October 1, 2021
By Noel A. Brennan, MScOptom, PhD, FAAO
We should reconsider the concept of “lag.” We have no idea how much accommodative lag there is in a given individual from clinical measures.
In their recent International Myopia Institute (IMI) report, Logan and colleagues wrote, “Current evidence does not point toward a role for accommodation and binocular vision in myopia development and progression.”1 The conclusion is appropriate and written with due care; it does not preclude an association, but it points toward lack of a cohesive evidence base for a causative role. To this end, the paper accurately states that “the role of accommodation and binocular vision in the development and progression of myopia is not fully understood” and that “further research is critical to understanding” their influence.
The authors are to be commended for their objective assessment of the knowledge in the field. Of course, this does not mean that binocular vision anomalies should not be addressed as part of holistic patient care, nor that the interaction of methods of myopia control and the binocular vision system should be ignored. Indeed, one article omitted from the cited papers in this IMI report is the article by Cheng et al. that considered the possible role of accommodative function on the efficacy of myopia control.2 The results from post-hoc analysis of this controlled, randomized, masked study advised that reduced accommodative response while wearing a myopia control soft contact lens “correlated with greater myopia progression,” suggesting that some subjects wearing this lens utilized the plus power afforded by the lens “for near viewing, inducing hyperopic defocus at the retina.” It seems that we do not want to relax accommodation, as has been proposed by some to reduce myopia progression — this is the demonstrably flawed principle behind using PALs to slow progression.3,4 Rather, it seems that accommodation should be fully functioning so as to “pull” the image shell as far forward as possible without restricting vision.
The Role of Accommodative Lag
A further revelation since the authors of the IMI report collated their information is a landmark publication on accommodative lag. Before discussing this paper, it is worth noting that there has been a considerable recent surge of belief, particularly among Chinese clinicians, that accommodative lag is involved in myopia development.5,6 There is little evidence to support this proposition. Certainly, Mutti et al. did not observe significantly elevated levels of measured accommodative lag prior to the onset of myopia in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study.7
However, the overall concept of accommodative lag is problematic. To paraphrase the description of Lopez-Gil et al., mismatch between (i) the image quality metric used to determine refractive state of the eye, and (ii) the focusing criteria used by the visual system to control accommodation, leads to spurious measurement of accommodative error.8 Other authors have also highlighted anomalies around measurement and understanding of accommodative lag.9-12
A recent paper on this topic should lay to rest the current widely accepted concept of accommodative lag. This incisive piece of work, entitled “Lags and leads of accommodation in humans: fact or fiction?” was recently published in the Journal of Vision.13 The authors made objective measures of refractive status in young adult subjects using a wavefront sensor and an autorefractor and found typical “measured” values of accommodative lag, in particular, and lead — similar to those that have been reported in the literature. However, they also performed subjective measures by placing a chromatic doublet offset lens optically at the pupil-conjugate plane. This placement enabled them to make changes in the optical distance of the stimulus at speeds (∼15 ms) less than those that would drive a change in accommodation. This part of the study allowed vision to be measured at distances around the stimulus distance without changes in accommodation. Remarkably, acuity was maximized very close to the stimulus distance up to a stimulus of 5D (see figure 1 for a typical example of one of the subjects). Thus, significant leads and lags of accommodation were not present despite their apparent existence from objective measures.
What Does This Tell Us?
There is a lot to unpack here. First and foremost, this work shows that clinical measures of accommodative lag are essentially meaningless for the purposes of understanding the accommodative system. Second, the measurements in this paper were made monocularly. Perhaps accommodative lag does exist when objects are viewed binocularly; however, the principle exposed by the authors persists in that conventional, objective, clinical measures will not accurately portray the accommodative status of the eye. Third, clearly an optical effect, which we have to date called “lag,” is still being measured clinically. So, what is this effect and what does it tell us? Previous authors implicate a change in the aberration structure of the eye, most specifically spherical aberration, during accommodation as the source of the artefactual measurements of lag.9,11,14 These real changes in the optics of the eye may affect the central and peripheral images at the retina and therefore actually be involved in myopia development. There is little doubt of the role of education and near work as risk factors in myopia development;15 further research is needed to shed light on the optical mechanisms involved.
So, what is the clinical relevance of the issues discussed here?
- First, eye care practitioners should absolutely assess and manage binocular vision in young myopes and pre-myopes, before, during, and after treatment to slow progression.
- Second, we should not attribute myopia susceptibility or progression to any binocular vision findings until a scientific evidence base for an association is established. Refractive error at a given age is the most reliable predictor of myopia onset that we currently have available.16
- Third, we should reconsider the concept of “lag.” We have no idea how much accommodative lag there is in a given individual from clinical measures.
Noel A. Brennan, MScOptom, PhD, FAAO, is Clinical Research Fellow, Myopia Control Platform, Johnson & Johnson Vision. This article is sponsored by Johnson & Johnson Vision.
- Logan NS, Radhakrishnan H, Cruickshank FE, et al. IMI Accommodation and Binocular Vision in Myopia Development and Progression. Invest Ophthalmol Vis Sci 2021;62:4.
- Cheng X, Xu J, Brennan NA. Accommodation and Its Role in Myopia Progression and Control with Soft Contact Lenses. Ophthal Physiol Opt 2019;39:162-71.
- Gwiazda J, Hyman L, Hussein M, et al. A Randomized Clinical Trial of Progressive Addition Lenses Versus Single Vision Lenses on the Progression of Myopia in Children. Invest Ophthalmol Vis Sci 2003;44:1492-500.
- Hasebe S, Ohtsuki H, Nonaka T, et al. Effect of Progressive Addition Lenses on Myopia Progression in Japanese Children: A Prospective, Randomized, Double-Masked, Crossover Trial. Invest Ophthalmol Vis Sci 2008;49:2781-9.
- Li SM, Kang MT, Peng XX, et al. Efficacy of Chinese Eye Exercises on Reducing Accommodative Lag in School-Aged Children: A Randomized Controlled Trial. PLoS One 2015;10:e0117552.
- Ma MM, Scheiman M, Su C, Chen X. Effect of Vision Therapy on Accommodation in Myopic Chinese Children. J Ophthalmol 2016;2016:1202469.
- Mutti DO, Mitchell GL, Hayes JR, et al. Accommodative Lag before and after the Onset of Myopia. Invest Ophthalmol Vis Sci 2006;47:837-46.
- Lopez-Gil N, Martin J, Liu T, et al. Retinal Image Quality During Accommodation. Ophthal Physiol Opt 2013;33:497-507.
- Collins M. The Effect of Monochromatic Aberrations on Autoref R-1 Readings. Ophthalmic Physiol Opt 2001;21:217-27.
- Subbaram MV, Bullimore MA. Visual Acuity and the Accuracy of the Accommodative Response. Ophthalmic Physiol Opt 2002;22:312-8.
- Plainis S, Ginis HS, Pallikaris A. The Effect of Ocular Aberrations on Steady-State Errors of Accommodative Response. J Vis 2005;5:466-77.
- Buehren T, Collins MJ. Accommodation Stimulus-Response Function and Retinal Image Quality. Vision Res 2006;46:1633-45.
- Labhishetty V, Cholewiak SA, Roorda A, Banks MS. Lags and Leads of Accommodation in Humans: Fact or Fiction? J Vis 2021;21:21.
- Thibos LN, Bradley A, Lopez-Gil N. Modelling the Impact of Spherical Aberration on Accommodation. Ophthal Physiol Opt 2013;33:482-96.
- Morgan IG, French AN, Ashby RS, et al. The Epidemics of Myopia: Aetiology and Prevention. Prog Retin Eye Res 2018;62:134-49.
- Zadnik K, Sinnott LT, Cotter SA, et al. Prediction of Juvenile-Onset Myopia. JAMA Ophthalmol 2015;133:683-9.