Evaluate the ocular surface of contact lens wearers for Demodex
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Demodex folliculorum and Demodex brevis are ectoparasites of phylum Arthropoda that inhabit the skin of humans.
D. folliculorum tends to reside at the base of eyelashes and is larger (0.3–0.4 mm); D. brevis preferentially resides in the sebaceous glands and is smaller (0.2–0.3 mm). Both adult mites are cigar-shaped with four pairs of legs to grip a cylindrical structure such as an eyelash.
Due to significant symptom overlap with other anterior segment conditions, Demodex infestation continues to be underdiagnosed and undertreated. Ocular demodicosis, or mite infestation, is characterized by the pathognomonic presence of cylindrical dandruff or collarettes at the base of the eyelashes and has been implicated in a variety of anterior segment conditions.
The literature describes a correlation between Demodex mites and blepharitis, eyelash alterations including madarosis, trichiasis and triangulation, conjunctivitis, keratitis and basal cell carcinoma of the lid (Fromstein et al., LuoX et al., Cheng et al.). Ocular demodicosis has various symptoms, including itching, lacrimation and hyperemia. However, Demodex mites are present in both symptomatic and asymptomatic individuals, and there is poor correlation between symptoms and Demodex infestation.
If there is a poor correlation of symptoms in the general population, how does this correspond to contact lens wearers? A recent publication demonstrated that the number of D. folliculorum mites did not differ between each eye, however the daily use of contact lenses, cosmetics and glasses may be some of the main culprits of infection (Vargas-Arzola et al.).
One study evaluated if Demodex infestation was more frequent in contact lens wearers compared with non-wearers (Jalbert et al.). The study included Asian women (20 contact lens wearers and 20 non-wearers) with a mean age of 27 years. Using confocal microscopy, Demodex was observed in a large majority (90%) of lens wearers and in 65% of non-wearers (P = .06).
The authors proposed several scenarios for the increased propensity for contact lens wearers to host Demodex. Due to its impact on the habitual ocular flora or lid margin health, contact lens wear may provide a more advantageous environment for Demodex mites to proliferate. Additionally, it has been established that blepharitis provides a favorable environment for Demodex infestation (Lee et al., Li et al., Kim et al.) and is associated with colonization of lid margins by microorganisms such as Staphylococcus epidermidis, Propionibacterium acnes, Corynebacteria, and Staphylococcus aureus (Liu et al., Kim et al.).
These same microorganisms have been discovered more frequently in contact lens wearers (Stapleton et al.). A possibility is that a contact lens may offer a more favorable environment for excessive bacteria and act as a vector for microorganisms, which may lead to further Demodex infestation.
Contact lens discomfort and lens dropout are highly prevalent conditions, remaining around 15% to 20%, even with advanced contact lens materials (Young et al., Richdale et al., Dumbleton et al.).
Another study investigated characteristics of the eyelid margins and tear film in contact lens wearers to determine whether these attributes were related to symptoms of contact lens discomfort (Siddireddy et al.). Existing daily wear soft contact lens wearers (6 male; 24 female) with median age of 23 years (range 18-41 years) were evaluated. Wearers were examined during a single visit, and the contact lens and dry eye questionnaire (CLDEQ-8) was used to evaluate ocular discomfort.
Based on the CLDEQ-8 responses, participants were grouped as symptomatic (n = 17) or asymptomatic (n = 13). In symptomatic wearers, grades of foam at meibomian gland orifices, expressibility and quality of secretions, tear evaporation rate both with or without contact lens wear, fluorescein tear breakup time and tear lipid layer thickness were significantly associated with symptoms of discomfort. A greater number of Demodex mites were detected on the upper eyelid of symptomatic lens wearers (2 ± 1 mite vs. 0 ± 0) compared with asymptomatic lens wearers (0 ± 0; P = .042), both with and without contact lenses. However, there was no correlation with comfort, which may be due to the relatively low level of infestation in the study population.
Other studies showed nearly 93% of wearers with contact lens intolerance were positive for Demodex, and 6% of patients with Demodex denied any symptoms of discomfort (Lee et al., Tarkowski et al.).
A positive correlation between the presence of Demodex and intolerance to soft contact lenses has been demonstrated. Yet, there were asymptomatic wearers with Demodex mites indicating that it might not be the singular reason for discomfort (Siddireddy et al.). Demodex mites may exacerbate symptoms of discomfort in lens wearers.
These studies illustrate the importance of evaluating the ocular surface, including the eyelashes and eyelid margins to assess Demodex infestation in contact lens wearers. Better management of the ocular surface could reduce contact lens discomfort and potentially improve retention of contact lens wear.
References:
- Bhandari V, et al. Middle East Afr J Ophthalmol. 2014;21(4):317–320.
- Cheng AM, et al. Curr Opin Ophthalmol. 2015;26(4):295–300.
- Dumbleton K, et al. Eye Contact Lens. 2013;39(1):92-98.
- Fromstein SR, et al. Clin Optom (Auckl). 2018;doi:10.2147/OPTO.S142708.
- Jalbert I, et al. Optom Vis Sci. 2015;doi:10.1097/OPX.0000000000000605.
- Kheirkhah A, et al. Am J Ophthalmol. 2007;143(5):743–749.
- Kim JT, et al. Cytokine. 2011;53:94–99.
- Lee SH, et al. Invest Ophthalmol Vis Sci. 2010;51:2906–2911.
- Li JJ, et al. Ophthalmol. 2010;117:870–877.
- Liu J,. Curr Opin Allergy Clin Immunol. 2010;10(5):505–510.
- Luo X, et al. Cornea. 2017;36 Suppl 1:S9–S14.
- Moris García V, et al. Arch Soc Esp Oftalmol. 2019;doi:10.1016/j.oftal.2019.04.003.
- Nicholls SG, et al. Int Ophthalmol. 2017;37(1):303–312
- Richdale K, et al. Cornea. 2007;26(2):168-174.
- Siddireddy JS, et al. Cont Lens Anterior Eye. 2018;doi:10.1016/j.clae.2017.10.004.
- Stapleton F, et al. Infect Immun. 1995;63:4501–4505.
- Tarkowski W, et al. Biomed Res Int. 2015;doi:10.1155/2015/259109.
- Vargas-Arzola J, et al. Acta Microbiol Immunol Hung. 2020;doi:10.1556/030.2020.01067.
- Young G, et al. Ophthalmic Physiol Opt. 2002;22(6):516-527.
For more information:
Melissa Barnett, OD, FAAO, FSLS, FBCLA, is a principal optometrist at the University of California, Davis Eye Center in Sacramento and Davis, Calif. She is an internationally recognized key opinion leader, specializing in ocular eye disease and specialty contact lenses. She can be reached at DrBarnett@UCDavis.edu.
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