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?
Participants aged 6 to 12 years (6 ≤ age ≤ 12 years). Written informed consent from legal guardians is mandatory.
Intermittent or constant exotropia at the distance of 6 meters, and intermittent exotropia or esophoria at the near distance of 33 centimeters;
Distance exodeviation ≥ 10 prism diopters (PD) measured via the prism and alternate cover test (PACT);
The difference between near and distance deviation ≤ 10 PD.
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).
Those with severe systemic diseases or cognitive impairment that hinders follow-up attendance and clinical examinations.
Parallel
DIMS glasses
DeviceMyopia control glasses with peripheral defocus control design.
DOT glasses
DeviceMyopia control glasses with diffusion optics technology.
Axial length
Measurement Tool: IOL Master 700 (Carl Zeiss Meditec AG, Jena, Germany), a high-resolution swept-source optical coherence tomography (SS-OCT) device for biometric measurement of the eye Measurement Type: Continuous parameters of ocular biometry, mainly including axial length, anterior chamber depth, lens thickness, vitreous depth and other axial dimensional parameters of the eye Unit of Measure: Ocular axial length (AL): Millimeters (mm) Anterior chamber depth (ACD): Millimeters (mm) Lens thickness (LT): Millimeters (mm) Vitreous chamber depth (VCD): Millimeters (mm)
Refractive error with cycloplegia
Equipment: Cyclopentolate 1%, trial frame, standard trial lens set and logarithmic visual acuity chart for clinical refractive examination Test condition: Completed cycloplegia with cyclopentolate (C) before examination Procedure: The child wears appropriate refractive correction as required. Conduct subjective refraction step by step to determine spherical power, cylindrical power and astigmatic axis. Adjust lenses continuously until the child achieves the clearest and most comfortable vision, then record all refractive parameters and best corrected visual acuity.
Stereoacuity
Distant stereoacuity: Equipment: Random Dots Distant Test (P/N 1006, Vision Assessment Corporation, Illinois, USA) Test distance: 3 meters Range: 63 to 400 arcseconds (log stereoacuity: 1.8 to 2.6 log arcsec) Procedure: The subject identifies stereoscopic shapes at 3 meters. If unable to identify shapes at the 400 arcsec level, record as "nil stereo" (log stereoacuity value: 3.2 log arcsec). Near stereoacuity: Equipment: Randot Preschool Stereoacuity test (Stereo Optical Co., Inc, Illinois, USA) Test distance: 40 cm Test disparities: 800, 400, 200, 100, 60, and 40 arcseconds Procedure: The subject identifies shapes at 40 cm. Record the smallest disparity at which the subject correctly identifies at least two of the three shapes. If unable to identify the largest disparity (800 arcsec), record as "nil stereo" (log stereoacuity value: 3.2 log arcsec).
Newcastle Control Score (NCS) score
Newcastle Control Score (NCS) score incorporates both objective and subjective measures of control into a simple grading system that differentiates and quantifies the various levels of severity in intermittent distance exotropia. Minimum and maximum values: Minimum 0, maximum 9. Interpretation of higher scores: Higher scores indicate worse control (i.e., worse outcome). A score of 0 represents perfect control, while a score of 9 represents the poorest control (constant exotropia or severe loss of control).
Strabismic deviation
Strabismic deviation is measured by using the prism and alternate cover test (PACT) with accommodative targets at distance (6 m) and near (33 cm), measured after 1 hour of monocular occlusion using prisms, where the endpoint is defined as no eye movement during alternate cover testing.
Near Point of Convergence
Equipment: Near point rule Procedure: A target is moved gradually toward the center of the subject's eyes at a speed of 1 cm/s until the subject reports double vision or the examiner observes an outward deviation of one eye. The distance from the target to the spectacle plane is recorded as the NPC distance in centimeters.
Fusional Vergence Amplitude
Equipment: Synoptophore (Haag Streit UK Ltd, Essex, UK) Targets: Fusion slides subtending a visual angle of 6 degrees horizontally Procedure: First, the subject moves the synoptophore arms by themselves to overlap and fuse the images (e.g., a butterfly and a cat). The examiner then slowly abducts or adducts the synoptophore tubes until the subject sees two distinct images (breakpoint). The range between the two breakpoints is recorded as the fusional vergence amplitude.
Accommodative Convergence / Accommodation (AC/A) Ratio
Method: Far gradient method Test distance: 6 meters Stimulus: Minus lenses (-3.00 D) Procedure: A change in accommodation is stimulated using minus lenses. The resulting change in deviation (in prism diopters) is divided by the change in lens power (3 D). AC/A ratio = change in deviation / 3.
Corneal topography
Measurement Tool: OCULUS Pentacam® (OCULUS Optikgeräte GmbH, Wetzlar, Germany), a rotating Scheimpflug camera system for anterior segment analysis Measurement Type: Continuous parameters of corneal topography, including curvature-derived parameters (anterior and posterior corneal curvature in diopters, D), elevation-derived parameters (anterior and posterior corneal elevation in micrometers, µm), and pachymetry-derived parameters (corneal thickness in micrometers, µm) Unit of Measure: Corneal curvature (keratometry, K1, K2, Kmax): Diopters (D) Corneal curvature radius: Millimeters (mm) Corneal thickness (pachymetry, CCT, thinnest point): Micrometers (µm) Corneal elevation: Micrometers (µm)
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