Tiny oil glands maintain eye comfort and clarity. These glands keep eyes moist and protected; their proper function impacts vision and overall eye health. Understanding their location and function highlights their importance.
Anatomy of Eye Oil Glands
The eyelids house several types of oil glands. Meibomian glands are located vertically within the upper and lower eyelids. The upper eyelid typically contains more glands than the lower. These glands are arranged in parallel within the tarsal plates, which provide shape to the eyelids.
Near the base of the eyelashes are two other types of oil glands. The Glands of Zeis are sebaceous glands associated with eyelash follicles, producing oil that lubricates the eyelashes. Adjacent to the Glands of Zeis are the Glands of Moll, modified apocrine sweat glands that contribute to the tear film and eyelid margin.
Role of Eye Oil Glands
The oils produced by these glands maintain a healthy tear film covering the eye’s surface. Meibomian glands secrete meibum, forming the outermost lipid layer of this tear film. This oily layer prevents the watery component of tears from evaporating too quickly, keeping the eye moist.
Beyond preventing evaporation, these oils lubricate the eye surface. They reduce friction as eyelids glide over the eye during blinking, contributing to smooth, comfortable movement. The lipid layer also forms a protective barrier, trapping debris and preventing foreign particles from reaching the eye’s surface. A stable tear film, supported by these oils, is also important for clear vision, as it creates a uniform optical surface.
Common Issues Affecting Eye Oil Glands
When oil glands do not function properly, various eye conditions can develop. Meibomian Gland Dysfunction (MGD) is a problem where meibomian glands become blocked or produce insufficient or poor quality oil. This malfunction leads to rapid tear film evaporation, a primary cause of evaporative dry eye syndrome. Symptoms include persistent irritation, burning, redness, and sometimes blurred vision.
A stye is an acute bacterial infection of an eyelid oil gland. External styes typically affect the Glands of Zeis or Moll at the base of the eyelashes, appearing as a painful, red bump on the eyelid edge. Internal styes, which are deeper, involve the meibomian glands and can cause pain, swelling, and tenderness within the eyelid.
A chalazion is a non-infectious lump forming when a meibomian gland becomes blocked and inflamed, often following a stye or occurring independently. Unlike a stye, a chalazion is typically painless after initial development and feels like a firm nodule within the eyelid. These conditions show how oil gland disruptions can lead to discomfort and affect eye health.