Which of the following involves the obstruction of a meibomian gland?

A chalazion involves the obstruction of a meibomian gland, which is a type of sebaceous gland located within the eyelid that secretes oil to lubricate the eye. When the meibomian gland becomes obstructed, the oil builds up and can lead to a firm lump on the eyelid, known as a chalazion. This condition is typically not associated with infection and may resolve on its own or with conservative treatment, such as warm compresses.

In contrast, a hordeolum, or stye, is an acute infection of an oil gland, typically leading to pain and swelling, but it involves a different pathology compared to the chronic obstruction seen in a chalazion. Conjunctivitis refers to inflammation of the conjunctiva, often due to infection or allergies, and does not specifically relate to the obstruction of a gland. Ectropion is a condition where the eyelid turns outward, which is more related to eyelid positioning rather than gland obstruction.

Understanding the specific functions and conditions related to various glands in the eye can help differentiate these terms and clarify their implications in ocular health.