Safety
Safety and red flags
Vision therapy exercises are, on the whole, very low risk — the main hazard is wasting time on the wrong thing. But a handful of symptoms are urgent, and a handful of situations need supervision. This page is short on purpose so it actually gets read.
Seek care urgently — do not train through these
- Sudden double vision that appears outside of exercise, especially if it is new.
- A new eye turn in an adult, or a sudden eye turn in a child.
- Sudden loss of vision in one or both eyes, even briefly.
- Flashes of light, or a sudden shower of new floaters.
- A curtain or shadow moving across your field of vision.
- Eye pain with nausea and haloes around lights.
- Double vision with headache, weakness, slurred speech, facial droop or a drooping eyelid.
- A pupil suddenly a different size from the other.
- Severe eye pain or sudden severe headache.
Several of those can be signs of retinal detachment, acute angle-closure glaucoma, a cranial nerve palsy or a stroke. None of them are training problems. If you are unsure, be seen — the cost of an unnecessary visit is far lower than the cost of a delayed one.
Stop the session if
- You get double vision that will not resolve when you back off the target.
- You develop a headache that is getting worse rather than settling.
- You feel dizzy, nauseated or unsteady beyond a mild passing wave.
- Your vision is blurring more as the session goes on rather than clearing.
- An eye starts aching sharply rather than feeling worked.
None of these mean you should never train again. They mean the dose was too high today. Come back tomorrow at a shorter duration or an easier progression.
The single most important rule
Never train through double vision
In every vergence exercise — on screen or with equipment — doubling is the stop signal, the point at which you back off. Pushing past it does not build range. What it builds is suppression: your brain learns to switch an eye off so the task becomes easy again. You will appear to improve at the exercise while getting worse at the thing the exercise was meant to fix.A note specific to screen-based training
- Free fusion should never hurt. A mild pulling sensation is the exercise; a sharp ache means you have gone too far. Reduce the separation.
- Do not chase the widest separation. A clean, verified fusion at a modest separation beats a strained one at a wide separation, which is usually suppression in disguise.
- Flashing displays. Skip the tachistoscope entirely if you have photosensitive epilepsy.
- Screen time is still screen time. If you are treating digital eye strain, doing the exercises on a screen is somewhat self-defeating — use the printable and window-based versions for that program.
- Brightness. Run the tools at a comfortable brightness in a room that is not much darker than the display.
Get supervision for these
| Situation | Why |
|---|---|
| Amblyopia patching in a child | Over-patching can cause reverse amblyopia in the stronger eye. The dose must be prescribed and monitored. |
| Constant strabismus | A constant eye turn needs a full assessment. Some types need surgery or prism; exercises alone can be the wrong tool. |
| Recent concussion | Symptom dosing is the entire skill. Too much sets recovery back. Ideally graded by a clinician. |
| Vertigo or a vestibular diagnosis | Gaze stability work is provocative by design and needs titrating to your condition. |
| After recent eye surgery | Get explicit clearance before any exercise, including palming. |
| Any active eye disease | Glaucoma, retinal disease, uveitis and similar need medical management first. |
| Photosensitive epilepsy | Avoid the tachistoscope and any flashing display. |
Things this site is not
- Not a diagnosis. The symptom finder narrows down a starting point; it does not tell you what you have.
- Not a substitute for an eye exam. Uncorrected refractive error causes many of the symptoms these programs target, and no exercise fixes it.
- Not equivalent to in-office therapy. For convergence insufficiency in particular, supervised therapy clearly outperformed home-only approaches in trials.
- Not medical advice. It is a well-organised, honestly-sourced educational library.
Normal versus not normal during training
Expected
- A mild pulling sensation during convergence work
- Brief blur when switching focus, which clears
- Mild eye fatigue that settles within an hour
- A passing wave of dizziness during gaze stability work, settling within 15–20 minutes
- Finding it genuinely hard at first
Not expected
- Double vision persisting after the session
- A headache lasting hours
- Vision worse the next morning
- Nausea or dizziness lasting beyond 20 minutes
- Sharp or stabbing eye pain
When to stop and reassess
If you have run a program consistently for six weeks with no movement in your checkpoint measure, stop. Either the diagnosis is wrong, there is an uncorrected prescription underneath it, or the condition needs supervised therapy. Grinding on for another six weeks is how people conclude that vision therapy does not work, when what actually happened is that they ran the wrong program.