Interstitial keratitis (IK) is

corneal The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical po ...

scarring A scar (or scar tissue) is an area of fibrous tissue that replaces normal skin after an injury. Scars result from the biological process of wound repair in the skin, as well as in other organs, and tissues of the body. Thus, scarring is a natu ...

due to chronic

inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...

of the corneal stroma. Interstitial means space between

cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...

i.e. corneal stroma which lies between the epithelium and the

endothelium The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the ve ...

Keratitis Keratitis is a condition in which the eye's cornea, the clear dome on the front surface of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves any of the following symptoms: pain, impaired e ...

means corneal inflammation.

Signs and symptoms

Acutely, early symptoms include a painful,

photophobic Photophobia is a medical symptom of abnormal intolerance to visual perception of light. As a medical symptom photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of ...

, red watery eye. This is due to active corneal inflammation resulting in vascular invasion and stromal

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dig ...

which can be diffuse or localized. This causes the pinkish discoloration of what was a clear transparent normal corneal tissue (called '' Salmon patch of Hutchinson''). Such vascularization is likely to result in blurring of vision secondary to corneal stromal scarring, the presence of ghost vessels, and thinning of the cornea, especially if it involves the visual axis.

Cause

By far the most common cause of IK is

syphilitic Syphilis () is a sexually transmitted infection caused by the bacterium ''Treponema pallidum'' subspecies ''pallidum''. The signs and symptoms of syphilis vary depending in which of the four stages it presents (primary, secondary, latent, and ...

disease. However, there are two possible causes of the corneal inflammatory response: an infection and/or an immunological response, such as a

hypersensitivity Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. They are usually referred to as an over-reaction of the immune ...

type reaction, or (rarely) Cogan syndrome. Infectious causes include syphilis (commonest), followed by other bacterial infections ( TB,

Leprosy Leprosy, also known as Hansen's disease (HD), is a long-term infection by the bacteria '' Mycobacterium leprae'' or '' Mycobacterium lepromatosis''. Infection can lead to damage of the nerves, respiratory tract, skin, and eyes. This nerve da ...

and

Lyme disease Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the '' Borrelia'' bacterium, which is spread by ticks in the genus '' Ixodes''. The most common sign of infection is an expanding red rash, known as erythema ...

) and parasitic infections (

Acanthamoeba ''Acanthamoeba'' is a genus of amoebae that are commonly recovered from soil, fresh water, and other habitats. ''Acanthamoeba'' has two evolutive forms, the metabolically active trophozoite and a dormant, stress-resistant cyst. Trophozoites are ...

Onchocerciasis Onchocerciasis, also known as river blindness, is a disease caused by infection with the parasitic worm '' Onchocerca volvulus''. Symptoms include severe itching, bumps under the skin, and blindness. It is the second-most common cause of blind ...

or river blindness,

Leishmaniasis Leishmaniasis is a wide array of clinical manifestations caused by parasites of the trypanosome genus '' Leishmania''. It is generally spread through the bite of phlebotomine sandflies, '' Phlebotomus'' and ''Lutzomyia'', and occurs most f ...

Trypanosoma cruzi ''Trypanosoma cruzi'' is a species of parasitic euglenoids. Among the protozoa, the trypanosomes characteristically bore tissue in another organism and feed on blood (primarily) and also lymph. This behaviour causes disease or the likelihood of ...

or '' Chagas disease'',

Trypanosoma brucei ''Trypanosoma brucei'' is a species of parasitic kinetoplastid belonging to the genus ''Trypanosoma'' that is present in sub-Saharan Africa. Unlike other protozoan parasites that normally infect blood and tissue cells, it is exclusively extracel ...

or '' African sleeping sickness'' and microsporidia)

Pathophysiology

The corneal scarring is the end result of the initial invasion of

blood vessels Blood vessels are the structures of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away fro ...

into the corneal stroma as part of the inflammatory response. Since normal corneal tissue should be avascular (no blood vessel) and therefore clear to allow light to pass, the presence of blood vessel and the infiltration of cells as part of the inflammatory process results in scarring or hazing of the cornea.

Diagnosis

A positive VDRL of Treponema pallidum immobilization test confirms diagnosis of luetic(syphilitic) interstitial keratitis

Treatment

The underlying cause must be treated as soon as possible to stop the disease process.

Corticosteroid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are in ...

drop can be used to minimize the scarring on the cornea along with

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy, ...

cover. However, residual scarring cannot be avoided which can result in long term visual impairment and corneal transplantation is not suitable due to high rejection rate from the corneal vascularization.Kanski JJ. "Clinical Ophthalmology 5th ed"

History

Previous long-standing eye infection which possibly during childhood time recalled as being treated with antibiotic and/or hospitalized over long period of time.

References

{{DEFAULTSORT:Interstitial Keratitis Medical signs Eye diseases Syphilis