What Is the Sclera?

One of the main components of the eyeball wall. It is the last 5/6 part of the eyeball fiber membrane. The anterior cornea is connected, and the posterior sheath of the optic nerve continues. The sclera is the thickest near the exit of the optic nerve, the thinner it becomes, the more it thickens at the tendon attachment (scleral thickness: 1mm at the posterior pole, 0.4-0.5mm at the equator and 0.3mm at the rectus attachment). At the junction with the cornea, there is an annular corneal sulcus on the outside and a scleral sinus in the deep. The sclera of a child is light blue, white in adulthood, and yellow in old age due to fat deposits. The scleral structure is tough and has the function of supporting and protecting the tissues in the eye.

Chinese name: sclera
Types of: Biological tissue
Definition: White part of eyeball

Commonly known: White-eye
Biological structure: Collagen and elastic fibers
transparency: opaque

Sclera-related diseases

Scleritis is the inflammation of the sclera itself, which is more severe than the scleral surface inflammation. Repeated attacks can cause the sclera to become thinner. It often causes many complications that affect the tissues of the eye. In severe cases, blindness can result. The disease is more common in middle-aged adults and more women than men.

The cause of scleritis is similar to that of superficial scleritis, but it is more associated with systemic collagen diseases, so it belongs to the category of collagen disease and is related to autoimmunity. In addition, it is related to granulomatous diseases such as tuberculosis, metabolic diseases such as gout, thyroid disease, infectious diseases Herpes zoster, herpes simplex and other diseases are also related.

Scleral scleritis classification

Scleritis classification can be generally divided into five types in clinical.

Scleral nodular prescleritis

The onset of this type is slow, but it often develops gradually. The superficial and deep blood vessels of the sclera are congested, and the appearance is purple or dark red. The sclera itself forms a nodule due to inflammation, infiltration and swelling, and cannot be pushed, but it is clearly separated from the upper surface scleral tissue, and about half of it is only a nodule. The affected eye usually feels pain or tenderness, but vision is not affected when the inflammation has not spread to the eye.

Diffuse scleral anterior scleritis

This type has a better prognosis, and generally has a better body condition. The clinical manifestations are more diffuse and superficial than the nodular prescleritis. About 1/3 of the cases invade the whole week. In severe cases, due to the high degree of edema of the bulbar conjunctiva, the sclera cannot be seen. At this time, epinephrine can be dropped to make the shallow Lamellar vascular congestion subsided later and helped diagnosis.

Scleral necrotizing scleritis

This is a more destructive type of scleritis, which is mostly seen in women. It often affects both eyes, and the symptoms are worse than other types. Most of the other comorbidities in the eye appear in the late stage, and most of them affect vision, and most of them are localized scleritis lesions. With the rapid development of the disease, occlusive vasculitis can occur in the outer blood vessels of the sclera, and non-vascular areas appear above and around the lesion. This is an important feature of this type. The lesion can be localized or spread. If the treatment is not timely, , The sclera will be trapped in necrosis, and the uveal membrane is exposed, or the sclera is dilated due to high intraocular pressure.

Scleral penetrating sclera softening

Also known as necrotizing sclera softening, this disease is relatively rare. Patients are mostly women over 50 years of age, and usually develop bilaterally, but the degree of the eyes is often inconsistent, the disease is hidden, and the progress is slow. About half of the patients are accompanied by rheumatoid arthritis, and the pain in the affected eye is mild, and the inflammation is not obvious. However, the sclera first has a non-vascular area, and then the scleral tissue softens and necroses. The surface becomes gray or yellow. Later it becomes thin or disappears completely. Out of the uveal tissue below, the expanded sclera can be punctured due to compression. Thicker blood vessels can be seen on the edge of the necrotic area, which is covered with a thin layer of connective tissue. The prognosis depends on the size of the necrotic area, but it is generally poor.

Postscleral scleritis

This type is rare and often occurs in one eye. Patients often have severe rheumatoid arthritis. Because the location of the lesion is not in the front, it is difficult to diagnose. The clinical manifestations are severe eye pain, blindness, diplopia, bulbar conjunctival edema, slightly protruding eyeballs, and often dyskinesias. Repeated attacks can make the sclera thin, and swollen or even punctured after formation; in addition, it can be complicated Keratitis, uveitis, exudative retinal detachment, optic papillary edema, cataracts and glaucoma. The distinguishing point between this type of scleritis and orbital cellulitis is that the former's conjunctival edema is much more severe than the latter, but the eyeball protrusion is not as obvious as the latter.

All types of scleritis treatment should be strengthened nutrition, improve the general condition, eye dilated pupils. Non-corticosteroid anti-inflammatory drugs such as oxybutazone or indomethacin are effective for scleritis. Although topical application of corticosteroids has some anti-inflammatory effects, caution must be taken because of the potential danger of thinning the scleral tissue, and it may cause eye damage in some patients Increased pressure. Individual severe cases can be tested with immunosuppressive agents under close observation; for cases of necrotizing scleritis puncture, allogeneic scleral transplantation can also be considered.