Autologous serum eye drops for dry eye

Abstract

Background: Theoretically, autologous serum eye drops (AS) have a potential advantage over traditional therapies based on the assumption that AS serve not only as a lacrimal substitute to provide lubrication, but also contain other biochemical components mimicking natural tears more closely. The application of AS in dry eye treatment has gained popularity as a second-line therapy in the treatment of dry eye. Published studies on the subject indicate that autologous serum could be an effective treatment for dry eye. Objectives: To evaluate the efficacy and safety of AS compared to artificial tears for treating dry eye. Search methods: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 3), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE, (January 1950 to April 2013), EMBASE (January 1980 to April 2013), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to April 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We also searched the Science Citation Index Expanded database (September 2013) and reference lists of included studies. We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 15 April 2013. Selection criteria: We included randomized controlled trials (RCTs) in which AS was compared to artificial tears in the treatment of dry eye in adults. Data collection and analysis: Two review authors independently screened all titles and abstracts and assessed full-text articles of potentially eligible trials. Two review authors extracted data and assessed the methodological quality and characteristics of the included trials. We contacted investigators for missing data. For both primary and secondary outcomes, we reported mean differences with corresponding 95% confidence intervals (CIs) for continuous outcomes. Main results: We identified four eligible RCTs in which AS was compared with artificial tear treatment or saline in individuals (n = 72 participants) with dry eye of various etiologies (Sjögren's syndrome-related dry eye, non-Sjögren's syndrome dry eye and postoperative dry eye induced by laser-assisted in situ keratomileusis (LASIK)). The quality of the evidence provided by these trials was variable. A majority of the risk of bias domains were judged to have an unclear risk of bias in two trials owing to insufficient reporting of trial characteristics. One trial was considered to have a low risk of bias for most domains while another was considered to have a high risk of bias for most domains. Incomplete outcome reporting and heterogeneity in the participant populations and follow-up periods prevented the inclusion of these trials in a summary meta-analysis. For the primary outcome, improvement in participant-reported symptoms at one month, one trial (12 participants) showed no difference in participant-reported symptoms between 20% AS and artificial tears. Based on the results of two trials in 32 participants, 20% AS may provide some improvement in participant-reported symptoms compared to traditional artificial tears after two weeks of treatment. One trial also showed positive results with a mean difference in tear break-up time (TBUT) of 2.00 seconds (95% CI 0.99 to 3.01 seconds) between 20% AS and artificial tears after two weeks, which were not similar to findings from the other trials. Based on all other objective clinical assessments included in this review, AS was not associated with improvements in aqueous tear production measured by Schirmer's test (two trials, 33 participants), ocular surface condition with fluorescein (four trials, 72 participants) or Rose Bengal staining (three trials, 60 participants), and epithelial metaplasia by impression cytology compared to artificial tears (one trial, 12 participants). Data on adverse effects were not reported by three of the included studies. In one study, there were no serious adverse events reported with the collection of and treatment with AS. Authors' conclusions: Overall there was inconsistency in the possible benefits of AS in improving participant-reported symptoms and TBUT and lack of effect based on other objective clinical measures. Well-planned, large, high-quality RCTs are warranted, in different severities of dry eye and using standardized questionnaires to measure participant-reported outcomes and objective clinical tests as well as objective biomarkers to assess the benefit of AS therapy for dry eye.