Despite identifying 34 trials related to treatments for blepharitis, there is no strong evidence for any of the treatments in terms of curing chronic blepharitis. Commercial products are marketed to consumers and prescribed to patients without substantial evidence of effectiveness. Further research is needed to evaluate the effectiveness of such treatments. Any RCT designed for this purpose should separate participants by type of condition (e.g. staphylococcal blepharitis or MGD) in order to minimize imbalances between groups (type I errors) and to achieve statistical power for analyses (prevent type II errors). Medical interventions and commercial products should be compared with conventional lid hygiene measures, such as warm compresses and eyelid margin washing, to determine effectiveness, as well as head-to-head to show comparative effectiveness between treatments. Outcomes of interest should be patient-centered and measured using validated questionnaires or scales. It is important that participants be followed long-term, at least one year, to assess chronic outcomes properly.
N-acetylcysteine in chronic blepharitis.
To investigate the effects of N-acetylcysteine (NAC) in chronic posterior blepharitis.
                This was a prospective randomized, controlled study that included 79 eyes of 40 patients with chronic posterior blepharitis. Routine ophthalmologic examination, Schirmer-1 test, fluorescein break-up time (FBUT), and mucous fern tests were carried out during the first visit of all patients. A topical steroid, topical antibiotic, and artificial tears were started in 36 eyes of 18 patients. The therapy group (43 eyes of 22 patients) was administered three daily doses of 100 mg oral NAC. All patients were examined weekly for 1 to 4 months (average, 24 +/- 0.7). A Schirmer-1 test and FBUT were administered at every visit, but mucous fern tests were administered every two weeks. The results of the first and last Schirmer-1 tests, FBUT, and mucous fern test were compared between the therapy and control groups. Student's t and Mann-Whitney U tests were used for statistical analysis.
                FBUT was significantly increased (p < 0.0001), and the mucous fern pattern was also significantly improved (p = 0.0096) in the therapy group.
                NAC is thought to increase FBUT and improve mucous fern pattern by blocking lipid peroxidation in chronic blepharitis.