Bacterial keratitis

The number of infectious keratitis cases is increasing worldwide. The vast majority of cases are bacterial in origin. Both gram positive (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae Corynebacterium diphtheriae) and gram negative (Pseudomonas aeruginosa, Acinetobacter species) bacteria can cause serious infections. One of the most common causes is related to contact lens wear. This can be in connection with overwear, overnight wear (orthokeratology), inadequate lens cleaning with tap water, lack of hygiene, and contamination of different solutions. Uncontrolled use of lenses ordered from the internet is also a source of danger. The other main cause is trauma, resulting from surface injuries (e.g. nails, plants), foreign bodies, mechanical and chemical injuries. Certain ophthalmological conditions also predispose to bacterial keratitis, such as dry eye, blepharitis, non‐healing ulceration, and previous eye surgery. Immunosuppressive treatment, autoimmune diseases, diabetes mellitus may also result in development of infection. In serious cases patients typically complain of pain, sensitivity to light, blurred vision, tearing, yellowish purulent discharge and various degree of visual loss. Clinical appearance includes epithelial defect and erosions, ulceration, stromal infiltrates with indistinct margins. In serious forms Descemetocele, even perforation can be present. Hypopyon may also appear in the anterior chamber. Diagnosis is based on the clinical picture. Culturing and smear sampling are necessary when the infiltrate is large and central, when there in contact lens wear in the history, the process is resistant to therapy, and appearance is atypical. Most cases can be successfully treated with empiric therapy. The first choice of treatment is usually fluroquinolone therapy. In severe cases moxifloxacin or cefazolin with tobramycin or gentamycin is advised. Eye drops in every hour should be applied both day and night for the first 48 hours as saturation dose. If there is no improvement in the clinical picture after 48 hours, repeat sampling for microbiological culture recommended. Corticosteroids may be considered after 2 days when the infective organism is identified, and the keratitis is responding to therapy. Cycloplegia may also decrease pain as well as synechia formation. In therapy resistant cases crosslinking may be an additional option if herpetic origin can be excluded. Amniotic membrane transplantation is recommended for non‐healing epithelial defects. In cases of non‐healing and rapidly progressive cases therapeutic corneal transplantation is recommended. However, surgery has a better prognosis in quiet eye.