Two Brisbane surgeons explain why the IC-8 comes closest to a silver bullet solution, as far as intraocular lenses go, for a difficult-to-treat patient group.
When it came to his cataract surgery work, Dr Joshua Hann operated like most ophthalmologists. He had a handful of intraocular lenses (IOLs) he consistently used – and they were delivering good outcomes.
But he had a nagging feeling. There was a subset of patients, albeit small, who would emerge with an underwhelming result.
“I felt as though they were being forced into a compromise in their lens options, if you could say that, because of their irregular corneal topography,” recalls the Brisbane ophthalmologist who established Eastside Eye Care in 2017.
“I’d have to advise them of their unsuitability for EDOF (extended depth of focus) or multifocal options, and I would even end up under-correcting their toric correction, so they’re probably going to be relying on glasses still in most situations.”
But he’d heard about the IC-8 IOL sporadically in the 12 months prior, and how it might be a good option in these types of cases.
“I started implanting IC-8 and it didn’t take long before I realised patients were not only just getting their toric correction, but they were getting the same, if not better, outcomes in their range of focus than those without a corneal problem implanted with a typical EDOF lens,” he says.
Today, the IC-8 is implanted in around 10% of all his cases, a significant number given it’s not considered a mainstream EDOF.
But for Dr Hann, the results speak for themselves and – along with Dr Cameron McLintock, another Brisbane surgeon and IC-8 user interviewed for this article – he’s encouraging more of his colleagues to consider adding it to their repertoire when appropriate.
The IC-8 is as simple as it is unique. It combines the well-known, proven principle of small aperture optics with the reliability of a hydrophobic acrylic monofocal IOL.
This pinhole effect mitigates the reduction in visual quality caused by defocused peripheral or aberrated light that can degrade retinal image quality. By allowing only central light rays to focus on the retina, patients can achieve more than 2.00 D of continuous, functional range of vision.1*
The IOL was originally developed and commercialised by AcuFocus and Bausch + Lomb acquired it in 2023.2 It was first launched in the Australian market in 2015.
It is recommended for unilateral implantation in the non-dominant eye, aiming for -0.75 D, with an aspheric monofocal or toric monofocal IOL in the dominant eye. Aside from its extended range of focus, it can tolerate up to 1.00 D deviation from the target manifest refraction spherical equivalent, and accommodate as much as 1.50 D of corneal astigmatism without requiring any axis alignment.1,3
When Dr Hann, also director of the Princess Alexandra Hospital Ophthalmology Department, first started implanting IC-8 he adopted this monovision approach, but he’s never been a major advocate due to his belief patients can be attuned to the asymmetry in their vision.
So he began implanting the IC-8 bilaterally and has been impressed with the outcomes in patients with irregular astigmatism. These include patients with keratoconus, or corneal scarring that didn’t reach the threshold for a corneal transplant and patients with previous pterygium surgery who have developed an irregularity transmitting to the centre of their cornea.
“Beyond that, I find the largest category is people with totally clear corneas that, in the routine of preparing for cataract surgery with their topography, have a central irregularity that is just not going to do well with any other type of lens,” he says.
Many of these patients wouldn’t have been identified if it wasn’t for corneal topography becoming standard in Dr Hann’s work-up. He marvels that it wasn’t routine earlier in his career. Today, everyone is scanned on his Pentacam device.
“In my clinic I would estimate 50% of people have irregular astigmatism or irregular, higher order aberrations on their cornea – and I wouldn’t have known that before routinely checking topography,” he says.
“These are the type of people who you perform operations on, fix their toricity, and they’d come back with an underwhelming result, and you wouldn’t really know why. It’s amazing how many people in their 50s and 60s you find out for the first time have keratoconus.”
Fellow Brisbane surgeon Dr McLintock adds that post-refractive surgery patients also benefit. At Vision for Life Institute, he analysed the outcomes of 166 IC-8 cases. Many of these had previous LASIK, photorefractive keratectomy (PKR), or radial keratotomy (RK) surgery.
“The IC-8 is a lens-based option to treat irregular astigmatism.
That was the attraction because it’s so hard to deal with that at the corneal level. Anytime you work on the cornea with laser or a transplant, often it’s complex and unpredictable,” he says.
He too prefers to implant the IC-8 bilaterally.
“Out of the 166 eyes, we found with a target refraction of plano, 94% achieved 6/9 unaided distance vision, 81% achieved N5 unaided intermediate vision and 94% achieved N4 near vision,” Dr McLintock says.
“For eyes with irregular corneas, that’s impressive.”
For Dr Hann, it was a relatively easy lens to introduce – “a low risk strategy” – because the expectations have always been set low for these patients.
He’s finding the IC-8 performs better with its range of focus than typical EDOF designs in the right patients. While many with the latter category can achieve N6 for near and intermediate, Dr Hann says they still require glasses occasionally.
His patients with an IC-8 achieve this too, but with a greater level of spectacle independence.
“I have many who are 6/6 for distance, but there’s a little bit more 6/7.5, 6/9 in patients who didn’t get close to that with their BCVA (best-corrected distance visual acuity) pre-operatively, but their near is probably 90%-plus at that N6 to N5 level,” he says.
It’s an excellent outcome considering that Dr Hann would have been concerned about implanting a toric monofocal in these patients, that would have only corrected for distance vision, and still may not have achieved 6/6.
“These people, with such good outcomes with the IC-8, are now the standard result, which is why I think more ophthalmologists would benefit from using it.”
Selecting the right patients
In saying that, Dr Hann and Dr McLintock note some important considerations. There’s a couple of reasons they keep IC-8 only to cases with irregular astigmatism.
For instance, if the patient has retinal pathology, obtaining an OCT scan could be more challenging due to the small aperture of the lens, and the same goes for accessing retinal tissue with a laser.
“So if someone’s got significant macular degeneration or diabetic retinopathy, I’d probably look to go down another path,” Dr Hann says.
“I’m mindful of not overusing it, because you’re not going to be able to anticipate all the people who may need some retinal intervention afterwards.”
However, there is literature showing the IC-8 IOL does not negatively affect retinal visualisation.
In patient selection, both ophthalmologists are scrupulous about pupil size – because those with a larger pupil diameter can struggle more with dysphotopsias.
“We measure pupil size beforehand with the lights off, but I don’t think that perfectly replicates the mesopic conditions people will find themselves in day-to-day. So although there is a threshold cut off that’s recommended, 5.5 mm, if you just go by that, you’ll probably get some who, for some reason or another, actually end up with a pupil a little bigger,” he says.
Apart from pupil size, Dr Hann can’t recall anyone with significant dysphotopsias.
“And it’s such a forgiving lens. With other premium IOL designs, you have to be very precise in your measurements and the power you choose, whereas with IC-8 – and not that I make this my practise – you can be off by 0.50 D or even 1.00 D and patients still get a great range of focus.”
Dr McLintock notes all patients should be counselled they will need to adjust to dysphotopsias to some degree.
“I know they’re marketed as an EDOF lens, but I discuss this lens as if it’s a multifocal. I explain the dysphotopsias can occur but are unlikely to be troubling – I haven’t had anyone that hasn’t been able to drive at night because of it.”
He also discusses the importance of centration. All his IC-8 cases are performed under topical anaesthetic, and he ensures the patient is fixing on the microscope light. He also uses a capsular tension ring.
“I want to see the corneal light reflex in the centre of that pinhole,” he says.
“The other critical thing here is the angle alpha, because if you’ve got a very deviated visual axis, the patient might not be seeing through the centre of the pinhole.”
For Dr McLintock, “the trick” isn’t sticking to one IOL design or philosophy. It’s about selecting the lens that suits the patient’s visual and lifestyle needs.
“The IC-8 certainly has its place,” he says.
“I think you’ve got to have a good reason to put these lenses in, but for those with irregular corneal astigmatism, it’s a great option, giving them more than what they might have achieved with more mainstream lens designs.”
References:
* Negative defocus range at logMAR 0.20 threshold for binocular defocus curve
1.Food and Drug Administration. (2002). IC-8 Apthera Intraocular Lens (IOL) – P210005: FDA Summary of Safety and Effectiveness Data. Accessed April 27, 2023. https://www.accessdata.fda.gov/cdrh_docs/pdf21/P210005B.pdf
2. Bausch + Lomb acquires AcuFocus … and small aperture IOL tech – Insight January 2023
https://www.insightnews.com.au/bausch-lomb-acquires-acufocus-and-small-aperture-iol-tech/
3. Burkhard Dick, et al. Prospective multicenter trial of a small-aperture intraocular lens. J Cataract Refract Surg. 2017;43(7):956-968.
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