How do you clinically differentiate between internal (meibomian gland infection) and external hordeolum (stye)?

Clinical Differentiation of Internal vs External Hordeolum

The key clinical distinction is anatomical location: external hordeolum (stye) presents as a painful, localized swelling at the eyelid margin involving the eyelash follicles or associated glands (Zeis or Moll glands), while internal hordeolum presents as a deeper, more diffuse swelling on the tarsal conjunctival surface involving the meibomian glands.

Anatomical Location and Presentation

External Hordeolum (Stye)

• Visible at the anterior eyelid margin near the base of the eyelashes 1
• Presents as a localized, pointed abscess that is easily visible on external examination 1
• The infection involves the glands of Zeis (sebaceous) or Moll (apocrine sweat glands) associated with eyelash follicles 1
• Typically appears as a small, red, tender bump on the outer edge of the eyelid 1

Internal Hordeolum

• Located deeper within the eyelid, involving the meibomian glands in the tarsal plate 2, 3
• Presents as diffuse swelling of the palpebral conjunctiva when the eyelid is everted 1
• The tarsal conjunctiva shows redness and swelling on slit-lamp examination with eyelid eversion 1
• May present with meibomian gland orifice abnormalities such as pouting or capping 1
• Often associated with posterior blepharitis and meibomian gland dysfunction 2, 3

Clinical Examination Technique

External Examination

• Perform examination in a well-lighted room with attention to the eyelid margin 1
• Look for abnormal deposits at the base of eyelashes and vascularization or hyperemia of eyelid margins 1
• External hordeola are evident on external examination without need for eyelid eversion 1

Slit-Lamp Biomicroscopy with Eyelid Eversion

• Evert the eyelids to examine the tarsal conjunctiva 1
• Assess the posterior eyelid margin for meibomian gland abnormalities 1
• Look for inflammation, nodularity, and thickening of the tarsal conjunctiva 1
• Evaluate meibomian gland orifices for signs of obstruction or inflammation 1

Associated Clinical Features

Pain Characteristics

• Both types cause acute-onset eyelid pain, but internal hordeolum may present with deeper, more diffuse discomfort 2
• Pain is typically associated with a palpable lump in both types 1

Drainage Patterns

• External hordeolum typically drains spontaneously through the skin surface 4, 5
• Internal hordeolum may drain into the conjunctival sac or require intervention 2, 4

Important Clinical Pitfalls

Red Flags Requiring Further Investigation

• Marked asymmetry or resistance to therapy may indicate sebaceous carcinoma rather than simple hordeolum 1, 6
• Unifocal recurrent lesions that don't respond to standard treatment warrant biopsy 1, 6
• Loss of normal eyelid margin anatomy or focal lash loss (ciliary madarosis) are concerning signs 1, 6
• Chronic unilateral blepharitis unresponsive to treatment, especially in older patients, should raise suspicion for malignancy 6, 7

Associated Conditions

• Both types are commonly associated with chronic blepharitis and meibomian gland dysfunction 2, 3
• History of recurrent hordeola suggests underlying seborrheic dermatitis or rosacea 3
• In children, recurrent hordeola may indicate chronic blepharokeratoconjunctivitis that requires ophthalmology referral 2, 3

Practical Clinical Algorithm

1. Inspect the eyelid margin externally in good lighting 1

   • If localized swelling at lash base → likely external hordeolum

2. Evert the eyelid to examine tarsal conjunctiva 1

   • If diffuse conjunctival inflammation and swelling → likely internal hordeolum

3. Assess meibomian gland function by gentle expression 1

   • Abnormal secretions or obstruction suggest internal hordeolum with MGD 2

4. Evaluate for underlying blepharitis 1

   • Look for lid margin telangiectasia, collarettes, and meibomian gland abnormalities 1