Cataract Surgery: Where Are We? AI, New-Gen IOLs & Emerging Technology

Cataract surgery has become one of the most successful procedures in modern medicine, with highly predictable outcomes for most patients. Despite this, both the surgery itself and the technology surrounding it continue to evolve.

The operation itself may appear relatively unchanged – we still remove an opacified crystalline lens and replace it with an intraocular lens (IOL) – but almost every aspect surrounding that procedure continues to improve.

Artificial intelligence (AI) is beginning to influence how we calculate IOL power, select patients, and analyse surgical outcomes. Phacoemulsification systems continue to become more efficient and controlled. At the same time, the IOL landscape has become increasingly complex, with new extended depth of focus (EDOF) and multifocal lenses attempting to provide greater spectacle independence while minimising the compromises traditionally associated with multifocality.

We are now also able to adjust the power of an IOL after implantation, while emerging IOL technologies may eventually allow us to treat diseases other than cataract at the time of surgery.

I doubt AI will replace cataract surgeons. However, it is likely to help us plan better, predict better, operate more safely and, perhaps, counsel patients better.

Artificial Intelligence in Cataract Surgery

It is difficult to discuss the future of almost any area of medicine without mentioning AI. Cataract surgery is no exception.

I doubt AI will replace cataract surgeons. However, it is likely to help us plan better, predict better, operate more safely and, perhaps, counsel patients better.

The most obvious current application is IOL power calculation.

Traditional IOL formulas use biometric measurements including axial length, keratometry, anterior chamber depth, and lens thickness to predict the IOL power most likely to produce the desired postoperative refraction. Increasingly, these calculations incorporate large datasets and machine-learning techniques.

The Barrett Universal II formula (calc.apacrs.org/barrett_universal2105) is widely regarded as a global benchmark, or gold standard, for routine IOL power calculation. The Kane formula (iolformula.com) is another contemporary approach that combines theoretical optics with data-driven techniques.

The Hill-RBF calculator (rbfcalculator.com) is perhaps the clearest example of a data-driven approach, using pattern recognition and artificial intelligence rather than relying solely on a traditional theoretical formula.¹

Does this mean that AI has solved IOL power calculation? Unfortunately, not. Modern formulas are remarkably accurate in normal eyes and, therefore, the potential improvement is relatively small. The more interesting application for formulas incorporating AI may be in the outliers – very long or short eyes, unusual anterior segment anatomy, and eyes that have previously undergone corneal refractive surgery.

The next step may be more interesting again.

Rather than simply asking AI, “What IOL power should I implant?”, we may eventually ask, “Which IOL is most likely to make this particular patient happy?” To me, this is a much more interesting use of AI than simply producing another IOL power calculation.

Think about the information we already collect when assessing a cataract patient: biometry, corneal topography, optical coherence tomography (OCT), pupil size, ocular surface assessment, and previous refractive surgery. At present, much of the integration of this information happens in the surgeon’s head. AI potentially gives us another way to bring it together.

AI could also help obtain and interpret preoperative patient questionnaires. A patient might be asked about reading habits, computer use, night driving, tolerance of glasses, previous experience with multifocal contact lenses, and their willingness to accept haloes or glare. These responses could then be integrated with clinical data to guide IOL selection.

This may also improve patient education. Rather than presenting patients with a catalogue of unfamiliar lens names, an AI-supported system could explain the available options in plain language, illustrate the likely range of vision, and describe the potential compromises. It could help patients understand that there is no universally perfect IOL – only an option that may be better suited to their eyes, lifestyle, and expectations.

AI is also being developed for use during surgery. Surgical videos can already be analysed to recognise instruments and surgical phases. Modern operating microscopes increasingly incorporate intraoperative OCT, allowing the surgeon to assess anatomy in greater detail during surgery. AI may eventually help interpret these OCT images, identify relevant structures and instruments, and provide additional safety information or warnings to surgeons in real time.

Finally, AI offers considerable potential after surgery. Cataract surgery can generate enormous amounts of data: refractive outcomes, complication rates, OCT images, posterior capsule opacification rates, IOL position, and patient-reported outcomes. Analysing this manually is difficult. AI potentially allows every operation to contribute to improving the next one.

For me, this may ultimately prove more important than some of the more futuristic applications of AI. Cataract surgery is already extraordinarily successful. The ability to identify the small, systematic reasons why our outcomes are occasionally imperfect may be where AI provides its greatest value.

While IOL technology tends to attract much of the attention in cataract surgery, phacoemulsification technology continues to evolve.

Phacoemulsification: How Much Better Can It Get?

While IOL technology tends to attract much of the attention in cataract surgery, phacoemulsification technology continues to evolve.

Over the past decade or so, Alcon’s Centurion platform has generally been considered the most widely used phacoemulsification system, in Australia and globally. Its Active Fluidics technology and, subsequently, the Active Sentry handpiece have provided excellent anterior chamber stability and allowed surgeons to operate at lower intraocular pressures.

Over the past year or so, the new Alcon Unity platform has taken this further. Unity incorporates a new ultrasound technology known as 4D Phaco, together with Intelligent Fluidics and additional monitoring of the surgical environment. Alcon reports faster nucleus removal, reduced energy delivery, and improved post-occlusion surge control compared with Centurion.

This raises an interesting question: when the existing technology is already extremely good, how much better can phacoemulsification become?

I have experience with both the established Centurion and the newer Unity phacoemulsification platforms, and I regard both systems as highly capable. In my view, the improvements offered by Unity are evolutionary rather than revolutionary. A routine grade 3 nuclear sclerotic cataract performed well using a modern phacoemulsification system is already remarkably controlled and efficient, and the patient is likely to have a great outcome whichever platform is used.

Nevertheless, incremental improvements matter.

Greater chamber stability, more efficient nucleus removal, and the ability to operate at more physiological intraocular pressures may be particularly valuable in dense cataracts, compromised corneas, shallow anterior chambers, and other more challenging eyes.

Modern cataract surgery is reaching a stage where progress may increasingly consist of accumulating small improvements rather than discovering a completely different way of performing the operation.

Unity is a good example of this.

A New Language for IOLs

Perhaps one of the most interesting recent developments has nothing to do with a new IOL. It is a new way of describing them.

Our terminology has become increasingly confusing. We now talk about monofocal, enhanced monofocal, EDOF, multifocal, and trifocal lenses. We further describe IOLs as diffractive, refractive, non-diffractive, wavefront-shaping, small-aperture, or spherical-aberration based.

The problem is that many of these terms describe how a lens works rather than what the patient can see.

Imagine telling a patient that an Alcon Vivity IOL is a “non-diffractive EDOF lens using wavefront shaping”. It may be technically correct, but probably not very useful.

The patient generally wants to know something much simpler:

“Will I see in the distance? Will I see my computer? Will I be able to read my phone? Will I need reading glasses? Will I see haloes at night?”

Recognising the increasing confusion surrounding IOL terminology, the European Society of Cataract and Refractive Surgeons (ESCRS) established a Functional Vision Working Group to develop a more useful way of classifying IOLs. The initiative has since expanded internationally, with involvement from the American, Asia-Pacific, and Latin American cataract and refractive surgery societies.

Rather than relying primarily on optical design, IOLs are classified using their monocular distance-corrected defocus curves.

At its simplest level, lenses are divided into Partial-DOFi and Full-DOFi, where DOFi refers to depth of field.

Partial-DOFi lenses provide excellent distance vision with varying amounts of additional functional range. They are subdivided into ‘narrowed’, ‘enhanced’, and ‘extended’ categories.

A conventional monofocal IOL will generally sit toward the narrowed end of this spectrum. Enhanced monofocal lenses provide somewhat greater depth of focus, while many lenses traditionally described as EDOF fall within the extended category.

Full-DOFi lenses provide a depth of focus of at least 2.3 dioptres at the 0.2 logMAR level and are subdivided into ‘steep’, ‘smooth’, and ‘continuous’, based partly on the shape of their defocus curve and the relationship between intermediate and near vision.2

This does not mean that terms such as EDOF or trifocal suddenly become incorrect. Optical design remains important. However, two lenses using very different optical technologies may provide remarkably similar functional vision.

For optometrists counselling cataract patients, I think function is a much more useful way of looking at IOLs. Patients care about what they will be able to see after surgery. They rarely care how we engineered the lens to achieve it.

EDOF IOLs: Different Ways of Achieving the Same Goal

The evolution of EDOF IOLs demonstrates the limitations of traditional terminology particularly well.

The objective is relatively straightforward: provide excellent distance vision and useful intermediate vision, with some functional near, while producing fewer haloes and less loss of contrast than traditional multifocal IOLs.

How manufacturers achieve this is anything but straightforward.

Vivity. Alcon’s Vivity is now a useful benchmark in this category. Rather than using a conventional diffractive multifocal optic, Vivity uses what Alcon describes as X-wave technology to stretch and shift the wavefront, creating an extended range of focus. Clinically, the attraction is straightforward. Patients generally achieve excellent distance and intermediate vision with relatively low levels of dysphotopsia, although reading vision remains limited compared with a trifocal IOL.

This is an important compromise to explain to patients. An EDOF lens is not simply a “multifocal without haloes”. We are exchanging some near vision for an optical profile that may be more forgiving.

PureSee. The Tecnis PureSee takes a different approach. It is also a non-diffractive EDOF lens but uses a purely refractive design, with smooth changes in refractive power across the posterior surface of the IOL to extend the depth of focus. Recent studies comparing PureSee and Vivity have generally found both lenses provide excellent distance and useful intermediate vision, with relatively small differences between them.3,4 I have personally implanted PureSee IOLs in hundreds of eyes and my experience has been very positive.

Different Optical Strategies

Other EDOF lenses achieve an extended range using different optical principles. The Mini Well IOL from SIFI, for example, manipulates spherical aberration across different optical zones to extend depth of focus. Bausch + Lomb’s LuxSmart also uses an aberration-based approach.

This creates an increasingly difficult nomenclature problem.

If a wavefront-shaping lens, a spherical-aberration-based lens, and a refractive EDOF lens all provide a patient with excellent distance vision, useful computer vision, and limited reading vision, should we primarily classify them according to their optical engineering, or according to the vision they actually produce?

This is precisely where the new functional classification becomes useful.

Full-Range IOLs: Can We Improve the Trifocal?

At the other end of the spectrum are patients who want greater spectacle independence, including near vision.

Traditional trifocal IOLs have been remarkably successful at achieving this. However, dividing light between multiple focal points inevitably has optical consequences, particularly haloes, glare, and some reduction in contrast sensitivity.

The challenge for the latest generation of IOLs is, therefore, not simply to provide distance, intermediate, and near vision; we can already do that. The challenge is to provide that range with fewer optical compromises.

Several newer IOLs are attempting to do this in different ways.

RayOne Galaxy. Rayner’s RayOne Galaxy is particularly interesting because its design is quite different from a conventional diffractive trifocal. It uses a non-diffractive spiral optic designed to produce a continuous range of vision. Artificial intelligence was reportedly used during development to optimise the optical design based on visual outcomes.

Early clinical results are encouraging. Whether Galaxy ultimately proves better than our established full-range IOLs is another question, and we will need longer-term comparative data to know.

Tecnis Odyssey. The Tecnis Odyssey represents another new-generation approach to full-range vision. It uses a proprietary diffractive design intended to provide continuous vision from distance through intermediate to near while improving contrast and reducing dysphotopsia compared with earlier multifocal technologies.

The manufacturer-reported results are impressive, although I remain cautious about drawing conclusions until we have more independent comparative data. I have started using Odyssey and, so far, my experience has been positive.

PanOptix Pro. PanOptix Pro by Alcon represents an evolution of the successful trifocal PanOptix platform. Alcon reports that the newer optic utilises approximately 94% of incoming light and produces less light scatter than the previous Clareon PanOptix design.

Changing the Power of the IOL After Surgery

Despite increasingly sophisticated biometry and IOL calculations, cataract surgeons remain prisoners of prediction.

We measure the eye anatomy, calculate an IOL power, implant it, and then wait to see where the refraction lands. In most cases we get what we hoped for. However, there are cases where we are disappointed. When you saw your last patient with a postoperative refractive surprise, did they fully understand the nuances of biometry and refractive predictability, or did they simply assume that the surgeon “got it wrong”?

The Light Adjustable Lens (LAL) by RxSight, which was recently approved by the Therapeutic Goods Administration, may represent a significant advance.

The LAL is a silicone IOL containing photosensitive macromers. Following cataract surgery and refractive stabilisation, controlled ultraviolet light is delivered to the lens. This causes redistribution and polymerisation of the macromers, altering the curvature and therefore the refractive power of the IOL.

Once the desired refractive result has been achieved, additional treatments “lock in” the final lens power.

The attraction of the LAL is obvious, particularly in post-refractive surgery patients. It could provide a way to refine the refractive result after the eye has healed, rather than relying entirely on a preoperative calculation affected by altered corneal optics.⁵

However, there are disadvantages. Patients require multiple postoperative visits and must wear UV-protective glasses for a few weeks until treatment is complete. The technology requires expensive capital equipment, and the overall patient journey is considerably longer than conventional cataract surgery.

The LAL is also made from silicone rather than the hydrophobic acrylic material most surgeons now routinely use. Silicone IOLs had largely been superseded by acrylic lenses by the time I commenced ophthalmology training and, consequently, I have never implanted one. Nevertheless, I find the concept of postoperative adjustability intriguing.

Figure 4. Light adjustable lens technology. Postoperative ultraviolet light treatment causes redistribution and polymerisation of photosensitive macromers, altering the shape and refractive power of the implanted IOL.

Can an IOL Do More Than Focus Light?

An even more unusual concept is emerging from SpyGlass Pharma. The investigational bimatoprost IOL (BIM-IOL) system combines an IOL with sustained delivery of bimatoprost, marketed under the brand name Lumigan in Australia. The aim is to provide prolonged intraocular pressure (IOP) lowering for patients with open-angle glaucoma or ocular hypertension undergoing cataract surgery.

The technology has now entered two Phase 3 trials, each planned to enrol approximately 400 patients, comparing the BIM-IOL system with standard care.⁶

Importantly, implantation of a BIM-IOL would not necessarily exclude other glaucoma treatment. Depending on the patient’s anatomy, disease severity, and target pressure, it may still be possible to insert a minimally invasive glaucoma surgery (MIGS) device during the same surgical episode. The IOL and MIGS would address pressure control through different mechanisms.

Whether this particular technology ultimately reaches routine clinical practice remains to be seen. However, I am hopeful that in future, for patients with open-angle glaucoma, the IOL used during cataract surgery could not only improve their vision but also help prevent the progression of their glaucoma.

Figure 5. The investigational SpyGlass BIM-IOL system. Two drug-eluting pads attached at the optic-haptic junction provide sustained delivery of bimatoprost following cataract surgery.

Where Are We Really Now?

Modern cataract surgery is already extraordinarily good. This makes future progress more difficult. The next major advance may not resemble the transition from extracapsular surgery to phacoemulsification. We hoped femtosecond laser-assisted cataract surgery might represent that next major leap, but this has not proved to be the case.

Instead, progress is occurring across multiple fronts. AI may improve our calculations and patient selection. New phaco systems are making surgery incrementally safer and more efficient. New-generation IOLs are providing greater spectacle independence with fewer optical compromises, while adjustable and drug-delivering IOLs challenge our traditional concept of what an intraocular lens can do.

Not every new technology will survive. Some will prove genuinely transformative, others will provide incremental improvements, and some will disappear completely. For optometrists and cataract surgeons, the challenge is not simply keeping up with what is new. It is determining what is genuinely better – and, most importantly, for which patient.