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Reading the manufacturers' fitting guide, while not being included in our top 10 tips, should be a starting point before attempting any multifocal fitting; all multifocal lenses have their quirks and nuances and practitioners have often spent a great deal of time in pre-launch trials preparing such guides in order to achieve maximum success.
? Avoid phoropters - there is no place for them in multifocal lens fitting. Assess best vision sphere (BVS) and all other over-refractions with a trial frame and full aperture trial lenses using subjective spherical refraction, OR using a spherical single vision contact lens (avoids BVD issues) and spherical over-refraction. Calculation doesn't always work. For example, you would expect the BVS of +2.75/-0.50 x 180 to be +2.50DS, but your patient may well prefer +2.25 or +2.75.
? Test for ocular dominance with the BVS in place using the blur method, rather than the sighting method. It is usually best to use a lens close to the required reading add to do this. For example, for a +1.50 reading add, we would use a +1.50 hand-held large aperture trial lens, presented in front of each eye in turn. The patient is asked which lens makes the vision most blurred and whichever option achieves this result will be the dominant eye. Avoid asking the patient which lens is better, as the patient will inevitably say it is better without either!
? Managing expectations of your patient prior to lens application is crucial. While wanting to avoid the dreaded 'compromise' word, communicating the fact that acuities may not be quite as good as the equivalent spectacle lens can, at times, be a tall order. Patients often appear to have very much pre-conceived ideas about how good, or not so good, a standard of vision they will accept. We find that males (regrettably) seem, in the main, to be far less tolerant of a small drop in acuity, be it for distance or near, and are often looking for a 'quick fix'. Females, on the whole, seem much more flexible and tolerant of small differences - accepting that this may also take some time to adjust, train the visual system, and get used to. Careful assessment of lifestyle, necessity and where the patient's visual emphasis lies is needed here - is the requirement mainly for distance or near, in the middle - or would the patient simply love to live without the burden of spectacles? Never underestimate the freedom afforded by contact lenses.
? Carrying out a full dry eye assessment as part of the pre-fit examination can greatly enhance the success potential of presbyopic contact lens fitting, and informing the patient of any underlying issues at the outset may result in both short- and long-term gains in this topical area. The tear film and its stability is very different in a typical 50 year-old starting off with contact lenses for the first time, compared to, say, a 15 year-old embarking on a similar journey. The very presence of a contact lens will inevitably disrupt the delicate balance of the tear film layers and may well induce some interesting and quite challenging pre and post lens tear management. Careful consideration to the 'dry eye' potential can provide the wearer with a notably more comfortable scenario, while at the same time adding value and an income stream to the practice, even in the unfortunate event that a successful fit is not achieved (Figure 1).
? Anything greater than an 0.50 cylinder is a possible cause of a poor result and it is notable that, while there has been every effort made in recent years to correct low cylinders in younger patients to maintain quality vision and retain them as contact lens wearers, low-astigmat presbyopes who get catapulted into centre near aspheric designs will almost certainly notice the effect this has on their vision. If they do, a toric design, or maybe an RGP design, may well be the answer here. Coopervision's Proclear Multifocal Toric and Mark'ennovy's toric multifocal both come with either D or N centre designs and we have had some excellent results using the new hybrid (RGP centre/SiH skirt) Duette Multifocal lens available from No7 Contact Lenses (Figure 2). Knowing whether any astigmatism present is corneal or otherwise is important here; no significant improvement in vision will be achieved by using a non-toric RGP design on an eye with anything but corneal astigmatism, whereas a soft toric design will cope with corneal, lenticular or even mixed astigmatism.
? There is no perfect multifocal design (yet), but there are a huge number of choices nowadays, certainly compared to the limitations of a few years ago. Have a reasonable number of options within your armoury and learn of the benefits (and limitations) of these designs. It is possibly better to start with a few, well established and recognised brands rather than an extensive range of every lens ever made and this should cover most cases while the professional builds a skill set. One general rule of thumb we follow is that myopes tend to prefer centre distance lenses whereas hyperopes tend to accept the centre near option more readily. The very well established principle of one centre near and one centre distance lens supported by Coopervision's Proclear Multifocal for some years (Figure 3) has recently become available in SiH (Biofinity) material. The new lens has a slightly modified design, with some subtle changes to the fitting procedure and is becoming increasingly popular in practice.
? If in doubt about what power to use for the first trial lens, always go more plus (probably more than you think). This may be reduced later by over refraction with minus lenses if required. The point here is that if plus lenses are used for over refraction it is possible that the improvement in vision may be due to the small amount of magnification provided by the trial lens, rather than the refractive change alone. Also remember that the presbyope is severely frustrated by an inability to read and even if the lens turns out to be a little over-plussed in the long run, the 'wow' factor at near on immediate application is worth its weight in gold - first impressions count and can have a long lasting impact.
? Depending on the result, it may be that a boost to either distance or near vision is required. In the first instance, follow recommendations in the fitting guidelines, especially for single add products such as the new Proclear 1 day Multifocal. For products with more than one reading add, reducing the add in the dominant eye will often improve distance vision; increasing the add in the non-dominant eye will improve near - but in the latter instance, have a try at increasing the positive spherical (distance) portion of the lens first. Avoid high adds for as long as possible and keep the chosen add as low as realistically possible - the lower the add, the less impact there will be on distance acuity.
? Assessment of near vision is best performed without the traditional reading chart. Ask the patient to check the inbox on their mobile phone and, just before you send them for a 20-minute walk to see how good these new lenses really are, ask 'what time do you make it now?' mentally gauging how easily they see the time on their watch (this also helps them to come back in the required 20 minutes!). A 'scoring' system of comfort and vision (in that order) where 1 is poor and 10 is outstanding, should hopefully be 8 or better. We regularly use the ring bound chart produced by CIBA Vision, using test type to N6, train tickets, Sat-Navs, spread-sheets, etc.
? Be confident! Probably the biggest single factor of presbyopic contact lens success is the manner and body language of the professional. Having familiarity with a broad range of products and a background of successes (and a few failures) gives the ECP the ability and level of self-assuredness to be able to say 'that is about as good as it gets'. Patients will accept this and happily wear, or at least commence the adaptation process with a higher potential for success. One glimmer of hesitation or uncertainty from the prescriber will translate to the patient. Likewise, confidence is highly infectious and will result in a significant increase in happy lens wearers. Know when to stop.
The recent launch of two new daily disposable multifocals from Sauflon and Coopervision will create massive opportunities in the multifocal sector of the market. 2013 will be the 20th anniversary of the launch of 1 Day Acuvue and many of the 20-25 year-olds that were fitted with this product will be already noticing presbyopic symptoms - not very many of them will want to embrace monthly lenses and solutions! Additionally, there is better scope for supplying single-use lenses to be worn on a part-time or social basis - clients who can use both spectacles and contact lenses are usually very happy to have the choice, and they are often the most valuable clients to your business financially. ?
? David Gould is a contact lens optician with two independent practices in Rossendale, Lancashire. Nick Howard is a contact lens optician and an independent training consultant