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Feature, Report

Inside the intraocular lens

31/10/2018By Matthew Woodley
Once almost exclusively restricted to cataract patients, IOLs are becoming an increasingly popular option for different types of patients who want to be as free from glasses as possible. MATTHEW WOODLEY and MYLES HUME examine the state of play in Australia and where the technology is heading.

While intraocular lenses (IOLs) have been a part of eye surgery for decades, recent advances have made the artificial implants an attractive solution for a variety of visual issues.

The arrival of trifocals and extended depth of focus lenses (EDOFs) has created an ever-expanding suite of intraocular lenses for surgeons and patients to choose from. Moreover, improved surgical techniques and more predictable IOL formulae mean the top 1% of cataract and refractive surgeons can now achieve ±0.50 D outcomes 90% of the time.

As such, while the use of IOLs was previously almost exclusively restricted to cataract patients, an increased number of people aged 55+ are exploring trifocals as a way of losing glasses altogether. Phakic intraocular lenses (PIOLs) are also being implanted more regularly in patients with high refractive errors when the usual laser options for surgical correction are contraindicated.

However, despite the massive improvements relative to where IOLs began, they are still not close to mimicking the natural lens due to issues with haloing, glare, negative dysphotopsia [shadowing on the retina], etc. Additionally, patient outcomes are still highly dependent upon the surgeon and how skillfully they are able to assess and manage the many variables associated with successful implantation.

For example, the Save Sight Institute (SSI)’s Dr Gerard Sutton, who recently won two gold medals at the World Ophthalmology Congress’ ‘Cataract Surgery Olympics’, believes one of the most important aspects of successful implantation is understanding the importance of dry eye.

"Australian ophthalmologists and their patients are extremely fortunate to have access to leading global technology"
Alina Zeldovich, USYD

“It sounds a bit boring but managing and treating dry eye before you perform measurements and calculations makes a huge difference. People who ignore that get average outcomes, people who pay close attention to that get good outcomes,” he explained.

“It doesn’t just affect the calculations, but it degrades the visual quality as well. A number of the lenses I have had to take out have been people with terrible dry eye who have had a multifocal lens put in and the quality of their vision is just terrible.”

Aside from managing the ocular surface prior to implantation, Sutton says utilising the most up-to-date and appropriate IOL formulae – such as the Barrett Universal II formula – and having a comprehensive understanding of them can have a profound impact.

“Better or more predictable IOL formulae has been a major advance from a patient outcome point of view. A lot of that has been understanding what keratometry, the curvature of the cornea, actually is and just refining those formulae,” Sutton said.

“I get a lot of referrals of patients who expect to get a good, unaided visual acuity and they don’t, and often the reason is the poor calculations that are done.”

Another of Australia’s leading cataract surgeons, University of Sydney (USyd) clinical lecturer Dr Alina Zeldovich, believes open and honest communication between doctor and patient is also vital to achieving desirable outcomes.

“All lenses are a compromise, however we now have more to work with than ever before. As long as the surgeon and patient are aware of this and have a frank and informed conversation about what best suits them, the results can be great,” she said.

“Australian ophthalmologists and their patients are extremely fortunate to have access to leading global technology, often far ahead of the US; we really have an excellent standard of care.

“However, if Medicare reviews, prosthetic reviews and health insurance companies lead to cuts in IOL reimbursements, we will lose this unique ability to provide our patients with all the amazing options available to them currently.”

Both Sutton and Zeldovich identified EDOFs and trifocal lenses as the two major recent technological advances that have significantly altered IOLs and the outcomes that can be achieved with them.

While not appropriate for all cases, Sutton says he now implants multifocal lenses in around 20% of cases.

“There are three or four different varieties that are working very well. They aren’t perfect and patients will still always notice some haloing around lights at night, but that’s become less of an issue and surgeons are becoming better in selecting who to put them in and, more importantly, who not to put them in,” he said.

“In my opinion, the contraindications are any abnormality of the cornea, dry eye, macular degeneration or any other retinal disease. They are absolute contraindications, while a relative contraindication would be people who rely on doing a lot of night driving, or amateur or professional pilots.”

Sutton said he still prefers multifocal IOLs to EDOFs, however Zeldovich argues they do have some advantages.

“With multifocals, depending on the type and profile, certain distances and tasks are clearer than others and the main cause of intolerance tends to be dysphotopsias,” she said.

“In my experience, EDOF lenses, although perhaps not providing the perfect clarity at reading distance, don’t have the levels of dysphotopsias that multifocal IOLs do.”

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Next-gen IOLS

Overall, while there are currently still many limitations with IOLs in comparison with the young crystalline lens, technological advances in recent years would suggest further improvements will continue at a fast pace.

Zeldovich predicted the next major trend will be light adjustable lenses, which are currently in the clinical trial phase. They can be altered by ultraviolet light post implantation, allowing patients to trial what they like and potentially change their minds without an additional operation.

Sutton also referenced light adjustable lenses, and said the Holy Grail for researchers and manufacturers, an accommodating IOL, could eventuate in the next decade.

“I haven’t seen anything that makes me think it will be in the next year or two, but there are a lot of people still working on that. There is already a lens where you can actually change the shape once it’s in the eye with ultraviolet light – the Calhoun light-adjustable lens – so there are a number of lenses trying to address accommodation in a different way to multifocal lenses,” he said.

One such lens is being developed by California-based company LensGen, which claims it’s developing the world’s first modular, fluid-optic, curvature changing IOL. The lens supposedly has the capability of changing its refractive power, within limits, to better match the performance of the original natural lens.

According to LensGen, Juvene’s design includes a standard monofocal lens optic as a base lens, functioning as a standard IOL, with an additional fluid lens present in the same structure that can change shape under the action of the eye’s ciliary focusing muscles.

"More predictable iol formulae has been a major advance from a patient outcome point of view"
Gerard Sutton, SSI

The US Patent Office granted LensGen two broad and comprehensive patents protecting its technology in June. It also received an additional US$4.4 million (AU$6.17 m), following on from US$21 million (AU$29.46 m) in Series A funding last year, however there is still no timeline as to when it will become available on the market.

Swiss Advanced Vision (SAV) is another company attempting to interrupt the IOL market, by developing an IOL with real-time autofocus technology that could be fitted alongside an implanted monofocal lens for distance vision, or added to patients who already have a monofocal lens but want to restore their visual accommodation.

The new approach, which is still in its early stages, involves the creation of an active lens with autofocus and wireless connectivity, termed Real-Time Autofocus Servo Control, or R-TASC.

“To our knowledge there is no current similar device under development. The main feature of the device is to change the lens focus function by autofocus means, therefore providing accommodation for the vision,” SAV R&D director Mr Alexandre Pascarella said.

“Some materials used in the device will be common to other intraocular lenses while some others required for the varifocal lens are more specific. But the proposed lens concept specifically dedicated to vision accommodation, its positioning, and its autofocus feature are totally new in the ophthalmic field.”

The active focusing function will require a power source and an energy gathering operation, both likely to be at the heart of SAV-IOL’s forthcoming development project. has reported the project could ultimately lead to an IOL platform able to incorporate augmented reality and other interactive or connected features.

IOL technology is not restricted to lenses. Earlier this year Alcon released a new delivery system, the AutonoMe, in conjunction with its latest IOL, the Clareon.

According to Alcon, the AutonoMe is the first and only automated, disposable, preloaded IOL delivery system in the world. The automated CO2-powered delivery mechanism, combined with an intuitive, ergonomic design is said to allow precise and simplified single-handed control of IOL insertion following cataract removal.

“With the introduction of Clareon AutonoMe, we are proud to commercially launch our latest innovations to benefit Australian and New Zealand surgeons and their cataract patients,” Alcon’s country business unit head of surgical in Australia and New Zealand, Ms Karen Fowler said.

“We have received great feedback from our local surgeons who have had early access to the technologies. Clareon AutonoMe builds on the comprehensive legacy of AcrySof by offering surgeons easy, intuitive control of IOL delivery with the newest optic material.”

Also released earlier this year, Zeiss’ IOLMaster 700 with Swept Source OCT technology is a tool that allows surgeons to directly measure the posterior corneal surface.

Zeiss says it combines unique telecentric keratometry measurement of the anterior corneal surface with measurement of the posterior corneal surface, in order to calculate what it describes as Total Keratometry. It also exclusively carries the Barrett TK Universal II and Barrett TK Toric formulae.

With the constant advances, high competition and increasing global demand – in terms of both capability and sheer volume – it doesn’t take a multifocal to see that IOL technology will become ever closer to the natural lens, both now and into the distant future.

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