This patient most likely has scleritis. Scleritis is inflammation of the fibrous layers of the eye underlying the episclera and conjunctiva and overlying the choroid. Patients may present with severe, continuous, boring ocular pain that radiates to the surrounding facial areas, redness, photophobia, and tearing. It most commonly affects both eyes and is frequently worse at night, and because of traction of the extraocular muscles on the sclera, pain is often worse with eye movement. Vision may be normal, but impairment may result from inflammatory involvement of adjacent ocular structures or loss of globe integrity. Roughly 50% of patients with scleritis have an underlying systemic disease, such as an inflammatory connective tissue disorder (rheumatoid arthritis) or infection (tuberculosis). Because scleritis can be a sight-threatening condition, it requires urgent referral to an ophthalmologist for further evaluation and treatment.
The episclera is a vascular fibroelastic structure superior to the sclera. Inflammation of the episclera, or episcleritis, is less commonly associated with pain or photophobia, as seen in this patient, but more commonly with redness, irritation, and tearing. This history is usually most helpful in differentiating scleritis from episcleritis, as they may be difficult to distinguish by physical examination alone. Episcleritis is also uncommonly associated with risk for visual impairment.
Keratoconjunctivitis sicca (dry eye) includes symptoms of dryness, irritation, and burning. This patient does not have a presentation consistent with dry eye.
Patients with subconjunctival hemorrhage present with blotchy redness (from extravascular blood) that is typically confined to one area of the conjunctiva. Subconjunctival hemorrhage is painless, occurs spontaneously, and resolves within several weeks. This patient's severe eye pain, diffuse redness, and persistence of symptoms argue against the diagnosis of subconjunctival hemorrhage.
Scleritis, painful inflammation of the fibrous layers of the eye underlying the episclera and conjunctiva, is often associated with systemic diseases including inflammatory connective tissue disorders and infections.
Bal SK, Hollingworth GR. Red eye. BMJ. 2005 Aug 20;331(7514):438. [PMID: 16110072]