Phlyctenular keratoconjunctivitis is an inflammatory syndrome caused by a delayed (aka type-IV) hypersensitivity reaction to one or more antigens. The triggering antigen is usually a bacterial protein (particularly from ''

Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often posi ...

''), but may also be a virus, fungus (particularly ''

Candida albicans ''Candida albicans'' is an opportunistic pathogenic yeast that is a common member of the human gut flora. It can also survive outside the human body. It is detected in the gastrointestinal tract and mouth in 40–60% of healthy adults. It is usu ...

''), or

nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...

Symptoms

* Irritation * Discomfort or pain * Foreign-body sensation * Tearing *

Blepharospasm Blepharospasm is a neurological disorder characterized by intermittent, involuntary spasms and contractions of the orbicularis oculi muscle, orbicularis oculi (eyelid) muscles around both eyes. These result in abnormal twitching or blinking, an ...

Photophobia 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 o ...

Mucopurulent discharge Mucopurulent discharge is the emission or secretion of fluid containing mucus and pus (''muco-'' pertaining to ''mucus'' and ''purulent'' pertaining to ''pus'') from the eye, nose, cervix, vagina or other part of the body due to infection and inf ...

(rarely) In cases where the cornea is affected, pain and photophobia are more likely, and corneal scarring can occur (potentially impairing vision).

Presentation

The syndrome is marked by the appearance of characteristic lesions, known as phlyctenules, on the cornea and/or conjunctiva. These usually manifest as small (1 - 3 or 1 - 4 mm) raised nodules, pinkish-white or yellow in color, which may ulcerate (or, more rarely, necrose) and are often surrounded by dilated blood vessels. Corneal lesions are usually triangular in shape, with the base at the limbus and the apex pointing towards the center of the cornea.

Diagnosis

Clinical findings of corneal lesion or corneal ulceration.

Treatment

The symptoms of phlyctenular keratoconjunctivitis are primarily treated with application of an appropriate

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 invo ...

eye drop, such as prednisolone acetate (Pred Forte) or loteprednol (Lotemax). Loteprednol is increasingly preferred due to its lower risk of elevating

intraocular pressure Intraocular pressure (IOP) is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk of glaucoma. Most tonometers are calibrated t ...

. The corticosteroid suppresses the immune response, reducing inflammation and improving most symptoms. The causative agent (i.e. the source of the antigen that triggered the hypersensitive immune response) should also be identified. ''

'' is usually the primary suspect, along with ''

Mycobacterium tuberculosis ''Mycobacterium tuberculosis'' (M. tb), also known as Koch's bacillus, is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, ''M. tuberculosis'' ha ...

'' in areas where TB is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

, followed by ''

Chlamydia trachomatis ''Chlamydia trachomatis'' () is a Gram-negative, Anaerobic organism, anaerobic bacterium responsible for Chlamydia infection, chlamydia and trachoma. ''C. trachomatis'' exists in two forms, an extracellular infectious elementary body (EB) and an ...

''. Active bacterial infections may be treated with a

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

or a combination antibiotic-steroid eye drop, such as tobramycin/dexamethasone (Tobradex). An oral

tetracycline antibiotic Tetracyclines are a group of broad-spectrum antibiotic compounds that have a common basic structure and are either isolated directly from several species of ''Streptomyces'' bacteria or produced semi-synthetically from those isolated compounds. ...

(such as

doxycycline Doxycycline is a Broad-spectrum antibiotic, broad-spectrum antibiotic of the Tetracycline antibiotics, tetracycline class used in the treatment of infections caused by bacteria and certain parasites. It is used to treat pneumonia, bacterial p ...

) may be used in systemic or particularly severe/intractable infections.

Erythromycin Erythromycin is an antibiotic used for the treatment of a number of bacterial infections. This includes respiratory tract infections, skin infections, chlamydia infections, pelvic inflammatory disease, and syphilis. It may also be used ...

may be an effective alternative, especially in

pediatric Pediatrics (American English) also spelled paediatrics (British English), is the branch of medicine that involves the medical care of infants, children, adolescents, and young adults. In the United Kingdom, pediatrics covers many of their youth ...

cases where the side effects of tetracyclines are unacceptable.

Artificial tears Artificial tears are lubricating eye drops used to relieve dryness and irritation of the ocular surface. Dry eye syndrome ( keratoconjunctivitis sicca) is a common ocular surface disorder and is characterized by disruption of the tear film and ...

can reduce dryness and discomfort from corneal lesions. Photophobic discomfort can be mitigated with dark

sunglasses Sunglasses or sun glasses (informally called shades or sunnies; more names Sunglasses#Other names, below) are a form of Eye protection, protective eyewear designed primarily to prevent bright sunlight and high-energy visible light from damagin ...

References

{{reflist Eye diseases

Symptoms

Presentation

Diagnosis

Treatment

See also

References