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Red Eye and Discomfort

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A 62-year-old man was referred for a cataract surgery evaluation with complaints of decreased vision, itching and
discomfort and redness in both eyes. His visual acuity was 20/50 best corrected in each eye, with normotensive intraocular pressures. The slit-lamp examination revealed visually significant nuclear sclerotic and cortical cataract in each eye. Significant lid margin disease as shown in the photo at right was also noted.

Diagnosis

The slit-lamp examination demonstrates significant meibomian gland dysfunction and anterior blepharitis with prominent cylindrical sleeves around the lashes, suggesting blepharitis caused by a mite. The laboratory test to aid the diagnosis is light microscopic examination of a plucked eyelash.

Testing

An eyelash with a cylindrical sleeve was removed at the slit-lamp using a pair of jeweler’s forceps. The plucked eyelash was then placed on a glass slide and covered with a cover slip and a drop of 2% fluorescein eye drop with proparacaine, which is readily available in the clinic for measuring intraocular pressure. Light microscopic examination revealed a single mite at the root of the eyelash (Figure 1).

Figure 1. Light Microscopy

A single mite clings to the root of the eyelash.

The microorganism was about 0.3 mm to 0.4 mm long, with a semi-transparent elongated body, consisting of 2 fused segments (Figure 2).

Figure 2. Demodex Mite

This microscopic organism was responsible for the patient’s blepharitis.

Based on these findings, we diagnosed demodex blepharitis. Female demodex mites are shorter and rounder than males. Both males and females have a genital opening, and fertilization is internal. Mating takes place at the opening of the follicles, usually at nighttime. The eggs are laid inside the hair follicles. The 6-legged larvae hatch after 3 to 4 days, and the larvae to develop into adults over 7 days. The total lifespan of a demodex mite is several weeks. The dead mites decompose inside the hair follicles or sebaceous glands.

Treatment

In an effort to improve the patient’s ocular surface prior to cataract surgery, he was treated with a 6-week course of tea tree oil scrubs^1,2 (available from TheraTears as Sterilid, or a 50% formulation at Whole Foods Markets), once at night, and topical broad-spectrum antibiotics. He had symptomatic and clinical relief with improvement in his meibomian gland dysfunction as well as elimination of the cylindrical sleeves. n

References

1. Gao YY, Di Pascuale MA, Li W, Baradaran-Rafii A, Elizondo A, Kuo CL, et al. In vitro and in vivo killing of ocular Demodex by tea tree oil. Br J Ophthalmol. 2005:89:1468-1473.
2. Gao YY, Di Pascuale MA, Elizondo A, Tseng SC. Clinical treatment of ocular demodecosis by lid scrub with tea tree oil. Cornea. 2007;26:136-143.