Here is a complete breakdown of the causes of a hordeolum:
Causes of a Stye (Hordeolum)
Primary Cause - The Bacteria
The direct cause is almost always Staphylococcus aureus - a bacterium that normally lives on the skin. When it infects a blocked or inflamed eyelid gland, a stye forms.
Occasionally other Staphylococcus species are involved.
What Gets Infected - The Glands
The bacteria target specific glands in the eyelid:
| Gland | Type | Leads to |
|---|
| Gland of Zeis | Sebaceous (oil) gland at lash follicle | External hordeolum |
| Gland of Moll | Sweat gland at lash follicle | External hordeolum |
| Meibomian gland | Large oil gland inside the tarsal plate | Internal hordeolum |
Risk Factors - What Makes It More Likely
These conditions predispose a person to getting styes:
Eyelid conditions:
- Blepharitis (chronic eyelid margin inflammation) - the most common predisposing condition; bacteria overgrow along the lid margin
- Meibomian gland dysfunction - blocked gland orifices allow bacteria to accumulate
Skin conditions:
- Acne rosacea - associated with chronic meibomian gland inflammation; patients often get recurrent styes and chalazia
- Seborrheic dermatitis - linked to blepharitis and eyelid overgrowth of Staph
Behavioral/hygiene factors:
- Touching or rubbing the eyes with unwashed hands - directly inoculates bacteria
- Wearing old or contaminated makeup - mascara and eyeliner can harbor Staphylococcus
- Not removing eye makeup before sleep - blocks gland orifices
- Wearing contact lenses improperly - can introduce organisms
Systemic conditions:
- Diabetes mellitus - impaired immunity makes infections more frequent and slower to resolve
- Immunocompromised states - any cause of reduced immunity (HIV, chemotherapy, steroids)
- High stress / poor sleep - weakens local immune defenses
Previous styes - having had one increases the risk of recurrence, especially if the underlying blepharitis or rosacea is untreated.
In Simple Terms
A stye happens when Staph bacteria get into a blocked or inflamed oil gland at the eyelid, usually because of poor lid hygiene, chronic blepharitis, or simply touching the eye with dirty hands.
Sources: Wills Eye Manual, Section 6.2 | Kanski's Clinical Ophthalmology, p.81 | Rosen's Emergency Medicine, p.893 | Tintinalli's Emergency Medicine, p.1581