This is one creepy topic!
You can’t read this blog with out a shudder or two, but the information here is very important to read and understand if you are truly dedicated to the health and safety of your clients’ eyes. Blepharitis is, unfortunately, a common skin condition around the eyes and lash mites are just a totally creepy reality. We all have ‘em! Eewwwwww!
One of the most important things for your clients to do between fills is keep those lashes clean. If you have had problem clients arriving with old makeup, greasy lashes crusting at the lash line, or cysts and styes, this is a great dose of info to keep you well-versed in the detriments of poor lid hygiene.
Proper consultation is essential upon your initial visit with a new client to help her avoid and/or manage the following complications with lash extensions (click here for link to download consult forms). During your consult, it is important to stress that natural oils are secreted from the follicles and lids regularly and that some of these oils travel down the lash cuticles in order to condition and protect the hairs, not unlike the hairs on the head. Because extensions and adhesive are now covering the cuticle, the oils can’t jump up over the end of a lash extension and shimmy down the smooth surface, so they begin to collect at the base. To avoid build up, you should soap and shampoo your lashes at least every other day.
Informing your clients of these basic facts helps them to understand the importance of keeping the eye area clean. Some clients think that if they don’t touch the lashes or clean them they will last longer. Not only is that not the case, but the following info will have them running for the nearest sink!
Before we get started (and totally freaked out), let’s clear one thing up now: lash extensions alone will not cause lash mites. Almost everyone has them, no matter what, though keeping the lid clean will reduce the likelihood of them overpopulating. Blepharitis is also not caused by lash extensions; this can develop for a number of reasons and poor lid hygiene is only one of them. These are not contagious conditions and a Blepharitis episode may not necessarily be a reason to remove lashes or not receive the service. Use your best judgment, as always, and if you have a serious concern, send your client to the eye doctor. If the skin is compromised, lash removal may require a doctor’s opinion. The solvents used for removal could exacerbate the condition and cause pain for the client (link to remover). Simple lid scrubs and proper cleansing can clear these conditions up well (link to lid scrub).
Let’s get technical:
Blepharitis (/blɛfərˈaɪtɨs/ BLEF-ər-EYE-tis) is an eye condition characterized by chronic inflammation of the eyelid. The severity and time course can vary. Onset can be acute, resolving without treatment within two to four weeks (this can be greatly reduced with lid hygiene), but more generally is a chronic inflammation varying in severity. 
Signs and symptoms that are associated with the chronic inflammation include:
Redness of the eyelids
Flaking of skin on the lids
Crusting at the lid margins, generally worse on waking
Cysts at the lid margin (hordeolum)
Gritty sensation of the eye or foreign-body sensation
Blepharitis does not tend to cause problems with the patient's vision, but due to a poor tear film, one may experience blurred vision. Eye redness and swelling tend to appear in more advanced cases, and they are rarely primary symptoms. The symptoms can vary slightly, based on the exact cause of the condition. Blepharitis that localizes in the skin of the eyelids may cause styes, or chalazia, which appear like red bumps, sometimes with a yellow spot if infection is present. Although pain is not common among Blepharitis symptoms, if the condition persists or becomes painful, the individual is recommended to seek medical attention. The following are the two types of Blepharitis.
Staphylococcal Blepharitis is caused by infection of the anterior portion of the eyelid by Staphylococcal bacteria. Patients notice a foreign body sensation, matting of the lashes, and burning. Collarette around eyelashes, a ring-like formation around the lash shaft, can be observed, which is an important sign of this condition. Other symptoms include loss of eyelashes or broken eyelashes. The condition can sometimes lead to a chalazion or a stye and because it is a more severe case it needs to be treated with an antibiotic. [2/3]
Posterior Blepharitis or Rosacea-Associated Blepharitis
Posterior Blepharitis is inflammation of the eyelids and dysfunction of the meibomian glands. Like anterior Blepharitis it is a bilateral chronic condition and is manifested by a broad spectrum of symptoms involving the lids, including inflammation and plugging of the meibomian glands and oozing of abnormal secretion upon pressure over the glands. It may be associated with skin rosacea, and there is growing evidence that in some cases it is caused by demodex mites. (see below for description on demodex mites) [1/4]
Treatment and Management for Both
If your client does wind up with Blepharitis and would like to continue receiving extensions, it is advised to have the client sign and additional waiver (Waiver).
The most important thing for your client is daily care! The routine needs to be convenient enough to be continued for life to avoid relapses, as Blepharitis is often a chronic condition. Luckily, it can be acute, and one episode does not mean it will be a lifelong condition.
A typical lid margin hygiene routine that you could recommend to your clients consists of three steps:
1. Softening of lid crust, debris, and oils: Apply a warm wet compress to the lids, such as a washcloth with hot water, for about two minutes.
2. Manual removal of lid crust and debris: After warm compresses, wash your face with a wash cloth. Use a baby shampoo and water diluted solution of 1/10 (lash cleanser link). Gently rub along the lids and lash line while eyes are closed. A moist cotton swab soaked in the warm water/baby shampoo may be used to rub along the lid margins while tilting the lid outward to spread lashes out.
3. Avoid the use of eye make-up until symptoms subside.
Often, the above is advised together with mild massage by pressing lids gently against the eye to mechanically empty glands located at the lash line.
Blepharitis caused by demodex mites can be treated using a diluted solution of tea tree oil and using a cotton swab for five to 10 minutes per day. It may be necessary to continue the treatments for four to six weeks to eliminate the infestation (link to tea tree oil). 
It may not always be Blepharitis. Physicians may also consider allergy testing and ocular antihistamines. Allergic responses to dust mite feces and other allergens can cause lid inflammation, ocular irritation, and dry eyes. Prescription ocular antihistamines and over-the-counter ocular antihistamines can bring relief to patients whose lid inflammation is caused by allergies (link to alergy eye drops on vitacost).
Researchers have found Omega-3 supplementation in the form of fish oil or flaxseed to be beneficial in reducing the primary symptoms of Blepharitis (link to vitacost). 
In less severe cases, clients with Blepharitis can keep their lashes. Proper hygiene is important for everyone with lash extensions, but it’s even more crucial for people with Blepharitis. Clients should use an ophthalmologist-tested eyelid cleanser like Chrissanthie (LINK), which has a touch of tea tree and citrus oil to help kill off bacteria and heal the irritated skin.
Blepharitis vs. Conjunctivitis
Although Blepharitis and conjunctivitis have similar symptoms, they are not the same. Blepharitis is a chronic and non-contagious condition, while conjunctivitis - more commonly known as pink eye - is a temporary viral, bacterial or chemical infection that is contagious.
Although pink eye is not dangerous, it can be contagious for two weeks after symptoms begin, according to the Mayo Clinic. The infection is often associated with respiratory infections or colds, and improper hand washing is a leading cause of spread. Like Blepharitis, symptoms include: redness, itching, a gritty feeling, tearing, and crusty eyes in the morning.
If you suspect a client might have conjunctivitis, you must reschedule the appointment and advise the client to see a doctor for treatment. Never work on a client with any broken skin, visible swelling, irritation near the lash line, weeping or gooping eyes, or a large stye. Err on the side of caution, as a spread of conjunctivitis or any other lid or eye disease could negatively impact your business drastically.
Now a bit about….
Proper definition: Demodex Folliculorum and Demodex Brevis, also known as lash mites, are typically found on humans. D. Folliculorum is found in hair follicles, while D. Brevis lives in sebaceous glands connected to hair follicles. Both species are primarily found in the face, near the nose, the eyelashes, and eyebrows, but also occur elsewhere on the body. 
Yup. This is real. They actually live inside the sebaceous glands and hair follicles. Some times several at a time! Research about human infection by Demodex mites is ongoing, yet a few studies suggest that there is an association between mite infection and rosacea. It is estimated that 1/3 of children and young adults, ½ of adults and 2/3 of elderly people carry the mites.  The mites are transferred through close contact of the face, hair, eyebrows, and the sebaceous glands on the nose. In the majority of cases, Demodex go undetected, without any adverse symptoms. Suppressed immune system, caused by stress or illness may cause mite populations to increase dramatically, resulting in a condition known as demodicosis, characterized by itching, inflammation, and other skin disorders. Blepharitis can also be caused by Demodex mites. Evidence of a correlation between Demodex infection and acne vulgaris exists, suggesting it may also play a role in promoting acne. 
Improper cleansing and not keeping lashes free of oil and build up of makeup and other skin care products will give these little guys more food and cause them to overpopulate. Usually, you can tell if a client has a overpopulation by seeing an orange crust at the base of the lashes. This is another condition that is treated best with a tea tree oil-infused cleansing product specifically made for the eyes and eye lashes (Chrissanthie/lid scrub pads).
So… yuck, huh? Ugh! I realize this might be T.M.I., but now you know everything you ever wanted to know (or seriously didn’t want to know!) about two of the most common chronic lid conditions that you may encounter in your practice. I don’t advise sharing too much of this with your clients Now try not to think too much about Demodex… EEK!
 Emmett T. Cunningham, Paul Riordan-Eva. Vaughan & Asbury's general ophthalmology. (18th ed. ed.). McGraw-Hill Medical.
R Scott Lowery (Jun 17, 2011). "Adult Blepharitis". Medscape.
James Garrity (August 2012). "Blepharitis". The Merck Manual.
Liu J, Sheha H, Tseng SCG. "Pathogenic Role of Demodex Mites in Blepharitis". Curr Opin Allergy Clin Immunol.
Jingbo Liu, Hosam Sheha, and C.G. Tsenga. Curr Opin Allergy Clin Immunol.
Marian S. Macsai (2008). "The Role of Omega-3 Dietary Supplementation in Blepharitis and Meibomian Gland Dysfunction (An AOS Thesis
 T. Rufli & Y. Mumcuoglu (1981). "The hair follicle mites Demodex folliculorum and Demodex brevis: biology and medical importance. A review
H. G. Sengbusch & J. W. Hauswirth (1986). "Prevalence of hair follicle mites, Demodex folliculorum and D. brevis (Acari: Demodicidae), in a selected human population in western New York, USA". Journal of Medical Entomology
Ya-e Zhao, et al. (2012). "A meta-analysis of association between acne ulgaris and Demodex infestation