Severe sight-threatening inflammation of the cornea and external eye requires aggressive systemic immunotherapy. Initiating such treatment, especially steroid-sparing immunomodulators, is outside the comfort zone for many of us, particularly in elderly patients with multiple comorbidities. Engaging a rheumatologist or other physician colleague to advise regarding the safety of various agents in individual cases is important, both from a clinical and governance perspective.

A stepladder algorithm helps plan treatment. Several questions arise regarding this.

• Which agents are on the stepladder?

• How does one decide which agent to use, and when?

• Do particular agents work better in some conditions and not in others?

In inflammatory cornea and external disease, broadly two stepladder algorithms may be used (figures 1 and 2). Figure 1 shows an algorithm for any non-pemphigoid-related inflammation, such as Mooren's ulcer, rheumatoid melt or Wegener's granulomatosis, atopic conjunctivitis or sclerokeratitis,1 Stevens Johnson syndrome with recurrent inflammation or scleritis,2 acanthamoeba scleritis,3 and necrotising scleritis.

For these external eye conditions, a stepladder algorithm with oral ciclosporin (for patients younger than 60 years of age) or methotrexate at the base is useful, then stepping up to mycophenolate or azathioprine if there is intolerance to these agents or no response, then stepping up to cyclophosphamide, and finally stepping up to biologicals such as antitumour necrosis factor (anti-TNF) agents, rituximab or intravenous immunoglobulin. Adding a short course of high-dose corticosteroids to any of these agents can help to control inflammation more rapidly. Ciclosporin and other calcineurin inhibitors work particularly well in atopic disease.1 ,4 Ciclosporin is well tolerated in patients younger than 60 years of age. In patients …