Keratoconus Appears to be Associated With Demodex Mites

Keratoconus, an eye disorder that leads to gradual curvature of the cornea, may be associated with Demodex infestation, suggests a small study published in the Oman Journal of Ophthalmology.

“There is increasing clinical and research interest in the potential contribution of Demodex to ocular surface disease,” wrote corresponding author Bengi Ece Kurtul, MD, of Mustafa Kemal University in Hatay, Turkey, and coauthors. “In this study …we found that Demodex mites unexpectedly were not detected in the control group, while Demodex mites were detected in the keratoconus group, with a rate of 21.1% for D folliculorum, and 26.3% for D folliculorum + D brevis.”

The cross-sectional investigation included 38 eyes of 20 patients with keratoconus and 40 eyes of 20 healthy subjects in a control group matched for age and sex. The mean age in the keratoconus group was 25.90 ± 7.01 years and in the control group was 26.52 ± 8.94 years.

In addition to detecting D folliculorum in 21.1% of eyes and D folliculorum + D brevis in 26.3% of eyes in the keratoconus group, the study found that the percentage of eyes with Demodex mites increased with keratoconus severity. In patients with mild/moderate keratoconus, 43.8% of eyes had Demodex mites. In patients with severe keratoconus, 66.7% of eyes had Demodex mites.

The number of symptomatic eyes for rubbing, itching, and tearing, as well as Ocular Surface Disease Index scores, were significantly higher in patients with keratoconus, both with and without Demodex mites, compared with controls. Tear break-up time levels were significantly lower in the keratoconus group.

The study found no differences, however, in ocular surface parameters between patients with keratoconus and controls.

“Demodex-related inflammation and associated eye rubbing may contribute to keratoconus progression. Microscopic examination of the lashes can provide important information of Demodex infestation, guiding us to make an adequate therapeutic strategy,” researchers wrote. “Even in people who do not have a keratoconus predisposition or a history of allergy, eyelash hygiene such as cleaning of eyelashes mechanically can be recommended as a general protection method.”

Reference

Kurtul BE, Kaya OM, Kakac A, Cetinkaya YF. Is there a relationship between keratoconus and ocular Demodex mites? Oman J Ophthalmol. 2023;16(2):287-292. doi:10.4103/ojo.ojo_270_22