How your tear production system contributes to watering eyes

Ophthalmic plastic surgery includes the management of patients with watering eyes. In particular, surgeons have to work out whether there is hypersecretion, which is an eyelid cause or a lacrimal drainage system block.

Patients with watering eyes do not lose their sight, but they do suffer severe functional problems from blurred vision, the sore skin under the eyes, often sticky eyes and smattering of tears on their glasses. As an oculoplastic surgeon, I have found over the last 20 years that it is very worthwhile looking after this group of patients, as the current results of lacrimal surgery are excellent and the patient’s quality of life can be significantly improved.

You may not be aware that your tears are produced by your lacrimal gland sitting up in your orbit towards the outer side just underneath the bone. These tears drain down onto the surface of the eye and are passed across to the medial corner of the eye towards the nose by the action of the eyelid muscle with each blink. This is called the eyelid orbicularis lacrimal pump. Some of the tears are also produced by accessory lacrimal tissue called “glands of Krause and Wolfring” in the conjunctiva and eyelids.

Each time you blink you are helping to distribute your tears across the external surface of your eye and at the same time you are propelling the tear meniscus along the lower lid margin towards two tiny openings at the medial corner of the eye, called the puncta. The tears are collected by these puncta, from what is called a tear lake, sitting between the two eyelids at the medial corner of the eye. Each time you blink, the tiny little puncta which are only about 1 mm in size, one in each upper and lower lid, will catch your tears and effectively suck in a little bit of the tear lake into the tear drainage system.

The tear drainage system has a lacrimal sac sitting buried at the corner of the eye between the eye and the nose and to get into the sac the tears have to go first into the puncta and then along very fine canaliculi, again about 1 mm diameter, which are in the medial part of the upper and lower eyelids, which then join to form a short common canaliculus which in turn opens into the lacrimal sac.

The lacrimal sac has a muscle around it which, with each blink, helps to pump the tears down along with hydrostatic pressure through a duct called the nasal lacrimal duct, which is hidden in a bony canal between the eye and the nose. The tears drain from the lacrimal sac through the nasal lacrimal duct and its lower opening beneath one of the shell-like turbinates inside the nose, called the inferior turbinate, onto the floor of the nose. These tears do not drain out your nostril but trickle along the floor and into your throat where you are not even aware that they are draining there.

So, immediately by understanding the production of tears, their passage along the lid margin and over the surface of the eye into the puncta, canaliculi and sac, and then down the nasolacrimal duct into the nose, you can quite rightly guess that anything that affects any of those steps is going to cause either a dry eye or a watering eye.
If there is damage to the lacrimal gland, and fortunately this happens very rarely or damage to the lacrimal gland openings, then you could get a very nasty dry eye. However, if there is damage to the eyelids or the openings of the tear ducts called the puncta or anywhere along the canaliculi sac, nasolacrimal duct opening into the nose or in the nose, then there will be a backup of tears, and you are very likely to experience troublesome watering.

It is my job as an oculoplastic surgeon to work out why you have a watering eye. Is it a problem of the tear drainage, or is it a problem with dry eye? For instance, you could be losing tears because of an evaporative dry eye due to meibomian gland dysfunction where the oil glands and your eyelids are not functioning properly. You can read more about dry eyes and Meibomian gland dysfunction in other blogs.

At Clinica London, we run the Tears Clinic, which has all the facilities and expertise required for assessing dry and wet eyes.