What is Chalcosis ?
Chalcosis or chalcosis bulbi refers to mild ocular inflammation due to an intraocular foreign body containing copper between about 70 to 85%. Chalcosis results in deposition of copper on lens capsule (sunflower cataract), Descemet’s membrane (Kayser- Fleischer ring), iris (green discolouration), sluggish pupillary response, vitreous degeneration and liquefaction, yellow retinal plaques and degeneration.
The intensity of inflammatory response due to copper containing foreign body depends upon the copper content. It may lead to
- Severe endophthalmitis if copper content is more than 85%
- Chalcosis if less than 85%
Foreign body containing less than 70% is relatively inert in the eye.
Chalcosis may be acute or chronic.
- Acute Chalcosis: Intraocular copper containing foreign bodies may produce purulent, sterile inflammatory response, which can arise within few days and lead to severe necrosis or abscess formation.
- Chronic Chalcosis: Intraocular foreign body, if not removed by operation or is too large to dissolve spontaneously, may lead to severe intraocular degenerative changes.
Intraocular copper rarely may be resorbed, but a longstanding Chalcosis may produce similar clinical features as are seen in Wilson’s disease (hepato-lenticular degeneration) with endogenous copper deposition. This includes characteristic Kayser-Fleischer ring and sunflower cataract (impregnation of copper within lens capsule in the pupillary area).
Intraocular foreign bodies containing copper are notorious for their destructive effect on the eye. The reason that they are non-magnetic generally makes them more difficult to remove as compared to iron or steel foreign bodies.
Chalcosis Symptoms
Symptoms vary according to the size, location and content of copper in intraocular foreign body.
There may be no reaction, if the copper content is less than 70%. The most intense reactions are associated with copper content more than 85%. Larger foreign bodies offer more surface area from which to liberate copper ion. A foreign body in mid- vitreous may not incite inflammation or it may be quietly encapsulated. Locations near vascularised retina and ciliary body are more prone to incite inflammation.
Acute Chalcosis presents rapidly with
- Inflammation
- Deteriorating vision
- Hypotony
- Retinal detachment.
Chronic Chalcosis may present with
- Low-grade intraocular inflammation
- Variable or no changes in visual function
- Gradual diminution of vision.
Chalcosis Causes
Copper containing foreign bodies are the most common non-magnetic foreign bodies.
Copper diffuses within the eye in its ionised form. Foreign bodies containing more than 85% copper typically form diffuse deposits, whereas foreign bodies with lower copper content usually causes more localised response. Copper has affinity for intraocular basement membranes e.g. Descemet’s membrane and Lens capsule.
Causes of Chalcosis includes
- Penetrating ocular injuries
- Wilson’s disease (hepato-lenticular degeneration)
Chalcosis Diagnosis
Diagnosis is based on clinical features such as
- Sclera: May show softening or abscess formation
- Cornea: There may be Kayser- Fleischer ring (usually superior and/or inferior). It may be circumferential as well.
- Anterior chamber: There may be cells and reactions. Copper- coloured metallic particles may be present.
- Iris: It may show greenish tinge.
- Lens: Sunflower cataract (chalcosis lentis) in anterior and posterior central lens capsule as a green- grey, almost metallic, disciform opacity, often with serrated edges and lateral radiations. There may be yellow or copper tinge.
- Vitreous: Greenish or reddish- brown deposits with degeneration.
- Retina: Granular deposits, retinal detachment or degeneration.
- Optic nerve: Papillitis.
There may be diminution of vision, visual field defects, abnormal electroretinogram, or ocular hypotension.
Histology
Histologically, no stain specific for copper exists. However, copper itself functions as a vital stain and shows as tiny opaque (black) dot in unstained sections.
Laboratory tests
- Visual field.
- Electroretinogram.
- Dark adaptometry, if required.
- B- scan ultrasonography to define status of vitreous and retina.
- Computed tomography to localise a foreign body.
- Radiographic spectrometry to check for the presence of intraocular copper ions.
Chalcosis Complications
Complications may be
- Retained intraocular foreign body.
- Retained intraocular foreign body may lead to progressive diminution of vision, defect in visual field, colour vision, dark adaptometry and electroretinogram.
- Intraocular inflammation.
- Intraocular deposition of copper.
- There may be development of ocular hypotony, cataract, and uveitis.
Chalcosis Prevention
Prevention involves use of protective eyewear designed to reduce ocular injuries.