Introduction
Phacoemulsification is likely one of the most generally used cataract surgical procedure methods that was initially launched by Kelman1 in 1967, which stabilized anterior chamber intraoperatively, shortened post-operative astigmatism, and expedited restoration by making an incision smaller than the traditional extracapsular cataract extraction (ECCE). Nevertheless, phacoemulsification requires high-power ultrasound (US) power, thus growing the danger of anterior and posterior capsular ruptures, corneal endothelial cell loss, zonular stress, extended surgical time, and problems corresponding to decreased visible acuity.
The horizontal chop approach launched by Nagahara is one other methodology that has been thought-about secure and efficient the place opposing forces created by the chopper cut up the lens nucleus. This system additionally requires a big degree of ultrasound power throughout nucleus disassembly, though it’s lower than that of the divide-and-conquer approach. The horizontal chop approach can induce fluid turbulence in balanced salt answer (BSS), which will increase the danger of anterior chamber instability, endothelial cell harm, and miosis. Alternatively, the vertical phaco-chop (phaco fast chop, or karate phaco-chop) approach has been adopted in circumstances with arduous cataracts, small pupils, and small anterior capsular incisions to reduce the US power publicity.
The abovementioned surgical methods all require a prolonged coaching interval to grasp every and one among them, throughout which surgeons usually encounter quite a few surgical challenges. The intricate means of ability improvement sometimes acts as a barrier to surgeons studying a brand new approach as soon as they develop into familiarized with a sure method tailored and individualized to confidently carry out the surgical procedure. Nevertheless, working on nucleus disassembly and phacoemulsification concurrently can elevate varied dangers in advanced circumstances, corresponding to average to extreme cataract, shallow anterior chamber depth, small pupils, unstable incision, or weak ciliary zonule. Stemming from these issues was the decision for a brand new approach that was not solely straightforward to be taught, but additionally steady with separate nucleus disassembly and phacoemulsification processes, and on the identical time requiring minimal US power and BSS. The guide prechop approach, first launched by Akahoshi2 in 1998, eliminated the usage of US power in fragmentation and considerably decreased each US power publicity and surgical time when put next with standard chopping procedures corresponding to divide-and-conquer,3 stop-and-chop,4 or the supracapsular flip5 approach.
The Akahoshi prechopper, a sort of combo prechopper, can be utilized in LOCS III N1 to LOCS III N3 cataracts with out elevating the danger of zonulopathy. For LOCS III N4 and above lenses, different sorts of prechopper in addition to an Inamura prechopper can be utilized. Nevertheless, such an method not solely will increase zonular stress, but additionally requires further devices, corresponding to a blunt nucleus manipulator or a sustainer to create counterforce, which provides further danger of zonular stress when incomplete or mis-directed separation happens. Lastly, standard prechop methods enhance the danger of posterior capsular harm or zonular weak spot in tough circumstances, corresponding to LOCS III N5 and above nucleus, mature or hypermature cataracts with arduous nucleus, or preexisting zonular weak spot.
The modified slim 1.7 mm neck prechopper (AE-4298, HI Kim-Inamura prechopper, ASICO, Inc., USA) goals to beat limitations of standard methods. It permits lens division in each tender and dense nucleus with out exerting a counterforce. The slim tip is appropriate for microincision cataract surgical procedure (MICS) with 1.8 mm or 2.0 mm incision. The large tip blade is designed to separate the nucleus with uniformly distributed power, decreasing the danger of ciliary zonular harm from shearing power when the blade is widened after inserted to the lens nucleus. As well as, the eagle’s beak formed tip permits the surgeon to take care of a gradual maintain of the nucleus fragment whereas offering a gradual power to separate the lens. For mature cataracts with arduous nucleus, the common chopper (AE-2591, HI Kim chopper, ASICO, Inc., USA) can be utilized as a substitute of further gear, corresponding to blunt nucleus manipulator or a sustainer, to carry out counter prechop in addition to standard horizontal chop or stop-and-chop methods.
This text goals to introduce an alternate prechop approach utilizing HI Kim-Inamura prechopper and common chopper which could be utilized safely and successfully in LOCS III N4 or higher-grade cataracts even with a skinny cortical layer. The approach not solely stabilizes fixation by making use of evenly elevated chopping power, but additionally separates the usage of phacoemulsification devices in lens fragmentation course of, intending to reduce intraoperative and post-operative problems.
Supplies and Strategies
Sufferers
Sufferers with age-related cataracts who underwent cataract surgical procedures utilizing modified prechop approach or phaco-chop phacoemulsification nucleotomy methods have been enrolled on this examine from Gyeongju St. Mary’s eye clinic, Gyeongju-si, Gyeongsangbuk-do, Republic of Korea, from Might 1, 2016 to April 30, 2017 (for Phaco-chop group) and from September 1, 2020 to August 30, 2021 (for Modified prechop group). The grading of the cataract was evaluated based mostly on the Lens Opacities Classification System III (LOCS III) by the identical doctor. Eyes with nuclear opacity graded between 2+ and 6+ have been included for evaluation on this examine. The exclusion standards included a historical past of ocular trauma or ophthalmic surgical procedure, ocular comorbidities, corneal problems, and an endothelial cell rely (ECC) of lower than 1500 cells/mm2. Sufferers with out common follow-up have been excluded as properly. This examine was accredited by the Institutional Assessment Board of Gyeongju St. Mary’s eye clinic (GMS-202112) and adopted the rules of the Declaration of Helsinki. Knowledgeable consent was obtained from every affected person.
Affected person Analysis
All sufferers acquired a full ophthalmic examination, which included the best-corrected distance visible acuity, manifest refraction, slit-lamp examination, intraocular strain measurement (NT-800, Topcon, Tokyo), ECC, central corneal thickness (CCT) by a non-contact specular microscope (SP-1P, Topcon, Tokyo), and biometry by A-mode ultrasound (Aviso, Quantel Medical) or coherence interferometry (IOLMaster, Carl Zeiss Meditec AG) and fundus examination. All sufferers underwent the identical pre-operative standardized administration.
Phaco Machine and Settings
The Stellaris PC® Phacoemulsification unit (Bausch&Lomb, St. Louis, MO, USA) and the outer diameter 0.74 mm–0.94 mm flared, 30° angulated needle, straight 1.8 mm MICS™ needle have been used for every cataract surgical procedure within the modified prechop group. The settings of the phaco machine have been as follows: the longitudinal a number of burst mode (burst period: 6/obligation cycle: 75) with 30% ultrasound energy, infusion bottle top of 80 cm, and vacuum 430 mmHg.
The Infiniti® phacoemulsification unit (Alcon Laboratories, Fort Value, TX, USA) and the 0.9 mm Reverse Kelman microtip have been used for every cataract surgical procedure within the phaco-chop management group. The settings of the phaco machine have been as follows: the torsional continuous mannequin with 100% amplitude, infusion bottle top of 100 cm, aspiration stream price of 38 mL/min, and vacuum 430 mmHg.
Surgical Approach
All of the surgical procedures have been carried out below topical anesthesia by one skilled surgeon (Hyungil Kim), who had beforehand used the modified prechop approach in additional than 5000 circumstances and carried out greater than 25,000 cataract surgical procedures previous to this examine.
Below topical anesthesia, a 1.8–2.0 mm or a normal 2.2 mm clear corneal incision is made alongside the steepest axis. A viscoelastic agent is injected into the anterior chamber. A steady curvilinear capsulorhexis is carried out utilizing the capsulorhexis forceps. The typical capsule opening diameter is 5.5–5.8 mm and is dependent upon various kinds of IOLs. As capsulorhexis has been accomplished, the cortical cleaving hydrodissection is carried out utilizing a 23-gauge twin port cannula (AE-7655, HI Kim-Inamura cannula, ASICO, Inc., USA), which injects BSS in numerous instructions with minimal zonule stress and permits the nucleus to rotate freely within the capsular bag (Figure 1) (Video 1).
Within the case of cataracts with comparatively tender nucleus (beneath grade 3), nucleus fragmentation is carried out in the identical manner as the traditional prechop maneuver. After filling the anterior chamber with sufficient dispersive ophthalmic viscosurgical gadgets (OVD), insert the modified slim 1.7 mm neck prechopper (AE-4298, HI Kim-Inamura prechopper, ASICO, Inc. USA) vertically and place it barely previous the anatomical Y suture on the middle of the lens (Figure 2). When passing via the endonucleus, open the prechopper blades slowly and the nucleus could be simply divided. After rotating the nucleus into 90 levels, chop the nucleus distally from the incision, adopted by chopping the nucleus proximally to the incision and phacoemulsify the divided quadrants (Figure 3A–G) (Video 2). If the nucleus doesn’t flip freely, nuclear chopping could be carried out radially across the incision (Figure 4) (Video 3).
Within the case of cataracts with arduous nucleus (above grade 4), nucleus fragmentation is carried out utilizing the counter prechop approach, launched as in following steps. Insert the two.0 mm common chopper with a rounded tip (AE 2591, HI Kim chopper, ASICO, Inc.) into the anterior chamber via the 1.0 mm paracentesis incision, slide it via the cortical layers, and place it on the nucleus equator, whereas the prechopper is positioned at 180 levels reverse simply earlier than the anatomical Y suture. Because the common chopper is pulled centrally with barely upward power, concurrently push the other prechopper centrally with slight downward power. Each devices must be dealt with with the identical quantity of power and may method one another slowly (Figure 5A–E) (Videos 4 and 5). The prechopper must be positioned on the middle of the nucleus, and gently opening the blades will fracture the arduous endonucleus. If further nuclear fracturing is required, the prechopper could be flipped over and positioned below the middle of the lens. By opening the blades, the nuclear fragmentation is efficiently accomplished (Figure 6). The nucleus is split into 4 or extra fragments utilizing common chopper with prechopper and adopted by phacoemulsification.
Consequence Evaluation
The ECC was measured 7 days previous to surgical procedure, in addition to 1 month and three months after surgical procedure. The CCT was measured 7 days earlier than surgical procedure, in addition to 1 month and three month post-operatively. All of the ophthalmic examinations have been carried out by the identical technician. The proportion of endothelial cell loss was calculated as follows: Lack of ECC (%)=(ECCpre–ECCpost)/ECCpre. The change in CCT was calculated as follows: Change in CCT (%)=(CCTpost– CCTpre)/CCTpre. Pre is brief for pre-operative and publish is brief for post-operative.
Statistical Evaluation
Statistical evaluation was carried out with SPSS software program package deal model 18 (SPSS Inc., Chicago, Illinois, USA). Usually distributed variables have been expressed as imply±normal deviation. The impartial samples t-test was used to check the imply values between the 2 teams, whereas paired t-test was used to check the pre-operative and post-operative information. A chi-square check was utilized to research the qualitative information. The edge for statistical significance was set at P<0.05.
Outcomes
A complete of 201 eyes of 201 sufferers (104 eyes within the modified prechop group, and 97 eyes within the phaco-chop group) have been enrolled for evaluation on this examine. The modified prechop group consisted of 104 eyes of 76 ladies and 28 males. The phaco-chop group consisted of 97 eyes of 57 ladies and 40 males. The demographic and scientific traits of the examine (modified prechop) and management (phaco-chop) teams are offered in Table 1. The imply age of the modified prechop group was 70.1±10.9 years. There have been vital variations between the 2 teams in gender and age; nevertheless, no vital distinction in nuclear opacity was noticed between the two teams. Additionally, no vital variations within the imply ECC (Table 2) and CCT (Table 3) pre-operatively have been discovered between the 2 teams.
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Desk 1 Affected person Demographics and Medical Traits |
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Desk 2 Comparability of Corneal Endothelial Cells Pre-Operatively and Publish-Operatively in Modified Prechop and Phaco-Chop Teams |
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Desk 3 Comparability of Central Corneal Thickness Pre-Operatively and Publish-Operatively in Modified Prechop and Phaco-Chop Teams |
No statistically vital variations within the absolute ECCs and losses of ECC all through the follow-up (P=0.307, 0.375, respectively, at 1 month; and P=0.252, 0.327, respectively, at 3 months, Table 2) have been noticed between the 2 teams.
Likewise, no statistically vital variations within the absolute CCT and alter in CCT all through the follow-up (P=0.662, 0.404, respectively, at 1 month; and P=0.618, 0.272, respectively at 3 months, Table 3) have been noticed between the 2 teams.
Dialogue
Some research have proposed various kinds of prechopping approach, utilizing 1 or 2 cystotome,6,7 reverse kind chopper,8 and phacoemulsification handpiece as a second chopper.9 Each center prechop6 and 1 cystotome-assisted prechop7 have a risk to potential iatrogenic damage through the introduction of the cystotomes via the incision. The principle chopping power throughout center prechop6 is in direction of the posterior capsule and zonule, which may result in elevated posterior capsular rupture and zonular dialysis or zonulopathy. The reverse kind chopper8 is comparatively arduous to control, particularly for physicians with much less scientific expertise, and poor manipulation of this gear can lead to breakage of the posterior capsule. The double-chop maneuver recommended by Kim9 can fracture a variety of lens densities, from very tender to dense and even in circumstances with small pupils; nevertheless, it doesn’t completely separate the usage of phacoemulsification instrument and lens fragmentation.
When utilizing double-chop maneuver, a clinician is required to constantly manipulate irrigation with a foot pedal from 0 to 1, whereas concurrently trying to insert the chopper and phacoemulsification ideas via the incision.
Additionally, after phaco tip and chopper are introduced collectively on the middle of the nucleus, lateral separation is critical to divide the lens. Incomplete or mis-directed lateral separation can result in elevated zonular stress. Subsequently, it may be difficult for physicians with much less expertise to hold out two hand counter prechop in each single case of cataract.
Since Nagy et al,10 some research confirmed potential benefits of utilizing femtosecond laser-assisted cataract surgical procedure (FLACS), which incorporates discount of endothelial cell loss, higher IOL place, improved circularity of capsulotomies, much less corneal swelling, and decreased efficient phacoemulsification time.11–15 Nevertheless, there are opposing examine outcomes that confirmed FLACS requiring extended working time,16 and highlighting the extra prices of the process.17 Current mid-term meta-analysis examine confirmed that there have been no vital variations present in visible acuity at 1 week and after 6 months or in posterior capsule rupture charges and endothelial cell loss after 6 months between standard cataract surgical procedure and FLACS.18 Furthermore, FLACS has resulted in additional frequent anterior capsular ruptures. The associated fee-effectiveness of the FLACS continues to be controversial.
The modified prechopper approach goals to get rid of the usage of a phacoemulsification tip through the fragmentation stage. The 2 traditional prechoppers, Akahoshi and Inamura prechoppers, can lower via LOCS III N1 to LOCS III N3 dense lenses with out vital zonular stress, and utterly separate two phases of the process. Nevertheless, in tough circumstances, corresponding to mature or hypermature arduous endonucleus with LOCS III N4 and above cataracts, and weak zonule, a prechopping approach utilizing traditional devices can enhance the danger of the posterior capsule damage and zonular lysis.
The modified 1.7 mm neck, prechopper employs the mixture of the mechanical benefits of an axe and the beak of an eagle.
The axe is an instance of a easy machine that acts as a wedge and modifications the course of the enter power. It capabilities by changing a power utilized to its blunt finish into forces perpendicular to its inclined surfaces. A wedge applies extra power to the thing (output power) than the person applies to the wedge (enter power) (Figure 7). The deal with of the axe additionally acts as a lever permitting the person to extend the power on the innovative. The perfect mechanical benefit (IMA) is the ratio of the depth of penetration to the width of the wedge, and could be calculated by the size of the blade divided by its width. The IMA worth of the HI Kim-Inamura prechopper is 0.16 mm divided by 1.7 mm, which is 10.625.
It is extremely tough to interrupt wooden throughout the grain as a result of it includes fracturing the tracheids. In distinction, splitting wooden alongside the grain is comparatively straightforward, particularly radially down the middle of the department, as this includes separating the tracheid cells. Likewise, a human crystalline lens is a mass of tightly packed lens fibers. The construction of the lens is just like the construction of an onion (Figure 8A and B).19 Subsequently, splitting alongside the lens orientation permits fracturing the nucleus far more simply. The beak of eagle tapers all the way down to a pointy, hooked level. It helps digging and ripping the flesh of prey into small items. The mix of the mechanical properties of an axe and the precept of a beak can multiply chopping power whereas sustaining a steady fixation.
Till the 3-month post-operative follow-up, there have been no vital variations within the absolute ECCs, losses of ECC, absolute CCT, and alter in CCT between the modified prechop group and the modified the phaco-chop group. This reveals that the prechop approach, which is comparatively straightforward for inexperienced persons, is a flexible and efficient maneuver.
In abstract, the one-hand prechop utilizing solely a modified prechopper is appropriate for tender nuclei from LOCS III N1 to N3 cataract. The counter prechop is appropriate for arduous nuclei from LOCS III N4 to N6 cataract.
The prechop approach utilizing a modified eagle kind prechopper is possible and could be carried out in a variety of cataracts, together with tender lenses (Video 1), LOCS III N1 to N4 cataracts (Video 2), and weak zonule cataracts (Video 4). Modified counter prechopping with a common chopper could be carried out over LOCS III N5 (Video 5), white cataracts (Video 6A and B), and even mature or hypermature cataracts with nuclear opalescence LOCS III N6 (Video 7). In tough circumstances, corresponding to varied pupil sizes together with small pupil, the modified prechop approach additionally could be carried out utilizing iris retractors (Video 8).
Though the prechop approach utilizing a modified eagle kind prechopper is a flexible and efficient maneuver, it isn’t appropriate for some circumstances corresponding to zonular lysis, extraordinarily dense cataracts, incomplete steady curvilinear capsulorhexis (CCC), and hypermature cataracts with little to no cortical layer as a consequence of emulsification. Within the distinctive circumstances talked about above, standard cataract surgical procedure together with sculpting and chopping with US power could also be required to facilitate lens disassembly.
A limitation of our examine is that no comparability has been made within the imply cumulative dissipated power. The settings we use are linear pulse mode, which doesn’t present the imply ultrasound energy required to calculate the cumulative dissipated power. Sooner or later, a follow-up examine that may evaluate whole ultrasound power is required.
In conclusion, the counter prechop approach utilizing the modified prechopper and common chopper is an alternate surgical process that may be carried out safely in LOCS III N1 to N6 nuclei, overripe nuclei, small pupil circumstances, and fragile suspensory ligaments.
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Determine 1 The illustration of 23-gauge twin port cannula, which injects BSS in numerous instructions. |
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Determine 2 Cross-sectional schematic of the prechopping. Insert prechopper vertically and place it barely previous the anatomical Y suture. |
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Determine 3 (A) On the level the place greater than 2/3 of the internal nucleus of the lens has handed, slowly unfold the prechopper blade to the facet to separate the nucleus. (B and C) The curved tip of the prechopper spans the nuclear floor vertically and rotates the lens 90 levels clockwise or counterclockwise. (D) Secondary nuclear cleavage is moreover carried out from the divided nucleus distant from the incision. (E) The nucleus near the incision can be cut up and finalized into 4 equal elements. (F and G) Flip your entire nucleus divided by 45 levels to place it in order that docking of the nucleus is straightforward throughout phacoemulsification. |
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Determine 4 Schematic of the radial nuclear chopping utilizing prechopper. |
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Determine 5 (A and B) Cross-sectional schematic of the counter prechopping. Pull the chopper centrally with barely upward power, concurrently push the other prechopper centrally with slight downward power. (C) The identical procedures like nuclear 1st nuclear chopping strategies. (D) The rotation of the cut up nuclei with two devices. (E) The ultimate nuclear fracturing with the prechopper and the common chopper. |
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Determine 6 Schematic of the lens division utilizing prechopper which could be flipped over. |
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Determine 7 The illustration of wooden splitting and wedge. |
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Determine 8 (A) Scanning electron micrograph exhibiting the orderly association of hexagonal lens fibers (arrows) within the vertebrate lens. Reprinted from Journal of Neuro-Ophthalmology, 24(4). Kaufman PL, Alm A. Adler’s Physiology of the Eye: Medical Utility. tenth ed. St. Louis, Mosby: Journal of Neuto-Ophthalmology; 348, Copyright 2004, with permission from Elsevier.19 (B) The schematic of the human crystalline lens. |
Disclosure
No writer has a monetary or proprietary curiosity in any materials or methodology talked about on this examine.
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