What causes inverted eyelashes

Normal eyelashes grow outwards, but there is a case where eyelashes grow inwards, which is called ingrown eyelashes. Once inverted eyelashes occur, they must be treated promptly, otherwise it will affect eye health. There are many factors that cause inverted eyelashes. We need to have a comprehensive understanding of its causes, which will be of great help in treatment. So, what causes inverted eyelashes? Let’s take a look at the reasons below.

There are many reasons for inverted eyelashes. In children and adolescents, it is mainly caused by abnormal growth direction of eyelashes, excess skin on the lower eyelid, sometimes excess skin on the lower eyelid combined with epicanthus, and congenital entropion. In middle-aged and elderly people, entropion is mainly caused by inflammation of the eyelid conjunctiva and scar contraction of the eyelid margin, as well as various other reasons. There are two main causes of trichiasis, including trichiasis without entropion and trichiasis with entropion. Entropion can definitely cause inverted eyelashes, but inverted eyelashes are not necessarily accompanied by entropion. Inverted eyelashes can exist alone. Entropion refers to an abnormal condition in which the eyelid margin rolls inward toward the eyeball.

Disease classification

Disease classification

1. Eyelash inversion without entropion: It is simply due to the abnormal growth direction of eyelashes or the pressure of the skin of the lower eyelid, causing the eyelashes to sweep towards the cornea.

2. Eyelid entropion with trichiasis

⑴ Congenital entropion

It is more common in infants and young children and only occurs on the lower eyelid. The incidence rate is higher in Asians and it is prone to occur near the inner part of the lower eyelid. Pathogenesis: Most of them are caused by traction of the epicanthus, overdevelopment of the orbicularis oculi muscle of the eyelid or incomplete development of the tarsal plate. Some infants and young children are relatively fat, and the root of the nose is not fully developed, and the root of the nose is very flat. In addition, there are epicanthus and hypochondrium, which can also cause entropion of the lower eyelid. Congenital entropion should be distinguished from lower eyelid fold. The former is that the eyelid margin itself curls inward, while the latter is a rare congenital abnormality with an extra skin fold on the inner side of the lower eyelid. This fold can pull the eyelashes on the inner side of the lower eyelid inward and bring them into contact with the cornea and conjunctiva, but the eyelid margin itself does not turn inward.

(2) Degenerative entropion

Degenerative entropion, also known as chronic spasmodic entropion or senile entropion, mostly occurs in the lower eyelid. Pathogenesis: a. Rupture of the lower eyelid retractor aponeurosis, resulting in weakness of the lower eyelid retractor muscle; b. Relaxation of the horizontal tension of the eyelid, relaxation of the orbital septum and lower eyelid skin, and loss of the function of restraining the contraction of the orbicularis oculi muscle, causing the lower edge of the tarsal plate to lean outward and the eyelid edge to lean inward; c. Mild enophthalmos, due to the reduction of orbital fat in the elderly and lack of sufficient support behind the eyelid; d. Overlap of the orbicularis oculi muscle, orbicularis oculi muscle spasm, upward curling of muscle fibers, and overlapping of the orbicularis oculi muscle in front of the orbital septum, resulting in entropion of the eyelid and trichiasis.

(3) Scarring entropion

Scarry entropion is caused by the contraction and traction of the conjunctiva and tarsal scar, which causes the eyelid to fall toward the eyeball. Both the upper and lower eyelids can be affected. It can mainly be caused by diseases such as trachoma scars, conjunctival burns, chemical injuries, conjunctival pemphigus and diphtheria conjunctivitis.

Pathogenesis: The contraction of the scar causes the posterior layer of the eyelid to be significantly shorter than the anterior layer, causing the eyelid margin to curl inward, resulting in scar entropion.

(4) Spasmodic entropion

It is more common in the lower eyelid and is caused by spasm of the orbicularis oculi muscle. Pathogenesis: It is common in acute eye inflammation, injury or intraocular surgery (such as cataract removal), because the stimulation causes reflex spasm of the orbicularis oculi muscle, especially the orbicularis oculi muscle fibers near the eyelid margin, resulting in inward rolling of the eyelid margin and formation of entropion. Because the tarsal plate of the lower eyelid is thin and narrow, spasm is more likely to occur, while the tarsal plate of the upper eyelid is wider and inversion is less likely to occur. This type of inversion is usually temporary and will disappear on its own once the irritating factor disappears.