of the lens during surgery[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Many techniques for hard cataracts have been described: step-by-step chop in situ[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], crater-and-chop technique[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], drill and chop[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], multilevel chop technique[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], terminal chop[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], consecutive drilling combined with phaco chop[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], and rotary chop[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. To minimize the ultrasound energy in phacoemulsification, many prechop techniques have been described[\u003cspan additionalcitationids=\"CR7 CR8 CR9 CR10\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. However, they require additional special instruments or the additional expensive femtosecond-laser platform. Some manual prechop techniques could not easily complete segmentation of the dense nuclear into two hemispheres.\u003c/p\u003e \u003cp\u003eWe introduce a modification of the drill-and-crack technique introduced by Hwang HS et al.[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] that can be used safely and effectively to remove hard nucleus. With our technique, the very hard nucleus can be split through the posterior plate without stress to zonular fibres. We propose that this alternative technique is smooth, safe, and effective, with a short learning curve and excellent early postoperative visual outcomes.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eNo additional equipment is required for this technique compared with traditional phaco beyond a capsulorhexis forceps (Mingren, Suzhou, China, patent no: ZL201520078867.9, Fig.1). It has a sharp triangular forceps head looking like the bow of a warship when it closes.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOur video example uses a megaTRON S4 System (Geuder, Heidelberg, Germany) with the following parameters: longitudinal phaco at 60% power in continuous mode, 90-cm bottle height, 350 mmHg of vacuum, and 30 cc/min of aspiration flow.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSurgical technique\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll coaxial microincisional cataract surgery (coaxial MICS) is performed under topical anaesthesia through a clear corneal incision with a side port. The size of main incision is 2.2 mm. After a continuous curvilinear capsulorhexis is made, the exposed phaco tip is extended to about 1.5\u0026ndash;2.0mm and then inserted into the anterior chamber with the bevel down. The superficial cortex are removed. With the phaco tip bevel down facing the nucleus, a deep, narrow hole is made by embedding the phaco tip near the geometric centre of the endonucleus (Fig.2). The angle of drilling is approximately 60\u0026deg;, and the depth is approximately two-thirds depth of the anteroposterior lens thickness, which can be measured by placing the phaco tip with a known diameter. When the entire exposed phaco tip has been embedded in the nucleus, it is removed and sodium hyaluronate is injected into the anterior chamber. The long Nagahara chopper is introduced into the anterior chamber through the paracentesis. The nucleus is gently engaged by the capsulorhexis forceps at the anterior pole, followed by a slight pull toward the main incision. Simultaneously, the chopper is slid under the capsule and rotated so the blade is perpendicular to the equator of the nucleus, resting at 5 o\u0026apos;clock in the bag, maintaining the chopper tip toward the hole. By this time, the capsulorhexis forceps has been repositioned and inserted into the hole. The Nagahara chopper and the capsulorhexis forceps are kept in apposition at the same radial meridian. The chopper is pulled obliquely up toward the centre along the lens fibre, while the capsulorhexis forceps is pushed slightly obliquely down to provide a counterforce (Fig. 3\u0026ndash;4). Once they meet, the capsulorhexis forceps is unfolded slightly and two instruments are gently separated laterally so the nucleus will be split completely into two hemispheres (Fig. 5). The hemispheres are rotated by the chopper and divided into quadrants. Each fragment is then aspirated and emulsified within the capsular bag. The main operation steps are shown in the operation screenshot (Fig. 6\u0026ndash;8).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePatients\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe drill and prechop technique has been adopted in 27 eyes of 25 patients with cataract harder than nuclear opalescence 4 on the Lens Opacities Classification System III scale with a hard nucleus in the past 6 months. All patients signed an informed consent for participation in this study. All patients were treated in accordance with compliance guidelines outlined by the Declaration of Helsinki.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eSince January 2022, we have completed 27 eyes of 25 patients using this technique. The postoperative visual acuity was significantly improved.We found that the intraoperative phaco time and energy decreased.No intraoperative complication such as iris injury, anterior capsule tears, zonulysis, or posterior capsule rupture with vitreous loss occurred during surgery.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eComplete splitting of the nucleus into two hemispheres is an essential step in accomplishing uneventful coaxial microincision phacoemulsification of mature cataracts. Endothelial cell loss was initially increased in MICS, especially in eyes with increased nuclear density because of increased cumulative dissipated energy, aspiration time, and volume of balanced salt solution used[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Some advanced phacoemulsification techniques may also decrease energy use. However, the techniques including various prechop techniques quite often does not succeed, resulting in incomplete nuclear segmentation and intact posterior plate, or the prechoppers are too wide to be used in MICS.\u003c/p\u003e \u003cp\u003eThe consecutive drilling combined with phaco chop technique introduced by Chen D et al.[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] to remove hard cataracts in MICS involves 3\u0026ndash;4 holes consecutively drilled into the endonucleus. The nucleus is deeply impaled with the last drilling and firmly engaged with high vacuum, and then chopped with chopper centripetally from the lens equator. The chopper and phaco tip are spread apart laterally after they approach at the centre of the nucleus. It combines the advantages of phaco-chop and phaco-drill[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Rotary chop introduced by Ifantides C et al.[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] created two or more partial thickness pilot holes around the periphery of the nucleus by the phaco tip. Then, tackle the nucleus with the chopper and phaco tip in two holes in a meridian. At least two holes need to be created in the technique. Moreover, drilling holes with high ultrasound energy may increase the risk of complications such as corneal burn and corneal endothelial damage in mature cataracts in MICS.\u003c/p\u003e \u003cp\u003eThe drill-and-crack technique, introduced by Hwang HS et al.[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] involves a deep hole in the central nucleus with the phaco tip and divides the nucleus with the prechopper inside the hole. Different from the consecutive drilling combined with the phaco chop technique[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] and rotary chop[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], it only drills one deep, narrow hole near the geometric centre of the endonucleus which could decrease the ultrasound energy. It offers easy and effective nuclear disassembly in patients with a hard nucleus cataract. However, it needs an Akahoshi prechopper[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] which is not applicable to MICS.\u003c/p\u003e \u003cp\u003eWe adopted the drill-and-prechop idea from the drill-and-crack technique[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] and the cystotome-assisted prechop technique[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. After digging a narrow, deep hole near the centre of the endonucleus, we used the Nagaharra chopper and the modified capsulorhexis forceps to split the nucleus. It can be considered a prechop technique. No phaco energy is wasted in the prechop procedure. We made a new capsulorhexis forceps which can perform the capsulorhexis and prechop. The modified capsulorhexis forceps (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) has a sharp triangular forceps head similar to a bow of a warship when it closes. Because of this feature, the nucleus is easily split into two unconnected hemispheres.\u003c/p\u003e \u003cp\u003eIn the cystotome-assisted prechop technique[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], after the capsulorhexis, the surgeon-bent cystotome is inserted into the lens while the Nagahara chopper is set around the lens equator. The cystotome and the chopper are then brought together in the centre to create a bisecting crack in the nucleus, dividing it into two hemispheres. The nuclear opalescence 3 nucleus are easy to split, but when splitting the nuclear opalescence 4 or 5 nucleus, the nucleus may rotate or cannot completely split the posterior plate. We replace the cystotome with our modified capsulorhexis forceps to do the prechop. When we firstly dig a hole in the endonucleus, the hardest part of the nucleus was wrecked. Then the counterforce of the chopper and the capsulorhexis forceps can totally split the nucleus.\u003c/p\u003e \u003cp\u003eWe performed the bisection without hydrodissection. Xu Chen et al.[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] made the point that after hydrodissection, the endonucleus may be rotatable, which makes holding and bisecting it difficult or impossible in the manual prechop technique. The surgeon can also choose to perform additional hydrodissection after the nucleus bisection procedure. Then, the hemispheres are rotated by the chopper and divided into quadrants.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, this technique could simplify the previous prechop techniques especially in MICS. It reduces the use of ultrasonic energy and the damage to corneal endothelial cells. It does not need additional instruments and it is easy to learn. It is an efficient, safe, simple, and swift procedure for full-thickness nuclear segmentation, giving consistent results, especially in hard mature cataracts. It will be helpful to experienced and inexperienced surgeons.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eMICS:microincisional cataract surgery\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll procedures followed the tenets of the Declaration of Helsinki. This study obtained approval from the ethical committee of Guangdong Hospital of Traditional Chinese Medicine.We have obtained signed informed consent for participation in this study and consent to publish from each participant to report individual patient data.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot Applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData are available upon request due to concerns about potential breach of confidentiality.The dataset is only available upon request to qualified researchers. Please contact the first author, Dr. Mao Xu, for access to the data set.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding.\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNo funding or sponsorship was received for this study or publication of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo;contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMX and YDW designed the study, acquired the data,MX wrote the paper, YY and JHD helped acquire the data and conceived of the reported analyses, WJL,TM and XXY supervised patients and helped acquire the data, YJQ sanctioned the study and edited the paper. All authors viewed and approved the final manuscript and had the opportunity to comment on earlier drafts.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot Applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003ePrasad R, Badhani A, Dogra GB. Terminal chop: New technique for full thickness nuclear segmentation in mature hard cataract. Indian J Ophthalmol. 2017;65:1415\u0026ndash;18.\u003c/li\u003e\n\u003cli\u003eVasavada A, Singh R. Step-by-step chop in situ and separation of very dense cataracts. J Cataract Refract Surg 1998;24:156\u0026ndash;159.\u003c/li\u003e\n\u003cli\u003eVanathi M, Vajpayee RB, Tandon R, et al. Crater-and-chop technique for phacoemulsification of hard cataracts. J Cataract Refract Surg.2001;27:659\u0026ndash;61.\u003c/li\u003e\n\u003cli\u003eKim DY, Jang JH. Drill and chop: modified vertical chop technique for hard cataract. Ophthalmic Surg Lasers Imaging. 2012;43:169\u0026ndash;72.\u003c/li\u003e\n\u003cli\u003eVasavada AR, Raj SM. Multilevel chop technique. J Cataract Refract Surg. 2011; 37:2092\u0026ndash;2094.\u003c/li\u003e\n\u003cli\u003eChen D, Tang Q, Yu F, et al. Consecutive drilling combined with phaco chop for full thickness segmentation of very hard nucleus in coaxial microincisional cataract surgery[J]. BMC Ophthalmol. 2019,19(1).\u003c/li\u003e\n\u003cli\u003eAkahoshi T. Phaco prechop: manual nucleofracture prior to phacoemulsification. Operative Tech Cataract Refract Surg 1998;1:69\u0026ndash;91.\u003c/li\u003e\n\u003cli\u003eHenriques JS, Alio JL, Akahoshi T, et al. Prechopping surgical techniques. Tech Ophthalmol 2009;7:139\u0026ndash;145.\u003c/li\u003e\n\u003cli\u003eAkahoshi T. Phaco prechop: mechanical nucleofracture prior to phacoemulsification. In: Yuan J-Q, Lim ASM, eds, The Frontier of Ophthalmology in the 21st Century. Tianjin, China, Tianjin Science and Technology Press, 2001;288\u0026ndash;322.\u003c/li\u003e\n\u003cli\u003eBhatti SS. Description of surgical technique: the Bhatti modification for small-incision cataract surgery of the Akahoshi prechop technique. Indian J Ophthalmol 2009;57:31\u0026ndash;33. \u003c/li\u003e\n\u003cli\u003eBerger A, Contin IN, Nicoletti G, et al. Middle prechop: fracturing the middle portion of the nucleus. J Cataract Refract Surg 2012;38:564\u0026ndash;567.\u003c/li\u003e\n\u003cli\u003eMoshirfar M, Churgin DS, Hsu M. Femtosecond laser-assisted cataract surgery: a current review. Middle East Afr J Ophthalmol 2011;18:285\u0026ndash;291.\u003c/li\u003e\n\u003cli\u003eHwang HS, Kim EC, Kim MS. Drill-and-crack technique for nuclear disassembly of hard nucleus. J Cataract Refract Surg. 2010;36:1627\u0026ndash;30.\u003c/li\u003e\n\u003cli\u003eMahdy MAS, Eid MZ, Mohammed MA-B, et al. Relationship between endothelial cell loss and microcoaxial phacoemulsification parameters in noncomplicated cataract surgery. Clin Ophthalmol 2012;6:503\u0026ndash;510.\u003c/li\u003e\n\u003cli\u003eJoo C-K, Kim YH. Phacoemulsification with a bevel-down phaco tip: phaco-drill. J Cataract Refract Surg 1997;23:1149\u0026ndash;1152.\u003c/li\u003e\n\u003cli\u003eChen X, Liu B, Xiao Y, et al. Cystotome-assisted prechop technique [J]. J Cataract Refract Surg. 2015; 41(1): 9\u0026ndash;13.\u003c/li\u003e\n\u003cli\u003eIfantides C, Sieck EG, Christopher KL. Rotary chop: A new technique for teaching chop and tackling mature cataracts[J]. Ophthalmol Ther, 2020; 9:321\u0026ndash;327.\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":"bmc-ophthalmology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"boph","sideBox":"Learn more about [BMC Ophthalmology](http://bmcophthalmol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/boph","title":"BMC Ophthalmology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Chop,Microincision,Phacoemulsification,Prechop,Hard nucleus,Teaching phaco","lastPublishedDoi":"10.21203/rs.3.rs-1836018/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1836018/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e:There are some techniques for disassembly of hard nuclear.It is challenging in hard cataract surgery through microincision.The classic chop or prechop techniques often do not succeed,resulting in incomplete nuclear segmentation.The authors describe a new chop technique for removing hard nucleus cataracts in coaxial microincisional cataract surgery.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e:We have termed this new technique“drill and prechop”.We create a deep hole (drill) in the central nucleus with the phaco tip and divide the nucleus (prechop) with the Nagahara chopper and the modified capsulorhexis forceps inside the hole.The chopper and the modified capsulorhexis forceps are spread apart laterally after they approach at the center of the nucleus, to create a complete fracture across the entire nucleus.Since January 2022, we have completed 27 eyes of 25 patients\u0026nbsp;with hard nucleus cataract using this technique. \u003c/p\u003e\u003cp\u003e\u003cstrong\u003eResult\u003c/strong\u003es:Complete segmentation of the hard nuclear into two hemispheres was implemented with this drill and prechop technique in all cases.The phaco time and energy decreased significantly.No intraoperative complication such as iris injury, anterior capsule tears, zonulysis, or posterior capsule rupture with vitreous loss occurred during surgery.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e:This technique simplifies the previous prechop techniques especially\u0026nbsp;for hard nucleus in microincisional cataract surgery. The technique is efficient, safe and simple.Even inexperienced surgeons are able to quickly master this technique.\u003c/p\u003e","manuscriptTitle":"Drill-and-Prechop Technique: Modification of the Drill-and-Crack Technique for Mature Cataracts","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-07-22 21:07:33","doi":"10.21203/rs.3.rs-1836018/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revision","date":"2022-09-15T08:19:05+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2022-08-13T15:58:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"b923e2be-cae9-4d7f-a9e1-e656d4741bb3","date":"2022-08-13T12:06:45+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2022-08-13T05:29:27+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2022-08-13T05:22:00+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2022-07-14T13:21:52+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2022-07-14T13:18:19+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Ophthalmology","date":"2022-07-07T15:36:48+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-ophthalmology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"boph","sideBox":"Learn more about [BMC Ophthalmology](http://bmcophthalmol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/boph","title":"BMC Ophthalmology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"257f5c18-5abf-4a99-bbda-ae976cc32368","owner":[],"postedDate":"July 22nd, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2022-11-04T18:14:28+00:00","versionOfRecord":[],"versionCreatedAt":"2022-07-22 21:07:33","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1836018","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1836018","identity":"rs-1836018","version":["v1"]},"buildId":"_2-kVJe1T_tPrBINL-cwx","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}