Equipment, Feature, Products, Report

Presbyopia: blending vision for better outcomes

More presbyopic patients are seeking a safe, effective and affordable surgical solution to break free from their spectacles. Ophthalmologist DR ANTON VAN HEERDEN discusses his early experience with a laser blended vision procedure in his new Melbourne clinic.

With Australian adults over the age of 45 now accounting for 45% of the population, there has arguably never been greater demand for the presbyopia-correcting expertise of cataract and refractive surgeons.

Estimates vary, but government data indicates that as many as 690,000 people live with presbyopia in Australia, with millions more considered hyperopic. As more people seek permanent spectacle independence, ophthalmic device manufacturers are meeting this demand with incremental improvements in intraocular lens designs and advances in laser surgery sophistication.

As an ophthalmologist who has made presbyopia correction a point of interest in his career, Victorian cataract and refractive surgeon Dr Anton van Heerden has been an early adopter of cutting edge procedures in this field.

Anton van Heerden.

He heads the Surgical Ophthalmology Services Department at the Royal Victorian Eye and Ear Hospital and is the director of Armadale Eye Clinic and Mornington Peninsula Eye Clinic.

Earlier this year, he became principal surgeon at Eye Laser Specialists, one of Melbourne’s newest laser eye clinics. It was the first to offer small incision lenticule extraction (SMILE) in the state on an ongoing basis and is Australia’s first and only clinic to provide Zeiss’s Presbyond Laser Blended Vision as a standard clinical offering.

In recent years, van Heerden has watched the presbyopia surgical market grow considerably due to a combination of factors.

“There’s a large population in their early 50s and they’re generally good income earners. For many there is a massive frustration with glasses, with reading glasses, in particular, a symbol of aging,” he says.

“But it really comes down to functionality. People in their 50s are a lot more active than they used to be. Another key driver is the fact that everyone is on screens and the presbyopia symptoms really become apparent when using smartphones and computers.”

The convergence of these factors has resulted in demand for presbyopia-correcting surgical solutions, including clear lens exchange procedures and conventional monovision laser methods.

But with the introduction of the Presbyond system into his clinic in January this year, van Heerden says he is witnessing a growing appetite for a blended laser correction option that eliminates many of the drawbacks and risks of the more traditional presbyopia-correcting surgical options.

 

Presbyond Laser Blended Vision program is written into the Zeiss MEL90 excimer laser system.

“Presbyond is a program that’s written into the Zeiss MEL90 excimer laser system. It’s an induction of spherical aberrations so you get an increased depth of focus for each eye – even though you have mini-monovision on the cornea,” he says.

“The concept is very similar to EDOF IOLs, so you have a greater range of focus per eye, which allows good distance, intermediate, near vision and binocularity. It’s unlike monovision laser where you only get good distance and near vision, so it’s really promising.”

To further explain the underlying principles of Presbyond, Zeiss product information states the dominant eye is corrected for distance vision to almost plano, while the non-dominant eye is corrected to be slightly myopic for near vision to -1.50 D.

This mini-monovision strategy is said to be further enhanced by a key difference: an increase in the depth of field of each eye using a wavefrontoptimised ablation profile to create a continuous refractive power gradient for the whole optical zone of the cornea.

As a result, customised fusion of the two images for near and distance vision is created for each patient to create a ‘blended vision zone’, making it easier for the brain to merge the images in both eyes and achieve true binocular vision. This is opposed to monovision laser, which can create an intermediate ‘blur zone’.

The blended vision zone allows the brain to easily merge the images in both eyes.

According to Zeiss, clinical studies have demonstrated that stereoacuity is maintained in Presbyond patients, with virtually no loss of contrast sensitivity. The side effects of conventional monovision, such as multiple images in one eye, are almost eliminated.

It is also proven to be tolerated by more patients than conventional monovision and is effective in treating up to 97% of all presbyopia-related forms of impairment.

Meeting demand

Van Heerden says almost half of all his patients presenting for laser assessment are now over the age of 50, so providing an advanced corneal refractive procedure has helped fill a distinct gap in his suite of procedures. From a financial perspective, it’s also several thousands of dollars cheaper to perform than a bilateral lensectomy.

“It’s great to be able to give patients the option. We get a lot of people over the age of 50 who are coming in for laser vision correction and we know that if we just correct their distance vision they are not going to be happy because they will still need glasses to read, and a lot of the time they don’t understand that until you explain it to them,” he says.

“Since we have opened in January, a third of our patients have had Presbyond, so a significant portion of our laser surgery is in that category.”

There is also little doubt that operating on the cornea is a safer option than inside the eye, particularly for a patient cohort that will typically live for several more decades.

“And that’s for a number of reasons: it’s quicker, safer, more predictable and it’s instantly reversible with a pair of glasses if needed,” van Heerden explains.

“If you’re operating on someone in their 50s, they are going to potentially live till their 90s, but you don’t know what the eye is going to do in that time. If you remove a healthy crystalline lens and put a multifocal IOL in, there’s still a good chance that even though they don’t have macular degeneration or glaucoma, they could develop those as a pathology down the track.”

While there are other competing laser techniques that adopt multifocality for presbyopia, van Heerden says Presbyond and its EDOF principle has produced impressive results in his patients so far.

Compared with standard myopic/hyperopic laser surgery, he says it demands more from the ophthalmologist in terms of the patient work up and counselling – a hallmark of most presbyopia correcting procedures.

Dr Anton van Heerden with his clinical team at Eye Laser Specialists in Melbourne.

This includes careful management of expectations, such as the fact they may need to drive with glasses for a short period, particularly at night.

“Whether it’s on the cornea or the lens, patients need to know there’s no perfect solution – we can’t give their accommodation back. Due to it being a mini-monovision set up, the compromise with Presbyond lies in the fact that it does take a bit of time for the brain to adapt, so it’s important to try iron out those patients,” van Heerden says.

“It’s not for the fastidious engineer, the perfect patient is a 55-year-old electrician or plumber who is a hands-on worker that’s frustrated with putting their glasses on and taking them off.”

Van Heerden says patients are also advised about the prospect of residual accommodation changes. They are warned they might require enhancement later on, but the customisable nature of Presbyond means surgeons can adjust the power in each eye.

In terms of the ocular system, van Heerden says patients must have a healthy eye, with normal corneas and best corrected vision of 6/6 or better in each eye. There should also be clear ocular dominance in order to set each eye for its respective distance and avoid issues such as cross dominance.

Patients undergo a cross-blur tolerance test which gives a good indication if they are suitable for Presbyond. A contact lens trial is not encouraged as many patients who tolerate Presbyond will not tolerate an extended contact lens trial.

“They must also have the normal requirements for laser, without any pathology – especially in the lens. If there is any cataract or pending cataract then obviously you’d avoid any corneal refractive surgery and opt for a lensbased option,” he says.

“People often ask about those who may develop a cataract in an eye that’s had Presbyond. Our formulas for working out the power of lenses post refractive surgery are now quite accurate, so that’s not an issue. The only thing that’s not advised is to put a multifocal lens in an eye that’s had a refractive corneal procedure.”

Mr John Ring, Zeiss Australia and New Zealand’s business development manager for refractive lasers, told Insight that Presbyond has been available in Australia since 2013-14, with a small number of trial sites conducting early Presbyond treatment on the older MEL80 excimer laser platform. Van Heerden has been the country’s first surgeon to provide it as a standard clinical offering and on the MEL90 platform.

The company conducts educational webinars by global experts, and offers in-person Presbyond courses, including by laser eye surgery pioneer Professor Dan Reinstein from London Vision Clinic.

“Each patient is different and Presbyond is another tool in the toolkit of the busy refractive surgeon to be offered to their patients,” Ring says. “As for the future, going by its strong uptake in New Zealand, Presbyond has the potential to be an important element in the suite of treatments available to Australian patients.”