Eyelash extensions have become hugely popular in recent times. Many women prefer professionally applied lash extensions to self applied false eyelashes because the former tend to last longer and many would say that it gives a more natural result. 

Lash extensions made of silk, nylon or other synthetic materials are usually attached to natural lashes individually using glue. The major cause for concern is the glue itself. The solutions used to remove the lash extensions and glue can be dangerous too. The glue may come in contact with the eye surface itself but even when it does not, over time, increased body temperature can cause a chemical change in the adhesive. Formaldehyde is a chemical glue and is known to be a serious eye irritant that can be toxic to the eye surface. Chemical irritants can cause inflammation of the cornea and conjunctiva, blepharitis (inflammation of the eyelid margin) and well as conjunctival erosion. Allergic reactions, as well as discomfort while wearing contact lenses and symptoms of dry eye are common results of chemical toxicity. 

Educate yourself about the solutions your technician uses and enquire about the hygiene methods to prevent infections.

Many women, afraid of ruining their lash extensions, avoid regular eyelid hygiene at home and this results in infection and blepharitis. Chronic lid infection and inflammation can, over time result in the loss of your natural lashes. 

If your eyes are irritated, red, teary, itchy, sensitive to light or painful, contact your optometrist immediately. If you have had eyelash extensions recently applied or removed, let your optometrist know. 

Reference:

nkcf.org
Amano Y, Sugimoto Y, Sugita M, Ocular Disorders Due to Eyelash Extensions, Cornea 31:121-5, 2012, PMID: 22134404