Sometimes the suspect behind trouble with reading, attention, or focus
isn't what everyone assumes. Run the investigation and find out if a hidden,
treatable eye-teaming problem deserves a closer look.
This is a screening tool, not a diagnosis. A "refer" result means
"this case is worth an eye exam," never "you have convergence insufficiency."
Symptoms overlap with ADHD, anxiety, and learning differences — that overlap is exactly the point.
Do not change anyone's treatment based on this screen.
1
The InterrogationSymptom survey
2
The StakeoutObserved behavior
3
The Field TestEye-teaming check
4
The TrailEye-tracking check
5
The TripwireBrock-string check
6
The Zoom LensFocus flexibility
★
The Case FileYour result
Tap any step above to jump straight to it — you don't have to go in order.
Exhibit 1 — Interrogating the witness
The Interrogation
15 questions about how the eyes feel during reading and close-up work. (CISS)
ADHD
Anxiety
Depression / MDD
Learning disability
Dyslexia / reading difficulty
Past concussion / head injury
Migraines
Past eye turn / lazy eye
New glasses recently
Lots of screen time
⚑ The Briefing — rule these out first
Some signs point to a problem that needs a doctor now, not a screening.
Check any that are new or sudden:
No red flags? Good — let's open the case. Ask the subject:
"When you do schoolwork, reading, or other close work, how often…" Tap a frequency for each.
0 of 15 answered
Exhibit 2 — Surveillance log
The Stakeout
What a parent, teacher, or counselor actually sees during reading and near work. Check every clue you've witnessed.
Exhibit 3 — Field test
The Field Test (NPC)
The one hands-on test. You'll move a small target toward the nose and watch the eyes. Takes ~1 minute.
What you need: a small detailed target — the tip of a pen, a single small letter on a card,
or a sticker on a pencil eraser. And someone to watch the subject's eyes.
Hold the target about an arm's length away, at eye level.
Slowly move it straight toward the bridge of the nose (~1 inch per second).
Tell the subject: "Keep it single and clear — say 'two' the instant it becomes double."
Meanwhile, watch their eyes. Note the moment one eye drifts outward — that's the real signal.
The animation below just shows the motion & gives a rough distance guide. Your real measurement is what you observe on the subject.
arm's length ───────────────────▶ nose
A
👃
40 cm
Press start, then watch the subject's eyes as the target approaches the nose.
What did you observe?
Exhibit 4 — Tailing the suspect
The Trail (eye tracking)
Convergence is one suspect; sloppy eye movements are another. This times how cleanly the eyes jump along a line of numbers — the skill behind not losing your place when reading.
How it works: the subject reads numbers out loud while you time them. We run it twice — first straight down a single column (no side-to-side eye jumps — that's pure naming speed), then across crowded rows (same numbers, but now the eyes must jump). Comparing the two tells the eye doctor whether a slow time is a reading problem or an eye-movement problem.
Best for ages 6+. Younger kids will just get frustrated. Use a finger only if they truly need it.
Warm-up — read these out loud. Practice until comfortable.
Part 1 of 2 — down the column. Read top to bottom, as fast as is accurate. Tap Stop the instant they finish the last number.
0.0s
Part 2 of 2 — across the rows. Same numbers, but tighter and not lined up — the eyes have to jump. Read straight across each row. Tap Stop on the last number.
0.0s
What did you observe?
Logged for the eye doctor: —. A big jump from the down-the-column time to the across-the-rows time points at the eye movements, not naming speed. (We don't grade the raw seconds here — that needs proper age norms.)
Exhibit 5 — Setting the tripwire
The Tripwire (Brock string)
A string and a few beads turn the eyes' teamwork into something you can actually see — including whether one eye is quietly switching itself off.
You'll need: a piece of string about 5 ft / 1.5 m long, and 3 beads — or tie 3 knots, or thread on 3 hair-ties / colored markers.
Tie one end to a doorknob, or have someone hold it at eye level.
Hold the other end gently against the tip of the nose, string pulled tight.
Slide the beads to near (~6 in / 15 cm), middle (~1.5 ft / 45 cm), and far (near the other end).
When the subject looks right at one bead, the two halves of string should cross in a clean X exactly at that bead — a little tripwire. Trouble signs: the X lands in front of or behind the bead (eyes not aiming together), or one half of the string vanishes (that eye is being switched off — suppression).
What did you see?
Exhibit 6 — Pulling focus
The Zoom Lens (focus flexibility)
Eye-teaming is one suspect; the eyes' focusing system is another — and it's the one most often mistaken for "not paying attention." This checks how fast focus can snap between near and far.
Set up two targets: a thumb (or a small word on a card) held about a foot / 30 cm from the nose, and something with fine detail across the room — a clock, a poster, a sign.
Look at the near target until it's razor-sharp, say "clear".
Snap to the far target until it's sharp, say "clear".
Keep swapping near → far → near, as fast as each stays clear.
Start the 30-second timer, then tap the big button every time they call a clear swap. Watch for one direction that stays blurry or lags behind.
30.0s
What did you see?
Clear swaps in 30s: —. (Very few swaps, or heavy lag clearing one side, can mean the focusing system is straining. Logged for the eye doctor.)
Case file — closed
The Case File
Investigation summary for the eye doctor.
Recommended next step
Take this summary to a
developmental optometrist, neuro-optometrist, or pediatric ophthalmologist
for a full binocular-vision exam. Find one near you:
Read this before you do anything. This screener does not diagnose convergence insufficiency —
it flags symptoms and patterns that may point to a binocular-vision problem. A real diagnosis
needs an eye-care professional measuring near point of convergence, eye alignment / phoria, and
fusional vergence. It also can't tell CI apart from ADHD or anxiety — they share symptoms.
Do not start, stop, or change any mental-health or learning treatment based on this result.
Detective Watts
Detective Watts, at your service. I'll walk you through every step of the case — hit “Brief me” any time you want the orders again.
