Investigating the underlying cause of contact lens (CL) discomfort and associated dropout should start with a complete review of proper care and compliance (Jones et al, 2013). Practitioners should then begin to alleviate the problem by determining and subsequently treating the underlying pathology, a feat that is often easier said than done since CL discomfort is a multifactorial condition (Nichols et al, 2013). One potential culprit on your differential diagnosis list is a Demodex mite infestation (Jalbert and Rejab, 2015).
Demodex mites are ectoparasites that can be found on the eyelashes, eyelids, and in meibomian glands; they also can be found in other body locations (Jalbert and Rejab, 2015). Microscopic evaluation is generally needed to observe the mites. It has been estimated that ~50% of the population has a Demodex mite infestation, and the likelihood of developing an infestation increases with age (Jalbert and Rejab, 2015).
While there are many types of Demodex mites, the larger and more frequently detected Demodex folliculorum tend to associate with eyelashes, while the smaller and less frequently detected Demodex brevis live deep within the meibomian glands (Jalbert and Rejab, 2015; Tarkowski et al, 2015). Demodex is transmitted via close skin contact or dust (Tarkowski et al, 2015).
When Demodex mites are present in large numbers, they have been associated with blepharitis (Kabataş et al, 2017), and the mites likely promote ocular symptoms; however, their involvement in ocular pathology is still under debate because not all investigations have found an association between mite infestations and ocular symptoms (Wesolowaska et al, 2014; Tarkowski et al, 2015). One potential reason for this discrepancy may be that symptoms are related to the overall number of Demodex on the eye and not just to their presence (Wesolowaska et al, 2014).
The association between blepharitis and Demodex mites is further supported by the strong association between mites and excessive cylindrical dandruff (Jalbert and Rejab, 2015; Kabataş et al, 2017). This association is likely related to the fact that Demodex mites eat skin cells, hair follicle oils, and hormones (Koo et al, 2012).
Impact on Lens Wear
A recent study by Jalbert and Rejab (2015) did not find a significant difference between CL and non-CL wearers when they compared the two groups for the presence of Demodex mites; however, when Demodex mites were detected, CL wearers had a significantly higher number of mites compared to non-CL wearers.
On a related note, Tarkowski et al (2015) found that people who had dropped out were significantly more likely to have Demodex infestations compared to current wearers. This seems to indicate that a mite infestation may also be detrimental to CL comfort.
A patient who is suffering from a Demodex infestation will likely complain of itching, though they may also indicate that they have ocular dryness, irritation, and fluctuating vision (Koo et al, 2012; Kabataş et al, 2017).
When a Demodex infestation is suspected, eyelid scrubs containing tea tree oil should be prescribed because they have been shown to reduce the number of mites present on the eyelid, while standard eyelid hygiene alone had little effect on the mites (Koo et al, 2012). Furthermore, scrubs were found to be effective only if patients followed their recommended treatment schedule; thus, good compliance is critical to reducing Demodex mites from eyelids, improving ocular symptoms, and helping to prevent CL dropout (Koo et al, 2012).
Good compliance has also been found to reduce the incidence of adverse events like stinging (Koo et al, 2012). Good eyelid hygiene compliance can be easily trained, and it should be reviewed on a regular basis with your patients (Guillon et al, 2012). CLS
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