A Comparative Study of the Efficacy of Myopia Control Lenses With Different Mechanisms on Controlling Myopia Progression in Patients With Intermittent Exotropia

A Comparative Study of the Efficacy of Myopia Control Lenses With Different Mechanisms on Controlling Myopia Progression in Patients With Intermittent Exotropia

The goal of this clinical trial is to compare the efficacy of myopia control lenses with different working principles in patients with intermittent exotropia aged 6 to 12 years. The main questions it aims to answer are:

Are there any differences in the clinical outcomes of DIMS and DOT glasses between children with intermittent exotropia and those with simple myopia (without intermittent exotropia)? Do DIMS and DOT glasses differ in their myopia control efficacy among children with intermittent exotropia? Does wearing DIMS or DOT glasses affect the binocular visual function of children with intermittent exotropia?

Intermittent exotropia (IXT) is a common ophthalmic disorder. It is clinically characterized by outward deviation of the eye position when patients fixate on distant targets, feel fatigued, or become inattentive. This condition impairs stereoscopic vision and visual quality, and may further deteriorate binocular fusion function, thereby considerably interfering with daily activities. Epidemiological data indicate that the prevalence of intermittent exotropia is approximately 4.7% in Asian populations. In China, it accounts for 75.64% of all strabismus cases, ranking first among all types of strabismus. Notably, more than 50% of children with intermittent exotropia are affected by myopia. Several studies suggest that these two conditions may share common pathogenetic mechanisms and present as comorbid disorders.

Currently, the mainstream designs of myopia control glasses are based on two core principles: peripheral defocus control and diffusion optics technology. Peripheral defocus glasses induce myopic defocus by refracting peripheral light to focus in front of or on the retina, which inhibits excessive axial elongation. Lenses adopting diffusion optics technology reduce the contrast of peripheral retinal images via microstructural design, so as to slow myopia progression. A number of clinical trials have verified the favorable efficacy of both lens types for myopia control in general children.

Nevertheless, systematic controlled studies comparing the myopia control effects between the two types of glasses in myopic children with concomitant intermittent exotropia remain scarce. Therefore, this comparative study focusing on this specific population possesses important clinical value and can also provide theoretical evidence for the formulation of individualized myopia management strategies.

Inclusion Criteria:

1. Participants aged 6 to 12 years (6 ≤ age ≤ 12 years). Written informed consent from legal guardians is mandatory.

2. Patients with basic-type intermittent exotropia (IXT) meeting all the following criteria:

   1. Intermittent or constant exotropia at the distance of 6 meters, and intermittent exotropia or esophoria at the near distance of 33 centimeters;
   2. Distance exodeviation ≥ 10 prism diopters (PD) measured via the prism and alternate cover test (PACT);
   3. The difference between near and distance deviation ≤ 10 PD.

3. Based on cycloplegic spherical equivalent (SE), the myopic refractive error of both eyes ranges from -6.0 D to -0.5 D.

4. The logMAR value of monocular distance best-corrected visual acuity (BCVA) measured by the ETDRS chart is ≤ 0.2, and no amblyopia is present.

5. Parents and children are willing to participate in this clinical trial and can complete the entire study protocol.

6. Children have healthy eyes without organic ocular diseases.

Exclusion Criteria:

1. Participants who have worn myopia control glasses or received other myopia interventions, including low-concentration atropine and phototherapy instruments, within the past 6 months (excluding DIMS and DOT glasses).
2. Those with severe systemic diseases or cognitive impairment that hinders follow-up attendance and clinical examinations.

4. Subjects with astigmatism of ≥ 2 diopters (D) in either eye after cycloplegia; individuals enrolled in other interventional trials.

5. Patients with active ocular inflammation in either eye. 6. Those diagnosed with ocular diseases or presenting with clinically significant abnormalities on ophthalmic examinations.

7. Participants are currently receiving visual function training or other clinical interventions for intermittent exotropia.

8. Individuals who decline to complete the 1-year follow-up period.