The medial canthus is the inner corner of the eye, where the upper and lower eyelids meet nearest the nose. This area houses delicate structures essential for eye health and function. Issues affecting it can impact tear drainage, eyelid stability, and overall eye protection, making its understanding important for maintaining clear vision and ocular comfort.
Understanding the Medial Canthus
The medial canthus is separated from the eyeball by the lacrimal lake, a small, tear-filled triangular space. Within this space lies the lacrimal caruncle, a small tissue body containing fine hairs and specialized glands that contribute to tear production and lubrication.
Immediately adjacent to the lacrimal caruncle, tiny openings called lacrimal puncta are found along the eyelid margins. These puncta are the entry points to the lacrimal drainage system, which includes the canaliculi and the lacrimal sac. The canaliculi transport tears from the puncta to the lacrimal sac, which then drains into the nasal cavity via the nasolacrimal duct. Additionally, the medial canthal tendon, a fibrous band, anchors the eyelids to the lacrimal bone, providing support and stability for proper eyelid movement and closure, essential for eye protection.
Common Conditions Affecting the Medial Canthus
Dacryocystitis, an infection of the lacrimal sac, often results from a blockage in the tear drainage system. Acute dacryocystitis typically presents with sudden pain, swelling, and redness in the inner corner of the eye, sometimes accompanied by pus-like discharge and fever. Chronic dacryocystitis develops more gradually, with milder but persistent symptoms such as constant tearing and occasional discharge.
Nasolacrimal duct obstruction (NLDO), or a blocked tear duct, is another frequent condition, affecting both infants and adults. In newborns, NLDO often occurs when a membrane at the end of the tear duct fails to open fully at birth, leading to excessive tearing that may become noticeable within the first 2 to 3 weeks of life. In adults, blockages can stem from chronic infections, inflammation, trauma, or even tumors, causing symptoms like persistent watery eyes, swollen eyelids, and yellowish-green mucus discharge.
The medial canthus is also a common site for skin lesions and growths, including various types of skin cancer. Basal cell carcinoma (BCC), the most prevalent form of eyelid cancer, frequently appears here, accounting for nearly 88% of all eyelid cancers. BCC often presents as a slowly enlarging, painless reddish nodule with pearly margins, or an open sore that does not heal and may bleed. BCCs in this region can be more invasive and challenging to treat.
Traumatic injuries and lacerations to the medial canthus can also occur, often from blunt force or penetrating objects. These injuries can damage the tear drainage system, leading to epiphora (excessive watering of the eye) or impaired tear drainage. Such trauma may also cause malposition of the medial canthus, impacting eyelid stability and potentially leading to complications like ectropion, where the eyelid turns outward.
Seeking Care and Treatment
Prompt medical attention is advisable for any persistent issues related to the medial canthus, especially if symptoms include pain, swelling, redness, discharge, changes in vision, or new or changing growths. An eye care professional, such as an ophthalmologist or oculoplastic surgeon, can perform a thorough evaluation. This assessment includes a physical examination to observe the lesion’s characteristics or the extent of the injury, and may involve probing and irrigation of the tear drainage system to check its function. Imaging studies like computed tomography (CT) scans may also be used to assess underlying bony injuries or the extent of a mass, particularly in cases of trauma or suspected tumors.
Treatment approaches for medial canthus conditions vary widely depending on the specific diagnosis. For infections like dacryocystitis, antibiotics are commonly prescribed, and warm compresses can help alleviate symptoms. Blocked tear ducts in infants often resolve spontaneously within the first year of life, but gentle massage of the area may be recommended. If conservative measures are insufficient, procedures such as tear duct probing or dacryocystorhinostomy (DCR) surgery may be performed to create a new drainage pathway.
Skin lesions, including basal cell carcinomas, are treated with surgical removal. Reconstruction of the medial canthus and eyelids often follows tumor removal or trauma repair, using various techniques to restore normal eyelid function, support the lacrimal drainage system, and protect the eye. In some cases of traumatic injury, surgical realignment of the medial canthus may be necessary to correct eyelid malposition.