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 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.|
- O’Donoghue L, McClelland JF, Saunders KJ, et al. Refractive error and visual impairment in school children in Northern Ireland. Br J Ophthalmol 2010; 94(9): 1155-9.
- Assem AS, Tegegne MM, Fekadu SA. Prevalence and associated factors of myopia among school children in Bahir Dar city Northwest Ethiopia, 2019. PLoS ONE 2021; 16(3 March): e0248936.
- Kim H, Seo JS, Yoo W-S, et al. Factors associated with myopia in Korean children: Korea National Health and nutrition examination survey 2016-2017 (KNHANES VII). BMC Ophthalmol 2020; 20(1): 31.
- Bez D, Megreli J, Bez M, et al. Association between type of educational system and prevalence and severity of myopia among male adolescents in Israel. JAMA Ophthalmol 2019; 137(8): 887-93.
- Li L, Li B, Yang L-Y, et al. Current situation and analysis of convergence insufficiency of primary school students in Nanchong. Int Eye Sci 2020; 20(2): 366-9.
- Hashemi H, Nabovati P, Doostdar A, et al. The prevalence of convergence insufficiency in Iran: a population-based study. Clin Exp Optom 2017; 100(6): 704-9.
- Wong EP, Fricke TR, Dinardo C. Interexaminer repeatability of a new, modified prentice card compared with established phoria tests. Optom Vis Sci 2002; 79(6): 370-5.
- Rouse MW, London R, Allen DC. An evaluation of the monocular estimate method of dynamic retinoscopy. Optom Vis Sci 1982; 59(3): 234-9.
- Wesson MD, Amos JF. Norms for hand-held rotary prism vergences. Optom Vis Sci 1985; 62(2): 88-94.
- McKenzie KM, Kerr SR, Rouse MW, DeLand PN. Study of accommodative facility testing reliability. Optom Vis Sci 1987; 64(3): 186-94.
- Jimenez R, Perez MA, Garcia JA, Gonzalez MD. Statistical normal values of visual parameters that characterize binocular function in children. Ophthalmic Physiological Opt 2004; 24(6): 528-42.
- Scheiman M, Wick B. Clinical management of binocular vision, 2nd ed. Philidelphia PA, USA: LW&W; 2002.
- Tran HDM, Sankaridurg P, Naduvilath T, et al. A meta-analysis assessing change in pupillary diameter, accommodative amplitude, and efficacy of atropine for myopia control. Asia Pac J Ophthalmol 2021; 10(5): 450-60.
- Cheng D, Woo GC, Drobe B, Schmid KL. Effect of bifocal and prismatic bifocal spectacles on myopia progression in children: three-year results of a randomized clinical trial. JAMA Ophthalmol 2014; 132(3): 258-64.
- Gwiazda JE, Hyman L, Norton TT, et al. Accommodation and related risk factors associated with myopia progression and their interaction with treatment in COMET children. Invest Ophthalmol Vis Sci 2004; 45(7): 2143-51.
- Chamberlain P, Peixoto-de-Matos SC, Logan NS, et al. A 3-year randomized clinical trial of MiSight lenses for myopia control. Optom Vis Sci 2019; 96(8): 556-67.
- Lam CS, Tang WC, Tse DY, et al. Defocus Incorporated Soft Contact (DISC) lens slows myopia progression in Hong Kong Chinese schoolchildren: a 2-year randomised clinical trial. Br J Ophthalmol 2014; 98(1): 40-5.
- Lam CSY, Tang WC, Tse DY, et al. Defocus Incorporated Multiple Segments (DIMS) spectacle lenses slow myopia progression: a 2-year randomised clinical trial. Br J Ophthalmol 2020; 104(3): 363-8.
- Damani JM, Annasagaram M, Kumar P, Verkicharla PK. Alterations in peripheral refraction with spectacles, soft contact lenses and orthokeratology during near viewing: implications for myopia control. Clin Exp Optom 2022; 105(7): 761-70.
- Scheiman M, Mitchell GL, Cotter S, et al. A randomized clinical trial of treatments for convergence insufficiency in children. JAMA Ophthalmol 2005; 123(1): 14-24.
- Allen PM, Radhakrishnan H, Price H, et al. A randomised clinical trial to assess the effect of a dual treatment on myopia progression: the Cambridge Anti-Myopia Study. Ophthalmic Physiological Opt 2013; 33(3): 267-76.