Accommodation and Myopia Revisited: From Causal Hypothesis to Clinical Phenotype

Dr. Alex Ong¹, FAAO, FOWNS, CPNP (US);

¹ Ong’s Optics Myopia Management Centre;

Richie Huang², Optometrist, FOWNS, CPNP (US)

² JD Optometry

 

Introduction

Accommodation has had a complicated relationship with myopia.

For several decades, accommodative lag was considered a plausible mechanism linking sustained near work with childhood Myopia. If the accommodative response consistently fell short of near demand, the resulting hyperopic retinal defocus was hypothesised to provide a stimulus for axial elongation. This reasoning contributed to interest in bifocal and progressive-addition lenses (PALs) as potential interventions for slowing myopia progression.

The evidence accumulated since then has substantially weakened this simple causal model. Longitudinal studies have not consistently demonstrated increased accommodative lag before Myopia onset, and accommodative lag has not proved to be a reliable predictor of subsequent Myopia progression. Large, randomised trials of conventional PALs have likewise shown only modest average treatment effects. ^(1–4)

Contemporary Myopia management has therefore moved appropriately toward interventions with stronger and more consistent evidence for controlling excessive ocular growth. Conventional PALs and bifocals should not be reconsidered as first-line Myopia-control treatments based on accommodative lag.

That, however, addresses only one question, but it does not establish that accommodation is clinically irrelevant in every child who has Myopia. This distinction is the focus of this perspective. Rather than asking whether accommodative lag should be restored as a dominant explanation for childhood myopia, a more clinically useful question may be:

Does accommodative function matter in this particular Myopic child?

These reframing separates three related but non-equivalent issues: the mechanisms underlying Myopia development, the efficacy of treatments intended to slow axial elongation, and the management of accommodative or binocular dysfunction in an individual child.

Accommodation may no longer occupy the centre of contemporary Myopia theory, however, it may nevertheless remain part of comprehensive Myopia care.

From a Causal Hypothesis to a More Nuanced Model

Accommodation provides the additional optical power required for clear near vision. When the accommodative response is smaller than the accommodative stimulus, accommodative lag occurs.

Historically, this underaccommodation was proposed to generate Hyperopic retinal defocus during sustained near viewing. Experimental evidence demonstrating that retinal defocus can influence ocular growth made the hypothesis biologically plausible, while several studies reported differences in accommodative behaviour between Myopes and emmetropes. ^(1,5–7)

The therapeutic logic appeared straightforward:

If accommodative lag contributes to Myopia progression, reducing accommodative demand might reduce progression.

This became one rationale for investigating bifocals and PALs. The difficulty was establishing temporality.

The Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) study provided one of the strongest challenges to the original model. Mutti and colleagues examined accommodative behaviour around the onset of Myopia and found that substantial increases in accommodative lag were not consistently present before children became Myopic. Greater lag became more evident after Myopia onset. ⁽²⁾ They concluded that increased Hyperopic defocus associated with accommodative lag might represent a consequence rather than a cause of Myopia.

Berntsen and colleagues subsequently studied 592 Myopic children and found that accommodative lag did not predict subsequent annual Myopia progression. ⁽³⁾ Other longitudinal studies have likewise failed to demonstrate a simple or consistent relationship between lag and progression. ⁽⁸⁾

These findings make the sequence: near work → accommodative lag → hyperopic defocus → axial elongation difficult to support as a universal explanation for childhood Myopia. The distinction between Myopia onset and subsequent progression is nevertheless important.

Recent synthesis of the accommodation and binocular-vision literature suggests that these factors are unlikely to represent major causal drivers of myopia progression, while leaving greater uncertainty regarding whether accommodative or vergence characteristics may contribute to the circumstances surrounding myopia onset in selected children. ⁽⁹⁾

The contemporary position should therefore not be that accommodation has been definitively proven irrelevant to refractive development. A more defensible conclusion is narrower:

Accommodative lag is not a sufficiently consistent population-level predictor or therapeutic target to serve as a primary basis for contemporary Myopia-control treatment.

That conclusion is important, but it is not the same as saying that accommodative function has no clinical relevance once a child is Myopic.

What the PAL Trials Actually Established

The Correction of Myopia Evaluation Trial (COMET) randomised 469 Myopic children aged 6–11 years to +2.00 D PALs or conventional single-vision spectacles. ⁽⁴⁾ After three years, refractive progression was −1.28 D in the PAL group and −1.48 D in the single-vision group. Axial elongation was 0.64 mm and 0.75 mm, respectively.

The treatment difference was therefore approximately 0.20 D and 0.11 mm.

The effect was statistically significant but clinically modest, with much of the difference occurring during the first year. The investigators concluded that the magnitude of benefit did not justify a change in routine clinical practice. ⁽⁴⁾

A secondary analysis identified a subgroup of children with larger accommodative lag and near esophoria who appeared to obtain a greater treatment effect, initially raising the possibility of an accommodation-related treatment phenotype. ⁽¹⁰⁾

However, this signal was not reproduced to the same magnitude when subsequent studies deliberately targeted children with high accommodative lag and near esophoria. COMET2 demonstrated approximately 0.28 D less progression over three years, while the Study of Theories about Myopia Progression (STAMP) trial similarly produced modest effects. ^(11,12)

Taken together, these findings do not support using high accommodative lag as an indication for conventional PALs as a primary Myopia-control strategy.

That conclusion should be stated clearly.

The significance of these trials for the present discussion lies elsewhere.

They demonstrate the difficulty of moving from an observed physiological characteristic to an effective treatment strategy. Even if accommodation differs between some Myopic and non-Myopic children, modifying accommodative demand does not necessarily translate into clinically meaningful control of axial elongation.

Treatment efficacy and physiological association are not interchangeable concepts.

Executive Bifocals and the Problem of Mechanistic Interpretation

Executive bifocal studies add an important qualification, although not necessarily in support of the accommodative-lag hypothesis.

Cheng and colleagues randomised 135 progressing Chinese-Canadian children to single-vision spectacles, +1.50 D executive bifocals, or executive bifocals incorporating 3Δ base-in prism. ⁽¹³⁾

After three years, Myopia progression was −2.06 D with single-vision spectacles, −1.25 D with executive bifocals, and −1.01 D with prismatic executive bifocals. Corresponding axial elongation was 0.82 mm, 0.57 mm, and 0.54 mm. These effects were substantially larger than those generally reported with conventional PALs. ⁽¹³⁾

However, executive bifocals should not be interpreted simply as stronger evidence that reducing accommodative demand slows Myopia. Their optical architecture differs materially from conventional PAL designs. A large portion of the inferior visual field is exposed to additional positive power, and prism may modify binocular demands. The intervention therefore changes not only accommodation but also retinal optics.

The 2025 International Myopia Institute review accordingly raises the possibility that the effects of executive bifocal designs may partly reflect the larger retinal area exposed to positive power rather than reduction of accommodative demand alone. ⁽¹⁾

This distinction is important.

An intervention may have been developed from one biological hypothesis yet produce its effect partly through another optical mechanism.

Executive bifocal efficacy therefore cannot be regarded as direct confirmation of accommodative lag as a driver of axial elongation.

Treatment Efficacy Is Not the Same as Clinical Function

This distinction leads to the central argument of this perspective. Evidence that conventional PALs provide insufficient Myopia-control efficacy does not establish that accommodation itself is clinically irrelevant.

Accommodation is a physiological function.
PAL efficacy is a treatment outcome.

They are related, but they are not equivalent.

Contemporary guidelines appropriately prioritise interventions with stronger evidence for controlling childhood Myopia. The 2025 Singapore Consensus Guidelines, for example, recommend against conventional bifocal and progressive-addition spectacle lenses as Myopia-control interventions because their clinical efficacy is inadequate relative to contemporary treatment standards. ⁽¹⁴⁾

That recommendation is consistent with the direction of current evidence and should not be interpreted as controversial.

Children with progressive myopia should not remain on inadequately effective interventions for excessive ocular growth when more effective evidence-based options are appropriate and available.

The important clinical boundary is different.

A child may simultaneously have progressive Myopia and an independently diagnosed accommodative or binocular disorder. In that situation, a PAL or bifocal may have a legitimate visual-function indication without being presented as an adequate primary treatment for axial elongation.

Conversely, prescribing an evidence-based Myopia-control intervention does not automatically establish that an accompanying accommodative or binocular dysfunction has been resolved.

These are separate therapeutic objectives.

Deprioritising an intervention for Myopia control is not equivalent to disproving a physiological function, and neither is it equivalent to eliminating an independent clinical indication.

Accommodation as Part of the Myopic Child’s Clinical Phenotype

A more useful contemporary position may therefore be to regard accommodation as part of the child’s clinical phenotype rather than as a universal mechanism of Myopia. Population-level evidence asks whether accommodative characteristics predict the development or progression of Myopia across groups of children.

Clinical assessment asks a different question:

Does this individual child demonstrate accommodative or binocular findings that are meaningful for symptoms, visual performance, treatment tolerance, or near-task function?

The World Council of Optometry Myopia Management Navigator continues to include accommodative and binocular-vision testing among the assessments relevant to children with myopia. ⁽¹⁵⁾ The IMI Clinical Management Guidelines likewise recognise binocular vision and accommodation as components of clinical evaluation. ⁽¹⁷⁾

This does not imply that these measurements should be used to determine whether a child requires Myopia control. Nor does it imply that every Myopic child requires treatment directed at accommodation.

It means that a diagnosis of Myopia does not remove the need to consider the functioning visual system.

A recent scoping review of accommodation and binocular coordination reached a similarly balanced conclusion. Accommodative and binocular abnormalities do not appear to be major causal determinants of Myopia progression, but selected children, particularly those with clinically meaningful or symptomatic binocular abnormalities, may still require appropriate management. ⁽⁹⁾

This provides a useful distinction between epidemiological mechanism and individual clinical phenotype.

An abnormality does not need to explain axial elongation before it can become clinically relevant.

Two Children with the Same Myopia May Not Require Identical Care

Consider two 10-year-old children, both with −2.00 D of Myopia and approximately 0.35 mm of axial elongation over the preceding year, considered excessive in the context of their age and clinical history.

The first has an appropriate accommodative response, normal facility and near phoria, and no near-vision symptoms. The second demonstrates substantial accommodative lag, reduced facility, near esophoria, and headaches during prolonged near work.

Both require evidence-based management of excessive ocular growth, but their complete Optometric management should not necessarily be identical.

The second child has an additional visual-function problem. A Myopia-control intervention may reduce axial progression without addressing accommodative or binocular dysfunction. Conversely, a near addition prescribed for an established visual-function indication should not be assumed to provide adequate contemporary Myopia control.

This distinction suggests two complementary domains of care:

Ocular-growth management determine whether refractive and axial progression are excessive and select an evidence-based intervention aimed at reducing further progression. Accommodation should not be used as a surrogate for these outcomes.

Visual-function management identify clinically meaningful accommodative or binocular dysfunction affecting symptoms, near performance, visual comfort or treatment tolerance, and manage it according to its own clinical indication.

This distinction may be particularly relevant during contemporary Myopia treatment. Dual-focus and multifocal Contact Lenses, Orthokeratology and Myopia-control spectacle lenses alter the child’s optical environment, while atropine can influence accommodation in a concentration-dependent manner. The 2025 IMI Digest indicates that accommodative and binocular changes associated with these interventions are generally small and do not appear to account for their Myopia-control efficacy. ⁽¹⁵⁾ This supports an important distinction: accommodation may not explain why a treatment controls axial growth, yet accommodative and binocular function may still matter to how an individual child functions while receiving that treatment.

The therapeutic endpoints are therefore different: control of ocular growth in one domain and optimisation of visual function in the other. A treatment appropriate for one should not automatically be assumed to fulfil the other.

This approach avoids two opposite errors: returning to accommodation as a universal explanation for Myopia, or assuming that once axial elongation is being controlled, accommodative and binocular function no longer matter.

Contemporary Myopia care may therefore need to answer two questions:

“Is this child’s excessive ocular growth being adequately controlled?”

and

“Does this child have an accommodative or binocular problem that also requires management?”

Treating Myopia or Treating the Myopic Child?

Modern Myopia management has appropriately shifted attention toward excessive axial elongation and its associated long-term ocular risks. However, successful care should not become simply:

measure axial length → prescribe treatment → measure axial length again.

Axial length is a critical clinical outcome, but it does not represent the entire visual system. Children may experience accommodative or binocular dysfunction irrespective of whether these abnormalities caused their Myopia.

The appropriate response is therefore neither to restore accommodation as a universal explanation for Myopia nor to disregard it because that hypothesis has weakened. A more proportionate approach is to assess accommodation when clinically relevant, interpret it in context, and manage it when a genuine visual-function indication exists, while excessive ocular growth continues to be treated using interventions supported by contemporary Myopia-control evidence.

These objectives are complementary rather than competing: we are not only treating myopia; we are caring for the Myopic child.

Conclusion

Accommodation deserves a different position in contemporary Myopia management from the one it occupied several decades ago. The evidence no longer supports a simple universal model in which accommodative lag produces sustained Hyperopic defocus that subsequently drives childhood Myopia progression. Longitudinal studies have substantially weakened that hypothesis, while conventional PALs generally demonstrate limited and inconsistent efficacy compared with contemporary Myopia-control interventions.

This perspective does not argue for restoring conventional PALs or bifocals as first-line Myopia-control treatments. However, limited efficacy should not automatically be equated with no efficacy, and an intervention that is no longer preferred should not necessarily be labelled ineffective.

Clinical trials of PALs and bifocals have not produced uniformly negative results. Average treatment effects have generally been modest, while some studies, optical designs and selected populations have demonstrated greater effects. These findings neither establish accommodation as a universal mechanism of Myopia progression nor justify positioning accommodation-based approaches alongside more consistently effective contemporary treatments. They do, however, make categorical dismissal difficult to justify.

The distinction is important: not sufficiently effective for routine first-line use is not necessarily the same as having no clinical effect or no potential role in an individual child.

Moving accommodation away from the centre of Myopia theory should therefore not mean removing accommodative and binocular function from clinical consideration. Accommodation should not be treated simply because accommodative lag is assumed to cause Myopia, but neither should it be dismissed when an individual child has a genuine accommodative or binocular indication.

The clinical question has evolved. Rather than asking only “Does accommodation cause Myopia?”, perhaps the more relevant question for contemporary practice is: “Does accommodation matter in this child?”

Recognising that distinction is not a return to an outdated theory. It is a more proportionate and individualised interpretation of the evidence.

 

References

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About the Authors

Dr. Alex Ong, DOptom, FAAO, FOWNS, CPNP (US)
Optometrist, Singapore
PGCert (Anterior Eye Diseases, Cataract & Glaucoma)
PGCert (Retinal Disease Recognition and Co-Management)
MSCO, B.Sc Optom, Dip. Optom

Dr. Ong is the Founder and Managing Director/Optometrist at Ong’s Optics Myopia Management Centre, established in 2005 and 2^nd generation owner of Ong’s Optics & Contact Lens Centre, established in 1985. With over two decades of clinical experience, his expertise spans evidence-based myopia management, ocular nutrition, binocular vision, orthokeratology, and geriatric vision care. He serves as a Key Opinion Leader for Menicon Japan and has taught as an adjunct lecturer at both optometry schools in Singapore. Dr. Ong is actively involved in optometric education and professional training across Asia. As a Certified Personalised Nutrition Practitioner (CPNP) with the American Nutrition Association, he integrates nutritional science with vision care to promote a proactive and preventive model of lifelong eye health. He is also a member  and fellows of American Academy of Optometry (AAO) and Ocular Wellness and Nutrition Society (OWNS).

 

Richie Huang, B.Sc. Optom, FOWNS, CPNP (US) Optometrist, Taiwan

Richie Huang is a practicing Optometrist and founder of JD Optometry Group in Taiwan. He is also the current President of the New Taipei City Optometrists Association and was the Past President of the Taiwan Optometrists Association (TOA). He specialises in elderly vision care and children’s vision development, combining clinical expertise with a strong commitment to professional education. As a Certified Personalised Nutrition Practitioner with the American Nutrition Association and members and Fellows of OWNS, his work covers within visual nutrition, paediatric myopia management, binocular vision and geriatric vision care, with strong engagement in public education and professional training. His passion for optometry is reflected in his ongoing contributions to public awareness and his leadership in advancing eye care standards across Taiwan.