Superficial and deep<unk> s<unk> s are a common human eye disease. They are caused by trauma, particularly with vegetable matter, as well as chemical injury, contact lenses and infections. Other eye conditions can cause<unk> s, such as entropion, distichiasis, corneal dystrophy, and keratoconjunctivitis sicca (dry eye). Many micro-organisms cause infective<unk> . Among them are bacteria, fungi, viruses, protozoa, and chlamydia: * Bacterial keratitis is caused by Staphylococcus aureus, Streptococcus viridans, Escherichia coli, Enterococci, Pseudomonas, Nocardia, N. Gonorrhoea and many other bacteria. * Fungal keratitis causes deep and severe<unk> . It is caused by Aspergillus sp., Fusarium sp., Candida sp., as also Rhizopus, Mucor, and other fungi. The typical feature of fungal keratitis is slow onset and gradual progression, where signs are much more than the symptoms. Small satellite lesions around the<unk>  are a common feature of fungal keratitis and hypopyon is usually seen. * Viral keratitis causes<unk> ation. It is caused most commonly by Herpes simplex, Herpes zoster and Adenoviruses. Also it can be caused by coronaviruses & many other viruses. Herpes virus cause a dendritic<unk> , which can recur and relapse over the lifetime of an individual. * Protozoa infection like Acanthamoeba keratitis is characterized by severe pain and is associated with contact lens users swimming in pools. * Chlamydia trachomatis can also contribute to development of<unk> . Superficial<unk> s involve a loss of part of the epithelium. Deep<unk> s extend into or through the stroma and can result in severe scarring and corneal perforation. Descemetoceles occur when the<unk>  extends through the stroma. This type of<unk>  is especially dangerous and can rapidly result in corneal perforation, if not treated in time. The location of the<unk>  depends somewhat on the cause. Central<unk> s are typically caused by trauma, dry eye, or exposure from facial nerve paralysis or exophthalmos. Entropion, severe dry eye and trichiasis (inturning of eyelashes) may cause<unk> ation of the peripheral cornea. Immune-mediated eye disease can cause<unk> s at the border of the cornea and sclera. These include Rheumatoid arthritis, rosacea, systemic sclerosis which lead to a special type of<unk>  called Mooren's<unk> . It has a circumferential crater like depression of the cornea, just inside the limbus, usually with an overhanging edge.
Corneal ulcer
Corneal abrasion
Band keratopathy
Bullous keratopathy
Periorbital cellulitis
Lattice corneal dystrophy
Macular corneal dystrophy
Ocular melanosis