As intraocular lenses continue to improve, their popularity is increasing among a variety of patients – even those who don’t require cataract surgery. MYLES HUME asks what it takes to treat one particular type of patient: the presbyope.
Despite best efforts to develop an intraocular lens (IOL) that closely mimics the natural lens, presbyopia correction remains one of the final frontiers for refractive and cataract surgery.
Nevertheless, the burgeoning over-40 patient population has emerged as a lucrative market for Australian eye surgeons, as an increasing number of presbyopes seek a permanent solution to their dependence on spectacles.
At present, multifocal and extended depth of focus (EDOF) IOLs offer the best answer to their demands for crisp, youthful vision at all distances, at least until a ‘Holy Grail’ true accommodating lens comes to market.
But despite major technological advances, these current premium IOL designs come with inherent drawbacks, including glare, haloes and reduced contrast sensitivity.
The success of a procedure also weighs heavily on the skill of the surgeon; a key challenge being they must be within ±0.50 D of the refractive target to satisfy the patient. Only the top 1% of surgeons can achieve that level of accuracy 90% of the time.
Exacerbating this is the fact that replacing a clear, natural lens is an elective procedure not covered by Medicare or private insurance. The $9,000 to $12,000 out-of-pocket cost to correct both eyes leaves patients demanding nothing short of near-perfection from their surgeon.
Thankfully, enhanced surgical techniques, cutting-edge optical biometry, more predictable IOL formulae and greater awareness of issues that determine poor candidates are all contributing to better outcomes. Insight looks at what it takes for eyecare professionals to satisfy the ever-expanding – yet challenging – presbyopic patient cohort with IOLs.
The rise of the presbyopic patient
Once considered a procedure effectively limited to cataract sufferers, IOLs have become available to a broader set of patients due to the convergence of technological, economic and societal factors.
Mobile phones, tablets and computers are placing an unprecedented demand on people’s near vision. At the same time, Western societies, including Australia, are grappling with an aging population that is generally affluent and keen to remain active later in life.
In some cases, the onset of dry eye disease, which affects one in five Australians, has made contact lens wear no longer possible. For many the prospect of spectacle wear is simply not an option, leaving them with the choice of IOLs or laser surgery.
Leading Australian refractive and cataract surgeon Dr Con Moshegov says the opportunity to regain life-long vision at all distances – without spectacles – was a prevailing factor for many when selecting IOLs.
This is a key advantage over laser surgery which, despite initially being cheaper, may only correct vision for a certain number of years.
“I think there is an awareness that IOLs are a good, viable alternative to laser vision correction. People have become a lot more comfortable with lens-based refractive surgery,” Moshegov, from Sydney’s George St Eye Centre, says.
One example is that advances in surgery have resulted in IOL delivery through smaller incisions. “So the procedure itself is less traumatic. Surgery has gotten much easier, safer and more predictable, which has resulted in us looking at IOL implantation in patients who solely want to get rid of spectacles,” Moshegov says.
“I also think the lens choices that are available to us are a factor; in the past the premium lenses certainly were not in the shape and form that they take now, and I think maybe people in this age bracket have more disposable income and are prepared to pay for this elective procedure.”
Prior to the arrival of premium IOLs, Moshegov says presbyopic patients were limited to blended/monovision correction, which required one IOL set for distance and one for near. However, the asymmetry this afforded, along with a loss of depth perception, made this option unpalatable for some.
Fortunately, symmetrical vision now offered with premium IOLs has made the option accessible to more patients, but Moshegov insists eyecare professionals still need to carefully manage expectations.
“It takes up a lot more chair time than your average cataract patient. You have your difficult personalities, such as people with obsessive or compulsive tendencies, so it is repeated to them that there are a number of negatives associated with multifocal lenses.”
Moshegov adopts a ‘Rule of Threes’ and plainly states to patients they will see continual improvement of visual compromises after three days, three weeks and three months.
“But then you get a small minority of patients who even after three months, even after six months, who will say the haloes are so unpleasant, or contrast sensitivity is so affected, that they want the lenses out,” he says.
“So I prepare my patients for the possibility of explanting these lenses and putting in alternative lenses that have fewer symptoms. But if you have fewer symptoms, then of course the reading distance won’t be as good, unless you give them monovision.
“Before I operate, I tell them about haloes, I tell them about glare, I tell them about the possibility of explantation and the possibility that the clarity might not be as good as it could be with monofocal lenses and I also prepare them for a secondary procedure if the refractive target hasn’t been met.”
A key challenge with premium IOLs is the need for the surgeon to come within 0.50D – or 0.75 D at worse – of the refractive target.
“You have got to nail it every time, and if you don’t the quality of their vision without glasses is poor,” Moshegov says. That wouldn’t be tolerated at my practice – they would be asking for their money back and consequently you have to be prepared to do something, and that is usually a laser touch up.
“That in itself confuses them because they say: ‘You told me I didn’t need laser to start with.’ So you have to explain that it’s different because we have already solidified the longsightedness with the lenses.”
In order to select ideal premium IOL candidates, Moshegov says it is important to confirm patients do not have ocular pathology such as pre-macular fibrosis, macular degeneration, glaucoma, severe dry eye or irregular corneas, such as keratoconus.
Like Moshegov, Professor Gerard Sutton, from Vision Eye Institute and the University of Sydney, says a healthy ocular surface is essential to determining a patient’s eligibility. A dry ocular surface can affect the calculations and degrade the visual quality.
“I only offer multifocal IOLs to patients who tick all the boxes, so they can’t have untreated dry eye, they can’t have macular degeneration, they can’t have an abnormal cornea because there is already a little bit of a compromise with the multifocal lens, but it’s a bigger compromise if their optical system is not perfect.”
According to Sutton, surgeons who ignore dry eye could leave the patient vulnerable to average outcomes and, in some cases, lens explantation.
An additional key contributor to the success of a procedure is the use of appropriate IOL formulae to predict the refractive outcome. Sutton’s view – support by numerous publications – is that the Barrett Universal II formula works best.
The formula itself was developed by Perth-based ophthalmologist Dr Graham Barrett, who is an associate professor at the Lions Eye Institute.
“There are a few other good formulae out there, but Barrett Universal II is just the best. It’s also linked with the instruments we use, like the IOL Master [optical biometry device], so it’s very easy,” he says.
“We take the measurements and then the machine will just punch out readings, and take into account that each surgeon has an adjustment factor. You need to let it develop after a certain amount of procedures, it’s like a fudge factor.”
Sutton recently contributed to a paper that examined the effectiveness of another Barrett formula, Barrett True K, when applied to post laser refractive patients.
“That has previously been an issue in terms of reducing the predictability of the lens power calculation, but we are now getting results that are now equivalent to patients with virgin eyes basically.”
Pursuing the true accommodating IOL
The compromises inherent in today’s premium IOL designs will be forgotten once a true accommodating IOL appears on the market.
Until then, surgeons insist that any current products sold as ‘accommodating IOLs’ are the subject of marketing hype, and that multifocal and EDOF IOLs remain the gold standard devices.
“There is no such thing as an accommodating lens. I have tried them all over the years and they don’t work. They don’t accommodate; in other words they are either good for distance or good for near, but they are not good at both,” Moshegov says.
A paper in the UK journal BioMed Central claims the arrival of an accommodating IOL that completely mimics the physiological capability of the human eye would end the development and clinical use of current premium IOLs as we know them. However, the researchers stated this could be some years away.
“A confounding factor in the development of the accommodating IOLs used in the past has been the contradictory and many times controversial and commercially biased information about their outcomes,” the paper, published in 2017, says.
The researchers go on to state that with an even more contradictory behavior inside the capsular bag, some ‘accommodating IOL’ models have added further confusion and discredit their use.
“The emerging models of accommodating IOLs should solve this controversy by providing sustainable and reliable evidence-based information obtained from well designed and properly performed clinical investigations,” they concluded.
In the absence of a true accommodating IOL, surgeons are recording successful outcomes with the leading presbyopic-correcting IOL models such as the Alcon Acrysof IQ PanOptix trifocal, Zeiss’ At Lisa tri family of trifocals, and Bausch + Lomb’s FineVision Trifocal.
More recently, Johnson & Johnson Vision released its Tecnis Synergy IOL to the European, Australian and New Zealand markets. It incorporates an EDOF design across the near and intermediate distances, while providing better than 6/6 for distance vision in a proof of concept study. “In fact, results better than 6/7.5 were achieved from 33cm to distance. Like the existing Symfony IOL, contrast and low-light performance provide superior quality of vision,” a company spokesperson said.
Thus far, Moshegov is impressed with the results. “It’s a multifocal lens with good intermediate vision, and it’s looking really good. I’ve only implanted about eight of these, so it is early days, but I have found the Tecnis lenses from Johnson & Johnson tend to give exceptional clarity.”
Future IOL market takes shape
While previous models of ‘accommodating’ models have struggled to gain acceptance among surgeons, it hasn’t perturbed IOL manufacturers who are locked in a race to bring a true accommodating IOL to market.
In March, leading IOL developer Alcon moved a step closer to that goal after acquiring Tennessee company PowerVision for US$285 million (AU$425 m).
The takeover sees Alcon add PowerVison’s FluidVision IOL to its portfolio. The lens design is said to utilise the eye’s natural accommodating response and transport fluid in the capsular bag-implanted IOL.
According to Alcon: “This groundbreaking fluid-based design creates a continuously variable monofocal lens, utilising the natural contraction of the eye’s muscles. This technology allows the patient to actively focus on objects, just as the natural crystalline lens does in a youthful eye, providing patients with a natural, continuous range of vision.”
Commercial availability of this product will be determined following significant additional development and clinical trials.
In Europe, Swiss Advanced Vision (SAV-IOL) continues to move forward with the development of the R-TASC Project, the first electronic IOL with real-time autofocus.
According to the company, R-TASC is “set to push the boundaries” of the ophthalmic world within the five to seven years, and has already confirmed the technical feasibility of this project. It is now seeking to raise US$20 million to bring this groundbreaking device to the market.
Moshegov says another option gaining traction is a two-lens combination, consisting of a monofocal IOL implanted in the capsular bag and a multifocal lens in front in the ciliary sulcus. Although he is yet to attempt the procedure, Moshegov says the multifocal lens has the additional refractive or diffractive rings which allow the eye to see near, without disrupting distance vision.
Should haloes, glare sensitivity or reduced clarity of vision cause issues, then the front multifocal can be easily removed. “This is a quicker and safer maneuver than having to ‘dial’ a multifocal IOL out of the capsular bag,” Moshegov says.
An example of this will be on display at the RANZCO Scientific Congress this month in Sydney, where Insight Surgical will launch the new Medicontur Dual lens procedure. This combines the implantation of the sulcus-based AddOn Trifocal lens and the capsular-based Medicontur Bi-Flex together in one operation.
According to the company, the procedure is a reversible option for patients, offering complete spectacle independence.
At the same event, Designs For Vision will showcase a new product from UK-based manufacturer Rayner. The Sulcoflex Duet procedure, which is “an adjustable solution” for presbyopes, involves the sequential implantation of a primary capsular bag IOL and a supplementary Sulcoflex Trifocal sulcus IOL, which can also “top up” any existing IOL.
Elsewhere, Californian company LesGen is continuing with clinical trials of its Juvene IOL, which also incorporates a modular “two-optic” approach comprising a fluid-filled front optic and a larger base optic.
“Our early results from the Grail Study indicate patients can be spectacle free, with excellent quality of vision, and refractive stability,” Les Gen CEO Mr Ramgopal Rao told Healio.
LensGen is now raising $60 million in Series B Financing in advance of a US Food and Drug Administration study for the approval of the Juvene IOL, which the company expects will begin in 2020.
Adopting a similar dual lens design, Silicon Valley company Atia Vision has designed a lens with an accommodating base, accompanied with a fixed lens exchangeable element.
All signs point to an intriguing period for IOL development, but eyecare professionals will temper their excitement around new products until hard clinical data supports their use. For now, surgeons and manufacturers will continue minimising visual disturbances with current premium models, while remaining optimistic that a true accommodating IOL awaits just around the corner.