Chalazion

It is observed as a protuberance in the thickness of the eyelid. It is caused by an obstruction in one of the Meibomian Glands. These are specialized sebaceous glands, which produce an oily liquid that is part of the tear and is essential to prevent it from evaporating. When the meibomian glands become inflamed, this secretion becomes thick and its excretion becomes difficult.

Orzuelo

It is seen as a superficial and very painful lump on the edge of the eyelid. It is caused by an infection of one of two types of glands: Zeiss or Moll, which are found at the base of the eyelashes. The cause of this disorder is a bacterial infection commonly caused by Sthaphylococcus aureus.

Blefaritis

It is a chronic inflammation of the margin of the eyelids, although it is a benign condition, it can have very annoying symptoms.
It may be associated with other dermatological conditions such as seborrhoeic blepharitis and rosacea. It can be complicated by superinfection by Staphylococcus aureus and generate a stye.
It can present permanent desquamation of the eyelids, reddening and frequent burning.

Pterigion

It is a tumor of benign origin, which is produced by abnormal growth of the conjunctiva (transparent tissue that lines the white area of the eye) to the cornea (transparent central area).
This abnormal tissue becomes inflamed due to lack of lubrication (lack of tears), sun exposure, wind or other irritants.
There is a sensation of a foreign body and burning sensation and if it has extended a lot towards the cornea, vision will be affected.

Conjunctivitis

It is an inflammation of the conjunctiva, which is the transparent membrane that lines the sclera (white area of the eye) and the eyelids.
The most frequent cause is viral, being very contagious. The associated symptoms are tearing, redness and sensitivity to light.
Other frequent causes: allergic, bacterial, associated with certain diseases and prolonged use of contact lenses.

Uveitis

The uvea is an intermediate layer of the eye, which is responsible for the vascularization of many important parts of the eye. There are different systemic diseases such as Rheumatoid Arthritis and Ankylosing Spondylitis, which can cause inflammation of this layer. It can also be caused by infection and exposure to toxins.
It may be of the previous type, which is the most frequent and benign, with the appropriate treatment may disappear in a few days, however it may be recurrent.
Inflammation of the posterior uvea can last for months and, despite adequate treatment, can cause permanent vision damage.

Palpebral ptosis or eyelid drooping

It is a permanent descent of the upper eyelid, usually caused by muscle dysfunction that is responsible for raising the eyelid. The most frequent cause is aging, other causes may be: lack of nervous stimulation, tumors or traumas that affect its function.
In children it is usually congenital, meaning that they are born with it and it usually happens because the muscle is born with a very poor or almost null function, in these cases it must be treated urgently, to avoid an inadequate development of vision.