Binocular Vision

Myopia Management & Binocular Vision Issues: Treat Simultaneously or BV First?

April 3, 2023

By Tim Fricke, BOptom, MSc, FAAO, Consultant, Brien Holden Vision Institute

It is worth looking for mutual benefits — constructive interference — between myopia and binocular vision issues to enable successful, simultaneous management. Intelligent assessment and diagnosis of each condition and understanding how one can affect the other will enable this. 

Myopia Management and Binocular VisionMyopia and binocular vision issues are among the most common conditions affecting children. Myopia prevalence varies most wildly — age, location, and other variables give rates anywhere between 2% (e.g., 7-year-olds in Northern Ireland,1 and 8-year-olds in Ethiopia2) and 80% (e.g., 15-year-olds in South Korea,3 and a subgroup of 18-year-olds in Israel4). The prevalence of binocular vision issues hovers between about 5% and 25% depending more on definitions than age and location.5,6 At these rates, we are bound to find both issues coexisting in children presenting for care.

The Occam’s razor philosophy suggests the solution with the fewest components is most likely correct. So, rather than looking at myopia and binocular vision issues as two independent problems when they present together in the same child, it is tempting to look for a single causative factor of both, then target management at that. However, while there are theories linking causative factors for myopia and binocular vision issues, there is little evidence in support. In practical terms, no binocular vision treatments will make myopia disappear, nor vice versa. So at some point, we will likely need to target treatments independently.

Binocular vision issues and myopia commonly cause symptoms that our patients want resolved, with short-term relief and long-term normalization and/or harm minimalization. The following principles and tips may be useful in these cases.

Ensure a thorough assessment and reach considered diagnoses:

  • Some binocular vision issues (e.g., accommodative excess, with or without convergence insufficiency) can generate pseudo-myopia (accommodation that remains during non-cycloplegic refractions). Cycloplegic refraction is the best way to differentiate pseudo-myopia from real myopia.
  • There are many ways to assess accommodation and vergence. Baseline assessment could include a battery such as history (i.e., are their symptoms consistent with a binocular vision issue?), posture (i.e., distance and near phoria for vergence7 and dynamic retinoscopy for accommodation8), vergence ranges,9 accommodative facility,10 and AC/A ratio.11 Results should enable the classification of binocular vision as normal, excess (accommodation, vergence, or both), or insufficient (accommodation, vergence, or both).12

Recognize the possibility of destructive interference in the simultaneous management of myopia and binocular vision issues:

  • Accommodation is affected by low-dose atropine for myopia control, even at the lowest concentration of 0.01%.13 When concentration is matched to individual pigmentation, low-dose atropine rarely has symptomatic accommodation effects. A significant exception is when there is pre-existing accommodation insufficiency. Even an asymptomatic tendency to accommodative insufficiency can become symptomatic after starting low-dose atropine for myopia control. If managing myopia with low-dose atropine in someone with accommodation insufficiency, baseline binocular vision measurements are essential, as is either forewarning your patient/family, or averting the complication by simultaneously prescribing bifocal14 or progressive addition15 spectacles.
  • Bifocal and progressive addition spectacle lenses show no anti-myopia effect in the presence of convergence insufficiency.14,15
  • Accommodation excess is unlikely to be controlled by orthokeratology, anti-myopia soft contact lenses,16,17 or spectacle18 lenses. Additionally, the anti-myopia effect of these treatments may rely on predictable peripheral refraction outcomes19 that may not occur in accommodation excess patients. While there is little evidence to guide us, I suspect accommodation excess patients are unlikely to do well with these myopia management options.

Recognize the possibility of constructive interference in the simultaneous management of myopia and binocular vision issues:

  • Convergence excess will tend to be alleviated by plus at near. This is clearest with bifocal spectacles (reasonable anti-myopia effects)14 or progressive addition spectacles (some anti-myopia effects),15 where the baseline AC/A ratio will indicate the likely binocular vision benefit. But it may also occur with anti-myopia soft contact lenses16,17 and spectacle18 lenses.
  • Accommodation excess, with or without a vergence component, may benefit from low-dose atropine.

Vision therapy is useful in treating binocular vision issues,20 but no concurrent anti-myopia effect has been shown:21

  • It is hard to predict constructive interference here. Still, any optical anti-myopia option (orthokeratology, novel soft contact lenses or spectacle lenses, even bifocal spectacles) should combine well with vision therapy for convergence insufficiency.
  • It is certainly worth avoiding making life harder than it needs to be! For example, accommodation insufficiency at the same time as low-dose atropine for myopia control is not recommended.

In summary, it is worth looking for mutual benefits — constructive interference — between myopia and binocular vision issues to enable successful, simultaneous management. Intelligent assessment and diagnosis of each condition and understanding how one can affect the other will enable this. 

 

Tim Fricke is an optometrist and international development practitioner. His research interests include vision development, binocular vision, epidemiology, quality of life, and access to care. He has taught pediatric and general optometry at multiple Australian, Asian, and African universities. He has been a Director at the Australian College of Optometry and the Brien Holden Foundation. He is a principal at MinneMerri Consultants, an honorary senior fellow at the University of Melbourne, and a PhD candidate at UNSW Sydney.

 

References

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