What Causes Watery Eyes?
Tears are produced by the lacrimal gland which is located in the area behind the outer part of the upper eyelid. They flow into the eye and lubricate the eye surface, forming part of the tear film that allows clear vision and easy movement of the eyelids over the eyes.
This is followed by drainage of tears through tiny ducts which begin at the inner corner of the eyelids (known as canaliculi) and lead to an adjacent collection area known as the tear sac.
From here, tears flow down a main tear duct known as the nasolacrimal duct that leads to an area of the nose known as the inferior meatus. This natural flow of tears can be disrupted in several ways, leading to troublesome tearing.
First, there may be an over-production of tears due to any cause of irritation or inflammation in the eye. For example, a patient with a bad case of conjunctivitis or inturned eyelashes may experience tearing as a result of over-production of tears.
Or, there may be failure for the tears to drain away into the nose due to obstruction at any point in the tear drainage pathway. Most commonly, the obstruction occurs at the nasolacrimal duct. The under-drainage results in excessive tearing.
Do Watery Eyes Pose A Risk To Your Vision?
Although excessive tears in the eyes may distort vision temporarily, tears by themselves do not harm vision. What is more important is to find out the root cause of the tearing as these can often be treated readily with relief of symptoms.
In the case of a blocked nasolacrimal duct, a big worry would be stagnation of tears in the tear sac, potentially leading to infection known as dacryocystitis. Left untreated, this condition can extend into the orbit and intracranially with serious consequences.
Blocked Tear Ducts – What Causes It? How Can It Be Treated?
Obstruction of the tear ducts at the higher or canalicular level may be related to age, chronic eye surface inflammation, trauma or certain chemotherapeutic drugs. These are less commonly seen. On the other hand, obstruction lower down at the nasolacrimal duct level is more common and is most often due to age-related narrowing or stenosis. Rarely, an adjacent tumour may compress on the nasolacrimal duct and cause the obstruction.
Nasolacrimal duct obstruction is managed surgically as it is a structural disorder. The gold standard treatment is to create a new outflow tract for tears above the area of obstruction so that tears flow directly from the tear sac into the nose, bypassing the area of obstruction below. This surgery is known as dacryocystorhinostomy.
There are two main surgical approaches with one requiring a small skin incision and the other relying on specialised endoscopic equipment to create the new conduit through the nose. Both approaches have their pros and cons and a good discussion with an oculoplastic surgeon is important to decide which approach is preferred.
Canalicular obstruction is more challenging to manage and will depend on the location and extent of obstruction. A detailed oculoplastic assessment is essential before a treatment plan can be customised for the patient.