Eye movements over telehealth: the smooth-pursuit problem.
Several bilateral stimulation approaches lean on smooth-pursuit eye movements — the client visually tracking a moving target. In the room, that is a clinician’s hand. Over telehealth, the usual workaround is a finger held up to the webcam, and it doesn’t hold up. Here is why, and what actually solves it.
This applies to every approach that uses therapist-paced eye movements — EMDR, Brainspotting, the Flash Technique, Accelerated Resolution Therapy, Eye Movement Integration, and others — and to fast and slow sets alike. Psy180’s pacing is one continuous range, so it adjusts to whatever your training calls for.
The current state of the art
Most clinicians who went remote did the obvious thing: hold a finger, a pen, or a pointer up to the camera and move it side to side while the client watches the video feed. It is intuitive, it needs no tools, and it sort of works. The problem is that the client is no longer watching a smoothly moving object — they are watching a video of one.
Video adds latency and drops frames. A consumer webcam call runs at a variable framerate, re-compresses motion, and introduces a few hundred milliseconds of delay that wanders as the connection shifts. The hand that looks smooth on the clinician’s end arrives on the client’s screen as a stimulus that stutters, lags, and occasionally skips.
Why lag breaks smooth pursuit
Smooth-pursuit eye movement is the system that lets your eyes lock onto and track a continuously moving target. It depends on the target actually moving smoothly — when the object jumps or stalls, the eyes fall back on small corrective saccades to catch up. A stuttering webcam target invites exactly that: the client’s tracking gets choppy because the thing they are tracking is choppy.
This matters more the faster the set runs. Faster, more continuous tracking makes the same amount of lag more visible and more disruptive. The result is a stimulus that is not what the clinician intends to deliver — not because the protocol is wrong, but because the delivery medium is fighting it.
The fix: render the motion, don’t stream it
The way out is to stop sending a video of a moving object and instead have both screens draw the same moving object. When the clinician’s device and the client’s device compute the target’s position from the same simple formula and the same shared clock, each one renders a smooth target locally. There is no video of the stimulus to buffer, no webcam framerate to inherit, and no compounding delay — just a clean target on the client’s own screen, paced by the clinician.
That is how Psy180’s synced visual works: the ball’s position is a function of frequency and elapsed time shared over a lightweight channel, so both sides land it in the same place every frame. The clinician keeps the webcam for the human part of the session — face, voice, presence — while the stimulus itself runs natively on each device instead of through the camera. You can pace the set continuously, at whatever speed your approach uses, and trust that what the client sees is smooth.
Smooth is not the same as appropriate
Whether to deliver eye-movement work remotely at all is a separate question from whether the stimulus is smooth. Positions differ across modalities and their training bodies; some do not endorse remote delivery. Check your modality’s own guidance, and make that decision client by client. Psy180 has no outcome data of its own — a smooth stimulus is a delivery property, not a treatment claim. We’ve summarized the evidence for and against, and what to prepare, in Is remote bilateral-stimulation therapy safe?