The evolution of intraocular lens technology and surgical technique have heightened patient expectations and spurred the era of refractive cataract surgery. Insight discusses the landscape with several seasoned ophthalmologists and the incremental gains that will transform the category for years to come.
Historically, the main candidates for cataract surgery were those with bad, dense cataracts. Surgeons had few options, but as technology has evolved, the candidate pool expanded to moderate cataracts. Today, those with mild cataracts – and presbyopes with a perfectly clear crystalline lens but who want a greater range of vision – are seeking out the services of surgeons.
As the most frequently performed elective surgery, with upwards of 250,000 procedures performed per year in Australia and 27 million globally, cataract surgery is a gateway to quality-of-life. And as technology, techniques and methods have advanced, optimising refractive outcomes have become a natural endpoint.
The pace at which the cataract category has developed – seeing ophthalmologists become “refractive cataract surgeons” – has been fulfilling for University of Melbourne academic and glaucoma and cataract subspecialist Associate Professor Simon Skalicky, as he can deliver better outcomes to patients.
“As we’ve gotten better at cataract surgery, the refractive outcomes have become more important. I don’t see refractive cataract surgeries as too distinct from cataract surgery these days,” he says.
Presbyopic patients seeking spectacle independence has been a major driver. But this isn’t possible without the refinement of intraocular lens (IOL) technology, especially the introduction of new generation extended depth of focus (EDOF) IOLs that are now offering a monofocal-like visual disturbance profile. Overcoming most of the symptoms of glare and haloes – still associated with multifocals – has been a major achievement for the industry.
Associate Professor Chameen Samarawickrama, from the Westmead Institute for Medical Research at Sydney University, says he recalls as a trainee in the public system in 2010 when monofocals were all he could offer patients. Similarly, in the private space, he only had access to simple multifocals.
Now, since the refinement of multifocals and emergence of EDOFs, the nature of his IOL selection has shifted drastically.
“Before, about 20% of my patients were multifocal, and 80% were monofocal. Now, about 45% of my patients are EDOF, 35% multifocal, and the residual 20% are specialty lenses or monofocal,” he says.
“EDOFs have been a wonderful technological advance in just the last few years to allow some of that correction of presbyopia; not obviously as strong as the multifocal but without the significant post-operative side effects of glare and halo.
“I still feel the story’s not over because while EDOFs do a great job minimising the side effects, they don’t achieve spectacle independence, and so we’re not quite where we want to be yet.”
Given the rate at which IOLs have progressed in recent years, A/Prof Skalicky hopes that a lens with the range of the multifocal IOL and the symptomatic profile of EDOFs will soon emerge.
Pre-operative focus
Meanwhile, Dr Mark Troski, a Melbourne-based cataract surgeon with more than 20 years’ experience in this space, says the surgical landscape progressed when incisions reduced in size, then with the introduction of phacoemulsification, followed by foldable lenses which reduced incision size even further.
However, for him – despite the research and technological advances – it has been the time spent consulting his patients prior to surgery that has been one of the largest transitions.
“Now, we spend less time actually performing the surgery and more time sitting with the patient discussing what their refractive wishes are and what we can realistically produce from the point of view of refractive outcomes – that’s now a huge part of our practices,” Dr Troski says.
Similarly, for A/Prof Skalicky’s practice, he is ensuring a comprehensive pre-operative consultation. For example, understanding the role of dry eye in cataract surgery outcomes has shaped his patients’ experiences for the better. While not part of his training, he says treating the ocular surface prior to surgery is important in maximising procedural precision.
“Dry eye can affect preoperative measurements and cause postoperative discomfort. One of the secrets cataract surgeons are learning and – me included – is how important it is to treat the ocular surface before cataract surgery for optimal outcomes,” he says.
A/Prof Skalicky says some patients don’t expect to have a conversation about dry eye preceding a cataract procedure, but it is a necessary conversation to get the most out of such a vital opportunity to remove the patients’ cataract and provide them vision they may not have experienced for many years.
He says in the two weeks leading up to surgery, he recommends patients use a combination of eyelid hygiene, such as applying warmth against the eyelids and then massaging with the fingers as well as preservative free lubricants.
“I’ve been doing that now for about five years and I noticed a significant improvement in patient satisfaction from dry eye symptoms as well as surgical outcomes,” A/Prof Skalicky says.
Toric talk
Outside of the operating room, Dr Troski says cataract surgery has seen as big an ideological shift as a technological one.
He was among the first in Australia to implant toric lenses for astigmatism. Not long after, he gave a lecture at an annual RANZCO meeting in Melbourne where he recommended toric lenses for all patients with astigmatism.
He says his audience was exasperated, as astigmatism correction was unheard of.
“About half the audience said, ‘Don’t do that – people like astigmatism’,” Dr Troski says.
In the years proceeding this, he witnessed a slow, discernible shift in the ideology as the industry embraced the technology. Dr Troski says now it is common practice and would be unthinkable to not use astigmatism correcting lenses. Today, Australia is one of the largest adopters of toric IOLs.
A/Prof Skalicky agrees and says toric lenses have been pivotal in shaping the procedure into what it is today.
“Before toric lenses, we weren’t getting anywhere near the refractive outcomes we wanted. There was no talk of spectacle independence, unless you happen to have no astigmatism,” he says.
“And so toric lenses shifted the goalposts for greater precision which was a really important milestone.”
Precision is king
When planning surgery, choosing the correct formula is one of the most important pieces in the puzzle.
A/Prof Skalicky says that the evolution of formulae for IOL power has advanced over the past 10-15 years, redefining surgical accuracy. “When I look back on the formula that we were using when I was in training, it’s very different from the formula that we’re using today,” he says.
A lot of that pioneering work came out of Australia, such as Professor Graham Barrett’s Barrett Universal II formula that uses a theoretical model eye in which anterior chamber depth (ACD) is elated to axial length (AL) and keratometry.
Previously, the SRK-II and Hoffer-Q formulas were the main formulae used by surgeons. So, when the Barrett Universal II formula emerged in the last decade, it offered a new level of accuracy for IOL selection.
“These formulae have led to greater precision and therefore stronger expectations from patients and clinicians for more precise outcomes,” A/Prof Skalicky says. “The formula combined with toric lenses, in my opinion, were pivotal for procedural outcomes.”
Dr Jack Kane, from Vision Eye Institute in Melbourne, is also among the pioneers shaping the surgical landscape, with the development of the Kane formula in 2017.
These formulae, coupled with the development of more advanced multifocal and EDOF IOLs, has had the greatest effect, according to Dr Kane.
“I’d done quite a bit of research into the accuracy of the different formulas – and I could see that there were points where they would all break down, and often at the extremes of the axial length,” Dr Kane says.
“And often, the patients that are getting the refractive cataract surgery have eyes that fall into these extremes of axial length. I aimed to make my formula accurate at the extremes of axial length.
“Currently, the formulas are extremely accurate, giving 90% of patients an outcome within 0.50 dioptres of target. Improving the accuracy of formulas beyond this will likely require a breakthrough in biometry, where a new measurement may allow us to improve our outcomes even more.”
What’s next?
On the horizon, Dr Kane says cracking the code of accommodative IOLs and further refinement in this space would shift the surgical landscape again.
“The ultimate goal is to develop an IOL that can either accommodate or mimic accommodation. This is where you have the visual quality of a single focus lens, but the ability to focus up close, and there are lots of people thinking about ways to do that,” he says.
“Then, combining that with some adjustability so that in the future and after you do surgery for someone who’s 60, they can have 30 years of slight adjustments in their IOL to keep their vision perfect even as the cornea changes throughout their life.”
Dr Troski agrees, saying although accommodative IOLs are in stages of infancy, a lens that restores accommodation could define the future of refractive surgery. However, the technology is limited by the ability to develop an IOL that mimics the patient’s natural lens.
Dr Kane adds: “There are different methods to mimic what happens during accommodation, whether that’s due to changes in refractive index of the IOL material, multicomponent lenses that move fluid into different compartments in response to capsule bag contraction or direct movement of the lens as the ciliary muscle contracts. Research is focusing on all these different methods to try and get them to work.”
Dr Troski places Australia at the technological forefront of the refractive cataract surgery landscape – often having access to technology before the rest of the world.
“All the new lenses that I’ve seen in my career, we’ve had in Australia long before they’ve had them in America and often before Europe,” he says.
“Australia has been right at the cutting edge of most of the new technology lenses.”
Despite this, A/Prof Samarawickrama says for indiscriminate and greater health outcomes these advanced technologies should be made available in the public health system.
For example, at Westmead Hospital he conducted a trial where about 60 multifocal lenses and 60 EDOFs were allocated to senior registrars with appropriate training and support.
“We audited the outcomes and found that with appropriate training and support the senior registrar’s outcomes were comparable to the international literature and actually better than standard cataract procedures,” A/Prof Samarawickrama says.
“We created a multifocal pathway to help direct registrars in selecting the correct patient for surgery. This along with mentoring by a senior ophthalmologist seems to work. So, I think there is tremendous value in being able to adopt this training in the public system for the senior registrars.”
He is also a proponent of co-payment models. That way, public patients can opt for a premium lens if they’re willing to pay the difference between the lens costs.
“I think that shift would be advantageous because it means that we’re offering a comprehensive service to our public patients,” A/Prof Samarawickrama says.
Currently, premium lenses are only available to those who opt to have surgery privately. Meanwhile those who have surgery in the public system are typically offered monofocal lenses, or torics if they meet certain eligibility (usually above two dioptres of corneal astigmatism).
“I believe adopting a co-payment system to facilitate access of these premium lenses to our public patients would be a wonderful shift for Australia’s healthcare system,” he says.
“Unfortunately, ophthalmology is increasingly becoming disconnected from the Medicare rebate system because technology has advanced so rapidly. Bulk-billing and no-gap surgery is becoming rarer. The rebates don’t match up anymore,” he says.
Despite this shortfall, Dr Kane says insured patients can receive toric lenses without any additional cost in the Australian health system.
“When you talk to people from overseas, they’re amazed that we have availability of toric lenses to correct low degrees of astigmatism because they’re not putting in torics unless there’s significant astigmatism,” he says.
To help navigate a complex technological landscape and match the right lens to patients’ eyes, A/Prof Samarawickrama says that emerging technology – such as the Hoya Vivinex Gemetric multifocal IOLs – is designed to shift the light distribution curve, to combine properties of multifocals and EDOFs.
“In one eye you can have distance and intermediate dominance but still have near vision and in the non-dominant eye you can have distance and near with mild intermediate vision,” he says.
Although the lenses are still in clinical trial phase, he hopes to see it successfully implemented in practise.
Beyond the procedure itself and chasing better outcomes for patients, A/Prof Skalicky says the community has a long way to go with sustainability. He wants to see the broader cataract community in Australia adopt the environmental ethics that their international counterparts have adopted.
“For example, there are some parts of the world such as cataract theatres in India, where the amount of plastic waste they produce from 100 cataract operations is the same as the amount of plastic waste that we might produce from one or two,” he says.
“Why is that? What are the forces in Australia that are making us use plastic? We need a case to move on to a more reusable and smaller carbon footprint way of doing things again.”
A/Prof Skalicky says the transition from cloth drapes to plastic drapes in the operating theatre, and replacement of reusable instruments to single use disposable instruments, was a step in the wrong direction, and is calling for the broader industry to revert back.
“To me, the great challenge now for cataract surgery is to somehow be part of the low carbon transition that is happening in a lot of industries,” he says.
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