Myopia Profile


What happens to binocular vision during cycloplegia?

Posted on March 22nd 2022 by Connie Gan

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Assessing refraction and binocular vision function is important in myopia management. How is binocular vision changed by cycloplegia testing?

The use of cycloplegic agents may be employed in examining myopic children to ensure the most accurate refraction possible.1 What does a cycloplegic agent do to binocular vision function? Typically, under these conditions we would expect a less minus refraction, and at near a reduced or absent accommodation response and a likely exophoric shift. However, LM presented this fascinating case where a patient with a history of exophoria exhibited a significant esophoric shift under cycloplegia. Here is the case.

LM Puzzling case. Young boy (Afro-American) 8 years old met yesterday. Strong heredity of high myopia. Referral for myopia control. Rx -3.00 -0.75 x 180 OU. Evolves -0.75D per year. Was diagnosed with exophoria-tropia (18 p.d. deviation with reserves of 30), with possible decompensation at near (from ref doc). Vision therapy has partially corrected the problem ... remains fragile. With its single vision glasses in place, I confirm high exo dist and near, well compensated. Which strategy to choose? Contact lenses will provide an exo shift ... so I didn't consider it. Anti-myopia glasses: we now have miyosmart .... will this be enough ??? I measured the axial length ... 25.3 mm OU !!!! NEAR the threshold of 26 that we do not want to exceed and he is 8 years old ... a lot more years of progression ahead. So atropine 0.025% considered as an adjunct therapy (+ glasses) ... (I would never have considered it if I had not measured the axial length). I also checked the refraction under cyclo and to see potential effect that atropine could have on his BV ... The Rx comes out at -2.50 instead of -3.00. Expected... but the patient falls in ESO! | !!!! Value of 10 p.d. when correction in place (16 uncorrected) !! I don't understand this shift ... Anyone have an idea ??

What could be happening?

OCJ How much accommodative lag does he have? What's his AC/A ratio?KG Fascinating case! A perfect highlight of the importance of both BV and axial length measurement. My only suggestion is if this eso was measured under cyclo conditions, perhaps he was trying to drive his drug-impaired accommodation with his vergence. Which he obviously couldn’t do if he didn’t have decent convergence reserves, indicating the exo is probably well controlled (if exo is present again in non-cyclo conditions).CS Agree Kate. More I dig into it, the more I find that phoria under cyclo are not that reliable.. He is definitively exo without cyclo, well compensated given the run of VT he completed successfully... So I will keep him in glasses (anti-myopia- DIMS lenses) and will add atropine (because of AL and his young age)... Will see...

The IMI Clinical Management Guidelines suggest that, when cycloplegia is used, to instill two drops of 1% tropicamide or cyclopentolate, given 5 minutes apart.In younger children especially, the accuracy of autorefraction is improved with cycloplegia.2

Why is there an esophoric shift with a cycloplegic agent?

Lyu et al found an increase in esodeviation under cycloplegia in 34 Korean children with hyperopia and esotropia.3 The cycloplegic agent used was a mix of 0.5% tropicamide and 0.5% phenylephrine. The authors proposed two explanations. Firstly, a decrease in fusional divergence effort may occur, as patients experience blurred vision due to cycloplegia and stop attempting fusion. This could make sense for children with pre-existing esodeviation, but could apply less to this case where the child has a history of significant exodeviation.

The second explanation was that the 0.5% tropicamide and 0.5% phenylephrine combination has been reported as insufficient to achieve complete accommodation paralysis in children with darkly pigment irides and high amplitude of accommodation.4,5 Hence a young patient may attempt to accommodate to overcome the near blur under incomplete cycloplegia and by doing so, drive more convergence.

Low-dose atropine and esophoric shifts

There have been case studies reported in India that 0.01% atropine induces an esodeviation in children with convergence excess esotropia, after switching from 1% atropine for myopia control.7,8 

A single case report7 involved a 10-year-old with a small near esophoria before 1% atropine treatment, which was changed to 0.01% after 18 months, due to complaints of photophobia. At 6 month follow up, the patient exhibited a poorly controlled near esophoria - despite being prescribed progressive addition spectacles for near support. This resolved on cessation of 0.01% atropine. Recommencement of 1% atropine, with a +3.00 Add for near, resulted in well-controlled exophoria at distance and near.

Another case series8 reported three myopes with a mean age of 5.3 years who developed convergence excess esotropia following use of 0.01% atropine eye drops. All had undergone surgery previously for intermittent exotropia. The authors pointed to the hypo-accommodation side effect driving excessive convergence.

These side effects are unexpected given that low-dose atropine has been shown to have minimal impact on accommodation amplitude and is generally well tolerated. In the LAMP study,amps were reduced by only around 2D in 0.025% and 0.05% atropine and barely at all with 0.01%. In children with pre-existing vergence disorders, these case studies highlight that the slight reduction in accommodation function could influence the accommodation-convergence relationship and lead to reflex over-convergence and increased esodeviation.

Myopia management for exophores

SZ Type Text hereSpecs with BI prism correction and vision training?LM Type Text hereVt already completed. He can compensate his phoria. Not constant so I would not Rx prism then.CS Distance center CL with high addLM Exo will be worst...LM Type Text hereI will keep him in [myopia controlling] glasses and will add atropine (because of AL and his young age)… Will see.

When considering spectacle and contact lens options for myopia control, spectacles can be more beneficial for exophores as shifting from spectacles to contact lenses in myopia creates an exophoric shift.10 When myopes view at near with spectacles, they experience base-in prism and less accommodation demand due to off-axis spectacle lens effects. These effects don't exist when viewing at near in contact lens wear, requiring increased convergence and accommodative effort by comparison. In patients with normal binocular vision function this may be inconsequential, but for some the resultant exophoric shift and increase in accommodative lag could cause difficulty.

Even though this child has reportedly well controlled exophoria, his binocular vision history led his eye care practitioner LM to preference myopia controlling spectacles. Read more in this clinical article What About the Exophores? 

Is there value in measuring binocular vision under cycloplegia?

While cycloplegia may reveal the 'true' refractive state, it may not necessarily give us a picture of the true binocular vision state when accommodation is active. The dynamic binocular visual system can compensate when accommodation is influenced by partial or full cycloplegia, leading to unexpected alteration in vergence function.

At baseline, prior to cycloplegia and on follow-up examinations, this case study and the literature confirm the importance of measuring binocular vision function to assess for any impacts due to low-dose atropine treatment.1

Take home messages:

  1. Cycloplegic agents may result in an esophoric shift due to the binocular vision system attempting to overcome near blur by driving excessive convergence.
  2. Exophores can benefit from myopia controlling spectacles, which have less accommodative and vergence demand at near compared to when wearing contact lenses.
  3. It is important to check the binocular vision status of a child who is being treated with low-dose atropine.

Further reading

Meet the Authors:

About Connie Gan

Connie is a clinical optometrist from Kedah, Malaysia, who provides comprehensive vision care for children and runs the myopia management service in her clinical practice.

Read Connie's work in many of the case studies published on Connie also manages our Myopia Profile and My Kids Vision Instagram and My Kids Vision Facebook platforms.

About Kimberley Ngu

Kimberley is a clinical optometrist from Perth, Australia, with experience in patient education programs, having practiced in both Australia and Singapore.

Read Kimberley's work in many of the case studies published on Kimberley also manages our Myopia Profile and My Kids Vision Instagram and My Kids Vision Facebook platforms.

This content is brought to you thanks to unrestricted educational grant from


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