The sclera is part of the outer skin of the eye and ensures the stability of the eyeball. It is a white, opaque layer that covers around 80 percent of the eye and protects it from external influences. In addition, the outer eye muscles, which are responsible for the movement of the eye in the eye socket, attach to the sclera.
The thickness of the sclera, which consists of firm connective tissue, varies between 0.4 and 1.2 millimeters. The thickest part of the sclera is located at the back of the eye, where the optic nerve exits the eye. The sclera is perforated at this point. The area is called the lamina cribrosa sclerae.
At the front of the eyeball is the cornea, which plays an important role in the refraction of light.

The sclera is the outer covering of the eye. It can be affected by injuries and inflammation © bilderzwerg | AdobeStock
Possible diseases of the sclera are dominated by inflammation: Deep inflammation of the sclera (scleritis) and episcleritis, which is less severe.
Inflammation rarely occurs in the sclera itself: They usually develop as a result of systemic diseases that later spread to the dermis. These include
In addition to inflammation, the dermis can also be affected by injuries, such as those caused by accidents.
In the case of jaundice(icterus), the sclera turns yellowish, similar to the discoloration of the skin and mucous membranes.
Scleritis
Scleritis can be localized in the dermis, i.e. locally pronounced, or diffuse, i.e. distributed. This inflammation often leads to complications and is chronic. The average age of those affected is 52 years.
The specific cause is usually difficult to determine. However, scleritis occurs in connection with chronic inflammation in the context of certain diseases or infections.
The focus of inflammation is most frequently located in the anterior region of the outer skin of the eye. Only five percent of cases have a posterior localization in the sclera.
The main treatment for this condition is to treat the underlying disease, usually with anti-inflammatory medication.
Complications can result from
- the recurrence of the disease (high tendency to relapse) and
- destruction of the dermis (necrosis).
Episcleritis
Episcleritis is an inflammation of the episclera, a structure between the sclera and the conjunctiva. It can be
- diffuse,
- within certain sectors or
- nodular (nodular)
in the sclera of the eye.
The causes of this disease of the outer skin of the eye are usually unclear. It usually occurs in conjunction with other underlying diseases or inflammatory processes. Patients are usually between 40 and 60 years old.
Episcleritis affects the sclera repeatedly at periodic intervals, whereby the periods can be very long. In contrast to scleritis, complications rarely occur.