Case Study: Why Visual Hygiene is Critical in Myopia Control

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February 23, 2026

By Alex Ong, Optometrist, CPNP (ANA), and Richie Huang, Optometrist, CPNP (ANA), B.Sc Optom

Abstract

In the era of evidence-based myopia management, clinical success is often defined by stable axial length and spherical equivalent refraction. However, this metric-driven approach can create a “tunnel vision,” causing practitioners to overlook the functional integrity of the binocular system. 

Here, I present a case of a young female patient successfully treated with orthokeratology for three years. Despite stable myopia, she developed acute acquired comitant esotropia (AACE) with distance diplopia. This article explores the pathophysiology of “Smartphone Squint,” the accommodative implications of restoring emmetropia and the necessity of monitoring binocular integrity alongside axial elongation.

The Paradox of Success

As optometrists, we are witnessing a paradigm shift where myopia is treated as a progressive condition to be managed rather than a simple refractive error. Our clinics are now equipped with biometers and topographers, and our “success” is plotted on growth charts.

However, there is a risk that in our pursuit of a stable retina, we neglect the motor system driving the eyes. A patient can be a “Myopia Success” (flat axial growth) while simultaneously becoming a “Binocular Failure.” This case serves as a crucial reminder that correcting the optics does not correct the visual behavior, and in some cases, effective refractive correction can unmask underlying binocular fragilities.

Case Presentation

Patient Profile: An 11-year-old Chinese female with a three-year history of OrthoK wear presented for her routine ocular health examination and myopia progression monitoring.

Myopia Status: Refractive control has been excellent. Axial length has remained stable throughout the treatment period, and unaided visual acuity is maintained at 6/6 (20/20) in each eye.

Chief Complaint: During the consultation, the patient casually reported occasional double vision (diplopia) at distance, specifically when watching television or looking at the whiteboard in class. She noted that she has to “squint” or partially close her left eye to resolve the diplopia. Notably, she reported no double vision during near tasks, such as reading or using her smartphone. She denied headaches or other systemic symptoms and is not currently on any medication.

Clinical Findings

• External Observation: Eyes appeared straight to the casual observer.
• Cover Test:
  • Distance: Esotropia (ET) of 6 Prism Diopters (PD). Patient reports diplopia.
  • Near: Esotropia (ET) of 10 PD. Patient reports single vision.
• Refraction: Over-refraction indicated Plano for each eye. Retinoscopy revealed low hyperopia (+0.50D), confirming that the OrthoK lenses were functioning correctly as an emmetropic correction.
• Behavioral History: Upon further questioning, the parent remarked that the patient has a habit of maintaining a very close working distance of approximately 10 cm for reading and handheld gaming. Family history is positive for esotropia on the maternal side.

The Diagnostic Puzzle

The clinical picture presents a paradox: Why does she have double vision at distance (where the deviation is smaller) but not at near (where it is larger)?

This apparent contradiction confirms the diagnosis of AACE with sensory adaptation:

1. At Near (10 PD ET): The deviation is chronic. The brain has developed Suppression (a facultative scotoma) to eliminate the image from the deviating eye, hence the lack of diplopia.
2. At Distance (6 PD ET): The deviation is a recent “decompensation.” The brain has not yet learned to suppress at distance, resulting in active diplopia.

Discussion

The ‘Tunnel Vision’ of Myopia Management

As highlighted in the introduction, the primary goal of modern myopia management is often reduced to a single metric: the stabilization of axial length. By this standard, the patient in this case study was a resounding success—her axial elongation had halted, and her refractive error was fully corrected. However, this case illustrates the dangers of clinical “tunnel vision,” where the focus on refractive and biometric data obscures the functional status of the patient’s binocular system.

But is an effective treatment strategy for myopia control always the most suitable for the patient’s overall ocular condition. While OrthoK successfully flattened this patient’s cornea, it simultaneously altered her vergence-accommodation balance. As noted in the IMI Clinical Management Guidelines,¹ practitioners must evaluate the suitability of a treatment not just by its ability to slow growth, but by its impact on the patient’s visual efficiency and comfort. In this case, the “myopia success” masked a developing “binocular failure.”

Mechanism and Diagnosis: The ‘Perfect Storm’

The clinical presentation—diplopia at distance but single vision at near—reveals a classic pattern of sensory adaptation. The absence of diplopia at near suggests a chronic deviation where the brain has developed deep suppression (facultative scotoma). Conversely, the diplopia at distance indicates a recent decompensation where suppression has not yet been established.

Two critical factors precipitated this decompensation:

1. The “Smartphone Squint” Phenomenon: Excessive near work at close distances creates a hypertonic spasm of the medial rectus muscles. The seminal study by Lee et al. (2016) established the direct link between this behaviour and AACE.² Our patient’s habitual 10 cm working distance is a potent trigger for this mechanism. Furthermore, Vagge et al. (2020) have highlighted that this is a growing epidemic, reporting a surge in non-neurological AACE cases coinciding with increased digital near-work during the COVID-19 lockdowns.³
2. The Accommodative Penalty of Emmetropia: By correcting the patient to emmetropia with Ortho-K, we re-introduced the full physiological accommodative demand. As detailed by Logan and Wolffsohn (2020) in the IMI White Papers,⁴ viewing a target at 10 cm requires 10.00 D of accommodation. Through the synkinetic near triad, this drives a massive amount of accommodative convergence.

While an uncorrected myope would have a reduced accommodative drive, the Ortho-K patient must exert full effort, fuelling the convergence excess. This risk is not theoretical; Cheung et al. (2022) documented a parallel case of an adolescent Ortho-K wearer developing esotropia, concluding that the refractive clarity provided by Ortho-K at ultra-near distances may actually encourage the behaviors that lead to strabismus.⁵

The Therapeutic Triad: Restoring Binocular Integrity

If binocular dysfunction needs to be addressed before the myopia strategy begins, one intervention could be vision therapy (VT). Otherwise, if the esotropia is allowed to persist, there is a significant risk of permanent suppression and amblyopia. Clinical expectations can be managed carefully through a transparent discussion with both parents and the patient. As noted in Mitchell Scheiman’s Clinical Management of Binocular Vision, training divergence (relaxing the medial rectus spasm) is generally more difficult than training convergence. While this makes the therapy challenging, it is by no means impossible.

Contingency Planning and Modality Shifts

While OrthoK remains a gold standard for myopia management, clinical decision-making should prioritize the integrity of the binocular system. In cases where VT fails to stabilize the deviation, or if patient compliance with VT is poor, the clinician must pivot. Continuing with a modality that leaves the binocular system fragile risks permanent suppression and amblyopia. In such scenarios, the treatment strategy must shift toward modalities that simultaneously manage myopia and actively support binocular alignment.

Multifocal Soft Contact Lenses (MF-SCL): Transitioning to a center-distance multifocal soft contact lens (MF-SCL) serves as an optimal contingency plan for the esotropic myope.7 Secondary analysis from the BLINK Study group confirms that children wearing +2.50 D add lenses exhibit a significantly reduced accommodative response compared to single-vision wearers.⁸ 

Progressive Addition Lenses (PALs): The COMET Study (Correction of Myopia Evaluation Trial) explicitly found that PALs were most effective in slowing myopia progression in a specific subgroup: children with near esophoria and a high lag of accommodation.⁹ 

Atropine: The use of atropine as an adjunctive therapy requires careful implementation in esotropic patients. While effective for myopia control, the mechanism of action involves cycloplegia and recent reports highlight that increasing atropine dosage can paradoxically induce or worsen esotropia.10 To mitigate this risk in patients with binocular instability, combining atropine with bifocals or PALs¹⁰ ensures the patient has clear near vision without exerting the excessive accommodative effort that drives the eye turn.

Conclusion: Beyond the Biometer

Myopia management cannot be reduced to a single metric on a biometer. While stabilizing axial length is a primary goal, it must not come at the expense of the patient’s binocular integrity. As demonstrated, a patient can be a “refractive success” with stable myopia yet simultaneously become a “functional failure” due to debilitating diplopia.

This case of AACE underscores the critical link between visual behavior and motor alignment. It challenges practitioners to look beyond the optics of the eye and address the mechanics of how the patient uses their vision. Whether through the rigorous application of VT to restore fusional reserves, or the strategic pivot to multifocal soft contact lenses or PALs to mechanically unload the convergence system, the clinician’s priority must remain the preservation of comfortable, single, binocular vision.

Ultimately, our role can evolve from being solely “myopia controllers” to becoming holistic guardians of visual development. By integrating binocular vision assessment into every myopia visit and remaining flexible in our treatment modalities, we ensure that our young patients do not just see a stable future, but a clear and singular one.

 

Dr. Alex Ong, DOptom, FAAO, CPNP (US) Optometrist, Singapore PGCert (Anterior Eye Diseases, Cataract & Glaucoma) PGCert (Retinal Disease Recognition & Co-Management) MSCO, B.Sc Optom, Dip. OptomDr. Ong is the Founder and Managing Director/Optometrist at Ong’s Optics & Myopia Management Centre, established in 2005. 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 Personalized 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.

Mr. Richie Huang, B.Sc Optom, CPNP (US) Optometrist, Taiwan Mr. Richie Huang is the Founder and Managing Director/Optometrist of JD Optometry Group (Taiwan, since 2007). He currently serves as President of the New Taipei City Optometrists Association (NTCOA) and is the immediate past President of the Taiwan Optometrists Association (TOA). His clinical interests span elderly vision care and children’s visual development, with a focus on paediatric myopia management, binocular vision, and visual nutrition. He combines frontline practice with professional education and public outreach, helping advance eye-care standards and equitable access across Taiwan. As a Certified Personalized Nutrition Practitioner (CPNP) with the American Nutrition Association, he integrates nutrition and vision science to promote a proactive, preventive approach to lifelong eye health.

 

References

1. Gifford KL, et al. IMI – Clinical Management Guidelines Report. Invest Ophthalmol Vis Sci. 2019;60(3):M184-M203.
2. Lee HS, Park SW, Heo H. Acute acquired comitant esotropia related to excessive Smartphone use. BMC Ophthalmol. 2016;16:37.
3. Vagge A, et al. Acute Acquired Concomitant Esotropia From Excessive Application of Near Vision During the COVID-19 Lockdown. J Pediatr Ophthalmol Strabismus. 2020;57(6):e88-e91.
4. Logan NS., et al., IMI Accommodation and Binocular Vision in Myopia Development and Progression, IOVS., 62(5), article 4; 1-21
5. Chung SA., et al. Acquired Esotropia in an Adolescent Wearing Orthokeratology Lenses,  J. Peadiatr Ophthalmol Strabismus, 2022, 59(1): e7-e10. 
6. Scheiman M, Wick B. Clinical Management of Binocular Vision: Heterophoric, Accommodative, and Eye Movement Disorders. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2014.
7. Walline JJ, Walker MK, Mutti DO, et al. Effect of High Add Power, Medium Add Power, or Single Vision Contact Lenses on Myopia Progression in Children: The BLINK Randomized Clinical Trial. JAMA. 2020;324(6):571–580.
8. Chandler MA, Robich ML, Jordan LA, et al. Accommodation in Children after 4.7 Years of Multifocal Contact Lens Wear in the BLINK Study Randomized Clinical Trial. Optom Vis Sci. 2023;100(7):425-431.
9. 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(4):1492-1500.
10. Guyton DL. Complication associated with low dose atropine for myopia. Ophthalmology Times. 2024.