A watery eye in a baby: when to wait and when to treat

It is one of the most common paediatric consultations: a baby a few weeks old with one eye that waters constantly and wakes up with discharge, while the other is perfectly normal.

In most cases this is a congenital blockage of the nasolacrimal duct, and most resolve without surgery. But it is worth understanding why it happens and which signs change the approach.

Where the tear goes

Tears are not produced in order to cry. They are produced continuously to keep the cornea lubricated and transparent, and then they have to drain.

From the inner corner of the eye, the tear enters through tiny openings — the lacrimal puncta — travels along small canaliculi, reaches the lacrimal sac and from there runs down the nasolacrimal duct into the nose. It is the reason your nose runs when you cry.

During fetal development, the lower end of that duct is closed by a membrane that normally opens around birth. When it does not, the tear cannot drain, pools in the sac and overflows.

How it presents

• Continuous watering, usually of one eye only.
• Discharge, especially on waking.
• Lashes stuck together in the morning.
• Eyelid skin irritated by the constant moisture.
• A white eye, with no significant redness of the conjunctiva.

That last detail is useful: in conjunctivitis the eye is red; in simple tear duct blockage the eye waters and produces discharge but stays white.

The timetable

A high proportion of these blockages open on their own during the first year of life. That is why the initial approach in an infant without complications is conservative:

Lacrimal sac massage. This is the main manoeuvre. With short nails and clean hands, gentle pressure with the pad of the index finger over the lacrimal sac, sliding downwards, several times a day. The pressure helps the membrane finish perforating.

It is important that the technique is taught by the ophthalmologist in clinic. Done in the wrong place or with insufficient pressure, the massage achieves nothing, and many parents arrive frustrated after months of doing it wrong.

Hygiene. Cleaning the discharge with saline and a clean gauze, always from the inner corner outwards.

Monitoring. Periodic check-ups to verify progress.

When the approach changes

There are situations in which waiting is no longer appropriate:

• Persistence beyond the first year of life. Probing of the tear duct is considered, a procedure in which the obstructing membrane is passed through with a fine probe.
• Repeated episodes of infection.
• Dacryocystitis, acute infection of the lacrimal sac: a red, hot, painful lump at the inner corner of the eye, sometimes with fever. It requires immediate medical attention, not waiting for the next appointment.
• A mucocele at birth: a bluish swelling in the area of the sac, which needs early assessment.

What must not be confused

Not every watery eye in a baby is a tear duct blockage, and here lies the main reason to seek advice rather than assume:

Congenital glaucoma also causes watering. But it comes with marked photophobia — the baby conspicuously avoids light — blepharospasm and an increase in the size of the cornea or the eye. It is an emergency with very different implications.

Conjunctivitis, a misdirected eyelash rubbing on the cornea, or a foreign body can also cause watering.

Telling them apart requires an examination, not a description over the phone. And that is the whole reason why persistent watering in an infant deserves an eye consultation, even though the most likely outlook is excellent.

In adults it is another story

It is worth clarifying because it causes confusion: tear duct blockage in adults has different causes — inflammatory, infectious, traumatic, age-related — and is not resolved with massage or probing. Treatment there is surgical, by means of a dacryocystorhinostomy, which is a separate subject.