MEYELens open pupillometry & gaze tracking
Hardware

Hardware assembly and physical design.

Using MEYELens is easy. Follow these steps to build your complete 3D-printed platform for pupillometry and eye tracking.

Overview

The hardware is centered on a 3D-printed wearable frame that can support one or more camera modules while allowing positional adjustment relative to the eye. The design emphasizes reproducibility, low cost, and practical adaptability across different users and experimental contexts.

The frame includes support elements for the front structure, nose positioning, side arms, and camera mounting. Depending on the intended use, the system can be assembled in simpler or more extended configurations, ranging from monocular pupil recording to combined eye-facing and world-facing acquisition.

1

Printing

Overview image of the MEYELens hardware
2

Assembling

Overview image of the MEYELens hardware
3

Testing

Camera mounted on the 3D-printed support

Bill of materials

List of all components required to build the eyewear platform.

Preview Component Description Quantity Notes Price per Unit(€) Link
PLA filament spool Printing filament PLA 1 3D-printed 1.43 Open
Eye-facing camera module Eye-facing camera Primary recording camera 1 Required 7.19-14.38 Open
World-facing camera module World-facing camera Scene camera for gaze mapping 1 Optional 7.19-14.38 Open
M2 and M3 screws and nuts Fasteners M3 and M2 screws and nuts Multiple Required 1.23 Open
External infrared illumination module IR illumination External LED source 1 Depends on the setup 41.2 Open
External infrared illumination module Extension Cables USB extension cable(s) 1 Depends on the setup 9 Open

Filament

The eyewear frame can be printed with standard 3D-printing filaments, we tested only PLA.

We mostly used Bambu Lab PLA filaments to print the MEYELens eyewear components. In our builds, we used Bambu Lab Matte Black PLA.

Tip: If you have a Bambu Lab printer, you can also find the MEYELens files on MakerWorld. The files are also uploaded to NIH 3D.
Print settings: More details on recommended print settings are available in the 3D Models page.
PLA filament used to print the MEYELens eyewear
Bambulab GUI with the open project.

Camera(s)

MEYELens can be assembled with one or two camera modules depending on the intended application.

The platform supports:

  • Single camera: pupillometry, optionally combined with chin-rest gaze tracking.
  • Dual camera: eye-facing and world-facing cameras for naturalistic gaze tracking.

Tested camera modules:

  • GC0307 - 640 × 480 px, nominal 30 Hz. The IR-cut filter was removed and the camera was used with an external 96-LED infrared illuminator.
  • GC0308 - 640 × 480 px, nominal 30 Hz, with built-in IR LEDs. We used a 50° lens for the eye-facing camera and an 80° lens for the world-facing camera.
Tip: Low-cost camera modules may not sustain the advertised FPS. In our tests, we often limited capture to 20 fps for stability.
Warning: For the GC0307, manual removal of the IR-cut filter can permanently damage the camera lens or sensor. If you decide to perform this modification, proceed carefully and follow a dedicated tutorial. You can watch an example video here: IR-cut filter removal tutorial.
Camera modules used in the MEYELens system
Example camera modules used for pupillometry and gaze tracking.
Tip: For the eye-facing camera, both 50° and 80° lenses are suitable, as long as you select an appropriate ROI around the eye. A 50° lens provides a closer view of the eye, while an 80° lens gives a wider view and can make camera positioning easier. For the world-facing camera, use a lens with a field of view of at least 80°, so that the camera captures a sufficiently wide portion of the visual scene.
Warning: Most camera modules are sold with the lens focused for distant objects. For MEYELens, the eye is much closer to the camera, so the focus usually needs to be adjusted manually. To do this, carefully rotate the small lens mounted on the camera module until the eye image is sharp at approximately 2.5 cm from the eye. The lens is often glued in place, so the first rotation may require some force. Be careful: forcing the rotation can damage the lens or the camera module. The 50° camera lens is usually harder to rotate than the 80° camera lens. A pair of tweezers can help you gently force the initial rotation and then adjust the focus. The depth of field is generally large enough that very fine tuning is not required.

Fasteners

Standard fasteners are required to assemble the MEYELens frame and secure the camera module.

Assembly uses mostly standard screws and nuts. Make sure these parts are available before starting the build.

  • M3 × 16 mm screws ×3
    Frame joints.
  • M3 × 12 mm screws ×4
    Ear supports, camera arm, and ball joint.
  • M3 nuts ×6
    Used for all M3 screws except the ball-bearing anchor, as in our build.
  • M2 × 10 mm screws + M2 nuts
    Camera mounting.
Tip: Use the exploded view as a reference while assembling the frame.
Warning: Before press-fitting each nut into the adjustment knob, add a small amount of cyanoacrylate glue. Glue the corresponding screw to the eyewear frame as well, so that only the knob rotates when adjusting the fit around the subject’s head.
Exploded assembly diagram showing the MEYELens fastener positions
Exploded view / assembly diagram.

Illumination

Infrared illumination can be configured in different ways depending on the experimental setup and portability requirements.

The illumination configuration depends on the camera module and the recording setup. If you use a camera with built-in LEDs, the integrated illumination is sufficient to obtain a good image of the eye. If you use the camera without the built-in LEDs external illumination is required to obtain bright and stable predictions. In this case there are several options:

  • External IR light source: the simplest option is to use an external infrared light source. This is easy to set up and can provide strong illumination, but it is less portable.
  • SMD LED configuration: a more difficult but portable option is to use small SMD LEDs soldered onto wires and positioned close to the camera lens (4 or 5 should be sufficient).
Tip: For the external illuminator, we provide a dedicated 3D-printable IR external support that helps position the light source during recordings.
Warning: When building custom infrared illumination, verify the electrical connections and avoid excessive light intensity close to the eye (generally 0.5 meters from face).
Infrared illumination configurations for MEYELens
Top: external infrared illuminator with the 3D-printable stand. Bottom: portable LED configuration with the objective and five LEDs.

Extension cable

Camera modules usually require an extension cable for practical use during recordings.

These camera modules have short cables, so a USB extension cable is needed for practical use. If you intend to use only one camera, a common USB extension cable is sufficient. For more flexible setups, we used double-headed USB extension cables such as this USB extension cable. This provides two USB inputs, which can be used either for a dual-camera setup or for one camera together with a custom IR LED array.

Tip: A double-headed extension cable is useful when you want to keep the setup compact while still connecting both the eye-facing and world-facing cameras.
Warning: Test the cable before data collection. Low-quality or very long USB extension cables can reduce camera stability, especially when using two devices at the same time.