Q: I am a 46 years old woman who has pain in the eyes. My eyes always remain dry; therefore I am using Restasis eye drops for infection. I have an autoimmune disease too. Please suggest how can I get blood serum for eye drops. How often do I have to have blood drawn and where to send it?

A:Serum is the fluid part of blood that is obtained after blood has clotted. It can be used as a tear substitute as it contains no preservative, is non-antigenic and its biochemical and biomechanical properties are similar to tears. It maintains the structure and function of the cells of the cornea better than pharmaceutical tear substitutes. These substitutes are used in conditions causing decreased epithelium trophic factors and their carrier molecules or non-healing epithelial defects. An ideal tear substitute should be able to sustain the corneal cells in addition to providing lubrication. The use of autologous serum eye drops for dry eyes is gaining popularity but protocols in published reports are incomplete and vary significantly. There are marked variations in production and treatment protocol and as yet in the United States; the FDA has not approved standardized protocol for its preparation. Clinical trials using serum have been attempted in kerato-conjunctivitis sicca due to Sjogren syndrome, graft-versus-host disease, neurotrophic keratitis, rheumatoid arthritis etc. Various studies have used different protocols where serum has been collected from 0 to 2 days, the duration of centrifugation and speed varying from 300-4000 g over 5 to 20 minutes, the concentration has varied from 20% to 100% (using sodium chloride or balanced salt solution as diluents), frequency of installation from hourly to 3 times a day, using antibiotic preservatives and storage temperature -20 to +4 0C. The use of laminar flow hood, filter sterilisation and positive pressure clean room is required to maintain sterility of the product. Several complications have been reported in these trials and further studies are required to have a protocol for manufacture to ensure stability, sterility and storage, define clearly the conditions where serum would help, its dose, concentration and dosing schedule. Moreover, it is necessary to know which fractionation of serum or its component(s) is/are the active portion. It is best if you consult an ophthalmologist who has the requisite experience in this form of therapy.