Though there is scant research to guide treatment, tea tree oil shampoo might successfully improve some cases of blepharitis, according to two physicians at the Eye Unit, Southampton General Hospital, Southampton, United Kingdom.
Tea tree oil acts against bacteria, fungus, mites, and inflammation, all of which may be involved in some forms of blepharitis, they said in an editorial for the journal Eye.
The editorialists wrote that blepharitis is “likely to be the most under-diagnosed, undertreated, and underappreciated eye disease worldwide.”
Though its aetiology is poorly understood, clinicians have traditionally blamed anterior blepharitis on local microbial colonisation or seborrhoea, while blaming posterior blepharitis on meibomian gland dysfunction.
Despite recent work by the International Workshop on Meibomian Gland Dysfunction, the poor understanding of the causes of the condition has inhibited progress in treatments, the editorialists wrote.
However, the writers say some progress is being made, citing a study in the same issue of Eye that found both fungus and Demodex mites were more common in people with blepharitis than in people who did not have the condition.
In that study, researchers from Mevlana University School of Medicine, Konya, Turkey, tested the eyelashes of 19 patients with chronic anterior blepharitis “of seborrheic or mixed seborrhetic/staphylococcal type” and 11 healthy age- and sex-matched controls for fungus. They used periodic acid-Schiff (PAS) staining in addition to fungal cultures and direct microscopy.
The PAS staining revealed fungal elements in 15 patients (79%) of the blepharitis group and 2 (18%) of the control group, a statistically significant difference (P= 0.002).
Previously, researchers have searched for fungus in blepharitis using fungal cultures, but this method has a high false negative rate, the researchers reported.
Through cultures, the researchers isolated Penicillium or Candida species, or Tricophyton verrucosum in four patients with blepharitis, but in none of the control subjects.
Using direct microscopy, they found fungal elements in 11 of the patients with blepharitis (58%), and Demodex mites in eight (42%). In the control group, they found fungal elements in one subject (9%) but no signs of mites in any.
Previous studies have identified such bacteria as Staphyloccus, Propionibacterium, and Cornybebacterium on the eyelids of people with blepharitis, the researchers noted. They explained that these organisms also appear on healthy eyelids, but in different proportions. For example, according to one report, the proportion of Propionibacterium is lower on the eyelids of people with blepharitis.
“This might also explain our results as it is known that the decrease of normal microbial flora results in accumulation of pathogen organisms including fungi,” the researchers wrote.
The Mevlana University researchers speculate that the fungi or mites could play a primary role in chronic anterior blepharitis, triggering inflammation, or other factors such as increased seborrhoea that might feed these organisms.
The Southampton General Hospital editorialists offer a similar hypothesis. “Excessive colonisation may be an epiphenomenon, indicating the possibility that microbes find the altered eyelid environment in blepharitis more hospitable than that of the normal eyelid,” they wrote.
Antibiotic and steroid drops could alter the commensal flora and actually favour colonisation by bacteria or fungi. However, they also note the “beneficial effect antibiotics have in patients with this condition.”
In posterior blepharitis, the primary aetiology of meibomian gland dysfunction presents an even more complex question, they noted.
The editorialists concluded by calling for more research and greater acceptance of diagnostic criteria set up by international workshops.
“In the meantime,” they wrote, “clinicians are left with making pragmatic options to reduce microbial flora based on their own experience. Anyone for a drop of tea tree oil shampoo?”