Hints on How to Identify that Non-Adapter

If you've been in optical practice for any length of time, you've most likely encountered at least one patient returning with their new glasses claiming they're "unusable". This situation can apply to all types of spectacle lenses, from multifocals to extended focus to single vision lenses. In essence, you have a non-adapter. Both first-timers in glasses and even existing spectacle wearers can experience non-adaptation.

The Problem with Non-Adaptation

Also known as non-tolerance, non-adaptation is when a patient experiences symptoms of discomfort due to their glasses. The experience of non-adaptation can arise from dispensing errors or factors relating to the ability of the patient to adapt. One systematic review and meta-analysis found the causes of non-tolerance to fall under one or more of the following issues:¹

• Error in refraction (47.7%)
• Lacking communication (16.3%)
• Suboptimal dispensing (13.5%)
• Simple non-adaptation (9.7%)
• Data entry error (8.7%)
• Binocular vision dysfunction (7.4%)
• Ocular pathology (6.4%)

Patients returning with their glasses due to intolerance is a problem, first and foremost, because it erodes confidence in the skill of both your optometrist and your dispenser. Even if the root of the difficulty is the patient's inability to adjust their head posture appropriately when reading in a multifocal, many will believe it was your practice staff's fault for giving them the wrong lens or advising them incorrectly.

In the best-case scenario, a patient needs to be given more coaching on using their new lenses and encouraged to allow more time for adaptation. In the worst-case scenario, the patient demands a refund and never returns while also advising their friends and family away from your practice.

Hints on Preventing Non-Adapters

Though it may not be possible to never encounter a non-adapter again, there are some steps you can take to identify a potential non-adaptation situation before it occurs. It can take a team effort from your optometrist and optical dispensers to ensure a patient is satisfied with their new glasses.

1. Get the prescription right.

Optometrists know that this can sometimes be easier said than done. The visual system can be fairly complicated. In addition to an accurate refraction, consider whether the refraction is comfortable for your patient. One way of doing this is to allow your patient to look around and take a few steps while wearing your proposed script in a (properly fitted) trial frame. Although you may have gotten each eye to 6/4.8 monocularly on the VA chart, are they comfortable binocularly? Are they a young hyperope who doesn't want or need the full plus? Does this patient need prism? An adult patient being corrected for astigmatism for the first time may need some gentle weaning into their full script over an extended period.

2. Take the time to understand your patient’s requirements.

Some practices may find they are getting patients returning with their single vision reading glasses saying they're not suitable for the computer. Though the glasses may be perfect for reading a book or a tablet, the patient spends most of their time on a desktop monitor, which is what they were expecting to use the glasses for. Another similar pitfall is prescribing a first pair of multifocals for a presbyopic patient who works on a computer the whole day. Though technology in multifocal lens design has come a long way, they remain the suboptimal lens choice for prolonged desktop computer work.

Though you may feel you know exactly what the patient needs, taking a few extra minutes to determine exactly what they want from their glasses, and where their problems lie, can make all the difference in a satisfied or dissatisfied patient. If a myopic patient is happy with their unaided near vision and is very content to remove their single vision distance glasses for reading, do they really need a multifocal and the adaptation period that comes with it? Many myopic patients, after spending hundreds of dollars on a pair of multifocal glasses, continue to habitually remove them for near vision.

3. Does the patient have contraindications to multifocal wear?

In theory, multifocal glasses should be suitable for most presbyopic patients for at least part of their daily activities. However, in reality, some patients are unable to adapt to multifocals easily if at all. Some may have difficulty finding the clear point in the lens for their activity while others can experience severe symptoms of blurry vision, headaches, swim in the peripheral field, difficulty with balance, and nausea.² This list is not extensive, but contraindications to multifocal wear can include:

• Pre-existing problems with gait or balance
• A history of motion sickness
• Vocational requirements that don’t work with multifocals, such as needing to look at close overhead screens at work
• Ocular pathology resulting in increased reliance on peripheral vision

One study also found that people with weaker convergence and phoria adaptation, and reduced vergence facility were more likely to fail adaptation to multifocal lenses.² It may therefore be worthwhile assessing vergence facility before recommending multifocal lenses to a first-time wearer.

4. Consider frame fitting.

Spectacle frames are more than just a fashion statement. A well-fitted frame should be chosen with the prescription, lens type, and patient’s facial features in mind.

If the prescription is over +/-4 dioptres, lens effectivity begins to come into play. If the optometrist has refracted a -8.00D in the trial frame with a back vertex distance (BVD) of 20mm but the frame the patient chose sits at a distance of 12mm from their eyes, they are effectively looking through a -8.55DS. If this patient is an early presbyope, this increase of half a dioptre of minus may be enough to make near work suddenly uncomfortable. It is good practice to record the BVD used during refraction if effectivity is expected to come into effect; many lens labs are able to account for this accordingly.

Patients with particularly deep-set eyes and prominent nose bridges may not be good candidates for multifocal wear. This is because the frame sits too far from the ocular surface, resulting in a keyhole effect and a reduction in the useful field of view.

5. Dispense accurately.

Ensuring pupillary distances (PDs) and optical centres are measured accurately can make all the difference to adaptation. As well as monocular PDs often being asymmetrical, bear in mind that convergence is also not always symmetrical between the eyes, so it is worthwhile checking near PDs rather than making assumptions.

Decentration of the optical centres can induce prismatic error; the greater the decentration, the greater the error and the more likely the patient feels symptomatically uncomfortable in their new glasses. Note that on occasion, prismatic error, especially base-in, can sometimes work in the patient’s favour. This can be true for patients with reduced convergence amplitude at near.

Summary

Minimising the number of patients returning due to non-adaptation to their new glasses is of benefit to your practice in a multitude of ways. While it may be impossible to identify every single non-adapter in advance, there are steps you can take to ensure you have as many satisfied spectacle wearers as possible.