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http://emedicine.medscape.com/article/1197726-overview
Dermatitis, Contact
Author: R Scott Lowery, MD, Assistant Professor of Ophthalmology, Department of Pediatric Ophthalmology and Strabismus, University of Arkansas for Medical Center, Arkansas Children's Hospital
Updated: Oct 30, 2009
Excerpt:
Emphasis added by Scout
Dermatitis, Contact
Author: R Scott Lowery, MD, Assistant Professor of Ophthalmology, Department of Pediatric Ophthalmology and Strabismus, University of Arkansas for Medical Center, Arkansas Children's Hospital
Updated: Oct 30, 2009
Excerpt:
Patients will have a history of exposure to an offending substance; in ophthalmology, it is most commonly topical ocular medications, such as neomycin, atropine, and preservatives (frequently benzalkonium chloride), and glaucoma medications. Of course, many common household items can be the culprit. In general, patients often have a history of exposure, through work or recreation, to a different environment than usual.
Physical
• Early contact dermatitis is characterized by erythema, edema, chemosis, eyelid induration, and exudative vesicular lesions. Chronic scaling, crusting, eczema, and lichenification occur.
• Areas of exposure to the offending substance are frequently the hands, face, arms, legs, and neck, and may give clues to the origin of the irritant or allergen.
• Irritant lesions usually occur 1-2 hours after exposure. Allergic lesions do not usually appear until 48 hours after exposure.
• In the eye, conjunctivitis with a papillary or cobblestone appearance, chemosis, injection, and tearing frequently occur.
• Blepharitis also may occur and may be accompanied by a keratitis. This keratitis frequently is appreciated as small yellow opacities near the limbus, often described as a fine punctate keratitis.
• Patients whose rash occurs in an elongated or linear pattern often will have had exposure to a plant, such as poison ivy or oak.
Causes
Irritant and/or allergen exposure causes contact dermatitis. Frequently encountered agents that may be responsible include drugs, soaps, lotions, cosmetics, metals, foods, dyes, preservatives, and plants. The list is almost endless, but the offending agent will have been encountered within 72 hours (if an allergic reaction) and within a few hours (if an irritant).2,3,4,5
Recent studies have shown an increase in positive patch test reactions to carbamates, balsam of Peru, thimerosal, formaldehyde, imidazolidinyl urea, and methyldibromoglutaronitrile.6 The rates of positive reactions to Dimethylol dimethyl (DMDM) hydantoin, diazolidinyl urea, and methylchloroisothiazolone/methylisothiazolone remained unchanged. All other antigens were noted to decrease during the studied time period.
Physical
• Early contact dermatitis is characterized by erythema, edema, chemosis, eyelid induration, and exudative vesicular lesions. Chronic scaling, crusting, eczema, and lichenification occur.
• Areas of exposure to the offending substance are frequently the hands, face, arms, legs, and neck, and may give clues to the origin of the irritant or allergen.
• Irritant lesions usually occur 1-2 hours after exposure. Allergic lesions do not usually appear until 48 hours after exposure.
• In the eye, conjunctivitis with a papillary or cobblestone appearance, chemosis, injection, and tearing frequently occur.
• Blepharitis also may occur and may be accompanied by a keratitis. This keratitis frequently is appreciated as small yellow opacities near the limbus, often described as a fine punctate keratitis.
• Patients whose rash occurs in an elongated or linear pattern often will have had exposure to a plant, such as poison ivy or oak.
Causes
Irritant and/or allergen exposure causes contact dermatitis. Frequently encountered agents that may be responsible include drugs, soaps, lotions, cosmetics, metals, foods, dyes, preservatives, and plants. The list is almost endless, but the offending agent will have been encountered within 72 hours (if an allergic reaction) and within a few hours (if an irritant).2,3,4,5
Recent studies have shown an increase in positive patch test reactions to carbamates, balsam of Peru, thimerosal, formaldehyde, imidazolidinyl urea, and methyldibromoglutaronitrile.6 The rates of positive reactions to Dimethylol dimethyl (DMDM) hydantoin, diazolidinyl urea, and methylchloroisothiazolone/methylisothiazolone remained unchanged. All other antigens were noted to decrease during the studied time period.