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

Comparatore attivo: IXT with DIMS

Dispositivo: DIMS glasses

Myopia control glasses with peripheral defocus control design.

Comparatore attivo: IXT with DOT

Dispositivo: DOT glasses

Myopia control glasses with diffusion optics technology.

Altro: Myopia with DIMS

Dispositivo: DIMS glasses

Myopia control glasses with peripheral defocus control design.

Altro: Myopia with DOT

Dispositivo: DOT glasses

Myopia 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)

Amplitude of Accommodation

Equipment: Near point rule (RAF rule) with a near visual acuity target (one line above the best corrected near visual acuity) Test distance: Starting from approximately 40 cm, moving gradually closer Procedure: The subject wears their distance refractive correction.Place the near target at 40 cm and ask the subject to keep it clear. Move the target toward the subject's eyes at a speed of approximately 1-2 cm/s until the subject reports sustained blur (cannot be made clear by further effort). Stop immediately and measure the distance from the target to the spectacle plane (in cm).

Behavioral scaled questionnaire

Eye Health Behavior Assessment Scale (EHBAS) [21] that developed by Chinese National Disease Control and Prevention Administration in 2023 will be used to assess the level of eye health behaviors in children. It consists of two scales, Eye Health Behavior Assessment Scale for Kindergarten and Primary School Students in Grades 1-3 -Parent Version (EHBAS-P) and Eye Health Behavior Assessment Scale for Primary School. The content of the scale mainly includes various items such as exposure to natural light, outdoor activity time, digital screen time, reading posture and environment, and sleep time. The Scale was calculated using a score of 0 for 'cannot do it', 1 for 'sometimes do it' and 2 for 'do it'. Based on the sum of the scale's scores, the eye health behaviors of children and adolescents were classified into three levels: poor, moderate and good.