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Ocular demodicosis.

Introduction

Blepharitis is a very common condition of the eye, responsible for about 5% of all eye conditions reported to general practitioners, with increased prevalence in the >50 age group. (1) It can be divided into the posterior and anterior subtypes, the former being more common and associated with meibomian gland dysfunction. The anterior subtype, however, is most commonly caused by stapylococcus, seborrheic dermatitis and rosacea. Demodicosis is a condition which refers to infestation with the parasitic mite demodex species, folliculorum or brevis (see Figure 1), and can lead to both types of blepharitis: anterior (d. folliculorum) and posterior (d. brevis). Recognizing demodicosis as the cause of blepharitis is often simple, due to pathognomonic cylindrical dandruff (Figure 2), and important, due to its recalcitrance to all standard medical therapies, except tea tree oil. (2) Nonetheless, demodicosis often goes unrecognized due to lack of awareness and is mistreated as a typical blepharitis. In this paper, we present a case of anterior blepharitis caused by the demodex folliculorum species.

Case Presentation

A 60 year old female, wife of a physician, presented to the clinic with eye irritation, burning, and itching that has been present over the past two years. She has seen multiple medical practitioners for this problem, including her primary care provider, two optometrists, and one ophthalmologist. She wears contact lenses but denies any decrease in visual acuity or peripheral vision. She denies scotomas, headaches, allergies, and other systemic symptoms, including musculoskeletal, gastrointestinal, or genitourinary symptoms. Her past medical history is significant only for a history of early cataracts. Her past medical trials with these providers include antibiotic drops, corticosteroid drops, cyclosporin (for dry eyes), and baby shampoo. Her social history reveals that her dogs sleep next to her.

On physical examination, she is found to have erythematous eyelid margins, with cylindrical dandruff at the base of most of the eyelashes (Figure 1). Her conjuctiva are also slightly red, and spontaneous tearing is noted. Her visual acuity is 20/20 bilaterally, and she does not have any seborrheic dermatitis or rosacea on any other visible portion of her body.

Based on her presentation-blepharitis with cylindrical dandruff, refractory to medical trials with standard agents, and a history of sleeping next to her dogs, a presumptive diagnosis of blepharitis due to ocular demodicosis (infestation with the mite demodex follicularum) was made. For confirmation, we epilated 4-6 lashes bearing the cylindrical dandruff and visualized the parasitic demodex mite under simple light microscopy. The patient was then started on a regimen of tea tree oil shampoo, whereby she would massage the 5% tea tree oil shampoo into her eyelid margins for 5 minutes, twice a day after washing her face with baby shampoo. She continued this practice for 4-6 weeks, along with hygiene measures (change bedding, keep pets out of bedroom, discard used makeup containers, treat spouse with same regimen), and achieved a full resolution of symptoms. After several months of being symptom free, her blepharitis returned for a period of 7 days but was promptly relieved again with another course of tea tree oil.

Discussion

Demodicosis is an infestation with the parasitic mite, demodex species (Figure 1), of which there are two types: demodex folliculorum and demodex brevis. Demodex occurs in the general population on the eyelids and nose in 4% of people less than 19yo, 30% of 20-80yo, and 47% of those greater than 80yo, but often it occurs as a commensal organism and does not cause symptoms. (6) For instance, demodex was found to be present in 100% of patients with cylindrical dandruff on their eyelashes--a pathognomonic sign of demodex infestation (Figure 2)--but also in 22% of those with clean lashes. (2,8)

Demodex folliculorum tunnels its way down the hair shaft towards the follicle. The abrasive action of its claws is believed to result in epithelial hyperplasia and increased keratinization. For nutrients, demodex pierces epithelial cells and consumes cytoplasm and debris. (3) During its life cycle, waste may accumulate and harbor bacteria, viruses, and rickettsia. (3) D. folliculorum may also serve as a vector for Staphylococcus aureus, and has been associated with a perifollicular lymphocytic infiltration. (4) The perifollicular inflammation, epithelial hyperplasia, and follicular plugging cause the clinical blepharitis. These follicular changes make the eyelash more brittle and can lead to madarosis (lash loss), misalignment, or trichiasis (lash abrasion of cornea). Left untreated, serious sequelae ranging from conjunctivits to corneal superficial opacities, corneal neovascularization, and marginal corneal infiltration can result when the inflammation spreads from the eyelid. (2)

Demodex brevis is a similar organism except that it infests the meibomian and sebaceous glands. It can affect the lipid layer of the tear film, leading to dry eyes, and occasional cylindrical dandruff formation. D. brevis infection predisposes to meibomian gland dysfunction and chalazion formation, including in the pediatric population. (5)

Demodex infestation is also the cause of two other conditions: a dermatologic condition known as Pitryiasis folliculorum (rosacea-like skin rash in humans) and mange in dogs. Mange is a disease in dogs which causes dogs to lose patches of their fur, and is most frequently associated with demodex canis, which is species specific, though demodex folliculorum has been documented to infest dogs and their owners. (7) For this reason, one of the hygiene measures used to eradicate demodex is keeping pets away from sleeping surfaces.

Testing can be performed for confirmation or in cases without cylindrical dandruff but a high index of suspicion. The simplest method is to epilate some lashes with cylindrical dandruff and visualize under a light microscope. Normal saline is generally sufficient to see the moving demodex mites, but flurosceine staining has been shown to enhance the detection. (9) In vivo laser scanning confocal microscopy has also been shown to be able to diagnose, predict the number of mites, and to follow the course of treatment non-invasively (without epilation of the lashes).(10)

Tea Tree Oil (TTO) is the gold standard therapy, as all standard medical therapies fail to kill demodex, even in vitro. (2) When combined with eyelid hygiene, TTO is able to eradicate demodex infestations in 77-100% of patients.(2) The simplest treatment regimen is 5% TTO shampoo massages twice a day for 4-6 weeks.(7)

Conclusion

The common presentation for demodicosis includes ocular irritation, blepharoconjunctivitis, cylindrical dandruff, and symptoms refractory to usual medical therapies in an immunocompetent person aged greater than 50. Cylindrical dandruff alone suggests demodicosis. Consider demodicosis in refractory cases of blepharitis, even in children. Treat with tea tree oil shampoo and eyelid hygiene to achieve complete symptom resolution and to prevent serious vision threatening sequelae.

Acknowledgement

The authors would like to express their appreciation for the help of the West Virginia Medical Journal Publications Review Committee.

References

(1.) NHS Choices. Blepharitis. May 2010. http://www.nhs.uk (Accessed 11-26-11).

(2.) Gao IY-Y, Di Pascuale MA, Li W, Baradaran-Rafii A, Elizondo A, Kuo C-L, Raju VK, Tseng SCG. In vitro and in vivo killing of ocular Demodex by tea tree oil. Br J Ophthalmol 2005; 89:1468-1473 doi:10.1136/bjo.2005.072363

(3.) Roque, M. "Demidicosis". Emedicine. http://emedicine.medscape.com/ article/1203895-overview#a0104 Accessed on 10/9/11.

(4.) Coston TO. Demodex folliculorum blepharitis. Trans Am Ophthalmol Soc. 1967; 65:361-92.

(5.) Liang L, Safran S, Gao Y, Sheha H, Raju VK, Tseng SC. Ocular Demodicosis as a Potential Cause of Pediatric Blepharoconjunctivitis. Cornea: December 2010--Volume 29--Issue 12-pp 1386-1391. doi: 10.1097/ICO.0b013e3181e2eac5.

(6.) Norn, MS. (1982), Incidence of Demodex Folliculorum on skin and lids of nose. Acta Ophthalmologica, 60: 575-583. doi: 10.1111/j.1755-3768.1982.tb00603.x

(7.) Morsy TA, el Okbi MM, el-Said AM, Arafa MA, Sabry AH. Demodex (follicular mite) infesting a boy and his pet dog. J Egypt Soc Parasitol. 1995 Aug; 25(2):509-12. PubMed PMID: 7665947.

(8.) Gao Y, Di Pascuale MA, Li W, Liu DTS, Baradaran-Rafii A, Elizondo A, Kawakita T, Raju VK, Tseng SCG, High Prevalence of Demodex in Eyelashes with Cylindrical Dandruff. doi: 10.1167/iovs.05-0275 Invest. Ophthalmol. Vis. Sci. September 2005 vol. 46no. 9 3089-3094

(9.) Kheirkhah A, Blanco G, Casas V, Tseng SC. Fluorescein dye improves microscopic evaluation and counting of demodex in blepharitis with cylindrical dandruff. Cornea. Jul 2007; 26(6):697-700.

(10.) Kojima T, Ishida R, Sato EA, Kawakita T, Ibrahim OMA, Matsumoto Y, Kaido M, Dogru M, Tsubota K. In Vivo Evaluation of Ocular Demodicosis Using Laser Scanning Confocal Microscopy. Investigative Ophthalmology & Visual Science, January 2011, Vol. 52, No. 1.

Kunj G. Patel

MS4, WVU School of Medicine

VK Raju, MD, FRCS

Monongalia Eye Center Eye Foundation of America

Corresponding author: VK Raju, MD, FRCS, Monongalia Eye Clinic, 3140 Collins Ferry Rd., Morgantown, WV 26505; vkr@vkraju.com
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Title Annotation:Scientific Article
Author:Patel, Kunj G.; Raju, V.K.
Publication:West Virginia Medical Journal
Article Type:Case study
Date:May 1, 2013
Words:1444
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