Extending Range of Vision with Advanced Technology IOLs

Optical designs came and went, and still the focus remained on achieving the best uncorrected near vision without losing too many lines of distance vision. However, the reliance on visual acuity as the best assessment began to fade when patients with presbyopia correcting IOLs returned for post operative visits, with excellent visual acuities, but complaints about the quality of their vision. These episodes triggered a realisation that visual outcomes assessments need to take into account what the patient requires for daily tasks, as well as being multidimensional, disease, and risk adjusted for functional quality of life.

Published studies on the lifestyles of those aged 55 and older have found that this population spends between 23 and 32% of its time in leisure activities, many of these requiring a range of vision, particularly intermediate.¹

Another study that evaluated how a presbyopic population used its vision found a trend towards greater usage of intermediate and near vision, primarily under photopic and mesopic lighting conditions.

With this in mind, the term ‘functional vision’ has increasingly been used to better capture not only patients’ visual needs, but also what is used to correct their vision after cataract removal and then assess it after surgery.

This is relevant not only for patients’ personal lives, but it also has some social and economic consequence. This is one of the reasons that the European Society of Cataract and Refractive Surgeons (ESCRS) created a working group to better define what functional vision is and why it is relevant. When we listen to our patients talk about their vision following cataract surgery, we realise that the most frequent complaint from patients is about their intermediate vision. They are not satisfied with it. If you consider this in the context of lifestyle – our increasingly ageing population that is working longer – it becomes clear that we need to address the requirements for intermediate functional vision in our cataract surgery.

ENHANCED MONOFOCAL IOLS

Quite obviously, we know that multifocal/ trifocal and diffractive extended depth of field (EDOF) IOLs will outperform monofocal IOLs when it comes to providing intermediate and near vision in patients. At the same time, we know that multifocal/ trifocal and diffractive EDOF IOLs come with some disadvantages, such as reduced contrast sensitivity, haloes, and glare.

Enter the new kid on the block – extended range of vision IOLs. This group of IOLs uses different designs to either cause an increase in the central curvature of the optics or by playing with the spherical aberration.

We know that individuals with the best quality of vision have a small amount of positive spherical aberration. If we allow for some spherical aberration, we can improve the depth of field.

These new IOLs manipulate the spherical aberration to improve the depth of field using negative or positive spherical aberration, or both. One point that is important to remember in this category of advanced technology IOLs, is that manufacturers utilise multiple types of optical principles to create an extended range of vision, resulting in different defocus curves for each IOL.

However, with these advanced technology IOLs, clinicians may still wonder if they are truly effective at distance, intermediate and near, and, more importantly, if they can provide real spectacle independence without any unwanted visual disturbances or dysphotopsia.

For example, with the RayOne EMV, when you look at the defocus curves produced with both eyes targeted for emmetropia, you can see a gain of intermediate vision compared with monofocal IOLs.

With a slightly myopic target -0.50 to -0.75 D in one eye you will see more gain in intermediate vision. With a higher degree of myopic target over -0.75 D in one eye, for example -1.25 D, the defocus curve of RayOne EMV shows further gain in near vision, while maintaining excellent binocular distance vision because of the large blending area between both eyes (Figure 1).

Due to this wide tolerance range, surgeons have the flexibility to use different offsets up to -1.5D, depending on what the patient’s visual needs are.

A clinical study performed in Prof Filomena Riberio’s clinic demonstrated that patients can gain 1.5 lines of intermediate vision with RayOne EMV, with no decrease in distance vision and some improvement in near vision. This is very relevant for the functional vision of patients in their daily lives.

Regarding contrast sensitivity, there was no statistical difference between RayOne EMV and a standard monofocal IOL in mesopic conditions, which is the lighting condition where many tasks are performed. The same result was seen under photopic lighting conditions.

Interestingly, the percentage of spectacle independence after Tecnis Eyhance and RayOne EMV implantation is quite different, with a higher degree of spectacle independence found in the RayOne EMV group.

Overall both IOLs, when compared to standard monofocal IOLs, can provide similar distance visual acuity, and similar contrast sensitivity but with less incidents of dysphotopsia compared to diffractive IOLs. With the additional benefit for RayOne EMV in providing better intermediate vision.

More recently, the RayOne EMV Toric model was introduced and has demonstrated similar visual performance compared to the non-toric model, while effectively reducing pre-existing astigmatism. The first evaluation involved 16 surgeons in eight countries, and 89 eyes of 56 patients receiving the RayOne EMV Toric. Most eyes (65%) were targeted for emmetropia, with some aiming for minimonovision (22%), targeting -0.25 D to -0.75 D in one eye, and 14% modest monovision, targeting -0.75 D to -1.5 D in one eye.

The one-month follow-up data showed a significant mean cylinder reduction from -1.32 D before surgery to -0.35 D after surgery, with 74% of the patients below 0.50 D of residual manifest astigmatism. Binocularly, mean change to uncorrected distance visual acuity (UDVA) was 0.00 ± 0.07 logMAR with 82% of patients 0.0 logMAR or better and 100% 0.2 logMAR or better. Mean binocular change to uncorrected intermediate visual acuity (UIVA) was 0.07 ± 0.14 logMAR with 73% of patients 0.1 logMAR or better. Very good vision; very useful vision!

When the patient-related outcome measures (PROMs) were assessed, the results showed that 94% of patients reported being satisfied or very satisfied. More interestingly, complete spectacle independence was achieved for distance and intermediate in 91% of patients and at all distances in 51% of patients, which was quite surprising. You would expect that with, for example, a trifocal lens.

The key takeaway from this first worldwide evaluation of the RayOne EMV Toric is that the range of functional vision was excellent, especially concerning intermediate vision, but actually also very good near visual outcomes, presumably thanks to the monovision setting, with predictable refractive accuracy.

ASSESSING FUNCTIONAL VISION

Vision assessment tools have been available for more than two decades but have been primarily seen as a research tool to be deployed for clinical studies. There is an increased demand for evidence assessing a patient’s visual function to understand the type of functional vision a patient has following cataract surgery. The ESCRS selected the CAT-QUEST 9SF questionnaire. This PROMs tool has pre-operative and post-operative versions and has now been validated in more than 12 languages.

Dr Yeo used the CAT-QUEST 9SF in a study where he assessed two groups of patients (30 patients, 60 eyes) – one group with bilateral emmetropia (21 patients) and then those who had modest monovision (nine patients).

The majority of patients in the emmetropia and modest monovision group, 90.5% and 77.8%, had no difficulty with their vision in their daily activities following surgery. While around 90% of patients in both groups were fairly satisfied or very satisfied with their vision, the most interesting PROMs result was for reading newspaper text: In the bilateral emmetropia group, 62% of patients had no difficulty, while for the group with modest monovision, it was 89% of patients. This demonstrates the higher level of functional near vision that is possible when RayOne EMV is used with modest monovision.

Another functional test question was concerning their ability to see the price tags of goods. In the bilateral emmetropia it was about 57% of patients, while for the modest monovision group it was 100%. Finally, when they looked at the PROMs question on patients’ ability to read TV subtitles, the distance vision was great with 95.2% for the bilateral emmetropia group and 100% in the modest monovision group. This suggests that having modest monovision did not affect the distance vision at all.

The conclusion that Dr Yeo reached from this evaluation was that the RayOne EMV is a versatile IOL: If you aim for bilateral emmetropia, it provides good distance, intermediate, and near. If you do modest monovision, there is a similar performance in both mesopic and photopic conditions. Patient satisfaction is very high; you have very good functional intermediate and near vision.

CONCLUSION

Advanced technology IOLs like the RayOne EMV are a real alternative to monofocal IOLs and should be considered the new standard of care for our patients. There is no learning curve, no additional chair time, and they can provide our patients with something that is very relevant: Not total independence of glasses, but independence from progressive glasses that we know have several issues in terms of quality of vision.

The correction of presbyopia in cataract surgery is really our opportunity to improve the quality of functional vision for our patients. The benefit of using the RayOne EMV is that you can implant it like a standard monofocal, and the patient just benefits from the additional depth of focus that they get. Similarly, if it is used in a modest monovision configuration, most of a patient’s daily activities will be achievable without any glasses.

And all this without inducing dysphotopsia or compromising binocular distance vision. That’s a huge benefit for patients demanding not only a broad range of vision, but also a high quality of vision.

This article was originally presented as a report to the Asia-Pacific Association of Cataract and Refractive Surgeons (APACRS) 2023 Rayner Breakfast Symposium.

Professor Graham Barrett AM MBBch FRANZCO is a consultant ophthalmic surgeon at Sir Charles Gairdner Hospital and a Clinical Professor in the University of Western Australia’s Centre for Ophthalmology and Visual Science. He is founding and current President of the Australasian Society of Cataract and Refractive Surgeons.

Professor Filomena Ribeiro MD PhD FEBO is Chair of the Ophthalmology Department of Hospital da Luz Lisbon and is Professor of Ophthalmology and Biomedical Engineering at the University of Lisbon. She is currently President  of the European Society of Cataract and Refractive Surgeons and Editor-in-Chief of JCRO, an online-only companion to the Journal of Cataract and Refractive Surgery.

Professor Oliver Findl MBA FEBO is a highly qualified consultant eye surgeon and currently holds the position of Chief of Department of Ophthalmology at the Vienna Hanusch Hospital in Austria. In addition to his clinical work, Prof Findl is an internationally renowned researcher in the field of ocular surgery. He is the Secretary and elected governing board member of the European Society of Cataract and Refractive Surgeons.

Dr Yeo Tun Kuan MBBS MMed FRCOphth FAMS is Head of Cataract, Implant and Anterior Segment Service, and Senior Consultant at the Department of Ophthalmology, Tan Tock Seng Hospital, Singapore. He is also Senior Clinical Lecturer for Yong Loo Lin School of Medicine, National University of Singapore and Clinical Teacher for Lee Kong Chian School of Medicine, Nanyang Technological University of Singapore. Dr Yeo is an invited member of the IOL Power Club and developed the EVO IOL formula (evoiolcalculator.com).

References

1. Ribeiro, F., Cochener, B., Hewlett D., et al., Definition and clinical relevance of the concept of functional vision in cataract surgery ESCRS Position Statement on Intermediate Vision: ESCRS Functional Vision Working Group. J Cataract Refract Surg. 2020 Feb;46 Suppl 1:S1-S3. DOI: 10.1097/j. jcrs.0000000000000096.
2. Ribeiro, F. et al., Analysis of daily visual habits in a presbyopic population, J Ophthalmology, 2023 Apr 8;2023:6440954. DOI: 10.1155/2023/6440954.
3. Ribeiro, F., Silva D., Matos, A.C., Gaspar, S., Visual outcomes and patient satisfaction after implantation of a presbyopia-correcting intraocular lens that combines extended depth-of-focus and multifocal profiles, \J Cataract Refract Surg. 2021 Nov 1;47(11): 1448–1453. DOI: 10.1097/j.jcrs.000000000000065.
4. The Ophthalmologist Supplement, Better Vision Without Compromise, First-in-eye real-world data collection reveals exciting results for the RayOne EMV Toric enhanced monofocal toric IOL. Published online 6 June 2023. Available at: theophthalmologist.com/subspecialties/ better-vision-without-compromise (accessed 16 Jan 2024).