Tears are far more than a response to emotion; they are continuously produced to maintain the health and clarity of our eyes. These fluid layers cleanse the ocular surface, provide lubrication, and deliver nourishment, making them indispensable for vision. A sophisticated system works constantly to manage this tear film, ensuring proper distribution and removal.
The Journey of Tears: Production and Drainage
Tear production begins in the lacrimal glands, located beneath the outer part of the upper eyelid. These glands secrete a watery fluid that spreads across the eye’s surface with each blink, forming a protective layer. This fluid contains water, oils, and mucus, which maintain a stable tear film and prevent evaporation.
After lubricating and cleansing the eye, tears are collected by tiny openings called puncta, situated on the inner corners of both the upper and lower eyelids. From the puncta, tears enter small tubes known as canaliculi. These canaliculi converge into a common canaliculus before draining into the lacrimal sac.
The lacrimal sac acts as a reservoir, holding tears before they flow into the nasolacrimal duct. This sac is nestled in a bony groove between the eye and the nose. The nasolacrimal duct is a narrow channel that extends downwards and opens into the nasal cavity. This allows tears to drain into the nose, which is why a runny nose often accompanies crying.
When Tear Drainage Goes Wrong
Problems arise when tear drainage is disrupted, leading to noticeable symptoms. A common issue is a blocked tear duct, which can be present at birth, known as congenital nasolacrimal duct obstruction. In adults, blockages are acquired due to inflammation, injury, or age-related narrowing of the ducts.
When tears cannot drain properly, they accumulate on the eye’s surface, causing excessive tearing, a condition called epiphora. This constant overflow can blur vision and irritate the skin around the eyes. Stagnant tears within the drainage system also create a breeding ground for bacteria, increasing the risk of infection.
An infection of the lacrimal sac is termed dacryocystitis, which presents with symptoms like pain, redness, and swelling in the inner corner of the eye. This condition can be acute, appearing suddenly with severe symptoms, or chronic, characterized by persistent low-grade inflammation and tearing. Blockages are the primary reason for dacryocystitis, as trapped tears allow bacteria to multiply.
Diagnosing and Treating Issues
Diagnosing tear drainage issues begins with a thorough examination and a review of the patient’s symptoms. A dye disappearance test is performed, where a fluorescent dye, such as fluorescein, is placed in the eye. The doctor observes how quickly the dye drains; prolonged retention indicates a drainage problem.
Further diagnostic steps include probing and irrigation, where a thin probe is inserted into the puncta and saline solution is flushed through the system. This procedure helps identify the location and nature of any blockage, and confirms if the fluid reaches the nasal cavity. Imaging studies like dacryocystography (DCG) are also used, involving injecting a contrast dye into the tear ducts and taking X-rays to visualize the drainage pathway and pinpoint obstructions.
Treatment approaches vary based on the cause and severity of the blockage. For infants with congenital blocked tear ducts, conservative management involves daily massage of the lacrimal sac, which helps open the membrane at the duct’s end. This massage applies gentle pressure over the inner corner of the eye. Many cases resolve spontaneously within the first year of life.
If conservative methods are insufficient, or for older children and adults, more invasive procedures may be necessary. Probing and irrigation can be therapeutic, as the probe can break through thin membranes or clear minor obstructions. Balloon dacryoplasty involves inserting a balloon-tipped catheter into the duct and inflating it to widen the narrowed passage.
For persistent or severe blockages, particularly in adults, a surgical procedure called dacryocystorhinostomy (DCR) is performed. This procedure creates a new pathway for tears to drain from the lacrimal sac into the nasal cavity, bypassing the obstructed nasolacrimal duct. DCR can be performed externally or endoscopically through the nostril. Antibiotics are prescribed for infections like dacryocystitis, alongside warm compresses, to clear the infection before addressing the underlying blockage.