The Effect of Phototherapy on Demodex Density: A Case-Control Study

This study employee as a case-control study to compare the Demodex densities before and after 20 sessions of narrow-band ultraviolet B (NBUVB) or ultraviolet A-1 (UVA-1) therapy in patients who will receive phototherapy for any dermatological indication. The study is going to be conducted at Istanbul Medeniyet University Department of Dermatology between June 2023 and August 2023. Ethical approval was obtained from Istanbul Medeniyet University Local Ethics Committee (decision number: 2022/0340).

Demographic and medical information, including age, gender, smoking and alcohol habits, dermatological indication of phototherapy, presence of facial involvement of the relevant disease, and use of medications or cosmetic products on the face in the last week, will be obtained through a standardized form. Patients will be evaluated by the researcher for the presence of clinical conditions associated with primary/secondary demodicosis, such as acne, rosacea, perioral dermatitis, seborrheic dermatitis, folliculitis, blepharitis, or pityriasis folliculorum.

The standardized skin surface biopsy (SSSB) technique is going to be utilized to assess Demodex density. Skin samples will be obtained from four regions of the participants' faces, including the forehead, right cheek, left cheek, and the nose, before phototherapy and after 20 sessions of phototherapy. The SSSB will be performed as follows: a 1 cm² square will be drawn on a glass slide using a ruler. The skin areas to be sampled will be gently swabbed with a dry gauze to induce irritation by this way to obtain more mites. Then, one drop of cyanoacrylate adhesive will be dropped onto the marked area on the glass slide, and the adhesive surface of the slide will be pressed onto the skin surface for approximately one minute. Afterwards, the slide will be gently lifted, and the sampled area will be examined under a light microscope at x10 and x40 magnifications after applying immersion oil. The presence of more than five Demodex mites per square centimeter will be defined as increased Demodex density.

Statistical analysis will be performed using IBM Statistical Package for the Social Sciences [SPSS] v.17. Means, standard deviations, or frequencies will be calculated for relevant variables as required. Paired samples t-test will be used to compare Demodex densities, and the McNemar test will be used to compare the presence of demodicosis between pre- and post-treatment. A p-value of less than 0.05 will be considered statistically significant.