An entropion occurs when either upper or lower eyelid margin turns inwards against the surface of the eye. This causes the eyelashes to rub against the surface of the eye

Symptoms
This can cause irritation and light sensitivity and this leads to more eyelid squeezing causing a cycle of further in turning of the eyelid margin. This can lead to abrasions infection and scarring of the cornea and cause blurred vision and eventually visual loss.
Causes
The most common cause in the lower eyelid is an age-related instability of the eyelid structures. Less common causes are due to scarring of the delicate lining of eyelid from injury or inflammation or old infections such as trachoma.
Treatment
Non-surgical treatments for entropion can include placing medical tape on the lower eyelid to turn the lashes away from the surface of the eye. Botulinum toxin injections can be used in the lower lid to turn it out. These are not permanent and wear off after a few months. The long term treatment frequently requires surgery to turn the eyelid margin and eyelashes away from the eye. This is normally done with an injection to numb the eyelid, sometimes sedation is needed in more complex cases.