Managing Adults with Myopia

There are some assumptions that eyes stop growing and progressing by around the age of 18. However, in everyday practice we see that this is often not the case. Adults frequently report worsening of their vision and we see progression in their refraction. The COMET studies¹ showed that 50% of children stabilise by age 15–16, which means another 50% will continue progressing. While it is true that we expect less progression with increasing age, adults can progress in their myopia well into their 20s. In a recently published Australian study² it was found that myopia progression in refraction and axial length continues for one-third of adults between age 20 and 28, albeit at a slower rate than during childhood years. As well, 14% of these adults had new onset of myopia during this time. This landmark study is the first known report of measured axial length changes in adult patients, proving that many adult eyes continue to elongate past age 18.

As adults generally don’t progress as rapidly as children, cases of significant myopic shift should be carefully evaluated with cycloplegic refraction

ASSESSING PROGRESSION

Axial length is not commonly measured in adults, mainly due to a lack of biometry instrumentation in standard optometric settings. But axial length is the gold standard for monitoring progression because of its objectivity, sensitivity, and repeatability. Refractions are dependent on patients’ subjective responses and practitioner decision making, and measurement uncertainties affect our assessment of progression. Axial length, which is about 10 times more sensitive at detecting change, is particularly helpful in high myopia cases, where accurate subjective refraction is more challenging and spectacle prescriptions are easily influenced by the effects of vertex distance. As adults generally don’t progress as rapidly as children, cases of significant myopic shift should be carefully evaluated with cycloplegic refraction to exclude potential effects of over-accommodation from sustained near work. Practices with biometry can use axial length as the metric going forward to monitor change.

Figure 1. Optic zone size difference between customised adult OK lens (left) and a child’s OK lens (right).

In cases of refractive progression in the absence of axial length changes, progression may be attributed to accommodation or other ocular changes, such as corneal curvature or crystalline lens thickness, meaning myopia management strategies may not be applicable in some cases. Corneal topography is recommended for patients with unusual progression in their myopia and astigmatism, to rule out the possibility of keratoconus.

MYOPIA MANAGEMENT OPTIONS FOR ADULTS

We have a range of effective optical and pharmaceutical options available to manage myopia progression in children: orthokeratology (OK), multifocal soft contact lenses, peripheral defocus spectacle lenses and atropine. The evidence base for these interventions in children is strong. For adults, we could offer the same options, however myopia management research for the adult population is lacking and we are unable to ascertain the effectiveness of these treatments. To date, there are no randomised controlled trials involving adult patients, and only limited data for adult OK based on small case studies.

If an adult patient is showing myopia progression, particularly measured axial elongation, we could offer myopia management as an off-label intervention, extrapolating what we know from research in children. To avoid setting potentially unreasonable expectations, care should be taken not to make guarantees about treatment effectiveness. We must also consider the visual implications of prescribing these treatments to adults, who have very different visual demands than children.

OK is an attractive option for adults who wish to enjoy clear daytime vision without glasses, and without the potential dryness issues of regular soft contact lenses. Of the 1,300 or so patients in my clinic currently wearing OK, around 20% are adult patients – some solely for the purpose of vision correction, and others with the intention of preventing further progression of their myopia. As all my OK lenses are custom-designed, I am able to make different design decisions when fitting OK to an adult versus a child.

Figure 2. Optomap image of a repaired retinal detachment in a patient with high myopia.

When aiming to maximise myopia control efficacy for children, I tend to design with small optic zone diameters that produce smaller treatment zones, moving the ring of mid-peripheral corneal steeping closer to the pupil margin. This helps maximise the amount of peripheral retinal myopic defocus generated by the OK treatment. For adults, however, such an aggressive design is likely to be difficult to tolerate, as the aberrations will cause significant halos and flare when driving at night and performing work in low-light conditions. Large optic zones are generally used for adult OK patients (Figure 1).

When it comes to OK, patient selection is important. Moderate-to-high myopia patients should be advised of OK vision expectations, such as slight variations in day-to-day unaided vision, halos around lights, reduced contrast in low light due to the induced aberrations, and the need for regular sleeping patterns. Consider the patient’s personality also; with OK we are not necessarily aiming for consistent 6/6 vision but to enjoy good, functional vision without daytime correction. Adaptable and easy-going patients will be the happier ones.

Atropine is commonly used in younger children, but maybe less appropriate for adults. Kids have large amplitudes of accommodation, and most can easily cope with the mild cycloplegic effects of atropine up to 0.05%. Adults may experience near blur symptoms with atropine because accommodation reduces with age. If a decision is made to prescribe atropine for an adult, begin with a low dose and schedule a review several weeks after commencing treatment to determine if a near addition is required, and the type of vision correction to be worn during treatment.

I have frequently prescribed multifocal soft contact lenses as a treatment for adult myopic patients with progression. This is a particularly good option in cases of high myopia where OK may not be suitable for the patient due to their refraction, corneal curvatures, or topography. Many adults are already soft contact lens wearers, so moving them from a single vision lens to a multifocal design is a relatively straightforward task. Of course, we do need to forewarn them that the optics are different, that they may initially notice ghosting or halos in dim light, a slight reduction in contrast, and there may be an adaptation period involved. Centre-distance multifocal lenses, such as the CooperVision Biofinity Multifocal and the VTI NaturalVue Multifocal 1 Day, are suitable options. While the CooperVision MiSight 1 day is one of my preferred soft lens treatments in children, with strong evidence for its effectiveness, in my experience adult patients find it difficult to adapt to this dual-focus design. When it comes to selecting the contact lens add power, adults are generally more comfortable in a lower add than we might optimally prescribe for children, keeping in mind the treatment ‘dose’ is potentially less. The distance minus power might also need to be slightly increased (typically -0.25D to -0.50D) to enhance distance visual acuity – this should be clearly communicated to patients who can be sensitive and concerned to see their lens power higher than they have worn in their single vision contact lenses.

The role of binocular vision in myopia development is not yet entirely clear, but there appears to be an association between high myopia and near esophoria.³ For adults exhibiting myopia progression, it is worth assessing their near phoria to determine if a near esophoria may be a risk factor contributing to their progression. Patients with near esophoria may benefit, at least in terms of near focussing efficiency and comfort, from having a near addition in the form of progressive addition spectacle lenses. OK has also been found to result in an exophoric shift in adult wearers, compared to those who wear single vision soft contact lenses,4 making it worth considering for patients who are showing progression, exhibiting near esophoria, and prefer to be glasses-free.

OCULAR HEALTH

Myopia is a disease with life-long risks of ocular complications. Cataract, glaucoma, myopic maculopathy, and retinal detachment are among the eye diseases associated with myopia. These pathological conditions tend to occur in middle-to-late adult life. Part of our role in primary care optometry is to educate adults with myopia – particularly those with high myopia – about these risks. For every dioptre of myopia, the risks of myopic maculopathy increase by 67%. Eyes with axial length of 26mm are at higher risk, and those with eyes exceeding 30mm have an extreme risk of vision impairment.⁵

The International Myopia Institute (IMI) Clinical Management Report (2019) recommended dilation fundus examination of the centre and peripheral retina, annually in high myopes and in others as indicated. The latest ophthalmic diagnostic instruments, such as optical coherence tomography (OCT) and ultra-widefield (UWF) imaging, allow for earlier detection and more precise monitoring of ocular pathologies.

With the aim to provide the best ongoing care for patients with myopia, our clinic invested in the Topcon Maestro OCT for imaging of the central retina, optic discs and macula screening; the Zeiss Humphrey Field Analyzer 3 for glaucoma testing; and the Optos California for peripheral retinal imaging. Optomap, a laser scanning ophthalmoscope, which takes a 200 degreewide image in a single shot without dilation, is invaluable in our clinic for our high myopia patients. It is particularly helpful for routine screening and documentation of any peripheral retinal changes, as well as educating patients and giving them peace of mind.

Adult patients who have had refractive surgery can often have a false sense of security about their ocular health. They may erroneously assume their myopia has been ‘cured’ and hence, miss their routine eye tests. A 36-year-old patient, who recently returned for review one year after a retinal detachment in her right eye, is a vivid reminder of why we do myopia management, and why we need to constantly remind high myopia patients of their risks of ocular pathologies. A high myope with axial length of 30.35mm who had refractive surgery about 15 years ago, she came to see me with complaints of photopsia and blurred vision onset a few days prior. She was promptly referred for retinal repair for a detachment encroaching on her macula; fortunately, her vision was able to be saved. Her spectacular Optomap image speaks a thousand words (Figure 2).

COUNSELLING PATIENTS

Sometimes our job as optometrists isn’t just to assess and treat our patients’ eyes, but also to provide counsel. Many adult patients with high myopia come in quite upset, worried about their eye health, their level of myopia, and that it might still be progressing. They may be saddened because they missed out on myopia management when they were younger. Perhaps they were not aware or offered such interventions, or they grew up in times when evidence-based myopia management did not really exist. Some patients are so concerned about their eyes, even if their myopia is not currently progressing, that they wish to explore the options to avoid any further deterioration. It’s important to assure them that their eyes are healthy, that further changes are unlikely, and that we will continue to monitor them closely. All high myopia patients should be reminded to watch for any sudden onset of new symptoms, and to avoid extreme sports and activities that may increase the risks to their eye health.

CONCLUSION

As myopia management in children becomes increasingly discussed in the community, we can expect more adults to make enquiries about myopia management for themselves. Young adults in their 20s can develop and progress in their myopia, and some may benefit from interventions to slow their progression. Monitoring progression accurately is essential, either via cycloplegic refraction or ocular biometry to track axial length changes.

While we don’t yet have evidence for treatment options in adults, with informed consent we can try the tools we have to treat children, while setting realistic expectations for treatment outcomes and quality of vision. Adults with myopia, especially those with high myopia, will need ongoing eye health assessments due to their heightened lifelong risks of ocular pathology and vision impairment.

The key to keeping myopia levels low for the best outlook in eye health is to start intervention as early as possible. So, let’s focus on driving forward myopia management in children, and also do our best to look after adults with the same condition.

Philip Cheng B.Optom, GCOT, FIAOMC is the clinical director of The Myopia Clinic in Melbourne. He has a particular interest in myopia management and orthokeratology. 

References 

1. Jane Gwiazda, Leslie Hyman, Mohamed Hussein, et al. The COMET Group; A Randomized Clinical Trial of Progressive Addition Lenses versus Single Vision Lenses on the Progression of Myopia in Children. Invest. Ophthalmol. Vis. Sci. 2003;44(4):1492-1500. doi: https:// doi.org/10.1167/iovs.02-0816. 
2. Lee SS, Lingham G, Sanfilippo PG, et al. Incidence and Progression of Myopia in Early Adulthood. JAMA Ophthalmol. 2022 Feb 1;140(2):162-169. 
3. Chung KM, Chong E. Near esophoria is associated with high myopia. Clin Exp Optom. 2000 Mar-Apr;83(2):71-75. 
4. Gifford K, Gifford P, Hendicott PL, Schmid KL. Near binocular visual function in young adult orthokeratology versus soft contact lens wearers. Cont Lens Anterior Eye. 2017 Jun;40(3):184-189. 
5. Tideman JW, Snabel MC, Tedja MS, et al. Association of Axial Length With Risk of Uncorrectable Visual Impairment for Europeans With Myopia. JAMA Ophthalmol. 2016 Dec 1;134(12):1355-1363. doi: 10.1001/ jamaophthalmol.2016.4009.