Pistachio Chop: A New Technique for Teaching Chop and Safer Approach

Pistachio Chop: A New Technique for Teaching Chop and Safer Approach

Dr. Ali Nowrouzi

*Correspondence to: Ali Nowrouzi. MD, FICOphth, FEBOs-CR. Cornea, Cataract and Refractive Surgery Unit, Department of Ophthalmology, Hospital Quironsalud Marbella, Marbella, Spain.

Copyright

© 2023 Dr. Ali Nowrouzi This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original   work is properly cited.

Received: 17 November 2023

Published: 01 December 2023

DOI:https://doi.org/10.5281/zenodo.10244963

Abstract

Purpose

To describe a new technique that can be safer approach for inexperienced phaco surgeons to master the chop technique. Pistachio chop is a new chop technique in that the partial superior cortex and epinucleus are aspirated by phacoemulsification (phaco), and with direct access to the central nucleus, which is adequately separated from the epinucleus by hydrodeliniation, the nucleus is chopped with the protection of inferior epinucleus. These separations help the surgeon to easily place the chopper deep into the body of the nucleus with better control and vision.

Observation

The patient in the technical video had a 3+ nuclear sclerosis cataract. The preoperative vision in this eye was 20/80, with no improvement with spectacle correction On postoperative day 1, visual acuity had improved to 20/40. By postoperative week 1, the best-corrected visual acuity was 20/20.

Conclusion and importance

This method avoids zonular stress. Additionally, inexperienced surgeons using this technique during cataract surgery can practice better the movements necessary for the chop technique in a safer environment.

 Electronic supplementary material

The online version of this article (https://youtu.be/Wg5gpubX584?si=Zd2zBVZRfzeCUXvc) contains supplementary material with surgical video of this technique.

Keywords: Cataract surgery, Chop, Phacoemulsification, Resident, Teaching phaco, Training


Pistachio Chop: A New Technique for Teaching Chop and Safer Approach

Introduction

Cataracts are the main cause of preventable vision loss worldwide [1], and the surgical approach is the only intervention available to regain vision. Different techniques have been explained for cataract surgery [2]. Phacoemulsification remains the standard approach for surgery. Cataract surgery in dense cataracts can lead to increased surgical complications, time, and endothelial cell damage [3].

The limited utilization of chop technique for beginner surgeons, mainly because of fear of posterior capsular rupture, has driven the author to develop a safe and efficient method of phaco-dependent nuclear chopping with a more controlled approach for the surgeons in the bigging of the learning curve for the chop technique.

Prior publications have confirmed the superiority of the chopping technique because of a decrease in phaco energy up to four-fold, lower total power, and less surgical time compared with divide and conquer [4, 5]. The utilized energy of the phaco increases proportionally in more dense cataracts [6].

There are many derivative techniques from the conventional chop, including stop and chop, horizontal and vertical. In the horizontal chop technique, the phaco tip is penetrated into the lens and lifted as the chopper is placed at the other extreme of the lens to initiate a horizontal crack. In the vertical chop technique, the chopper is depressed to propagate the crack. Finally, stop and chop using a central groove with more phaco energy usage to create space to subsequently sub-chop the heminucleus [7].

It is essential for inexperienced surgeons to do safe practice to master multiple surgical techniques. Avoidance of doing the chopping technique is likely due to the difficulty of the chop maneuvers as well as the risk of posterior capsular damage for inexperienced surgeons.

The proper distance of the second instrument from the phaco tip and the depth of this instrument with incomplete cracking is one of the main challenges for chop technique.

Here, we describe a new technique that can be a safer approach for inexperienced phaco surgeons to master the chop technique. We have termed this new method “pistachio chop,” since the partial superior cortex and epinucleus are aspirated by the phacoemulsification (phaco) and with direct access to the central nucleus part, which is usually adequately separated from the epinucleus by hydrodeliniation, the central nucleus is chopped with the protection of inferior epinucleus. (Fig. 1)

 

Methods

This single-patient surgical case report does not include any identifiers. All necessary surgical consent was obtained from the patient.

An adequate chopper is the only recommended instrument in this technique besides traditional phaco equipment.

The recommended chopper is the one to have a blunt tip and enough length with the proper angulation at the neck to allow the chopper tip to enter between the epinucleus and nucleus Our video example uses the blunt tip straight chopper.

Traditional chop phaco settings can be used with no adjustments needed. Our video example uses a Stellaris elite System (Bausch & Lomb, New jersy USA) with the following parameters: longitudinal phaco at 12% power in burst mode, 63 mmHg intraocular pressure (IOP), 440 mmHg of vacuum.

(https://youtu.be/Wg5gpubX584?si=Zd2zBVZRfzeCUXvc) video file.

 

Surgical procedure

At first, a limbal paracentesis is created. Preservative-free intracameral fydrane (Thea ( 0,04 mg tropicamida, 0,62 mg fenilefrina hidrocloruro and 2 mg de lidocaína hidrocloruro 1%) is instilled into the anterior chamber followed by a dispersive ophthalmic viscosurgical device (OVD). A 2.2 mm tri-beveled clear corneal incision is made temporally 100°–110° away from the paracentesis. A continuous curvilinear capsulotomy is created, and hydrodissection is performed. Mobility of the lens is essential; ensure adequate nuclear rotation before initiating chop. The most important part of this procedure is adequate hydro delineation to separate the epinucleus from the nucleus to have a protective layer between the nucleus and capsular bag. Choosing patients with adequate anterior chamber depth for this technique is recommended. The author also recommends another layer of viscosurgical device (OVD) between the epinucleus and posterior capsule in beginners. The phaco tip is introduced through the main wound, and anterior cortical material is removed inside the area of the capsulotomy. The chopper is introduced inside the eye and placed between the nucleus and epinucleus. The phaco tip is angled steeply posteriorly in the mid-periphery of the nucleus, next to the capsulotomy edge, with either bevel-down or bevel-up phaco technique. Using the chop ultrasound setting described above, the phaco tip should be burrowed into the nucleus by foot position three until the instrument sleeve reaches the lens surface. Next, return to foot position 2 (vacuum) and discontinue any phaco energy (as is typical in a routine chop technique). Place your chopper tip deeply between the nucleus and epinucleus. Bring the chopper and phaco tip together to initiate a crack, then use both instruments to separate the two heminuclei and propagate the crack.

 

Figure 1: Pistachio Chop: After adequate hydro delineation separate the epinucleus from the nucleus to have a protective layer between the nucleus and capsular bag. The phaco tip is introduced through the main wound, and anterior cortical material is removed inside the area of the capsulotomy. The chopper is introduced inside the eye and placed between the nucleus and epinucleus. The phaco tip is angled steeply posteriorly in the mid-periphery of the nucleus, next to the capsulotomy edge. Using the chop ultrasound setting, the phaco tip should be burrowed into the nucleus by foot position three until the instrument sleeve reaches the lens surface. Next, return to foot position 2 (vacuum) and discontinue any phaco energy. Place your chopper tip deeply between the nucleus and epinucleus.

Bring the chopper and phaco tip together to initiate a crack, then use both instruments to separate the two heminuclei and propagate the crack.

Figure 2

 

Results

The patient in the above technical video had a 3+ nuclear sclerosis cataract (based on the World Health Organization’s simplified cataract grading system). The preoperative vision in this eye was 20/80, with no improvement with spectacle correction. Using the Pistachio chop technique for nuclear disassembly, the cumulative dissipated energy after the case was 7 %.  On postoperative day 1, visual acuity had improved to 20/40. By postoperative week 1, the best-corrected visual acuity was 20/20.

 

Discussion

This new pistachio chop technique is an acceptable approach for multiple reasons. First, it easily lends itself to the teaching of chop techniques.

For horizontal chop,  the main challenge for inexperienced surgeons is placing the horizontal chopper underneath the anterior capsule and out along the lens equator. Poor visibility and uncontrolled maneuvers during chopper placement in the periphery create an uncomfortable and risky environment for the surgeon. This uncertainty leads to improper superficial chopper placement, culminating in a horizontal chop maneuver that cannot create a full crack in the nucleus. Pistachio chop allows beginners to become comfortable with the horizontal chop maneuver inside the well-visualized safety zone of the capsulotomy. This method avoids zonular stress.

Additionally, inexperienced surgeons using this technique during cataract surgery can practice better the movements necessary for the chopping technique in a safer environment. There is another possibility of combining this technique with the tilt and tumble phaco technique for beginners who want to be even in a safer environment. After the tilting of the nucleus by hydrodissection and a proper hydrodeliniation to separate the epinucleus from the nucleus to have a protective layer between the nucleus and capsular bag this combination is even more separated from the posterior capsule. Adding a small amount of cohesive viscoelastic between the tilted nucleus and posterior capsule increases the protection of the posterior capsule.

Aspiration of the epinucleus part after complete nucleus aspiration needs proper precision in this procedure, and it might be a risky situation to provoke damage to the capsular bag. Controlled aspiration with a small amount of phaco energy is recommended if it is necessary for dense epinucleus.

Proper case selection with 3+ nuclear cataracts with adequate ACD is essential to do this technique. Hard cataracts and lower ACD are not recommended for this approach as it is impossible to achieve good separation of epinucleus and nucleus by hydrodeliniation.

A second reason that pistachio chop is favorable is that it lends itself well to lenses with zonulopathy.

 

Conclusion

In summary, we describe a new technique coined “pistachio chop” that facilitates learning of the chopping technique. Similar techniques have not been described in the literature outside of a traditional central groove being created by consecutive drilling with the phaco tip. We hope that this new technique enhances our ability to train the next generation of phaco surgeons and allows experienced surgeons to more safely tackle cataracts with zonulopathy. This method avoids zonular stress. Additionally, inexperienced surgeons using this technique during cataract surgery can practice better the movements necessary for chop technique in a safer environment.

 

Patient Consent

This report does not contain any personal identifying information.


Acknowledgements and Disclosures

Funding: 
No funding or grant support

Conflicts of Interest:

The following author (AN) have no financial disclosures

Authorship:
The author attest that they meet the current ICMJE criteria for Authorship.

Acknowledgements:None.
Author Declaration form : The form is attached.

 

Figure legend: The phaco tip burrowed into the nucleus with continuous vacuum (position 2) with chopper tip deeply between nucleus and epinucleus.

Video legend: After adequate hydrodeliniation to separate the epinucleus from the nucleus to have a protective layer between the nucleus and capsular bag, the phaco tip is introduced through the main wound, and anterior cortical material is removed inside the area of the capsulotomy. The chopper is introduced inside the eye and placed between the nucleus and epinucleus. The phaco tip is angled steeply posterior in the mid-periphery of the nucleus, next to the capsulotomy edge with bevel-down phaco technique, Using the chop ultrasound setting, the phaco tip should be burrowed into the nucleus by foot position 3 until the instrument sleeve reaches the lens surface. Next, return to foot position 2 (vacuum) and discontinue any phaco energy (as is typical in a routine chop technique). The chopper tip is placed deeply between nucleus and epinucleus. Bring the chopper and phaco tip together to initiate a crack, then use both instruments to separate the two heminuclei and propagate the crack.


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