Routine eye examination for every screened congenital CMV infant is not earning its place

Design

Retrospective review of eye examination records within a population newborn screening programme

Population

394 infants screening positive for congenital CMV in Ontario, July 2019 to January 2022; 347 examined, of whom 51 were symptomatic

Primary outcome

Prevalence of cCMV-attributable ophthalmic findings in symptomatic and asymptomatic infection

Effect

2 infants with unilateral chorioretinal scars: 0.58% of screen-positive infants, 3.9% of symptomatic; 0 of the asymptomatic group

Consensus guidance has recommended an eye examination for every newborn with congenital cytomegalovirus. This Ontario study asked what that yields when applied to infants found by population newborn dried blood spot screening rather than by clinical suspicion.

Of 394 infants who screened positive between July 2019 and January 2022, 347 (88.1%) had an eye examination, and 51 of those (14.7%) had symptomatic infection. Two infants had unilateral chorioretinal scars attributable to CMV — 0.58% of all screen-positive infants, and 3.9% of the symptomatic ones. No infant with asymptomatic infection had any CMV-related ocular finding.

The detail that decides the argument is that both affected infants had already been referred to ophthalmology on clinical grounds, with significant systemic manifestations, before their screening result was known. The examination found nothing that clinical assessment had not already flagged. The authors propose restricting referral to symptomatic infants and those with other features the treating physician judges relevant — which would remove a large number of examinations, and the appointments, sedation and parental anxiety that come with them, without a demonstrated cost.

• Refer infants with symptomatic congenital CMV for ophthalmology assessment.
• Do not refer an asymptomatic screen-positive infant for eye examination as a matter of routine.
• Keep audiology follow-up regardless — the hearing risk is real and often late, and nothing here changes that.
• Refer any infant where the examining clinician has a specific concern, screening result or not.
• In settings where paediatric ophthalmology capacity is the bottleneck, this frees appointments for children who need them.

Why it matters

Universal newborn CMV screening multiplies the number of infants a routine-examination rule applies to, and the rule was written before that.

Don't overread it

Two events cannot establish that asymptomatic congenital CMV never causes ocular disease — only that this programme found none.

The statistics, in plain English

Two events in 347 examinations is a yield of 0.58%, and with numbers that small the confidence around the true rate is wide — this study cannot prove the risk in asymptomatic infants is zero. What it can show is that a population screening programme running for two and a half years found no asymptomatic case, and that both cases it did find were already clinically apparent. That is an argument about what the test adds, which does not require the underlying rate to be exactly zero.

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