Differential Diagnosis for Red Sclera

Single Most Likely Diagnosis

• Subconjunctival Hemorrhage: This condition is characterized by the appearance of blood underneath the conjunctiva, the clear membrane covering the white part of the eye (sclera). It can cause the sclera to appear red and is often painless, without discharge, itching, or changes in vision. The fact that the condition has persisted for 3 months suggests a recurrent or persistent cause, but the lack of other symptoms aligns with subconjunctival hemorrhage.

Other Likely Diagnoses

• Pinguecula: A pinguecula is a yellowish patch or elevation on the conjunctiva, near the cornea, that can become red and inflamed. It's often related to UV exposure and can be asymptomatic aside from the cosmetic concern of redness.
• Conjunctivochalasis: This condition involves a redundant, loose, or prolapsed conjunctiva between the globe and the lower lid, which can cause chronic redness without significant discomfort or vision changes.
• Scleral Vascular Malformation: Abnormalities in the blood vessels of the sclera can lead to persistent redness without other symptoms.

Do Not Miss Diagnoses

• Rheumatologic Diseases (e.g., Rheumatoid Arthritis, Lupus): Although less common, systemic diseases can cause scleritis, which might present with redness. Scleritis is typically painful, but some forms can be painless. Missing these diagnoses could lead to significant morbidity if not treated properly.
• Ocular Malignancies (e.g., Conjunctival or Scleral Tumors): Rarely, redness of the sclera could be a sign of an underlying tumor. While unlikely, the potential severity of these conditions warrants consideration.

Rare Diagnoses

• Scleromalacia Perforans: A rare, painless form of scleritis associated with rheumatoid arthritis, characterized by thinning of the sclera.
• Episcleritis: An inflammatory condition of the episclera, a thin layer on top of the sclera, which can cause redness. It's usually sectoral and can be associated with systemic diseases.
• Foreign Body Sensation without a Visible Foreign Body: Sometimes, a small foreign body can cause chronic inflammation and redness without being visible upon examination.

Each of these diagnoses has a different level of urgency and potential impact on the patient's health, emphasizing the importance of a thorough examination and diagnostic workup to determine the underlying cause of the red sclera.