What lies ahead? The future of cataract and refractive surgery
What does the future hold for cataract and refractive surgery, and ophthalmology in general? The seeds of many developments have already sprouted, offering a glimpse of changes that could transform the field over the next 10 to 20 years.
“With new technology it’s very rare that you have a completely new, disruptive change, it’s more like a continuous process,” said Pablo Artal PhD, Director of the Centre for Research in Optics and Nanophysics and the Laboratory for Optics at the University of Murcia, Spain. He believes that much near-term progress in ophthalmic instruments and devices will involve more sophisticated applications of existing diagnostic technology including optical coherence tomography (OCT), intraoperative aberrometry and adaptive optics.
Other developing technologies likely to reshape ophthalmic surgery include true accommodating intraocular lenses (IOLs), minimally invasive glaucoma surgery (MIGS) and femtosecond (FS) laser platforms, said ESCRS President David J Spalton FRCS, FRCP, FRCOphth. He is a consultant ophthalmologist at Parkside Hospital, London, UK, author of the highly regarded Atlas of Clinical Ophthalmology, and actively supports ophthalmic research in the UK.
Combining corneal crosslinking (CXL) with donor stromal or artificial implant technology could greatly expand the patient population eligible for corneal refractive surgery by transforming it into a tissue-adding procedure that strengthens the cornea, instead of a tissue-subtracting procedure that weakens the cornea, said Gholam A Peyman MD, Professor of Ophthalmology/Basic Medical Sciences at the University of Arizona, Phoenix, USA, and Professor of the College of Optical Sciences at the University of Arizona, Tucson, USA.
Big data will provide a lot of the evidence for how new and even well-established ophthalmology treatments perform in the real world, said Mats Lundström MD, PhD, of Lund University, Sweden, who heads the ESCRS’ European Registry of Quality Outcomes for Cataract and Refractive Surgery (EUREQUO). EUREQUO currently includes records from more than two million cataract and about 50,000 refractive cases in Europe since 2008.
However, big data’s biggest impact may be on how individual surgeons do their jobs, said David W Parke II MD, Chief Executive Officer of the American Academy of Ophthalmology (AAO).
On the far horizon are prospects for pharmaceutical cataract treatment and a world of potential genetic and stem cell regeneration technologies, especially for paediatric ophthalmology, as well as better understanding of the pathophysiology of many eye diseases, Dr Spalton said. “These are interesting times,” he added.
Several accommodating IOLs are in development that change focus by changing lens curvature, much like the natural crystalline lens, Dr Spalton said. These include NuLens’ sulcus-fixated DynaCurve, and PowerVision’s in-the-bag FluidVision, which has demonstrated up to 5.0 dioptres accommodation in pilot studies. Alcon has just bought into PowerVision, which is a “vote of confidence” in the lens, he noted.
However, current accommodating IOL designs are somewhat bulky, requiring a large insertion incision – about 3.5mm for the current foldable FluidVision – which can induce significant astigmatism, Dr Spalton noted. “That has to come down; you’re looking at sub-3.0mm to get into clinical practice.”
Dual optics are another mechanical accommodating IOL principle, such as the Akkolens Lumina, a sulcus-fixated IOL that moves two progressive lenses across each other in response to ciliary muscle contractions. Injected liquid IOLs are also in the pipeline, but also have problems, including posterior capsule opacification (PCO) and achieving emmetropia, Dr Spalton said.
Dr Artal believes it may take at least five years before a really effective mechanical accommodating lens is available. Electro-optical accommodating IOLs, such as ELENZA’s Sapphire, are also in development, though these are probably at least 10 years off, he added.
MIGS devices, including trabecular bypass and suprachoroidal shunts, as well as tubes and trabeculectomy enhanced with anti-fibrotics, will likely transform glaucoma treatment, Dr Spalton said. “I perceive going from relying on topical drops first to a MIGS procedure approach, and if that fails, going on to drops as secondary and then trabeculectomy as tertiary. If that is successful it will make a tremendous difference both to workload and better pressure control,” he added.
Better understanding of glaucoma pathophysiology, such as the possible role of intracranial pressure, also may lead to more effective glaucoma treatment, John P Berdahl MD, of Sioux Falls, South Dakota, USA, told the 2016 ASCRS•ASOA Symposium & Congress in New Orleans, USA. Low intracranial pressure relative to intraocular pressure not only pushes the disc back, causing cupping, it also may slow axonal transport across the lamina cribrosa to the retina, Dr Berdahl said. This suggests glaucoma may be treatable with something like vacuum goggles that bring the pressure differential back in line.
However, these pressure relationships are not yet understood, Dr Spalton said. A good surgical drainage device is a better short-term bet for improving glaucoma outcomes, he believes.
Femtosecond laser-assisted cataract surgery (FLACS) is another technology that is here to stay, Dr Spalton said – even though a recent EUREQUO study found virtually no difference in outcomes between conventional phacoemulsification and FLACS. But FLACS is more precise and makes cataract surgery easier, and its advantages are likely to grow more apparent as the technology is refined, Dr Spalton said.
Dr Peyman believes FS lasers will get smaller, possibly to the point of mounting on the operating microscope. They will also continue to revolutionise corneal refractive surgery and vitreal surgery, and encourage new procedures requiring precision impossible to achieve with manual surgery, he said.
“Many of the standard techniques will remain and are useful, but cannot provide the precision needed for future ophthalmic surgery,” added Dr Peyman, who has more than 100 ophthalmology-related patents, including the first 23-gauge vitrectomy device and the original LASIK concept.
CORNEAL REFRACTIVE SURGERY
One such application is a corneal refractive technique that Dr Peyman calls MESIK (“meso implant keratomileusis”), for mid-stromal implant and keratomileusis. It involves cutting a pocket with a FS laser, injecting riboflavin and crosslinking deep in the stroma, and injecting a donated stroma lenticule or artificial implant. This gets the eye close to emmetropia, and any residual error can then be corrected by surface ablation.
The combination of crosslinking and adding tissue should strengthen the cornea, Dr Peyman said. Crosslinking not only stabilises the cornea, it may also dampen any rejection response because it kills any living cells that might provoke a response in the donor tissue, and leukocytes that initiate the response in the recipient.
This approach might also be used to modulate healing responses in other parts of the eye, Dr Peyman added. Perhaps most significantly, using riboflavin and UV light to damage remaining epithelial cells after cataract removal might prevent their proliferation, possibly eliminating PCO and reducing capsule fibrosis. “It has the potential of bringing us one step closer to an ideal accommodative IOL,” he said.
Dr Artal also looks for more FS and other laser applications combined with crosslinking to change the shape or possibly the refractive index of the cornea, without cutting or ablating tissue. “When this happens it will be a real turning point in refractive surgery. I will consider it myself at that time.”
3D OCT images of the entire eye are close to reality and will render many current cataract diagnostic devices obsolete, including ultrasonic and optical interference devices, Dr Artal said. “There are prototypes doing this kind of thing right now.”
Intraoperative aberrometry is another existing technology with great potential, particularly for implanting toric lenses, Dr Peyman said. “The units provide real-time information on the degree of the astigmatism and the exact axis allowing intraoperative adjustment of the IOL,” he added.
Dr Artal sees adaptive optics, which he helped to develop, becoming common in the near future. Using deformable mirrors or liquid crystal modulators and wavefront technology, these devices can realistically simulate the effects of different IOLs, including multifocal, extended-depth-of-focus or monovision, so patients can gauge their tolerance before having them implanted.
“With diffractive IOLs, some patients love them and some patients hate them, but if they don’t find out they hate them until after surgery, it’s a problem,” he said.
Big data will become an increasingly powerful force shaping ophthalmology practice, said Jeffrey Willis MD, PhD, a researcher at the University of California, Davis, USA, and Genentech. It is particularly helpful for studying low-incidence diseases and complications, he noted.
In a study of myopic choroidal neovascularisation (mCNV), Dr Willis and colleagues recently examined data on three million patients from the AAO’s Intelligent Research in Sight (IRIS) Registry, data from the US Census Bureau and results from more than 11,000 patients in the National Health and Nutrition Examination Survey (NHANES) database in the USA. The study found, with high reliability, that mCNV occurs in about 41,000 adults in the USA, or about 0.017 per cent. This prevalence rate is lower than that found in previous, much smaller studies.
The value of utilising such big data is the ability to quantify the disease burden and the risk factors of rare conditions such as mCNV. This can potentially help with the development of more effective treatments, Dr Willis said. In particular, this could help provide more robust and current information on the prevalence of rare diseases.
Similarly, EUREQUO studies have illuminated risk factors for relatively rare outcomes in cataract surgery, including previous corneal refractive surgery and “refractive surprise”, Dr Lundström said. It has also examined the impact on outcomes of changing indications for cataract surgery and wide variations in cataract surgery rates among European countries. “Big data makes it possible to find out things that are difficult or impossible to analyse with a single unit or surgeon,” he added.
In the USA, many ophthalmologists use IRIS to document quality and outcomes for reimbursement from the public Medicare programme. IRIS now contains records of more than 88 million office visits to more than 14,000 ophthalmologists and eye care professionals.
But big data’s biggest impact may be on how individual surgeons do their jobs, Dr Parke said. “Using the IRIS registry for knowledge generation or payment are secondary. It was really developed as a quality improvement tool, and that is where so much potential lies – to help individual physicians become even better once you know what you are actually doing, not what you think you are doing.”
WHO WILL PAY?
However, tightening health service budgets will play a huge role in how quickly and widely new technologies disseminate, Dr Spalton said. For example, using a FS laser can add €1,000 to the cost of cataract surgery. The price will have to come down dramatically if it is to be widely used.
“There is no appetite for increased expenditures. The public system is pretty much bankrupt, private insurance tries to cut premiums and fees, and there is a limit to what patients will pay for a top-up fee,” Dr Spalton added.
It’s a general problem that needs to be addressed for physicians to deliver the best patient care, Dr Peyman said. “In the past price was not a major factor for the use of instruments. With limitations imposed on the health budget and the need to treat millions of patients, this paradigm needs to be changed. Otherwise, one cannot provide optimum care for most of the patients.”
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