Table 2.

Differentiating features between infectious and non-infectious scleritis

	Infectious scleritis	Non-infectious scleritis
Etiopathogenesis	Direct invasion of the pathogenic organisms including bacteria, fungi, viruses and protozoans	Connective tissue disorders
		Rheumatoid Arthritis
	Autoimmune response to microbes	Systemic Lupus Erythematosus
	Post-surgical and post traumatic infection	Relapsing Polychondritis
	Spread from contiguous structures	Systemic Vasculitis
		Granulomatosis with Polyangiitis
		Microscopic Polyangiitis
		Polyarteritis Nodosa
		Churg Strauss Syndrome
Key clinical features	Purulent exudates, scleral ulcers, scleral abscesses, and scleritis associated with hypopyon.	Not associated with pus/abscesses. Diffuse/nodular tender congestion of deep episcleral vessels with oedema of sclera
Investigations	Culture and staining	Biopsy is contraindicated
	Tissue biopsy	Antinuclear antibody
	Mantoux test	Anti-neutrophil cytoplasmic antibody
	Syphilis serology	Rheumatoid factor
Treatment	Anti-microbial therapy.	Topical and systemic corticosteroids
	Role of steroids is controversial/contra indicated	Immunosuppressive agents