What this trial measures

• Refractive error (D)From enrollment to the end of the 3-year study, every 6 months

  Measured with an autorefractor

• Axial length (mm)From enrollment to the end of the 3-year study, every 6 months

  Measured with a biometer

• Viewing distance (cm)From enrollment to the end of the 3-year study, every 6 months

  Measured using the Visual Environment Evaluation Tool (VEET). VEET contains multiple time-of-flight (ToF) infrared sensors embedded in the temple arms of the glasses.The sensors emit infrared light toward objects in front of the wearer. The device measures the time required for the reflected infrared light to return to the sensor. Using the speed of light, the system calculates the distance between the eye/glasses and the viewed object.

• Illuminance (lux)From enrollment to the end of the 3-year study, every 6 months

  Measured with the Visual Environment Evaluation Tool (VEET). VEET uses photometric light sensors that detect the light intensity. The sensors convert incoming light into electrical signals proportional to brightness, and the device reports illuminance in lux, the standard unit for light exposure.

• Wavelength of the environmental light (nm)From enrollment to the end of the 3-year study, every 6 months

  Measured with the Visual Environment Evaluation Tool (VEET). The VEET measures light wavelength using integrated spectral light sensors that analyze the composition of incoming light across different portions of the visible spectrum. Rather than only measuring brightness (illuminance), the device also characterizes the spectral distribution of light reaching the wearer.

• Eye vergence (degree)From enrollment to the end of the 3-year study, every 6 months

  Using an eye tracker (Pupil Labs). Pupil Labs eye trackers measure eye vergence by tracking the gaze direction of both eyes separately and then calculating the angle between the two visual axes. Vergence refers to the inward or outward rotation of the eyes when focusing at different viewing distances: Convergence → eyes rotate inward for near targets Divergence → eyes rotate outward for distant targets Pupil Labs estimates vergence using these steps: 1. Track each eye independently 2. Estimate each eye's gaze vector in 3D 3. Compute where the two gaze vectors intersect 4. Calculate the vergence angle between them

• Pupil size (mm)From enrollment to the end of the 3-year study, every 6 months

  Using an eye tracker (Pupil Labs). Eye trackers measure pupil size using infrared video imaging and computer vision algorithms that detect the pupil boundary in images captured by eye-facing cameras. The eye tracker shines infrared (IR) light onto the eye using tiny IR LEDs. Infrared light is invisible to the user and produces stable illumination conditions for imaging the pupil. Small cameras pointed at the eyes continuously record high-speed grayscale images of the eye. The pupil appears darker than surrounding structures when using the "dark pupil" technique commonly used in wearable eye trackers. Finally, computer vision algorithms analyze each frame to locate the pupil region, identify the pupil edge, and fit a geometric shape to detect the pupil size in mm.