The caruncle, a small part of the eye, resides at its inner corner. This fleshy, pinkish-red nodule may seem insignificant, yet it plays a role in maintaining eye health and comfort. Understanding its structure and function helps appreciate its contribution to vision.
What is the Caruncle?
The caruncle, formally known as the lacrimal caruncle, is a soft projection located at the medial canthus, the inner corner where the upper and lower eyelids meet. It appears as a reddish, conical-shaped body that fills the lacrimal lake, a small triangular space that collects tears. This nodule is an island of modified skin.
The caruncle’s composition includes skin, hair follicles, sebaceous glands, sweat glands, and accessory lacrimal tissue. Fine, slender hairs are sometimes present on its surface. The sebaceous (oil) glands and sweat glands contribute to the eye’s natural secretions.
Its Role in Eye Health
The glands within the caruncle produce components of the tear film, a thin, protective layer covering the eye’s surface. Specifically, the sebaceous glands contribute an oily secretion that forms the lipid layer of the tear film. This oily layer reduces tear evaporation, keeping the eye sufficiently lubricated.
The caruncle also collects debris and foreign particles that enter the eye. The “sleep” or “eye boogers” that sometimes accumulate in the inner corner of the eye are a normal result of this cleansing process, consisting of gland secretions, dust, and trapped particles. This mechanism maintains a clean ocular surface and protects against irritants.
Common Caruncle Concerns
Variations in the caruncle’s appearance, such as slight redness or fine hairs, are generally normal and do not indicate a problem. However, the caruncle can become inflamed, a condition known as carunculitis. This inflammation can cause symptoms like redness, swelling, or discomfort in the affected area.
Cysts, such as sebaceous cysts, can also form in the caruncle if the oil or sweat glands become clogged. These cysts may appear as a palpable mass, sometimes yellow, and can lead to inflammation. While most caruncular lesions are benign, persistent pain, significant swelling, unusual discharge, or any changes to vision warrant a consultation with an eye care specialist. Such symptoms might indicate an infection, an allergic reaction, or an underlying condition requiring professional evaluation.