A school screening is a filter with the sensitivity dial turned deliberately towards catching things. It is designed to over-refer, because the cost of a wasted appointment is far lower than the cost of a missed amblyopia. That design choice shows up in the numbers.

The AHRQ evidence report prepared for the USPSTF pooled 34 accuracy studies. Where the prevalence of vision disorders resembled the general population — roughly 1% to 8% — six of seven studies found false-positive rates between 62% and 99%. Where prevalence was higher, false positives fell to between 3% and 65%. The USPSTF's own summary is that false positives are "usually greater than 75%" when prevalence is under 10%.

Read that the right way round. It does not mean screening is useless. It means the letter in your hand carries much less information than it feels like it carries, and the honest sentence is: we do not yet know whether anything is wrong.

In 2018–19 the New York City School Vision Program screened 193,084 children. 42,827 failed. Sixty-nine percent of those families received follow-up outreach — letters, fortnightly phone calls, insurance help, pre-addressed envelopes. Only 39% completed an eye exam.

Then the same programme did something different in its community schools: it sent optometrists into the buildings and examined children on site. Follow-up went to 90%, and glasses reached nearly every child who needed them. The racial, ethnic and socioeconomic gaps that existed in the referral model were eliminated.

That is the most useful thing in this whole article, and it is not about parenting. The barrier is the trip — finding a clinic that takes your insurance, booking it, taking time off, getting there. Interventions that shorten that trip work. A cluster trial in Baltimore and a scoping review of adherence studies both point the same way: phone calls beat letters, transport help beats phone calls, and bringing the exam to the child beats everything.

This is the part most parents do not know, and cost is the barrier reported most often in the literature. Under the federal EPSDT benefit — Early and Periodic Screening, Diagnostic and Treatment — every Medicaid-enrolled child under 21 is entitled to vision services that include, in the government's own wording, "screening, diagnosis and treatment for defects in vision… such as eyeglasses."

Not a state option. Not a pilot. A federal entitlement covering the exam and the glasses. Researchers studying why families do not follow through repeatedly find the problem is not absence of insurance but lack of awareness of what the insurance already covers.

The state figures are from a 2021 review in Optometry and Vision Science covering all 50 states and DC. There is no federal requirement for school vision screening at all: 40 states and DC mandate it, four recommend it, and six — Alabama, Idaho, North Dakota, South Dakota, Wisconsin and Wyoming — do neither. What your child was tested on depends on which state you live in.

This is worth saying because it is true and almost nobody writing about screening says it.

The Cochrane review of vision screening in school-age children — seven studies, 9,858 children randomised — found that not one included study compared screening against no screening at all. Every trial compared different ways of handling children who had already been screened. What that evidence does show clearly is that giving children free spectacles gets them worn: about 400 per 1,000 versus 250 per 1,000 with a prescription alone. What it shows weakly is any academic effect. And the reviewers concluded that health-education interventions "do not appear to improve spectacle wearing in children."

The USPSTF, meanwhile, has a recommendation for screening children aged three to five, and an explicit "insufficient evidence" statement for under-threes. For school-age children it has no recommendation at all — the entire age band this article is about sits outside its assessed evidence base.

None of that is a reason to bin the letter. It is a reason to hold the whole system loosely: screening is a cheap net, it catches a lot, it misses some, and what demonstrably helps children is not the screening itself but removing the friction between the referral and the exam.

There is an obvious next sentence for a company that sells glasses, which is that every child should have a full eye exam every year. We are not writing it, because the American Academy of Ophthalmology says the opposite: routine comprehensive eye examinations performed on healthy, asymptomatic children have no proven medical benefit. AAPOS lists annual comprehensive exams for children who pass screening on its Choosing Wisely list of things not to do.

Optometry's professional body takes a more aggressive line and recommends annual exams from age six. We are noting the disagreement rather than picking the side that suits us.

The defensible position: a failed screening warrants an exam. A pass plus real symptoms warrants an exam. A pass with no symptoms does not.

A pass is weaker reassurance than it sounds. The AHRQ report puts the negative likelihood ratio of acuity charts at 0.39 to 0.70, meaning passing only modestly lowers the odds that something is wrong. A 2026 meta-analysis of teacher-delivered screening put pooled sensitivity at 0.70 — roughly three in ten children with a real problem missed — though those studies are mostly outside the US and should not be read as a US school figure.

What passes a distance chart routinely: moderate farsightedness the child focuses through, convergence insufficiency, and anything to do with near vision or colour in the forty states that do not test them. We wrote about that in full in what a school screening misses.

Wondering what the exam itself involves? What happens at your child's first eye exam walks through it test by test. If your child passed but something still seems off, read what a school screening misses and 7 signs your child needs glasses. If amblyopia is mentioned at the appointment, our guide to lazy eye explains why glasses alone resolve a surprising share of cases.

NYC School Vision Program, PLOS ONE (2022) · AHRQ evidence report for the USPSTF (2017) · USPSTF: Vision in Children Ages 6 Months to 5 Years · Cochrane: Vision screening in school-age children (2018) · Medicaid.gov: EPSDT · AAO: Vision Screening · AAPOS via AAFP: Choosing Wisely · Prevent Blindness: Screening requirements by state · AFP: Childhood Eye Examination in Primary Care (2023) · AAP HealthyChildren: Vision Screenings