 body sensation.20 Other reported signs and symptoms were subjective lash loss, heavy lids, and misdirected lashes.21
One notable characteristic of the infestation is the past unresponsiveness to conventional treatments for blepharitis, dry eye, and allergy. Patients will have a history of trying out different treatment strategies with little to no success. The failed treatments are typically for ocular surface conditions mainly because the infestation has many of the same signs and symptoms. Ineffective treatments include artificial tears, cyclosporine, antihistamines, doxycycline, lid hygiene, baby shampoo, and steroids.
CYLINDRICAL OR CUFF DANDRUFF
Cylindrical or cuff dandruff is a fine, waxy, sometimes dry, debris seen with slit lamp at the base of lashes contiguous with the lids. A smooth transparent collar of mite feces, keratin, and lipids surrounds the bases of lashes for 1 to 2 mm. This collar has the appearance of sometimes clear plastic insulation about the lash.11,22,23
One hundred percent of the patients with CD have Demodex infestation. Gao et al.24 found that the average count of Demodex was 12.9 mites per patient with CD compared with 0.35 mites without. The significant difference was more than 30 times higher when CD is present. Clinical severity judged by CD correlates well with greater numbers of Demodex.24
Demodex is extremely difficult to see with the naked eye and requires magnification. The size of a mite is about half the diameter of a grain of table salt.25 The bodies of both D. folliculorum and D. brevis are worm shaped. The gnathosoma is composed of the mouth and feeding parts. Gnathosoma has sharp stylet-like chelicerae used to cut and take food. Pedipalps are used to hold the food. The rest of the body consists of the head and neck area called prosoma or prodosoma. Adults have four pairs of legs in the prosoma. Opisthosoma forms the tail.26 The morphology has been described and measured by Desch and Nutting27 (Table 1; Fig. 1).
When viewing with the microscope, identification of Demodex is easier with knowledge of relative sizes for comparison. Adults are distinct, with well-developed head, neck, and legs. The other forms are more difficult to identify. In 1842, Simon identified D. folliculorum to be 0.3 to 0.4 mm long.3 The adult folliculorum average length for both males and females is about 0.286 mm, calculated using Desch measurements. Larva (length, 0.283 mm) is about the same length and width. Protonymph (length, 0.364 mm) is about 25% or one-fourth longer than the adult, with about the same width. Nymph or deutonymph (length, 0.392 mm) are much longer than adults, about 35 to 40% longer and 15 to 20% wider. The size range of 0.3 to 0.4 mm stated by other authors probably includes adults and the larger nymphs (based on Desch findings). Demodex brevis adult average length for males and females is 0.186 mm and about 50% shorter in length than D. folliculorum.
LASH SELECTION AND LIGHT MICROSCOPE VIEWING TECHNIQUES
Sampling the lashes with CD is more likely to yield better results than random epilation.23 Demodex usually resides in compact and opaque CD or deeper in the follicle. Because of this, Demodex can be very difficult to detect. Addition of fluorescein or alcohol has been used to enhance viewing with a microscope of the epilated lash.23,24 Fluorescein solution creates a yellowish contrast and induces instant dissolution and expansion of CD. Together, both properties helped significantly increase detection of mites compared with the time before the fluorescein was added. When the CD is immersed in fluorescein, it becomes semitransparent. This allows better viewing of mite structures within and behind the CD.23
Alcohol is effective in enhancing microscope confirmation of mites present. Gao et al.24,28 found that Demodex embedded in CD could not be counted unless 100% alcohol is added to stimulate them to migrate out. Drawbacks of alcohol were sometimes it could take up to 20 minutes for the mites to become visible. Alcohol can also kill the mite in 3.9 minutes.24,28
Coston11 described