The Cartridge Pull-Through Technique for Small-Incision Intraocular Lens Explantation

Intraocular lens (IOL) exchange remains an important component of modern cataract and refractive surgery. Common indications include dysphotopsias, refractive surprise, lens intolerance, decentration, opacification, and the desire to transition to a different optical platform.¹

One of the greatest technical challenges during IOL exchange is removing a foldable acrylic IOL through a small corneal incision while minimizing surgical trauma and preserving wound integrity. Traditionally, surgeons have either enlarged the incision or bisected the lens within the eye prior to extraction. While effective, these approaches may increase surgical manipulation and introduce additional risk to intraocular structures.²

The cartridge pull-through technique, first described by Sachiko Fukuoka, MD, and colleagues in 2021, provides an elegant alternative for small-incision IOL explantation.³ By using a modified injector cartridge as a receiving sleeve, the IOL can be folded and extracted through a relatively small incision while maintaining excellent control throughout the maneuver.

In this article, I describe the surgical steps and pearls that have made this one of my preferred techniques for IOL exchange surgery.

Surgical indications for this method

The cartridge pull-through technique can be useful in a variety of IOL exchange scenarios, including:

Dysphotopsia-related lens exchange
Refractive surprise
Multifocal or extended-depth-of-focus (EDOF) IOL intolerance
IOL opacification
Lens decentration or instability
Secondary lens exchange following refractive lens exchange or cataract surgery
Cases where maintaining a relatively small corneal incision is desirable

A rundown of required instruments

The following equipment is recommended:

MONARCH Cartridge B (Alcon)
IOL extraction forceps (Fukuoka IOL Extraction Forceps or equivalent)
Sinskey hook
Cohesive ophthalmic viscosurgical device (OVD) such as Provisc
Large surgical scissors for cartridge modification
Standard anterior segment instrumentation

Cartridge preparation

Prior to surgery, the proximal base of the cartridge is trimmed using surgical scissors. This modification allows the extraction forceps to be advanced completely through the cartridge while maintaining adequate maneuverability and visualization during lens capture.

Surgical technique: A step-by-step guide

The procedure follows seven discrete steps, each building on secure control of the optic to ensure the lens exits the eye intact.

Step 1: Prepare the anterior chamber.

After establishing adequate anterior chamber access, fill the chamber with a cohesive OVD to maintain space and protect the corneal endothelium. Carefully dissect the IOL free from any capsular adhesions and elevate the optic out of the capsular bag onto the iris plane.

Step 2: Position the IOL for capture.

Using a Sinskey hook, rotate and position the IOL centrally over the iris. The optic should be oriented so that the optic-haptic junction can be easily visualized and accessed. Proper positioning at this stage greatly facilitates secure lens capture during the extraction maneuver.

Step 3: Create the incision and advance the cartridge.

A corneal incision of approximately 3.0 to 3.2 mm is created or enlarged as needed. The modified cartridge is then introduced through the incision with the bevel facing downward. The cartridge tip is advanced into the anterior chamber and held in a stable position throughout the lens capture process.

Step 4: Advance the extraction forceps.

The extraction forceps are inserted through the back end of the cartridge until the tips emerge from the cartridge opening. The forceps are then advanced into the anterior chamber while the cartridge remains stable.

Step 5: Obtain a secure grip on the optic.

Using the forceps, grasp the IOL optic near the optic-haptic junction. A firm, full-thickness purchase of the optic is essential. A superficial grasp may result in slippage during extraction and loss of control of the lens. Once a secure grip has been achieved, confirm lens stability before proceeding.

Haptic orientation varies with optic grasp position during IOL extraction

The way the haptics behave as the lens is drawn into the cartridge is not fixed—it changes depending on exactly where along the optic the instrument takes hold:

Off-center grasp (toward one haptic): When the optic is grasped a bit closer to one haptic's base, the haptic on the opposite (far) side tends to angle upward, toward the corneal surface.
- To avoid corneal contact from the leading haptic, the surgeon needs to rotate the cartridge barrel so that haptic is directed away from the cornea as it's drawn through. This is the preferred location to grasp the IOL.
Central/midline grasp: When the grasp point sits roughly midway between the two haptics, both haptics tend to deflect posteriorly, toward the vitreous cavity.
- In this scenario, if the lens is withdrawn before both haptics are fully captured within the cartridge, there's a risk of inadvertent trauma to the iris or to the capsular bag. As such, this grasping position is not recommended.

Step 6: Draw the lens into the cartridge.

While maintaining the cartridge in a fixed position, slowly retract the forceps. As the optic is pulled toward the cartridge opening, the foldable acrylic lens progressively rolls and folds into the cartridge lumen.

A critical pearl is to keep the cartridge tip inside the anterior chamber during this maneuver. Premature withdrawal of the cartridge can interfere with lens folding and make extraction more difficult.

Step 7: Remove the lens-cartridge complex.

Once the optic has fully entered the cartridge, continue withdrawing the forceps and cartridge together as a single unit. The folded lens can then be removed through the corneal incision without additional intraocular manipulation. Following explantation, the surgeon may proceed with implantation of the replacement IOL using standard techniques.

Surgical pearls for success

Use generous OVD to maintain chamber stability and protect the endothelium.
Position the optic centrally over the iris before attempting capture.
Grasp the optic near the optic-haptic junction for optimal control.
Ensure a full-thickness bite of the optic to prevent slippage.
Keep the cartridge tip within the anterior chamber until the optic is fully folded into the cartridge.
Maintain slow, controlled traction throughout the extraction process.
Avoid sudden movements that may place stress on the capsule, zonules, iris, or corneal endothelium.

Potential pitfalls to avoid

I would be remiss without mentioning the potential pitfalls which can occur when performing this procedure. Several pitfalls can compromise this technique. Inadequate lens capture is the most common: a shallow grasp of the optic may result in slippage during extraction, so obtaining a secure, full-thickness bite is essential.

Premature cartridge withdrawal is another risk—removing the cartridge before the optic has folded into the lumen makes extraction more difficult and reduces control of the maneuver.

Chamber instability, whether from OVD loss or anterior chamber shallowing, can complicate lens capture and increase the risk of endothelial trauma.² Finally, excessive traction during withdrawal can place unnecessary stress on the capsule, zonules, and incision; a slow, controlled pull is preferred throughout.

Top reasons I prefer the cartridge pull-through technique

Although several techniques are available for IOL explantation, the cartridge pull-through technique has become one of my preferred approaches for removing foldable acrylic lenses for the following reasons:

This technique avoids sharp intraocular cutting instruments.

Many traditional explantation methods require bisecting or trisecting the IOL within the anterior chamber using intraocular scissors or other sharp instruments.

While effective, introducing a sharp instrument into the eye carries inherent risk. By avoiding intraocular lens cutting altogether, this technique may reduce the risk of inadvertent capsular tears, zonular damage, iris trauma, and endothelial injury.²

It removes the IOL as a single piece.

One of the major advantages of this technique is that the entire lens is removed intact. When an IOL is cut into multiple pieces, there is always the possibility that a fragment may be difficult to retrieve or inadvertently left behind.

This concern is especially relevant in eyes with a compromised or open posterior capsule, where a lens fragment could potentially migrate into the vitreous cavity.² Removing the lens in one piece eliminates these concerns and simplifies the explantation process.

The patient receives a relatively small incision.

The procedure can typically be performed through a 3.0 to 3.2 mm corneal incision without requiring significant wound enlargement.

Maintaining a smaller incision helps preserve wound architecture and may reduce surgically induced astigmatism, as larger, unfolded en bloc extractions have been associated with substantially higher rates of induced astigmatism compared to folding or bisection techniques.² This approach also facilitates a more familiar surgical workflow.

The cartridge provides excellent control.

The cartridge acts as a receiving chamber that guides the lens in a controlled and predictable fashion during extraction. Once a secure grasp has been obtained, the lens follows a reproducible path into the cartridge and out of the eye. This level of control reduces the need for multiple manipulations within the anterior chamber.

The technique protects intraocular structures.

Because the lens folds progressively within the cartridge, there is less uncontrolled movement of the optic during removal. This controlled extraction may help minimize contact with delicate structures such as the iris, corneal endothelium, and capsular remnants.

Cartridge pull-through is simple, efficient, and reproducible.

Perhaps most importantly, the technique is straightforward to learn and easy to incorporate into routine IOL exchange surgery. The required instrumentation is readily available, the steps are intuitive, and the maneuver can be performed efficiently once mastered. For surgeons who perform lens exchanges regularly, it represents an elegant and atraumatic method of IOL explantation.

Conclusion

The cartridge pull-through technique is a valuable addition to the anterior segment surgeon's toolbox for IOL exchange surgery. First described by Fukuoka and colleagues, the technique allows foldable acrylic IOLs to be removed through a relatively small corneal incision while avoiding intraocular lens cutting and maintaining excellent control throughout the procedure.³

By combining a controlled extraction pathway with single-piece lens removal, the technique offers a safe, efficient, and reproducible approach that may help minimize trauma to intraocular structures while simplifying the challenges of IOL explantation.