Crohns disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea (which may be bloody if inflammation is severe), fever, abdominal distension, and weight loss. Complications outside of the gastrointestinal tract may include anemia, skin rashes, arthritis, inflammation of the eye, and fatigue. The skin rashes may be due to infections as well as pyoderma gangrenosum or erythema nodosum. Bowel obstruction may occur as a complication of chronic inflammation, and those with the disease are at greater risk of colon cancer and small bowel cancer.While the precise causes of Crohns disease (CD) are unknown, it is believed to be caused by a combination of environmental, immune, and bacterial factors in genetically susceptible individuals. It results in a chronic inflammatory disorder, in which the bodys immune system defends the gastrointestinal tract, possibly targeting microbial antigens. While Crohns is an immune-related disease, it does not appear to be an autoimmune disease (in that the immune system is not being triggered by the body itself). The exact underlying immune problem is not clear; however, it may be an immunodeficiency state.About half of the overall risk is related to genetics, with more than 70 genes having been found to be involved. Tobacco smokers are twice as likely to develop Crohns disease as nonsmokers. It also often begins after gastroenteritis. Diagnosis is based on a number of findings, including biopsy and appearance of the bowel wall, medical imaging, and description of the disease.
Physiological inability to close the eyelids during sleep (nocturnal lagophthalmos) may also cause exposure keratopathy. Mechanical causes
Chemical or thermal burns to eyelids or conjunctiva, ocular cicatricial pemphigoid, or symblepharon may cause incomplete or inadequate eyelid closure. Exophthalmos
Exophthalmos  is the unilateral or bilateral bulging of the eye anteriorly out of the orbit causing increased exposure of cornea. It may be seen in many conditions like Graves ophthalmopathy, Orbital cellulitis, Orbital pseudotumor etc. Surgical
A weak bell phenomenon may result in exposure keratopathy after ptosis surgery. Postoperative lagophthalmos following blepharoplasty is another common cause of secondary exposure keratopathy. Diagnosis
Fluorescein staining may be used to detect for epithelial defects, corneal infection or perforation of the cornea. Tear break-up time and ocular protection index assessment can be done to reveal dry eye. Exophthalmometry can be used to measure degree of exophthalmos. Prevention
If increased corneal exposure is detected, several preventive measures can be done to prevent keratitis. Aritificial eye drops and eye ointments may be used to keep the eyes moist. Since frequent use of eye drops with preservatives can promote inflammation, it is better to choose preservative free artificial tear drops and lubricating eye drops. Bandage silicone hydrogel or scleral contact lens may be used to protect cornea. But, risk of infection is more  with bandage contact lens use. Moisture goggles may also be used to protect cornea. Temporary or permanent tarsorrhaphy may be indicated to treat lagophthalmos. Gold weights can be inserted into the upper eyelid to treat fasial nerve palsy.