Fuse the two rings into one. You've truly got it when you see both the ＋ above and the ring below at the same time — each exists in only one image. If one is missing, blink and relax.
images 34 mm apart
This trainer renders with WebGPU. Use a recent Chrome, Edge, or Firefox 141+. On Linux you may need to enable chrome://flags/#enable-unsafe-webgpu or launch with --enable-features=Vulkan.
Two images, one for each eye. Aim your gaze so they fuse into a single three-dimensional picture — then follow it as it glides toward you and away. This trains vergence: the eye-teaming muscles that a day of fixed-distance screen work leaves stiff.
Focus on a point in front of the screen — your fingertip helps. The gaze lines cross. Works at any image separation.
Relax and gaze through the screen into the distance. Needs the separation set near or below your eye spacing (IPD).
Pointing both eyes at the same spot in depth is active muscular work called vergence: converging to look near, diverging to look far. It is coupled to accommodation (the lens focusing) and coordinated with fast jumps (saccades) and slow tracking (pursuit). Like any motor skill, the speed, range, and stamina of this system respond to practice — and a day of staring at one fixed distance gives it none.
Home exercises like pencil push-ups, the Brock string, and fusion cards are classic orthoptics — usually prescribed for convergence insufficiency (CI): eyes that tire, blur, or double during near work. This is the best-evidenced corner of vision therapy: the NIH-funded Convergence Insufficiency Treatment Trial found structured vergence training clearly effective for symptomatic CI in children, and a Cochrane review reached similar conclusions. Free-viewing stereograms like the ones here are the same drills in on-screen form: fusing two offset images at a controlled disparity is exactly the workload a vergence program prescribes.
Long screen sessions hold vergence and accommodation at one distance for hours, reduce blinking, and are associated with digital eye strain. The break reminder here implements the 20-20-20 habit recommended by the American Academy of Ophthalmology; see also the AOA on computer vision syndrome.
Honesty matters more than marketing: none of this changes the shape of your eye or lens, so it cannot fix refractive errors such as nearsightedness or presbyopia — glasses do that. The strong evidence is for convergence problems and their symptoms; for general "tired screen eyes" the rationale is sound but less rigorously studied. And lingering double vision, a sudden change, or one eye drifting are reasons to see an optometrist or ophthalmologist, not to train harder.
Hold a standard bank card against the screen and drag the slider until the outline matches its width (85.6 mm). This tells VERGE how many pixels equal a millimetre.
3.79 px/mm
Fix on something at least 6 metres away and let your eyes rest.