Internal stye: what it is and how it manifests on the eyelid

Have you ever noticed a painful spot not on the surface of the eyelid but seemingly within its thickness? This is often how an internal stye begins: there is swelling, but no "head" is visible on the skin. We explain what this condition is, why it appears, and when it's time to see a doctor.

What is an internal stye

A stye, or hordeolum, is an acute purulent inflammation of the hair follicle of an eyelash or of the Zeis sebaceous gland near the lash root. An internal stye is a separate form: a lobule of the meibomian gland becomes inflamed. These glands lie within the thickness of the eyelid just behind the eyelashes and secrete an oily fluid that lubricates the eye.

The cause in both forms is bacterial: in 90–95% of cases Staphylococcus aureus is responsible. Both adults and children are affected, more often against a background of weakened immunity, for example after a cold. An internal stye runs a less acute course than an external one.

What a stye inside the eyelid looks like

Externally the eyelid swells and reddens, tenderness appears, and the conjunctiva of the eyelid is also red and swollen. If the eyelid is pulled back, a circumscribed painful induration is visible on the inner side. After 2–4 days a yellowish head with pus may form at its apex — an internal stye opens not onto the skin but into the conjunctival sac.

The eye may become red and watery, but vision is not affected by a stye. Usually one eye is involved, although there may be several styes, including on both eyes. Sometimes headache, fever, and enlargement of the nearby lymph nodes are added.

Internal stye on the lower and upper eyelid

Meibomian glands are present within the thickness of both eyelids, so an internal stye occurs on both the lower and the upper eyelid. The symptoms are the same: tenderness, redness, swelling of the eyelid margin.

Why an internal stye occurs

It all starts with bacteria that get into the gland duct. Then risk factors play a role:

• weakened immunity, for example after a cold;
• chronic blepharitis or rosacea;
• hypothermia, endocrine disorders, chronic diseases of the gastrointestinal tract;
• demodicosis and other eyelid problems.

How an internal stye differs from a chalazion

A chalazion is a small induration due to blockage of the meibomian gland duct. It often develops specifically after an internal stye: the redness and swelling subside, but the gland does not empty, and a dense nodule remains in the eyelid that does not hurt. This is the main difference — a stye is painful, a chalazion is not. A hard and almost painless induration is more likely to be a chalazion, and if there is no induration but the eye is red, swollen, and watery, it may be conjunctivitis or blepharitis.

The diagnosis is confirmed by examination of the eyelid: the doctor assesses where the induration is located, whether it is painful, and whether there is pus. Rarely, eyelid skin cancer looks like a chalazion — if suspected, a biopsy may be needed. A chalazion often resolves on its own in about a month; if it grows, the doctor discusses removal, more often from inside the eyelid so that no scar remains on the skin.

When to see an ophthalmologist

If a stye does not improve within a few weeks, that is a reason to book an appointment. You should see a doctor urgently with severe pain or marked swelling, with changes in vision, with pus from the eye, and with spread of the infection to the eye and eyelid.

You must not squeeze a stye or pull out the eyelash next to it: this way the infection can spread toward the orbit. Complications are rare, but they include orbital phlegmon, cavernous sinus thrombosis, and meningitis. A large stye sometimes interferes with vision, and a recurrent one is most often associated with concomitant diseases that the doctor looks for separately.

An internal stye by itself is not a reason to call an ambulance. 103 or 112 — if signs of infection spread appear: high fever, severe headache, increasing swelling around the eye with worsening of general condition.

This article is for reference and does not replace a doctor's consultation: showing the eyelid to a specialist is faster than dealing with the consequences on your own.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer