Part 1 of this series highlighted the opportunity to increase the prescribing rate for multifocal contact lenses in the UK and examined the design principles behind the currently available lens options.1
We saw that presbyopes remain under-represented among contact lens wearers since relatively few are switched from single-vision to multifocal lenses and almost as many each year are switched out.2,3 Dropout from multifocals is also higher than from single-vision lenses,4 not only due to dissatisfaction with vision but also to issues relating to the ageing eye, such as tear film changes and reduced comfort.
Multifocal contact lenses differ between manufacturers, and brands, and behave differently on the individual eye. A lens that provides good visual stability and comfort – and has optics optimised according to pupil size by age and also by distance refraction – has the potential to increase multifocal prescribing and improve success rates. In addition, the lens needs to centre well on the eye, be made of a material compatible with the ageing eye, and come in a modality that is flexible and easy for patients to use.
This article will introduce a new daily disposable option, 1-Day Acuvue Moist Multifocal, designed to meet these specific patient needs. The technical features of the lens will be examined with respect to vision, comfort, ocular health and fitting success, and the fitting procedure and clinical performance described.
Technical features
The daily disposable 1-Day Acuvue Moist Multifocal is an optimised aspheric, centre-near (CN) design. The lens is available in three reading additions and is manufactured from the proven 1-Day Acuvue Moist material, etafilcon A with Lacreon technology. Technical features of the lens are summarised in Table 1.
Vision
Optimised optical design for pupil size
Part one emphasised the importance of optimising the optical power distribution within the optic zone to align with the population average pupil size. While most eye care practitioners are aware that pupil size varies with different light intensity, age and near focus, variation with distance refractive error is not commonly known.5 This variation has the potential to impact visual performance with multifocal contact lenses.
Dumbleton et al6 measured pupil size and visual acuity among 304 patients aged 18-78 years (mean age 39.5 ± 14.2 years) at three luminance levels: 250cd/m2 (simulated daytime), 50cd/m2 (indoor lighting) and 2.5cd/m2 (simulated night driving). The population was divided into pre- (=39 years), early and mid (40-54 years) and established (=55 years) presbyopes.
[CaptionComponent="1457"]The study found that age and distance refraction, as well as luminance, affects pupil size and VA. Older patients and hyperopes have smaller pupil sizes, and this difference is most significant at low luminance. Figure 1 illustrates the gradual decrease in average pupil size with age. Figure 2 shows that, in the same group of presbyopes, myopes also have larger pupils than hyperopes.
[CaptionComponent="1458"]The authors conclude that this study supports the need for variations in optical design for multifocal contact lenses not only according to near addition power but also based on refractive status.
Most, but not all, previous soft multifocal designs account for the variation in pupil size with age.1 However, the design principle incorporated in 1-Day Acuvue Moist Multifocal, known as IntuiSight Technology, accounts for pupil size variance due to refractive error as well as age. This design distributes the optical power within the part of the lens that is usable based on pupil size and provides distance, intermediate and near correction. The result is 183 optimised, centre-near designs across the prescription and add ranges.
Note that the new design is not the same as Acuvue Oasys for Presbyopia, the two-weekly replacement reusable lens which has an aspheric multi-zonal centre-distance optical design.
Optimised optical design for depth of focus
Figure 3 shows differences in the Low, Mid and High designs of 1-Day Acuvue Moist Multifocal on an unaccommodated eye focused on a distant object. Optical engineers evaluated the performance of these designs by considering the point spread function, i.e. the blur circle created by an incident light ray on the retina. The goal was to minimise the point spread function area to maximise vision; this was accomplished using a computerised model based on thousands of clinical data points collected over 10 years.
[CaptionComponent="1459"]The minimum point spread function progressively increases as expected with reading addition, but the differences are relatively small. The range over which the point spread function stays constant, or the lens depth of focus, increases from the Low to the High add lens.
In each case, the total depth of focus is a combination of the lens and patient’s visual system. Patients using the Low add have a greater amplitude of accommodation than patients needing a Mid or High add, so the Low add lens is designed to provide less depth of focus.
Figure 4 illustrates the spot size of all three designs with a near target at 40cm with the residual accommodation for patients who would be targeted for each add. Note that at the retina, the point spread function, and therefore vision quality, is similar for all three designs.
[CaptionComponent="1460"]Alignment with the pupil and ocular surface
With soft multifocals, both the centration of the lens and how the complex optics are maintained when on eye will impact on the quality of vision that the lens can provide. If the complex front surface optics were to be significantly altered as the lens drapes over the cornea, or if they were misaligned with the pupil centre, the visual outcome could be compromised.
1-Day Acuvue Moist Multifocal is specifically designed to reflect the natural shape and function of the ageing eye, a concept which – combining the three key features of the lens – is described as Eye-Inspired Design (Figure 5). The aspheric, central back surface closely matches corneal curvature to maintain the integrity of the front surface optics, and the spherical back surface periphery enables good centration to optimise lens fit and align the optical design with the pupil.
[CaptionComponent="1461"]Comfort
Tear film stability
As we saw in Part 1, choice of material for soft multifocals is almost as important as design, especially since tear stability reduces with age.7 The aim is to select a material that maintains a stable tear film and thus provides consistent vision performance, as well as minimising symptoms of dryness and discomfort.
The material used in 1-Day Acuvue Moist Multifocal is the proven 1-Day Acuvue Moist material, etafilcon A with Lacreon technology.
Koh et al8 used aberrometry to investigate tear film stability in a group of symptomatic daily disposable soft lens wearers. Total higher order aberrations and subjective ocular dryness with 1-Day Acuvue Moist, a lens with the embedded wetting agent polyvinyl pyrrollidone (PVP) from core to surface,9 were significantly decreased when compared with a lens of the same material without PVP (1-Day Acuvue).
These authors concluded that locking in PVP to the lens matrix provides a cushion of moisture at the lens surface that helps maintain a stable tear film. Studies have also shown that PVP does not blink away over time, remaining in the lens throughout the day for long-lasting comfort.10,11
With 1-Day Acuvue Moist, 83 per cent of wearers seldom or never experience eye irritation (and only 1 per cent experience frequent eye irritation).11
Lysozyme biocompatibility
Recent research has also shed more light on the biocompatibility of etafilcon A with lysozyme, a naturally occurring protein in the tear film.
Within hours of contact lens wear, even daily disposables accumulate deposits including lysozyme.12 While lysozyme has beneficial properties in its natural, active state, denaturing of lysozyme has been shown in vitro to trigger the release of inflammatory biomarkers that can lead to irritation.13,14
Laboratory studies have demonstrated that, due to its specific chemistry, etafilcon A selectively attracts significant amounts of lysozyme while maintaining it in its functional native state. This material has been shown in vitro to help maintain low levels of inflammatory biomarker release.13
Edge design
Edge design is another lens feature known to impact lens comfort. The Infinity Edge design used in 1-Day Acuvue Moist Multifocal gives the lens a smooth, tapered edge profile with the apex posteriorly located and minimal edge height to minimise lid interaction. Greater edge height can lead to greater lid interaction and discomfort.15
Edge design, lysozyme biocompatibility and locked-in moisture, combined with its low modulus, all contribute to the 1-Day Acuvue Moist Multifocal material and design, helping to deliver comfortable lens wear and make it particularly suitable for the ageing eye.
Health
Corneal physiology
In addition to patient comfort, minimal impact on corneal physiology is a primary concern when fitting any contact lens. Moezzi et al16 compared open-eye corneal swelling between eyes wearing 1-Day Acuvue Moist and no lens wear. Central and peripheral corneal swelling with the spherical hydrogel lens was <1.5 per cent and comparable to no lens wear during daily wear. Limbal and bulbar hyperaemia, and corneal staining were also unremarkable.
Daily disposable lenses have very low rates of corneal infiltrative events (CIEs), according to a recently reported year-long observational study.17 This large post-market surveillance registry found no serious adverse events, no CIEs and a very low rate of any symptomatic adverse events. In 471 years of patient wear of 1-Day Acuvue Moist, there were only three non-serious events (0.6 per cent/year). In the 121 patients aged over 40 years, who together had 97 years of experience with the lens, the rate of symptomatic adverse events with this lens was again 0 per cent.
The 1-Day Acuvue Moist material also incorporates Class 2 UV blocking to help protect against transmission of harmful UV radiation to the eye.
Clinical performance
The clinical performance of the new lens has been investigated in a recent multi-site study conducted in the US. The two-week dispensing study at 21 sites was with existing presbyopic contact lens wearers (including multifocal, spherical distance with readers and monovision wearers).18
A total of 275 presbyopes took part, with an age range from 40-67 years and average age of 50 years. Distance prescriptions ranged from +4.00D to -6.00D, with 181 myopes and 94 hyperopes, and add powers from +0.75D to +2.50D. Patients were grouped according to reading add as Low (n=76), Mid (n=89) and High (n=110). Investigators were required to follow the fit guide when fitting the subjects with 1-Day Acuvue Moist Multifocal daily disposable lenses.
The exceptionally high fit success rate was 94 per cent after approximately 10 days’ wear with just two pairs of lenses or less trialled (four or fewer lenses in total); 81 per cent were successfully fitted with three lenses in total (first pair plus one change) and 69 per cent with the first pair tried.
1-Day Acuvue Moist Multifocal delivered crisp, clear reliable vision at all distances, with consistent performance across refractive and add power ranges. This occurred even with more difficult to fit (Mid and High add) presbyopic patients. Binocular distance, intermediate (at 64cm) and near (at 40cm) logMAR acuity are summarised in Table 2.
Overall, 86 per cent of patients achieved distance VA of 0.0 (6/6) or better. Almost all (98 per cent) achieved intermediate VA of 0.1 (N8 at 65cm) or better and a similarly high proportion (95 per cent) attained 0.2 (N6 at 40cm) or better at near. VA levels were high at all distances for virtually all patients in the Low, Mid and High groups. Myopes and hyperopes achieved similarly high levels at distance, intermediate and near.
The lens achieved excellent centration (judged clinically as centred or slight decentration in all subjects) on a wide range of eyes. In fact, the lens has been shown to centre well on a range of corneal shapes across different ethnicities, with keratometry readings from 8.71mm to 6.95mm (38.75D to 48.50D). This optimal physical fit supports the optical design elements of the lens, by aligning them properly with the patient’s pupil to provide optimised positioning for optical correction.
The new lens had also reduced symptoms of dryness compared to patients’ previous lenses; at the two-week visit, 72 per cent seldom or never experienced dryness compared to 55 per cent prior to refitting. The average comfortable wearing time was 13 hours, or 89 per cent of the total average wearing time (14.3 hours).
Fitting procedure
As with all multifocal contact lenses, reading the fitting guide – then following it – is the first step to success. Other fitting tips include going back to first principles to elicit the full prescription before determining the maximum plus power at distance. When optimising the final prescription, avoid the phoropter and instead opt for a trial frame with full aperture lenses. Assess vision using real-world situations and a scoring system rather than VA alone.
[CaptionComponent="1462"]For optimal and easy fitting and minimal chair time, practitioners can use the simple guide (Figure 6). Looking at each step in detail, the fitting procedure is as follows:
Step 1 – Distance Rx
- Select patients with <1.00DC
- Determine the maximum plus spherical refraction to achieve best visual acuity
- Apply a back vertex distance correction if >±4.00D
Step 2 – Dominant eye
- Best selected using the +1.00D blur test as this helps identify the eye that least tolerates blur in the distance
Step 3 – Reading add selection
- Determine the minimum required to give the patient satisfactory near vision
- Refer to the table provided to select from Low, Mid or High add lens choice
Step 4 – Visual performance
- Allow 10 minutes to settle
- Assess distance, intermediate and near vision using ‘real world’ examples (eg view across the road, across the practice, mobile phone) and check against driving standard (if driver)
- Change one lens, as directed in the fitting guide, if distance or near vision is not satisfactory for the patient
- Trial for three or more days and reassess if necessary.
The fitting guide sets out the adjustments to try in the dominant and non-dominant eye to enhance either distance or near vision based on reading addition and dominance. Results from the study highlight how, with the fitting guide, 1-Day Acuvue Moist Multifocal provides for a predictable and positive fitting experience to minimise chair time, since adjustments required can be made at the first visit with a very high probability of success.
Depending on patient needs, a combination of vision correction may be desirable.19 Spectacles, distance contact lenses, and distance contact lenses with over-readers, can be useful to provide flexibility for different visual situations. The daily disposable modality is particularly suited to presbyopes for this reason.
While monovision may work with some patients requiring low adds, as they get older and need a higher add they can experience ghosting and poorer subjective performance as the disparity between eyes increases.20 Monovision can also interfere with depth perception, night vision and intermediate vision performance.21
Finally, remember that effective patient communication is an important element in success with multifocals, from detailed discussion of lifestyle and occupation to managing expectations.22 Think carefully about your conversations with presbyopes, be sensitive to their needs and demonstrate the difference that multifocals can make.
Patients most likely to succeed may be those who have a strong motivation to wear contact lenses, whether they are existing wearers or not. But try not to prejudge patients’ interest in multifocals; many will be unaware of this form of contact lens correction and want to know about all the options open to them.
Do not wait until patients notice changes to their near vision before discussing presbyopia and its correction. Note that putting off recommending multifocals until later in presbyopia not only places more difficult adaptation conditions on patients. It all also misses an opportunity to introduce them to the benefits of multifocal contact lenses at an early stage.
Conclusions
1-Day Acuvue Moist Multifocal utilises innovative new technology to deliver an optical design optimised for add and refractive error in order to provide optimum vision for patients.
The aspheric/spherical back surface maintains lens centration of the optics over the pupil for visual stability. The lens comes in the flexible and convenient daily disposable modality and the proven etafilcon A material for excellent wettability, comfort and a low adverse event rate. The sophisticated, eye-inspired design and simplified fitting process deliver a high fitting success rate with minimal chair time.
With this latest innovation, eye care practitioners have the ability to meet the needs of the ageing eye, increase the prescribing rate for multifocal contact lenses and deliver real benefits to more presbyopic patients.
In the final article in this series, Anna Sulley and Anne Madec Hily will report on practitioner experiences with 1-Day Acuvue Moist Multifocal and the results of in-practice assessments in the UK and US.
References
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2 Internal analysis based on independent third party data or research, 2015.
3 ACLM, 2014.
4 Sulley A, Young G and Hunt C. Factors in the success of new contact lens wearers. Optom Vis Sci 2014 E-abstract 145020.
5 Cakmak HB, Caqil N, Simavli H et al. Refractive error may influence mesopic pupil size. Curr Eye Res 2010;35:2 130-6.
6 Dumbleton K, Guillon M, Theodoratos P et al. The effects of age and refraction on pupil size and visual acuity: implications for multifocal contact lens design and fitting. Poster at BCLA Clinical Conference, May 2015.
7 Patel S, Boyd KE and Burns J. Age, stability of the pre-corneal tear film and the refractive index of tear. Cont Lens Anterior Eye 2000;23:2 44-7.
8 Koh C, Maeda N, Hamano T et al. Effect of internal lubricating agents of disposable soft contact lenses on higher-order aberrations after blinking. Eye Contact Lens 2008;34:2 100-5.
9 Sheardown H, Liu L and Jones L. Chemical characterization of 1-Day Acuvue Moist and 1-Day Acuvue contact lenses. Invest Ophthalmol Vis Sci 2006;47: E-Abstract 2388.
10 JJVC Data on file, 2005 and 2007.
11 JJVC Data on file, 2009. Post-hoc analysis. Adults aged 25-34 (n=71) P<0.05.
12 Subbaraman L, Glasier MA, Varikooty J et al. Protein deposition and symptoms with daily wear etafilcon lenses. Optom Vis Sci 2012;89:10 1450-9.
13 Jones L et al. Determining qualitative and quantitative uptake of lysozyme by various contact lens materials. Poster presentation at BCLA Clinical Conference, May 2015. Based on in vitro data. Clinical studies have not been done directly linking differences in lysozyme profile with specific clinical benefits.
14 Omali N, Subbaraman L, Coles-Brennan C et al. Biological and Clinical Implications of Lysozyme Deposition on Soft Contact Lenses. Optom Vis Sci 2015;92:7
15 Maïssa C, Guillon M and Garofalo RJ. Contact lens-induced circumlimbal staining in silicone hydrogel contact lenses worn on a daily wear basis. Eye Contact Lens 2012;38:1 16-26.
16 Moezzi A, Varikooty J, Shultze L et al. Open-eye corneal swelling with etafilcon A daily disposable hydrogel contact lens compared to no lens wear. British Contact Lens Association Clinical Conference, June 2014.
17 Chalmers RL, Hickson-Curran SB, Keay L et al. Rates of adverse events with hydrogel and silicone hydrogel daily disposable lenses in a large post-market surveillance registry: the TEMPO Registry. Invest Ophthalmol Vis Sci 2015;56:1 654-63.
18 Moody K, Karkkainen T, Clark R et al. Visual acuity performance across different near add powers with a new multifocal daily disposable lens. Poster presentation at BCLA Clinical Conference, May 2015.
19 Aslam A. Contact lenses and spectacles: a winning combination. Optician 2013; 246:6425 26-28.
20 Rothman SM. Monovision contact lens fitting: a chancy answer for presbyopic contact lens patients. J Behav Optom 1992;3:5 123-124.
21 Kollbaum PS, Dietmeier BM, Jansen ME et al. Quantification of ghosting produced with presbyopic contact lens correction. Eye Contact Lens 2012;38:4 252-9.
22 Bharuchi S and Donne S. Conversations in practice: managing the long-term wearer. Optician 2014;248:6472 23-30.
Dr Kurt Moody is global R&D platform director for presbyopia, Sheila Hickson-Curran is director, global medical operations and Ben Wooley is senior principal R&D design engineer at Johnson & Johnson Vision Care Inc in Jacksonville, Florida. David Ruston is director of professional affairs Western Europe for Johnson & Johnson Vision Care
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