AUSCRS 2020: Challenging Conventions

Challenging Cases and Complications

The first session for AUSCRS 2020 was chaired by Prof Graham Barrett (WA). Speakers were Dr Andrea Ang (WA), Dr Brendan Vote (TAS) A/Prof Tim Roberts (NSW) and Prof Barrett.

Descemet’s Disasters

A/Prof Roberts spoke about the challenge of inadvertent Descemet’s membrane detachment during cataract surgery (acknowledged by Prof Barrett to be “one of the scariest things to happen”).

This complication is relatively infrequent, potentially vision threatening and the clinical course and optimal management isn’t fully understood.

Risk factors are advancing age, pre-existing endothelial diseases, hard cataract, prolonged surgical time, a ragged clear corneal incision, inadvertent wound trauma inserting a blunt instrument, such as the phaco handpiece or IOL injector, and inadvertently injecting balanced salt solution or an ophthalmic viscosurgical device into the cornea above Descemet’s membrane rather than into the anterior chamber.

Most are peripheral and resolve spontaneously, but they can be large and central and this may lead to corneal decompensation and opacification with reduced or loss of vision if not managed appropriately.

Timely intraoperative identification of the membrane is important as further inadvertent detachment can occur with ongoing manipulation. However, detachments can go unnoticed because, as A/Prof Roberts said, “We are so trained as surgeons to pick up almost everything else going, but we don’t seem to pick up a subtle tear in Descemet’s. A tiny barb on your side port blade leading to an incomplete opening into the anterior chamber can be all it takes – small things can lead to bigger problems.”

The key message was attention to small details and meticulous care inserting instruments and injecting fluid is essential (and if you see a Descemet’s membrane detachment, don’t tug at it, that will only make it worse).

The CRAW!

Kitted out as Thing 1 from Dr Seuss and with blue hair, Dr Brendan Vote delivered an entertaining presentation on managing an iris prolapse in surgery, which is most often caused by an overly aggressive hydro dissection and/or flow pressure dynamics.

Other predisposing factors for iris prolapse are a floppy iris (diabetics, intraoperative floppy iris syndrome); inadequate pupil dilation; poor corneal incision construction; orbital/posterior segment pressure; shallow angle closure, and small eyes.

Referring to Bernoulli’s principle, Dr Vote explained why pressure gradients cause iris prolapse. “Like the lift on an aircraft wing, the higher the flow escaping the eye, the lower the pressure anterior to the iris, lifting it to the wound. The closer the wound is to the iris margin, the more likely the iris will prolapse.”

Pushing the iris back into place is the worst thing you can do. Management for a minor iris prolapse is by tapping or stroking the main wound with a phaco tip to reposition the iris. Any repositioning of the iris should be done via the side port, after neutralising the pressure gradient. Keep movements in and out of the eye to a minimum and once rectified, consider a plug with visco adaptive sub-incisionally, anterior to the iris to hold it. As the prolapse is generated via fluid flow, remember to lower your bottle height, intraocular pressure, aspiration flow and vacuum for the remainder of the procedure.

What’s with the blue hair? Dr Vote’s blue hair was in support of Australia’s first dedicated ophthalmic gene therapy (CRISPR) centre currently being built in Hobart, to support the work of Prof Alex Hewitt. You can find out more at tasmanianeye.org.

IOL Selection

AUSCRS’ second session was hosted by Professor Gerard Sutton (Sydney). Speakers were Dr Patrick Versace (Sydney), Dr Peter Sumich (Parramatta NSW), and Dr Con Moshegov (Sydney) as well as Prof Sutton. The session highlighted the enormous variety of intraocular lenses (IOLs) available and the complex selection process. Each of the speakers had their own strong views, paving the way for robust discussion.

Trifocals

Dr Moshegov reviewed the history of multifocal IOLs, and the compromises overcome to deliver satisfactory vision at all distances while minimising unwanted visual phenomena. In preparation for the session, he had audited refractive surgical patients over 12 months who had been implanted with trifocal IOLs (20 patients, 40 eyes with J&J Tecnis Synergy and 26 patients, 52 eyes with Zeiss At Lisa). His audit concluded that trifocal multifocals have eliminated intermediate vision issues and provided patients with binocular vision at all distances. However, while most patients are independent of spectacles, quality of vision remains suboptimal. Haloes, starbursts, and glare sensitivity are present in all of these eyes. Dr Moshegov acknowledged the latest generation of extended depth of focus (EDOF) and mono vision IOLs remain strong alternatives to trifocals.

Asymmetric Optical Design

Dr Patrick Versace prefers to implant IOLs using an asymmetric refractive optical design, which he says give a good expansion of the range of vision without the unwanted visual phenomena often seen with multifocal and traditional EDOF IOLs.

He explained that asymmetric optical design is not as unusual as it may sound as the eye is not a symmetric system. Implanting a ‘symmetric‘ diffractive lens often results in an asymmetric system and there are the associated problems of haloes and glare.

“I’m attracted to a pure refractive lens design – asymmetric refractive lenses such as the Oculentis MF15; the Femtis MF15, the Acunex Vario and the Sulcus MF15 (a rescue lens) – are seemingly bifocal lenses that perform as an EDOF lens,” he said.

Among patients in his study, Visual performance and positional stability of a capsulorhexis-fixated extended depth offices intraocular lens, published in Journal of Cataract and Refractive Surgery Vol 46, No 2, Feb 2020, 92% achieved 6/7.5 and N8; 69% achieved 6/6 and N6. He reported, 60% of these patients never, and 40% sometimes, wear spectacles. Haloes and unwanted visual phenomena are “remarkably absent… this is a lens that works and does what it promises”.

Monovision

Dr Peter Sumich prefers working with monovision IOLs, describing them as “the best of both worlds” for presbyopes, who he believes to be the most challenging patients seen on a day-to-day basis.

“You really have to get into the head of your presbyopic patient because often what they’re asking about isn’t really what they need,” he said. That means finding out about their job, hobbies, their use of electronic devices, reading, driving, application of make-up etc. and most importantly, whether they are prepared to work to make monovision IOLs work for them.

Patients most suited to monovision IOLs are in the low, medium or high expectation range. Low expectation patients are often cataract patients needing a small amount of add, whereas refractive patients usually have higher expectations. Ideal patients also have a low-to-moderate appetite for risk. More adventurous patients are better suited to a multifocal IOL.

Dr Sumich acknowledged the trade-offs with monovision – there is less binocularity which can lead to rivalry between the eyes, and less stereopsis, depending on the amount of monovision you’re giving the patient. Near eye glare remains a problem, particularly at night. On the flip side, he said “monovision IOLs are rehearsable and reversible… It’s not hard to laser away the monovision or implant an add on lens to achieve multifocal vision, which is its great advantage.”

Dr Sumich’s final tips were:

• Always do the distance/dominant eye first to achieve better patient acceptance,
• The Tecnis Eyhanc is a great lens for blending between eyes,
• Don’t be afraid to use multifocal lenses if that’s what the patient wants,
• When describing likely outcomes, refer to real world scenarios such as using a mobile phone and driving in the daytime,
• Have the patient’s spouse in the room who will remind them of the full conversation later, and
• Remind the patient that glasses will still be needed – and if they can’t accept that statement, carefully consider whether to proceed with surgery.

EDOF

Gerard Sutton described extended depth of focus IOLs as “a confusing space” with different types of EDOF lenses and disagreement about whether some EDOF lenses are true EDOF lenses.

Focussing on the Vivity lens (Alcon) he said, “This lens divides the wavefront into an advanced and a delayed wavefront, both of which hit the retina at different points, giving a spread of the wavefront across a larger area, which changes the nominal power of the lens.”

Results from an audit of 42 of Dr Sutton’s patients implanted with Vivity (two weeks to three month outcomes) showed good results for uncorrected distance vision without being “absolutely fantastic”, while intermediate and near visual acuity were “pretty good”.

Dr Sutton has had no intraoperative complications, or complaints of haloes, glare or visual disturbance; one patient requires refractive enhancement.

Outcomes, Devices and Technologies

The third session was hosted by Dr Jacqui Beltz (Melbourne) with speakers; Dr Ben LaHood (Adelaide), Dr Brian Harrisberg (Sydney), Dr Michael Lawless (Sydney) and Dr Beltz.

Future Surgical Outcomes

Dr Ben LaHood, having removed his tie to comply with AUSCRS’s rules demanding casual attire, provided his predictions on how cataract surgery outcomes will improve in the future.

While many future developments around improving refractive outcomes focus on post-operative adjustments, he said opportunities remain for pre-operative improvements, especially for unusual eyes.

Optical coherence tomography biometry, using refractive index segmentation, will be beneficial for eyes with unusual ratios, and particularly beneficial in improving refractive outcomes for long eyes.

Raytracing (which will hopefully become available from Zeiss in the near future) will become routine, allowing greater prediction of vision quality rather than simple estimation of residual refractive error. This will be especially beneficial for non-standard eyes, and a valuable tool that enables surgeons to demonstrate to patients, the retinal image quality that can be achieved using different lenses.

Our understanding of astigmatism will improve – we will find many opportunities to further improve astigmatism calculations, the most significant of which will be the measurement of lens tilt. We will routinely measure crystalline lens tilt and take that measurement into consideration. Additionally, we will routinely factor into our astigmatism calculations the expected IOL tilt, and the effects of angle alpha/kappa on induced astigmatism. IOL tilt is the most likely suspect in searching for the missing link between the astigmatism we attempt to correct and that which we are able to measure accurately.

These incremental improvements in pre-operative calculation and prediction may, however, be overshadowed by more forgiving IOLs such as Alcon’s Vivity and the inevitable development of post-operative laser adjustment of IOLs. These technologies allow us to improve patient satisfaction regardless of our progress to further minimise residual refractive error. In the (hopefully) distant future, we may even see cataract reversing treatments.

Supplementary Multifocal Sulcus IOLs

Dr Brian Harrisberg delivered a much anticipated presentation on visual outcomes achieved with supplementary multifocal sulcus IOLs.

While the best place for a multifocal IOL (MFIOL) is in the bag, in the case of patients previously deemed unsuitable, there can be reason to put it in the sulcus.

Factors making patients unsuitable include:

• The risk of failure to neuro-adapt post-surgery,
• The risk that the IOL technology significantly falls short of their expectations,
• Difficulty determining preferred working distances, and
• Potential for late development of an eye disease, such as macular disease.

The dual lens procedure is a solution that places a multifocal IOL – such as the 1stQ AddOn plano powered trifocal lens – in the ciliary sulcus, and a monofocal or monofocal toric correction in the bag in one procedure. This is a safe and easily reversible surgery.

Dr Harrisberg presented an assessment of audited patients who had the Liberty 677MY trifocal implantation (18 patients, 28 eyes); the Liberty 677MTY trifocal toric implantation (17 patients, 29 eyes); or a dual lens implantation (15 eyes of eight patients were implanted with the bi-flex 877PA monofocal or 677TA monofocal toric and the 1stQ AddOn plano trifocal).

Visual acuity improvements were almost identical across groups for distance and near, and low rates of dysphotopsia were reported. All patients noted some night vision issues but they were never mentioned as bothersome.

Three months post-operatively, a patient visual function questionnaire found that 100% spectacle independence was achieved for all distances (far, intermediate and near) in all groups. Highly predictable outcomes were achieved. The patients gave an average satisfaction score close to 9/10 for all solutions.

Cornea in Cataract and Refractive Surgery

The fourth and final AUSCRS session was hosted by Dr Rick Wolfe, and included presentations from Dr Greg Moloney (Sydney), Dr Aanchal Gupta (Adelaide) and Dr Ben Connell (Melbourne).

Descemet’s Stripping

Dr Moloney spoke about Descemet’s stripping or Descemetorhexis without endothelial keratoplasty (DWEK) for patients with Fuch’s dystrophy. It has been six years since he performed this procedure for the first time in Australia and following its success, he said, “DWEK is no longer an experimental trial based therapy”.

Topical Rhokinase has now been determined as the driving force behind cell migration across an intact Descemet’s membrane, as opposed to mitosis which was previously suspected. Dr Moloney said limited endothelial migration can be relied upon to generate and heal the cornea, so long as there is sufficient peripheral endothelial reserve and you follow ‘the rules’. Those “rules” are now well defined and can be found in Dr Moloney’s published papers as well as www.youtube.com/watch?v=E7qhbsfx_yY&t=571s.

In essence they are:

• Motosis must be present but limited
• Strip Descemet’s only to remove focal pathology in presence of endothelial reserve
• Minimise stripped zone
• Injured storm in contact with aqueous produces chronic scarring
• Peel don’t scrape
• Topical Rhokinase inhibitor improves speed and chance of clearance, mainly via inducing migration
• In Fuch’s, successful clearance creates a stripped zone with optical properties (inning)
• First learn DMEK!

He said the results that can be achieved for patients with Fuch’s dystrophy, using DWEK as opposed to corneal graft, are exciting.

Laser Correction for Keratoconus

Dr Aanchal Gupta spoke about the emerging use of laser correction for keratoconus.

While cross-linking (CXL) successfully stabilises vision for keratoconic patients, it cannot be seen as a vision solution as it does not improve vision. With CXL alone, patients remain reliant on glasses and in some instances, where glasses are not sufficient and patients are intolerant of rigid contact lenses, they are locked into a situation with no vision correction option.

In combining topography-guided laser correction with corneal cross-linking, Dr Gupta said, “We’re aiming to improve visual quality, regularising the cornea and in many instances, reducing the asymmetry between the two eyes.”

Explaining the procedure she said, “The refraction comes from the manifest refraction as always, but in this instance you have to account for the higher order topographical errors – the higher order ablation profile from the excimer software is going to have a refractive effect – it needs to be incorporated into the refractive input. We also need to account for residual corneal thickness to allow for cross linking.”

Challenges of keratoconus include:

• Pre-operative refractions – often poor best corrected visual acuity (BCVA),
• A mismatch between topography determined and subjective refractions,
• Topography guided lasers compensate differently (so you need to understand your excimer laser platform), and
• Corneal thickness is often insufficient to deliver full correction (however this procedure aims to significantly, rather than fully, correct a patient’s vision).

Dr Gupta said an audit of over 200 eyes of her own patients shows that combining laser correction with cross-linking statistically significantly improves uncorrected visual acuity (UCVA) by three to four lines, BCVA by one to two logmar lines, as well as astigmatism and keratometry measurements. However, case selection is extremely important – it’s not a treatment for all patients with kerataconus; ideal candidates are those with mild-to-moderate disease and no corneal scarring.

Countering concerns that removing the tissue over the thinnest part of the cornea further weakens an already weakened cornea, she said evidence shows weakening is limited to less than 10-12% of the cornea (John Marshall 2006) and the ablation profile of the Wavelight EX500 excimer laser provides more treatment in the superior thick cornea, allowing redistribution of the corneal tension in fibres and improvement in shape (Cummings 2012). “You’re weakening the cornea a little bit with laser but strengthening it significantly with the cross-linking,” she added.

While laser correction and cross-linking has been shown to be successful in treating suitable keratoconic candidates, Dr Gupta said long-term follow-up with a larger population study is necessary.

Conclusion

AUSCRS 2020 may have been down on spontaneous antics but it certainly surpassed expectations when it came to robust clinical discussion peppered with light-hearted banter. We look forward to AUSCRS 2021 in Noosa, from 20 –23 October. Visit www.auscrs.org.au.