In the last article we discussed the fitting of multifocal lenses. What happens when that patient returns to your practice with a problem? This final article takes a look at the aftercare and, in particular, troubleshooting to hopefully resolve any reported concerns.
Initial questioning of performance
In the first instance, a review of the patient goals that were set at the initial fitting stage may help to determine if these goals have been achieved, need tweaking or whether, in fact, the patient has moved the goal posts and has new demands. In reality, when faced with a list of issues, it may be appropriate to determine which are the most significant and look at solving those first. While reviewing a case history, it is worthwhile trying to determine the extent of any problems that the patient may mention.1 For example, a patient may tell you that they can’t read. However, with careful questioning, you may discover that they have a specific difficulty reading ingredients in small and poorly contrasting print on food items but manage day-to-day tasks with ease. Recently, a patient of the authors said they struggled to see a golf ball in the distance but managed to drive their car and watch television wearing their multifocal (MF) lenses with ease.
During the initial aftercare consultation, it is important to take as detailed a history as possible. Ask the patient to score subjectively how well they undertake the tasks that they perform daily, such as driving, digital screen use, reading and so on. When visual concerns are identified, it is important to listen carefully and let the patient explain the depth of the problem. Open questioning is of benefit in these situation when trying to understand the impact of the problem. As eye care professionals, we are all experienced in taking detailed symptoms and histories. In the case of a MF contact lens wearer, it is important that they are given time to discuss their vision and that these discussions are well documented, preferably reflecting their own words.
Typical problems in any soft lens fitting will be related to one or more of the following:
- Less than acceptable vision
- Issues relating to poor lens fitting
- Tear film-related disturbance
- Comfort concerns
Figure 1 shows a flow chart outlining a systematic approach to problem management. It is not exhaustive, but should offer a good overview of the management approach to the sorts of problems that typically arise in aftercare situations.
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Remember care systems must also be considered. In the authors’ experience, if the patient is happy with the lenses when new but finds that after a few days or weeks the vision and/or the comfort has deteriorated, then changing the solution would probably be the first consideration. If not already used, a change to a preservative free system is useful.
When evaluating MF performance and success it is important to recognise that patient satisfaction will not be accurately communicated simply by Snellen and near chart acuity measurements. General patient feedback is the best barometer of performance when assessing patient response to MFs. Eye charts for distance and near provide only some of the information required regarding vision. Subjectively scoring specific visual tasks (television viewing, driving, tablet and smartphone use) proves far more useful. In the authors’ opinion, a score of 6 (out of 10) or below will need addressing before sending the patient away with completely new trial lenses, while 7 and above usually indicates it would be worth getting the patient to persevere for an extended adaption period. Making a judgement of the success or not of MF contact lenses based on consulting room acuity tests alone is probably unwise.
Over-refraction
It is always best to consult the relevant contact lens manufacturer’s fitting guide to help improve either distance or reading vision. Over-refraction with ±0.25 flippers may elicit a favourable response. Remember that this initially should be done monocularly, with both eyes uncovered. Avoid using a phoropter head or, where possible, a trial frame. Phoropter heads particularly may cause issues for wearers of lenses that are pupil dependent, as many MF designs are. Do remember to check vision at both distance as well as near to ensure that any changes considered for one viewing distance do not then result in a problem at another. Once again, it is important to perform any over-refraction on real-world objects and ask the patient to give a subjective score each time. The authors strongly advocate the use of the great outdoors for ‘tweaking’ the distance prescription in MFs. Get the patient to look at a distant object, perhaps a car number plate or a sign post, and see if vision improves with any over-refraction. Likewise, any over-refraction to a near prescription should be done using an object with which the patient has described difficulty with (perhaps a tablet, smartphone or newspaper). Over-refraction with MF contact lenses may be ambiguous and may depend on factors other than refraction, such as the lens surface wettability or the cornea being healthy and uncompromised.
Enhanced/modified monovision
If no improvement is possible to distance vision by amending the dominant eye correction, it may be possible to achieve a positive result by either amending the distance power of the non-dominant (near) lens or reducing the reading addition. This is known as modified monovision. Another option is to consider fitting one eye with a single vision lens while retaining a MF lens on the other eye. This is enhanced monovision. The use of this enhanced or modified monovision may be appropriate in situations where either distance or near vision are blurred and over-refraction over MFs has not given an appropriate improvement in vision.
Take a look at the refractive details of a patient in Table 1.
In this example, a single vision toric lens could be used to improve distance vision in the dominant eye. Enhanced monovision might also be considered, achieved by fitting a single vision spherical in one eye. Enhanced monovision can also be used to improve near vision when a MF lens is performing poorly. Modified monovision involves modifying distance or reading vision by using two different add powers. The usefulness of enhanced/modified monovision cannot be over-emphasised.
Lens fit and ocular health matters
Lens fit assessment may offer clues as to why vision may sometimes remain poor after over-refraction. The complexity of design of MF lenses means centration is more important in some designs than in others. Lens fit can be affected by two key variables – lens parameters and ocular features.2 Some lenses decentre temporally because the nasal sclera is higher that than the temporal sclera, as a result of the nasal sclera approaching the peripheral cornea at a relatively flat angle.3 Vertical decentration of an MF lens is most likely attributable to lid position as a result of either lid laxicity or tightness.
Decentration of a contact lens in situ has particular significance in the fitting of MF lenses. It is important to remember that the central optic zones of most commercially available MF lenses are extremely small, approximately 2.0mm. Furthermore, the pupil is typically decentred superionasally, and ageing causes natural pupil miosis. Because of such influences, great care must be taken to ensure good centration if a MF lens is to offer the best visual outcome.4 Reviewing contact lens fit carefully is even more relevant in the case of MFs, a topographer or video slit lamp may help to show small shifts in centration of the lens (Figure 2). If no visual improvement is possible and the lens is decentred it may be worth changing the lens design at this stage.
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It is well known that as the eye ages there are changes to lid anatomy and tear composition. This, along with systemic disease and medications can cause further changes in the eye, which may result in poor comfort or vision with contact lenses. It is important to question patients about any changes in their general health or medication. Slit-lamp examination of the ocular adnexa, conjunctiva and cornea may provide vital clues to why a contact lens is not performing well. Blepharitis, meibomian gland dysfunction, lid wiper epitheliopathy (LWE) and lid parallel conjunctival folds (LIPCOF) could each or, together in any combination cause a problem with wettability of a contact lens causing dryness, reduced comfort and vision (Figure 3 and 4).
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Since this is an aftercare on a presbyopic patient, it is well worth confirming if there is, or has been, a change to the crystalline lens. Early cataracts can cause both high and low contrast visual changes, which are sometimes difficult to improve, even with a new prescription.
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Change the lens
With an ever-increasing number of MF options available, a new fit with a different material or design may prove successful.
In the event of the an over-refraction providing little improvement, the lens fit is stable, lenses are clean, wetting well and slit-lamp examination is normal, re-confirming the refraction and dominance is the next step.
Small changes in sphere or cylinder in either distance or near may have an impact on the quality of visual tasks with MF contact lenses. If the spectacle correction has changed, then a re-fit using the appropriate fitting guide should be attempted. As mentioned earlier in this series, remember the prevalence and degree of astigmatism increases with age.
If the patient has some degree of astigmatism, or this has changed since their last refraction, it is worth reassessing sensory dominance and confirming if the vision becomes blurred with a fogging lens. A review of 11,624 spectacle prescriptions found the prevalence of astigmatism of 0.75DC and 1.00DC to be 47.4 per cent and 31.8 per cent respectively, and in both eyes 24.1 and 15 per cent respectively. It was also estimated that one third of potential contact lens wearers require astigmatic correction.5
Correction of astigmatism with soft reusable MF contact lenses is possible using, for example, Proclear Multifocal Toric (Coopervision), Saphir Multifocal Toric (mark’ennovy), Gentle 80 Multifocal Toric (mark’ennovy). Another alternative is to consider enhanced/modified monovision.
In the case in Table 1, the patient may note blurred vision when a fogging lens is applied to the left eye. In this case it may be wise to consider fitting the right lens with a MF toric or modified monovision.
Alternatives
If the practitioner feels bold enough, and has enough time, then there are always alternatives to monthly soft lenses. These can take the form of rigid gas permeable lenses (RGPs, typically translating in design), hybrids and semi-scleral lenses. In this introduction to the topic, we won’t go into great detail regarding the fitting. It is worth noting, however, that the rigid optical zone of these lenses can give excellent visual results, often better than soft lenses, and where the astigmatism is fully corneal, can provide excellent vision. Where there might be residual astigmatism (due to internal lenticular astigmatism) then either a toric or bi-toric RGP MF or a toric semi-scleral could be the answer. Only yesterday a patient was saying how happy he was with his MF RGP lenses, and he was an engineer! With regard to RGP MF fitting, firstly it is not as complex as you think, especially if the patient is already an RGP wearer and then this should be your first choice. (A future CET article on more complex fitting approaches will appear in Optician in the summer). Centration is probably the key to success with this type of lens and there are plenty of designs and manufacturers to help and many workshops on RGP fitting from both the manufacturers and organisations such as the BCLA.
Yet more options
As the technology and designs of scleral lenses continues to change, so have the fitting techniques and the types of patients that are now considered candidates for scleral lenses. Patients with normal, regular corneas are now successfully fitted, especially when their visual needs exceed typical soft lens parameters. For those patients with astigmatism wanting a MF option, scleral lenses can result in a clear, stable vision with comfort equivalent to a soft lens. This option is also particularly well suited for patients who struggle with refractive change or mild ectasia after Lasik surgery.
Tips for success in multifocal aftercare
- Use loose trial lenses or a flipper for over-refracting to provide a more natural environment
- Check vision binocularly to simulate a real world environment
- Always attempt to satisfy the patient’s primary visual goals, keeping in mind that for some individuals a day of being spectacle free for 80 per cent of the time may be considered a success
- Consider using enhanced/modified monovision if vision at certain distances is unsatisfactory in MFs
- Light is your friend – tell your patient this fact at the fitting/dispensing visit. Make them aware of the importance of good lighting for detailed visual tasks
- MF lenses are designed to work together
- Binocular performance with MF lenses always outperforms monocular performance. Share this fact with your patient, and discourage them from comparing each individual eye’s performance
- In the case of modified or enhance vision, tell the patient that their vision will be different between each eye as you emphasise binocular viewing. Again, if you don’t tell them, this difference will be among the first thing they will tell you on their return
Final point to remember
If given the option, 78 per cent of presbyopic spectacle wearers would consider trialling MF contact lenses.6
Model answers
Correct answer is in bold italic
1 Which of the following is the most likely reason why phoropter heads are not recommended for over-refraction of multifocal contact lenses?
A Too expensive
B They are less acurate than a trial frame
C It is not possible to observe the lens on the eye during over-refraction
D Reduced light level impact on the pupil dependent vision
2 Which of the following best describes the adjustment of vision through a pair of MF contact lenses by reducing the addition before the non-dominant eye?
A Modified monovision
B Enhanced monovision
C Monovision
D Over-refraction
3 Which of the following is the most likely cause of an MF lens riding high?
A Steep fit
B Keratoconus
C Lid influence
D Dry eye
4 Which of the following is able to best reveal small amounts of decentration?
A Retinoscopy
B Slit-lamp with graticule
C Topography
D Refraction
5 Which of the following statements about lid wiper epitheliopathy is true?
A It can only be detected using lissamine green
B It must be considered as a possible cause of complications with MF lenses
C It is present in all eyes
D It is irrelevant as a cause of discomfort for contact lens wearers as does not have contact with a contact lens surface
6 Which of the following best represents the percentage of people with 0.75DC or more of astigmatism?
A 35
B 42
C 47
D 52
References
1 Woods J et al. Early Symptomatic presbyopes – what correction modality works best? Eye Contact Lens, 2009 Sep;35(5) 221-6.
2 Yager J, Hansen, D The influence of decentration and add power on visual acuity of the Sunsoft Multifocal Soft Lens AAO Meeting Scientific Poster 1995.
3 Caroline P, Andre F. CL Spectrum, Vol 29 August 2013 Page 56.
4 Walker M, Caroline P. Soft Lens centration based on scleral shape measurement Soft Special Edition World Wide Vision XV.
5 Young et al. Prevalence of astigmatism in relation to soft contact lens fitting Eye Contact Lens,
6 Neadle SW et al. Do presbyopes prefer progressive spectacles or multifocal contact lenses? BCLA abstract May 2010.
Indie Grewal is an optometrist and franchise partner with Leightons in St Albans. Keith Tempany owns an independent practice in Dorset and was the winner of Contact Lens Practitioner of the Year at the 2014 Optician Awards