Oman Journal of Ophthalmology

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 13  |  Issue : 2  |  Page : 57--62

Scoop and chop - A modified phaco-chop technique for pseudoexfoliation and cataract


Aparna Rao, Priti Sahay, Gopinath Das, Sarada Sarangi, Debananda Padhy 
 Glaucoma Services, LV Prasad Eye Institute, Mithu Tulsi Chernai Campus, Bhubaneswar, Odisha, India

Correspondence Address:
Aparna Rao
Glaucoma Service, LV Prasad Eye Institute, Patia, Bhubaneswar - 751 024, Odisha
India

Abstract

PURPOSE: The purpose is to evaluate the results of the modified direct phaco-chop technique of cataract surgery in eyes with pseudoexfoliation. METHODS: All patients with pseudoexfoliation and visually significant cataract with normal intraocular pressure (IOP) and optic nerve that underwent cataract surgery by the same surgeon using Infiniti®, OZil® Torsional handpiece (Alcon Labs), were included for this retrospective hospital-based study. Direct vertical or horizontal chop technique was used in all cases with parameters set as required for quadrant removal with high vacuum after the initial cleanup of cortex under the capsulorhexis. To allow better visualization of the hardness of the nucleus core, the sides of the lens were scooped out a central well with vacuum with maximum chopping done centrally within the rhexis as the first step to enable better assessment of the depth of burying the chopper for direct chop. Intraoperative details recorded and analyzed included ultrasound time and cumulative dissipated energy. The mean visual acuity and IOP before and after surgery were recorded at 1 day, 1 week, and 1 month. Complications during or after surgery were noted. RESULTS: A total of 138 patients with a mean age of 62 ± 6.7 years underwent phachop technique of phacoemulsification for nuclear cataract grades of nuclear sclerosis 2–4 with significant improvement in visual acuity from baseline (0.26) to 3 months (0.82), P < 0.001. The mean ultrasound torsional amplitude and cumulative dissipated energy (CDE) were greater for brown cataract of grading >3, P = 0.02. A total of 8 patients had intraoperative zonular dialysis in 1 quadrant (none in >1 quadrant), which was not associated with intraoperative vitreous prolapse in 6 eyes. CONCLUSIONS: Direct modified phaco-chop technique may be a safe technique in pseudoexfoliation due to minimal zonular stress with successful outcomes and reduced complications.



How to cite this article:
Rao A, Sahay P, Das G, Sarangi S, Padhy D. Scoop and chop - A modified phaco-chop technique for pseudoexfoliation and cataract.Oman J Ophthalmol 2020;13:57-62


How to cite this URL:
Rao A, Sahay P, Das G, Sarangi S, Padhy D. Scoop and chop - A modified phaco-chop technique for pseudoexfoliation and cataract. Oman J Ophthalmol [serial online] 2020 [cited 2020 Oct 25 ];13:57-62
Available from: https://www.ojoonline.org/text.asp?2020/13/2/57/285271


Full Text



 Introduction



Pseudoexfoliation syndrome (PXF) is an age-related fibrillopathy characterized by various ocular and systemic associations apart from the deposition of exfoliative material over different ocular structures.[1] This entity is associated with several distinct ocular features and associations, which include poor pupillary dilatation, dens cataract, and zonular laxity. These associations, in particular, pose a challenge to most surgeons while operating on these patients for cataract.[2],[3] Earlier methods of cataract surgery have been replaced with newer phacoemulsification techniques, which are not only faster but also safer with closed chambers assured throughout the surgery.[4] Several phacoemulsification techniques have evolved over time which reduces the overall surgical time as well the ultrasound power delivered, thereby minimizing intraoperative complications and better postoperative outcome.[5],[6],[7],[8] These nuclear fragmentation techniques fall out of purpose for pseudoexfoliation with weak zonules and nondilating pupils. The machines used for the process have also undergone tremendous evolution with newer machines equipped with better delivery methods of ultrasound power, ensuring faster nuclear removal with minimal energy. The Ozil technology is one such technology which has substantially reduced ultrasound power affording easy surgery even in dens cataracts. Yet, surgery in pseudoexfoliation is often wrought with frequent zonular dialysis and vitreous prolapse due to preexisting zonular laxity in these patients. Therefore conventional divide and conquer methods have given way to stop and chop and other methods of nuclear fragmentation. Nagahara et al. developed a phaco-chop technique which involves direct cracking of the nucleus manually with the phacotip immobilizing the nucleus. This method is highly beneficial in eyes with zonular laxity since most of the procedures of nuclear removal are carried out with minimal zonular stress. Combined with the use of capsular tension rings, the surgical outcomes have improved drastically as compared to divide and chop technique in pseudoexfoliation. This study evaluates the results of a minor modification or enhancement of this technique in eyes with pseudoexfoliation and different nuclear density.

 Methods



All patients with pseudoexfoliation and visually significant cataract with normal intraocular pressure (IOP) and optic nerve that underwent cataract surgery by a single surgeon from 2011 to 2015 were included for this study approved by the Institutional Review Board of LV Prasad Eye Institute, MTC, India. Those with raised IOP, disc or field changes suggestive of glaucoma, preoperative zonular dialysis >1 quadrants, and associated corneal or retinal pathology were excluded from the study. Preoperatively, all patients had slit lamp and retinal examinations and best-corrected visual acuity (BCVA) and IOP measurements. The firmness of the nucleus was graded on slit lamp and eyes with very hard brown cataract nuclear sclerosis (NS) >4 (Lens Opacities Classification System III classification) were excluded.

All surgeries were performed by a single surgeon using the same machine

(Infiniti®, OZil® Torsional hand piece; Alcon Labs) which uses torsional US under topical or local peribulbar anesthesia The height of the infusion bottle was kept at 110 cm while the aspiration flow rate and vacuum set to 35 mL/min and 350 mm Hg, respectively. Intraoperative details recorded and analysed included ultrasound time (UT) and cumulative dissipated energy (CDE).

Surgical technique

All cases underwent superior clear corneal incision with 2.2 mm Keratome followed by capsulorhexis around 5–5.5 mm in size with 26G needle. Direct vertical or horizontal chop technique was used in all cases, with the former being preferred in small pupils and poor dilatation with parameters set as required for quadrant removal with high vacuum [Figure 1] and [Figure 2]. The surgeon used an infinity (Alcon labs) machine with a Kelman-type microtip (45°) in all cases. An initial cleanup under the capsulorhexis area using vacuum to assess the nuclear core density on table and to aid in correct depth unto which the phacotip would be buried to hold the nucleus while cracking. Contrary to conventional clean-up of the cortex in direct chop techniques, this modification entails only clean of the central portion of the nucleus core more than the peripheral cortex while ensuring that the clean-up area remains well within the rhexis avoiding going beyond the central 4 mm. This step allowed a better assessment of the hardness of the nucleus even in hard cataracts allowing the surgeon to gauge the depth of penetration into the nucleus with the chopper in the next step as well as debulk the cataract allowing more space for in-the-bag manipulations in direct chop technique. Care is taken to limit the peripheral limit of scooping of the nucleus within the rhexis margin, which therefore serves as a visual guide during the nuclear crack procedure beyond which the phacotip should not be advanced to avoid injury to the capsule or rhexis. Thereafter, phaco-chop was done using a short blunt chopper (avoid using a sharp-tipped chopper since that may cause inadvertent PC (Posterior capsule) tear while driving the chopper into the depth of the nucleus core in the center) with the phacotip being buried into the central nucleus core and then held in foot pedal position 2 to stabilize the nucleus while the chopper was placed under the capsulorhexis though the side port and driven toward the phacotip to enable nuclear division by movements of the two instruments in opposite directions [Figure 3]. The nucleus, therefore, is held by the phacotip during the whole time of cracking process with cleavage planes in the nucleus, aiding cracking of the nucleus with no tension on the zonules. This process is repeated for each of the split nuclear halves and then followed by quadrant removal and cortical aspiration. Throughout surgery, a balanced salt solution was used as the irrigation solution. Intraoperative details recorded and analyzed included ultrasound time and cumulative dissipated energy.{Figure 1}{Figure 2}{Figure 3}

Patients were discharged the same day after surgery and reviewed the next day for postoperative treatment with tapering doses of topical steroids for 4 weeks. The mean visual acuity and IOP before and after surgery were recorded at 1 day, 1 week, 1 month, and 3 months. Complications during or after surgery were noted.

 Results



Of 432 patients with exfoliation and cataract fulfilling inclusion criteria, 138 patients with a mean age of 62 ± 6.7 years underwent phachop technique of phacoemulsification for nuclear cataract grades of NS 2–4. [Table 1] shows the baseline clinical parameters of the patients included in the study.{Table 1}

Poor dilatation <4 mm was seen in 33 eyes, all of which were managed with viscodilatation (n = 18) and Kuglens hooks (n = 6). Preoperative phacodonesis with zonular dialysis <1 quadrant was present in 11 eyes, while intraoperative finding of the loose bag with no obvious zonular dialysis or vitreous prolapse was seen in 9 eyes. A total of 8 patients had intraoperative zonular dialysis in 1 quadrant (none in >1 quadrant), which was not associated with intraoperative vitreous prolapse in 6 eyes. Intraoperative vitreous prolapse was managed with automated vitrectomy with successful in-the-bag AcrySof IOL in all eight eyes without any further extension of dialysis or any other complication. All eyes, therefore, received in-the-bag AcrySof intraocular lenses in this study.

The capsulorhexis could be completed in all cases with 26G needle while 2 eyes required small relaxing during IOL insertion. Direct chop was successful in chopping the nucleus in first attempt in 116, while 22 eyes required a second attempt in eyes with >3 nucleus grade. None of the patients experienced any corneal haze or edema during the surgery. The mean ultrasound torsional amplitude and CDE were greater for brown cataract of grading >3, P = 0.02 [Table 2]. All surgeries were successfully completed with none of them being converted to other phaco techniques or extension of wound. Last piece was removed by visco expression through the main tunnel in 2 eyes due to suspected zonular dialysis, which was however, not confirmed during later stages of the surgery.{Table 2}

There was a significant increase in mean Snellen BCVA at 3 months' postoperatively (from preoperative 0.26 at baseline to 0.82 at 3 months, P < 0.001) with none of the eyes having corneal decompensation or corneal haze at final follow-up. An IOP spike was seen in 12 eyes which however resolved with postoperative acetazolamide for 3 days in all eyes. The disc and field remained normal throughout the follow-up. No patient experienced IOL decentration postoperatively or vitreous incarceration in wound. Eleven eyes had transient corneal stromal edema which resolved in a mean period of 7 ± 3 days with postoperative steroids for eight times daily, which were tapered after a week.

 Discussion



We found very few complications with this modified direct chop technique of phacoemulsification in eyes with PXF, which are usually associated with hard brown cataracts. An initial scoop of the nucleus and debulking enabled better assessment of the depth the chopper has to be driven in the center of the nucleus core allowing better grip of the nucleus and successful cracking without much difficulty. This also allows the surgeons more space for direct in-the-bag manipulations under the capsulorhexis during the nuclear-cracking step since the peripheral rim of the debulked nucleus serves as a visual guide or limit beyond which the phacotip should not be taken to avoid inadvertent rhexis extension or capsular tear. This becomes even more important in pseudoexfoliation where eccentric rhexis may be required in eyes with subluxated hard cataracts where the peripheral limit of nuclear clean up would serve to identify the rhexis margin. Contrary to conventional methods of direct chop and cortical clean up initially, this modified technique mandates minimal clean-up of the cortex centrally to enable visualization of the nucleus core while remaining within the rhexis and leaving out cleaning the peripheral zone near to the zonules. This allows ease of the phaco-chop technique even in nondilating pupils since the area of clean up gives a visual clue to the margin to which the phaco probe should be restricted while chopping and nucleus fragmentation. Furthermore, clean up centrally and restricting or peripherally allows minimization the stress on zonules during the debulking procedure. The direct phaco-chop technique involves cracking of the nucleus with the phacotip engaging the nucleus, thereby minimizing tension on zonules. Pseudoexfoliation is often associated with denser cataract, poorer endothelial cell counts with frequent zonular laxity or weakness.[1] These eyes often are associated poor dilatation with harder cataract posing a challenge to cataract surgeons. In such cases, direct phaco-chop is a viable and safer option as compared to divide and conquer, which involves more energy and zonular stress.[5],[6],[9]

The phaco-chop technique was first presented by Nagahara which reduces phaco power and time since nuclear division is done manually, thereby drastically reducing total ultrasound energy.[10] Although the efficiency for cracking the nucleus is similar, several studies have shown that this technique is associated with reduced phaco time as compared to other techniques such as stop and chop or divide and conquer.[5],[6],[7],[8] This is because the technique uses manual methods of cracking the nucleus making use of cleavage planes in the nucleus. Further, the nucleus is engaged by the phacotip putting no stress on the zonules which is maximal benefit in eyes with pseudoexfoliation. This obviates the need for the use of capsular tension rings, especially in very hard cataract where placement on the rings by itself may be traumatic. While the use of other assisting equipment like capsular rings may be used by clinicians according to the surgeon's preference, we feel this technique may be used by all irrespective of the availability of assistive devices in every situation. The OZil technology further reduces occlusion during the process of fragment removal, which results in reduction in IOP spikes. All these reasons combined with reduced power make it the preferred technique for cataract extraction in eye pseudoexfoliation. The initial step of scooping of the nucleus in the center within the rhexis area enables debulking allowing more space for manipulations with the direct chop technique while reducing the effect of additional procedures on zonules.

Our study did not find severe surgical complications in any patient though transient corneal edema was found in 11 eyes which resolved over follow-up. Oxidative stress markers are known to be elevated in patients with PXF.[1] Surgery on these eyes therefore, often leads to marked postoperative inflammation and IOP spikes.[1],[11] This may be attributed to pigment release and fluid turbulence during surgery, thereby inflicting stress on the trabecular meshwork. Faster nucleus removal and reduced surgical time along with minimal complications would therefore presumable reduce postoperative inflammation.[5],[6],[7],[8],[11],[12] In this study, we did not find any patient with significant postoperative inflammation though transient IOP spikes were seen in 6 eyes requiring systemic acetazolamide for 3 days. Other complications are also common in pseudoexfoliation syndrome, including zonular laxity or preoperative dialysis.[5],[13],[14],[15],[16],[17] This is a major challenge for cataract surgeons which mandates the use of capsular tension rings and other maneuvers for successful IOL implantation. A loose bag during surgery is often seen in chronic hypermature cataract where reduced tension/pull of zonular fibers of the lens is responsible for excessive movement of the lens and bag during capsulorhexis or other surgical procedures. Such a finding often entails reduction of bottle height and reduction of overall turbulence with minimal zonular stress during each stage of phacoemulsification. All these could be achieved with the phaco-chop technique in this study.

Studies have shown that use of blunt chopper is beneficial as compared to sharp chopper traditionally described in the phaco-chop technique.[18] The blunt chopper may be beneficial in reducing trauma to the posterior capsule while cracking the nucleus though this cannot be proved beyond doubt. The function of the chopper is to impale and crack the nucleus while the phaco-tip holds the nucleus. Risk factors for a poor visual outcome or endothelial loss in phacoemulsification include total surgical time, poorly dilating pupils, increased nuclear hardness and increased ultrasound power. The type of chopper, therefore, would have minimal impact on the overall outcome even in pseudoexfoliation.

We did not compare this technique with divide and conquer since this was a noncomparative study. Yet, the results are comparable to earlier studies comparing phaco-chop and divide and conquer techniques in cataract surgery. We also have presented short-term surgical outcomes which cannot directly reflect long-term results.

 Conclusions



This techniques and clean and chop techniques could be a useful technique of phacoemulsification in patients with pseudoexfoliation and cataract with minimal complications and good outcome after surgery.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1Ritch R, Schlötzer-Schrehardt U. Exfoliation syndrome. Surv Ophthalmol 2001;45:265-315.
2Naumann GO. Exfoliation syndrome as a risk factor for vitreous loss in extracapsular cataract surgery (preliminary report). Erlanger-Augenblätter-Group. Acta Ophthalmol Suppl 1988;184:129-31.
3Skuta GL, Parrish RK 2nd, Hodapp E, Forster RK, Rockwood EJ. Zonular dialysis during extracapsular cataract extraction in pseudoexfoliation syndrome. Arch Ophthalmol 1987;105:632-4.
4Linebarger EJ, Hardten DR, Shah GK, Lindstrom RL. Phacoemulsification and modern cataract surgery. Surv Ophthalmol 1999;44:123-47.
5Wong T, Hingorani M, Lee V. Phacoemulsification time and power requirements in phaco chop and divide and conquer nucleofractis techniques. J Cataract Refract Surg 2000;26:1374-8.
6Park J, Yum HR, Kim MS, Harrison AR, Kim EC. Comparison of phaco-chop, divide-and-conquer, and stop-and-chop phaco techniques in microincision coaxial cataract surgery. J Cataract Refract Surg 2013;39:1463-9.
7Vajpayee RB, Kumar A, Dada T, Titiyal JS, Sharma N, Dada VK. Phaco-chop versus stop-and-chop nucleotomy for phacoemulsification. J Cataract Refract Surg 2000;26:1638-41.
8Park JH, Lee SM, Kwon JW, Kim MK, Hyon JY, Wee WR, et al. Ultrasound energy in phacoemulsification: A comparative analysis of phaco-chop and stop-and-chop techniques according to the degree of nuclear density. Ophthalmic Surg Lasers Imaging 2010;41:236-41.
9Susić N, Kalauz-Surać I, Brajković J. Phacoemulsification in pseudoexfoliation (PEX) syndrome. Acta Clin Croat 2008;47:87-9.
10Buratto L. Techniques of phacoemulsification. In Buratto L, ed, Phacoemulsification: Principles and Techniques. Thorofare, NJ, Slack 1998; 71–170.
11Cimetta DJ, Cimetta AC. Intraocular pressure changes after clear corneal phacoemulsification in nonglaucomatous pseudoexfoliation syndrome. Eur J Ophthalmol 2008;18:77-81.
12Koch PS, Katzen LE. Stop and chop phacoemulsification. J Cataract Refract Surg 1994;20:566-70.
13Awan KJ, Humayun M. Extracapsular cataract surgery risksin patients with exfoliation syndrome. Pakistan J Ophthalmol 1986;2:79-80.
14Carpel EF. Pupillary dilation in eyes with pseudoexfoliation syndrome. Am J Ophthalmol 1988;105:692-4.
15Freyler H, Radax U. Pseudoexfoliation syndrome – A risk factor in modern cataract surgery?. Klin Monbl Augenheilkd 1994;205:275-9.
16Lumme P, Laatikainen L. Exfoliation syndrome and cataract extraction. Am J Ophthalmol 1993;116:51-5.
17Moreno J, Duch S, Lajara J. Pseudoexfoliation syndrome: Clinical factors related to capsular rupture in cataract surgery. Acta Ophthalmol (Copenh) 1993;71:181-4.
18Kim DY, Jang JH. Drill and chop: Modified vertical chop technique for hard cataract. Ophthalmic Surg Lasers Imaging 2012;43:169-72.