How do tears normally drain from the eye?
Tears are produced by the lacrimal glands of the eye, which are in the upper outer part of the eye socket. The tears lubricate and clean the surface of the eye.
The tears normally drain away from the front of the eye through two drainage holes in the corner of the eye next to the nose, one in the upper and one in the lower eyelid. These holes are the start of the drainage system, becoming tubes (called cannaliculi) which travel horizontally towards the nose where they enter the tear sac. The tear sac is a larger diameter tube which travels vertically downwards, and leads into the nose itself through the bone of the nasal sidewall.
Why is my eye watering ?
A watery eye may be due to a number of factors. In general, these may be divided into factors causing overproduction of tears or problems with drainage of the tears from the eye.
Overproduction is usually due to irritation of the eye by infection around the eyelid or eyelashes ( termed blepharitis). Sometimes the tears don’t wet the surface of the cornea properly leading to dry eye symptoms of irritation and further tear production.
Occasionally there is a problem with eyelashes scratching the eye and causing an increase in tear production.
Problems with tear drainage into the tiny openings of the tear duct in the eyelids may occur if there are problems with the position of the eyelid, or by blockage and narrowing of the tear duct openings themselves. The other main cause of poor tear drainage is a blockage or narrowing in the tear duct itself. This usually causes constant watering and sometimes a sticky and mucky eye. Alternatively however, there may be no obvious physical blockage in the tear duct but the tears do not drain through it in an effective way – this is termed a ‘functional’ blockage of the tear duct.
What may I notice if this happens ?
If the tears don’t drain properly, they start to overflow out of the eye itself onto the cheek. This may interfere with vision, particularly when reading and driving, and is often worse outside (especially in cold and windy conditions) affecting activities such as golf, bowls or gardening. Soreness of the lower eyelid and cheek skin may occur as a result of the constant irritation from salty tears. Stagnation of the tears may cause infections around the surface of the eye.
Occasionally an infection of the tear sac itself may develop (dacryocystitis). This is a very painful condition as the infection can stretch the tear sac to bursting point.
Wearing contact lenses can be impossible if the eyes are constantly watery, especially if there is a sticky discharge as well.
What can be done to help this ?
Depending on the cause for the eye watering, there are a number of treatment options. Lubricants are very useful if there is a problem with the tears not wetting the cornea adequately. Antibiotic eye drops and ointments may be necessary if there is an infection around the eyelids or eyelashes (blepharitis). Often these treatments are prescribed by a General Practitioner.
If these measures do not cure the problem then it is time to consider surgical options. If the watering is due to an abnormal lower eyelid position this may need an operation to correct it. Alternatively, if the tear duct opening is narrowed or not visible, it can be stretched or ‘snipped’ to open it up and allow the tears to drain properly. If there is a blockage in the tear duct, either physical or ‘functional’, the problem can be solved by an operation to bypass the tear duct and create a new drainage pathway into the nose directly from the tear sac itself – this operation is called a Dacryocystorhinostomy (or DCR). Traditionally this requires an incision at the side of the nose, next to the eye, and a small section of the bone between the eye and the nose is removed to create a new passage into the nose. It does, however, create a small scar on the nose, but this is usually not noticeable.
Is it possible to perform the surgery without leaving a scar?
It is possible, if space allows, to perform the same operation by using a small camera (an endoscope) and delicate instruments, by going up into the nose. This technique is called an endoscopic DCR. Like the traditional operation, this creates a new passage from the eye to the nose as before, but with no skin incision. The normal anatomy of the eyelid and eyeball is left undisturbed, which can be beneficial. However, this approach is not possible in all patients, especially those with a reduced nasal space.