“What if we simply stopped putting viscoelastic into every routine cataract eye?”

It sounds provocative. Ophthalmic viscosurgical devices (OVDs) have been part of cataract surgery for decades, and for good reason. They create and maintain space, facilitate capsulorhexis, protect the corneal endothelium and make intraocular lens (IOL) implantation easier.

But cataract surgery has changed. Modern phaco machines offer sophisticated fluidics. Surgical techniques have become increasingly controlled, and IOL delivery systems have evolved considerably.

So, I began asking myself a simple question: Do we really need an OVD at every stage of every routine cataract operation? That question led me to develop a zero-OVD approach to phacoemulsification, with a further modification at the stage where OVD dependence seems hardest to escape: IOL implantation. Instead of filling the anterior chamber and capsular bag with viscoelastic, I use controlled BSS irrigation and hydration to maintain the surgical environment and facilitate IOL implantation.

The concept is not that OVDs are unnecessary. They remain extremely valu,able – and sometimes essential. Rather, the question is whether some of the functions traditionally assigned to OVDs can, in selected cases, be achieved through fluidics, surgical technique and controlled hydration.

Start with the chamber, not the viscoelastic

The principle is simple. After creating the surgical incisions, I establish and maintain the anterior chamber using BSS and controlled irrigation rather than injecting an OVD. This changes the surgeon's relationship with the anterior chamber. With conventional surgery, OVD creates a relatively passive working space. With a fluid-based approach, the surgeon must actively maintain that space. The incision, irrigation, aspiration and phaco parameters become part of the chamber-maintenance strategy.

This is why I would not describe zero-OVD surgery simply as “phaco without viscoelastic.” It is better understood as phaco in which fluidics become part of the surgical architecture. And there is an important distinction: BSS does not reproduce all the physical properties of an OVD. It does not provide the same coating, viscosity or mechanical barrier. The technique therefore depends more heavily on surgical control.

Capsulorhexis without the viscoelastic cushion

Capsulorhexis can be performed under a stable BSS-filled chamber. There is, however, less passive support than a cohesive OVD can provide. For that reason, I focus on maintaining a stable chamber and using controlled, deliberate movements during the capsulorhexis. The objective does not change: a centered, appropriately sized continuous curvilinear capsulorhexis. What changes is how the working environment is created. This is one of the recurring themes of zero-OVD surgery: the goal remains the same; the mechanism used to achieve it changes.

Hydrodissection becomes even more important

Efficient hydrodissection is valuable in any phaco procedure. In a zero-OVD approach, I consider it particularly important because efficient nucleus mobilization can reduce subsequent manipulation. Once the nucleus rotates freely, the surgeon can work more predictably and avoid unnecessary mechanical stress. The principle is straightforward: If the nucleus is easier to manipulate, there is less reason to compensate with additional force or ultrasound energy. This becomes particularly relevant when the surgeon is not relying on a layer of dispersive OVD as an additional protective barrier over the endothelium.

Phacoemulsification: let the fluidics do more of the work

The absence of OVD should never mean accepting more endothelial trauma. Quite the opposite. Without an OVD, I become more conscious of every factor that can affect the endothelium: nuclear density, ultrasound exposure, fluid turbulence, surgical duration, fragment position and mechanical manipulation. The objective is to keep the phaco tip and nuclear fragments in a controlled working zone and to minimize unnecessary energy. This approach places greater emphasis on fluidics. Stable irrigation provides chamber maintenance. Controlled aspiration allows the surgeon to manipulate material without excessive chamber fluctuations. Efficient nuclear disassembly reduces the amount of time and energy required. In other words: The absence of OVD does not remove the need for protection. It makes the surgeon more responsible for creating it through technique. That is an important distinction.

The real challenge: implanting the IOL

If eliminating OVD during phaco is the first challenge, eliminating it during IOL implantation is the more interesting one.

Conventionally, after cortical cleanup, the capsular bag is filled with cohesive OVD. This creates space for the IOL and provides a controlled environment for lens delivery and positioning. It is an elegant technique. But it also creates another task: the OVD must subsequently be removed.

So, I began asking: Can the IOL implantation environment be created with controlled hydration instead?

This led to what I call hydration-assisted IOL implantation.

Rather than filling the chamber and capsular bag with OVD, I maintain the anterior chamber with controlled BSS irrigation and introduce the IOL into the fluid-filled surgical environment. The objective is not to leave the eye unsupported. The objective is to use controlled fluid flow to maintain the space needed for IOL delivery and positioning.

The distinction is important. BSS and OVD do not perform identical functions. OVD provides viscosity and a physical barrier; BSS does not. The innovation therefore lies not in pretending that BSS behaves like viscoelastic, but in asking whether the mechanical advantages provided by an OVD are necessary for IOL implantation in selected routine cases when fluidics and surgical technique are carefully controlled.

Why avoid the OVD at the end?

One practical attraction is obvious. When no OVD is introduced, there is no OVD to remove. Conventional IOL implantation requires careful aspiration of residual OVD, including material that may remain behind the IOL. Residual OVD has been associated with postoperative intraocular pressure elevation, which is one reason meticulous removal remains an important part of cataract surgery. Hydration-assisted implantation potentially eliminates that step.

There is also a conceptual simplicity to maintaining the chamber with the same fluid medium throughout the operation. The surgeon does not transition from BSS to OVD and then back to BSS.

However, these should be regarded as potential practical advantages, not established clinical superiority. Whether they translate into shorter surgical times, lower postoperative IOP, better endothelial outcomes or other measurable benefits requires proper comparative evaluation.

But what about the corneal endothelium?

This is where the discussion becomes more nuanced. It would be easy to make the claim that eliminating OVD automatically reduces endothelial injury. That would be wrong. Dispersive OVDs can provide valuable endothelial protection, and their role in cataract surgery is well established. The zero-OVD concept takes a different position. Endothelial protection is not dependent on one factor alone.

The surgeon can influence it through minimizing ultrasound energy; controlling surgical duration; maintaining chamber stability; preventing nuclear fragments from approaching the endothelium; optimizing irrigation and aspiration; minimizing unnecessary manipulation; and maintaining an appropriate distance between instruments and the cornea.

The technique therefore asks whether, in appropriately selected routine eyes, these factors can provide sufficient control without the additional use of an OVD. That is a much more modest – and, in my view, more useful – question than claiming that OVDs are harmful.

Know when to stop proving a point

Perhaps the most important principle of the technique is knowing when not to use it. Zero-OVD surgery should never become a dogma. I would have a low threshold for introducing an OVD when additional protection or space is needed — for example, in eyes with significant endothelial compromise, advanced corneal disease, very dense nuclei, unstable anterior chambers, zonular weakness or complicated cataract surgery. If the chamber becomes unstable or the surgical situation changes, there is no prize for refusing an OVD. The surgeon should always be able to change strategy. That is why I see zero-OVD surgery as an additional technique rather than a replacement for conventional surgery. A useful innovation should expand the surgeon's options.

What changes when the OVD is gone?

For me, the most interesting effect has been the change in surgical awareness. An OVD provides a degree of passive assistance. Without it, every movement becomes more deliberate. I become more conscious of: chamber stability; phaco tip position; fluidics; nuclear manipulation; ultrasound exposure; and the relationship between instruments, fragments and the corneal endothelium.

This makes zero-OVD surgery less about simply removing a product and more about transferring responsibility from the material to the surgical technique. That may ultimately be the most important concept behind the approach.

Is it better?

I would not claim that yet. There is published evidence that cataract surgery without viscoelastic can be performed in selected cases, but the existing literature does not establish that OVD-free surgery is universally superior to conventional OVD-assisted cataract surgery. And it does not establish the clinical superiority of hydration-assisted IOL implantation. Those questions remain open. What I find more interesting is whether we can challenge the assumption that OVD is mandatory for every stage of routine cataract surgery.

That is a different proposition. It is not: “OVDs are bad.” It is: “OVDs are useful – but are they always necessary?”

A different way of thinking about cataract surgery

Cataract surgery has evolved enormously. Phacoemulsification is more efficient. Fluidics are more sophisticated. IOL delivery systems have become more controlled. Incisions are smaller. Yet some elements of our surgical routine remain remarkably unchanged. Perhaps that is not a problem. But perhaps it is worth questioning. For selected routine cataract cases, modern fluidics may allow the surgeon to maintain the anterior chamber without an OVD. And hydration-assisted IOL implantation extends that concept to the final stage of surgery — the point at which conventional technique has perhaps been most dependent on viscoelastic. The goal is not to eliminate OVDs. It is to use them when they provide meaningful additional safety — and to recognize when controlled fluidics and surgical technique may be sufficient. For me, that is the real idea behind zero-OVD phacoemulsification. Not less protection. Not less technology. Different technology, deliberately applied.