Basic Phaco Chop techniques

Phaco chop, introduced by Kunihiro Nagahara in 1993, remains one of the most efficient nucleus-disassembly techniques in modern cataract surgery — it uses mechanical force from a second instrument rather than ultrasound energy to divide the nucleus, reducing phaco time, total energy delivered, and stress on the zonules compared to divide-and-conquer.

Horizontal chop

The original Nagahara technique. The phaco tip is embedded centrally in the nucleus under high vacuum to hold it fixed. A chopper is passed under the anterior capsular rim, hooked around the lens equator, and pulled horizontally toward the phaco tip — the two instruments move toward each other in the horizontal plane, splitting the nucleus into two hemi-sections.

• Best suited to softer nuclei (grade 1-2+ nuclear sclerosis)
• Requires an intact epinuclear shell to guide the chopper safely under the capsule
• Less effective in hard, brunescent cataracts, where the posterior nuclear plate resists horizontal cleavage

Vertical chop

The chopper is positioned centrally, just in front of or beside the impaled phaco tip, and moved downward using the side-port incision as a fulcrum — the vertical vector force cracks the nucleus from the posterior plate forward, rather than relying on an intact epinucleus.

• More versatile for dense/brunescent nuclei, weak zonules, small pupils, and eyes with capsulorhexis irregularities
• Does not require the chopper to be slid under the capsule — reduces risk of capsular or zonular trauma in fragile eyes
• Preferred approach for hard cataracts; often combined with a higher torsional ultrasound amplitude and a sharper "karate chopper" to embed safely in dense tissue

Stop-and-chop (hybrid technique)

Developed by Paul Koch as a bridge for surgeons transitioning from divide-and-conquer to full chop. An initial central groove is sculpted and the nucleus is cracked into two halves using conventional divide-and-conquer, creating working space — chopping is then used to further divide each half. This hybrid remains a practical teaching step for residents building chop skills.

Choosing a technique

Selection depends on nuclear density, zonular integrity, pupil size, and surgeon experience — not a single "correct" answer. As a working rule: horizontal chop for soft-to-moderate nuclei, vertical chop for dense or unstable eyes, and stop-and-chop as a transitional technique while building chopping proficiency. Newer instrument variants (nitinol ring prechoppers, mechanical prechop devices) continue to be studied as ways to further reduce phaco energy, particularly in dense cataracts.

Key references: Nagahara K. Phaco chop technique. Presented at ASCRS/ASOA 1993.  |  Vertical Chop Technique, EyeWiki.  |  Chopping techniques in cataract surgery. Curr Opin Ophthalmol. 2023 (review).