Blepharitis is a frequent inflammatory condition of the eyelid and represents one of the most important reasons for ophthalmological consult, affecting up to 47% of patients seen in clinical practice.11 12 No standard of care has been approved for the treatment of blepharitis so far and further efforts are warranted for a better understanding of the etiopathogenetic mechanisms.13 14
Antiseptics are gaining interest in different fields in ophthalmology, from the prevention of postsurgical endophthalmitis to the treatment of anterior segment infections.15 They provide a broad spectrum of efficacy thanks to the absence of induced microbial resistance which is in contrast to the growing concern about antibiotic resistance and the selection of multidrug resistant bacteria in ophthalmology.16 Hypochlorous acid is an oxidising agent that shows its antimicrobial activity penetrating the cell wall and inhibiting DNA and protein synthesis by oxidation of thiol-containing proteins and enzymes.17 Bitton et al recently performed an in vitro evaluation of 0.01% hypochlorous acid that showed to be effective in reducing Staphylococcus spp and Pseudomonas aeruginosa on bacterial isolates from patients with blepharitis and keratitis, maintaining low concentrations of S. epidermidis (part of the normal skin flora) with selective bactericidal activity.7 A previous clinical study on the effect of hypochlorous acid through ultrasonic atomisation for Demodex blepharitis/MGD-DED demonstrated that pure hypochlorous acid can improve the eradication rate of the Demodex mite by shortening its average survival time.18
To the best of our knowledge, this is the first study to investigate the efficacy of two different products for the treatment of blepharitis combining the collection of clinical and antimicrobial parameters. We evaluated the efficacy in vivo of wipes containing 0.01% hypochlorous acid and wipes containing hyaluronic acid in improving clinical parameters and reducing the eyelid bacterial load in patients affected by blepharitis associated with mild to moderate DED.
Our clinical results showed in HOCL group a significant improvement in the following parameter: NIKBUT, BUT, TMH and OSDI score; instead, in HYAL group a significant improvement was observed only in TMH and OSDI score parameters. According to our results, we postulate that the improvement in TF stability seen in HOCL group could be related to the reduction of bacterial load and the subsequent lipolytic exoenzyme activity with the improvement of meibomian secretion which may justify a better symptomatic response.
Microbiological analysis supported our clinical findings, showing a significant microbial reduction in both groups, more pronounced in HOCL group with a mean reduction of 90% compared with the 62% of HYAL group. Both products showed an influence, with no difference among different bacterial strains, suggesting a wide spectrum activity towards inhabitants of the eyelid microbiota. The most representative species were found among Gram+, in particular CoNS and S. aureus. The most common Gram bacteria were klebsiella spp and proteus mirabilis. Other studies investigated the bacterial composition of donor conjunctiva in corneal transplantation, showing similar results compared with our baseline microbial assessments since the most common bacteria isolates were CNS and S. aureus.19 20 The antimicrobial activity seen in HYAL group may be due to the mechanical removal of residual debris and the subsequent action in reducing the resident microbial colonies. In HOCL group, the combination of the mechanical activity of the sterile wipe contained in the product and the chemical activity of hypochlorous acid was responsible for the higher rates of bacterial eradication.
The limitations of our study were the involvement of a relatively small number of patients as well as the limited time of follow-up during the treatment period. Other limitations of our study were the lack of the follow-up after the discontinuation of the treatment to verify the long-term efficacy of hypochlorous acid in chronic blepharitis, and the absence of analysis of tear inflammatory molecules levels that might be correlated with blepharitis symptoms. Further larger multicentric studies are warranted to assess the best treatment options for blepharitis.
According to our findings, wipes containing hypochlorous acid can be safely used in blepharitis considering the satisfying clinical and microbiological results along with the absence of adverse effects seen in our study. Wipes containing only hyaluronic acid seem to be less effective despite a similar safety profile.
In conclusion, products containing antiseptic agents, such as hypochlorous acid, can be considered a valid option in the treatment of blepharitis associated with DED. Furthermore, the antimicrobial activity showed by hypochlorous acid may extend its employment in the field of prophylaxis of several ocular procedures.