Assessment guide · 10 min read
Concussion Eye Test: What Vision Testing Really Shows
An eye test cannot diagnose a concussion. What it can do is show whether the systems that aim, focus and steady your eyes are working — and after a head injury they very often aren't. That is a real, treatable finding, but it is not the same as a test coming back positive for concussion, and that difference matters more than anything else here.
The phrase concussion eye test covers at least six procedures: a two-minute number-reading card used on a sideline, a symptom-provocation screen run in clinic, an infrared pupil camera, an eye-tracking device, a bedside check of how your eyes follow a finger, and a full binocular vision exam lasting the better part of an hour. They measure different things and carry different weight.
This guide covers each: what VOMS screens for, the real argument about King-Devick, why convergence and focusing problems surface weeks later, where pupillometry has got to, what neuro-optometric rehabilitation involves, and who performs it.
Can an eye test detect a concussion?
No single eye test diagnoses a concussion, and none rules one out. Diagnosis is clinical — a person takes a history, examines you, and reads every test result in that context.
The clearest statement comes from the regulator. The EyeBOX is the one vision-based device the FDA has cleared for concussion, and its clearance describes it as an aid in the diagnosis of concussion, not a standalone assessment. Sensitivity was 80.4% and specificity 66.1% — roughly one concussion in five missed, a third of uninjured people flagged. FDA notes plainly that not all patients with concussion have eye-tracking abnormalities.
The consensus agrees. The 6th International Consensus Statement on Concussion in Sport warns that any screening short of a multimodal evaluation of symptoms, signs, balance, gait and cognitive change may be inadequate, and a 2025 review in Eye and Brain finds no gold standard acute diagnostic test isolating the visual system alone. Scans don't settle it either: CDC guidance says do not image routinely for pediatric mild TBI.
When should you get your eyes checked after a concussion?
Most vision trouble after a concussion settles on its own inside a week or two. Persistence past that point — or a specific alarming sign — is what earns an exam.
The Defense Health Agency's fact sheet on vision problems after concussion puts it directly: many people have visual problems in the first one to two weeks, and it usually resolves without treatment. If it hasn't, that sheet lists who to ask for — an optometrist, ophthalmologist, neuro-optometrist, occupational therapist or physical therapist.
Some findings aren't a rehabilitation question. Get emergency care for the CDC danger signs — a headache that keeps getting worse and does not go away, or looking very drowsy and not being able to be woken up. And the American Academy of Ophthalmology warns clinicians not to miss a traumatic optic neuropathy, Horner syndrome or cranial nerve palsy: a newly drooping lid, a pupil that stays larger than the other, or double vision that never resolves belongs in front of an eye doctor now. Our guide to concussion symptoms has the rest of the red flags.
What is VOMS testing?
VOMS — the Vestibular/Ocular Motor Screening — is a symptom-provocation screen: you perform seven short eye and head movement tasks and rate your headache, dizziness, nausea and fogginess from 0 to 10 after each.
The tasks are smooth pursuit, horizontal and vertical saccades, horizontal and vertical vestibulo-ocular reflex, near point of convergence, and visual motion sensitivity. A baseline rating is taken first, so what gets recorded is the change each task produces. Near point of convergence is the one hard measurement: the distance in centimeters at which a target brought toward you doubles.
In the original VOMS validation study of 64 concussed patients and 78 controls, 61% of patients reported symptom provocation on at least one item. A near point of convergence of 5 cm or more, and a score of 2 or more on any item, each substantially raised the probability of correctly identifying a concussed patient; a model combining them reached an area under the curve of 0.89.
Two caveats. What VOMS produces is a map of which movements make you feel worse — useful for aiming treatment, not a diagnosis. And the consensus was split on it: VOMS was not included in the sideline SCAT6, having failed to reach sufficient consensus, but a modified VOMS is a recommended part of the office-based SCOAT6 used from 72 hours on. That is where it belongs — in clinic, days later, guiding rehabilitation.
Is the King-Devick test accurate?
It depends when you use it. King-Devick has reasonable value in the first day or two and very little after that, and should never be read on its own.
The test is rapid number naming: you read strings of numbers aloud off cards or a tablet as fast as you can, and the score is your time. The optimistic figure is a 2015 meta-analysis, summarized in that Eye and Brain review, which reported 86% sensitivity and 90% specificity, with concussed athletes slowing by about 4.8 seconds against their own preseason baseline.
A larger study tells a harder story. Across 320 concussed and 1,239 control collegiate athletes, King-Devick reached an area under the curve of 0.724 at 0–6 hours and 0.701 at 24–48 hours — but at a cutoff set to catch 80% of concussions, specificity was only 46% and 41%. Once athletes were asymptomatic the AUC fell to 0.513, a coin toss. The authors concluded it should never be used as a standalone assessment.
Then the baseline problem. The test is scored against your own pre-injury time, and people get faster with practice. Among 183 semi-professional rugby players tested through a season, each repeat trial improved the time by 0.60 seconds on average, performance plateaued only at around 30 trials, and the median gap between first attempt and best was 4.2 seconds. Set that against the 4.8 seconds meant to signal an injury: a stale baseline can manufacture a result, or hide one.
What is convergence insufficiency after a concussion?
Convergence is both eyes turning inward together to hold a single clear image up close. When it fails, near work doubles or blurs, your eyes ache, and you lose your place in a paragraph.
It is common. Among 100 adolescents seen in a concussion program, 69% had at least one vision diagnosis — convergence insufficiency in 49%, more than one diagnosis in 46%. In adults whose symptoms haven't settled, a 2024 meta-analysis found 20.4% of people with post-concussion syndrome had symptomatic convergence insufficiency.
Here screening and diagnosis part company again. A receded near point of convergence on VOMS is a flag, not a diagnosis: the Eye and Brain review notes it had a sensitivity of only 63% alone for any oculomotor abnormality, and that adding accommodative amplitude and a symptom survey still caught only 76% of affected adolescents at 61% specificity. Diagnosis needs fusional vergence amplitudes, convergence facility and the rest of a binocular workup.
Why do reading and screens still hurt weeks later?
Usually because the focusing system, not the aiming system, is the one that hasn't recovered. Accommodation is the eye's ability to shift focus to near distance and hold it there, and concussion disrupts it at least as often as convergence.
In that same adolescent cohort, accommodative disorders showed up in 51%. The Eye and Brain review adds that 57% of adolescents had accommodative dysfunction at 4 to 12 weeks post-injury, mostly accommodative insufficiency, and that reduced accommodation has been reported in up to 67% of adults after mild TBI — with one series finding combined vergence and accommodative dysfunction as common as either alone.
Light sensitivity is the other half of screen intolerance and the most common visual symptom of all — yet no clinical test quantifies it well, and the review is explicit that glare acuity is not a substitute. If this is still your life at two months, it belongs in the conversation about persisting post-concussive symptoms, not written off as eye strain.
What do saccade and smooth pursuit tests show?
They show how quickly and accurately your eyes jump between targets and track a moving one. Watched by eye alone they catch only obvious abnormality; measured on equipment they catch a great deal more.
After concussion, saccades can show increased latency, reduced accuracy and abnormal amplitude — but the Eye and Brain review is candid that precise smooth pursuit errors are hard to detect without specialized recording equipment, and that simply watching someone look between targets may miss abnormalities altogether. And performance on these tasks blends eye control with attention, language and executive function, so a poor score does not localize the problem to the eyes.
Can a pupil test show a concussion?
Quantitative pupillometry reliably finds group differences between concussed and uninjured people, but it is not yet a bedside yes-or-no test for an individual. (The penlight check for an unequal or unreactive pupil is a different thing — a neurological red flag.)
The clearest data comes from 98 concussed adolescent athletes and 134 controls measured with infrared pupillometry a median of 12 days after injury. Eight of nine pupillary light reflex metrics were significantly greater in the concussed group — maximum pupil diameter 4.83 mm versus 4.01 mm, time to 75% redilation 1.81 seconds versus 1.51. The authors' own framing was that these may serve in the future as objective physiologic biomarkers. In healthy controls, exercise alone produced smaller pupils and a slower reflex — so a pupil measured after a game is not the same as one measured rested, a real obstacle to sideline use.
What happens in a full eye exam after a concussion?
A post-concussion vision exam is far longer than a standard sight test, and looks at almost nothing a sight test looks at. The AAO describes the workup as visual acuity with refraction, color vision, pupil evaluation, a full ocular motility assessment covering pursuit, saccades, vestibulo-ocular response and convergence, plus visual fields and a dilated fundus exam — with the Eye and Brain review adding convergence amplitudes, accommodative amplitude and facility, and stereoacuity.
One thing to know before booking: best-corrected visual acuity is generally not affected by concussion. Passing the letter chart at 20/20 says nothing about whether your convergence or accommodation is intact — many people are reassured by a normal eye test that never tested the thing that is wrong.
Does neuro-optometric rehabilitation actually work?
For concussion-related convergence insufficiency specifically, yes — that now has randomized trial evidence. For concussion in general it does not, and no honest clinician will tell you otherwise.
Neuro-optometric rehabilitation — vision therapy — means supervised office sessions retraining vergence and accommodation, with home exercises between them. The CONCUSS randomized trial enrolled 11- to 25-year-olds with persisting symptoms and symptomatic convergence insufficiency 4 to 24 weeks after injury. With immediate twice-weekly therapy, 46 of 52 (88%) were classed successful or improved against 4 of 52 (8%) in the delayed group, and mean near point of convergence improved by 7.9 cm versus 1.8 cm. Once both groups had done all 16 sessions there was no difference — starting sooner shortened the time spent symptomatic rather than changing the destination.
Simpler interventions have support too: Brock string exercises, trialled in 50 people within 10 days of concussion, improved near point of convergence by 8.9 cm against 3.8 cm with usual care. Read this narrowly: a specific eye-teaming problem responds to a specific therapy — it is not evidence that vision therapy treats fogginess, headache or mood. Our overview of what concussion treatment involves sets it beside the other options.
Who performs concussion eye tests?
Different tests belong to different professions. Sideline screens are run by athletic trainers and team physicians; VOMS by physical therapists, athletic trainers and physicians in concussion clinics; full binocular vision exams by optometrists and ophthalmologists.
The American Optometric Association states that doctors of optometry can diagnose and treat the visual symptoms of concussion, and that a comprehensive eye exam can pick up signs of an undiagnosed concussion and prompt a referral. The Eye and Brain review agrees from the medical side: the model is multidisciplinary, with concussion physicians handling cognition while optometry or ophthalmology handles the visual exam. If you aren't sure which door to knock on, our two-minute specialist quiz maps your dominant symptom to the profession that treats it.
Availability is the constraint. Across the 3,205 verified listings in our directory, 405 offer vision or neuro-optometry — the thinnest of the widely-needed services, against 1,069 offering vestibular care. Only 186 offer both under one roof, so if you have dizziness and reading trouble, plan for two appointments. Telehealth barely helps: 40 of those 405 offer it, because this work is hands-on.
What should you do next?
If you are in the first week or two and your eyes feel wrong, that is expected and usually temporary — pace your screen time and watch for the danger signs above. If you are past two weeks and screens, reading or busy environments still dictate your day, ask to be assessed rather than waiting.
Our directory is free, carries no sponsorship or ranking, and covers all 50 states and DC. You can search it by service, state and city for vision and neuro-optometry providers near you — every listing is verified against the provider's own public website.
Find a concussion specialist near you
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Frequently asked questions
Can an optometrist tell if you have a concussion?
An optometrist can find the vision problems a concussion causes, which is not quite the same thing. The American Optometric Association says a comprehensive eye exam can detect the visual signs of an undiagnosed concussion and lead to a referral into a concussion care team — but the diagnosis itself is clinical, made by a clinician weighing history, symptoms and examination together.
Does a normal eye exam rule out a concussion?
No, and this catches a lot of people out. Best-corrected visual acuity is generally not affected by concussion, so reading the letter chart at 20/20 says nothing about whether your convergence, focusing or eye-teaming is working. A standard sight test does not test the systems that concussion actually disrupts.
Can you fail a King-Devick test without having a concussion?
Yes, easily. In a study of 320 concussed and 1,239 control collegiate athletes, at a threshold set to catch 80% of concussions the test's specificity was only 46% at 0–6 hours and 41% at 24–48 hours — meaning most uninjured athletes flagged were false positives. Practice effects make it worse: players in one season-long study improved by an average of 0.60 seconds on each repeat attempt.
Do your pupils change after a concussion?
Measurably, yes, but not in a way you or a coach could see. Using infrared pupillometry, eight of nine pupillary light reflex metrics differed between 98 concussed adolescent athletes and 134 controls — maximum pupil diameter averaged 4.83 mm versus 4.01 mm. A pupil that is visibly unequal or unreactive after a head injury is something else entirely: that is an emergency-room sign, not a research measurement.
Should a child have their eyes checked after a concussion?
If symptoms are still there after a week or two, it is worth doing. Among 100 adolescents seen in a concussion program, 69% had at least one vision diagnosis — convergence insufficiency in 49% and accommodative disorders in 51% — and 46% had more than one. Those problems affect reading and classroom work directly, so finding them changes what school accommodations a child needs.
How long do vision problems last after a concussion?
For most people, one to two weeks, and they usually resolve without treatment. When they persist, they can persist for months: a randomized trial of vision therapy for concussion-related convergence insufficiency enrolled people who were still symptomatic 4 to 24 weeks after injury. No one can give you a timeline for your own recovery, which is why persistence past two weeks is the trigger to be assessed rather than to keep waiting.
Educational content only — not a substitute for professional medical advice, diagnosis, or treatment. Reviewed by Jon MacKay, PharmD, BCACP against current clinical guidance; last updated August 2026.