The ocular manifestations and functional effects of occupational argyrosis

Clinical and Forensic Aspects of the Different Subtypes of Argyria

Argyria encompasses the different cosmetic alterations that can develop if enough silver particles deposit in a specific tissue, typically in the skin, ranging from localized dark-blue macules to a generalized slate-gray/bluish tinge following systemic absorption. This work aims to fully review the state of the art regarding pathophysiology, diagnosis, treatment, and relevant clinical and forensic features of argyria. Argyria has been diagnosed in a wide range of ages, both sexes and varied ethnicities, with no known individual predisposing factors. Ultraviolet radiation with subsequence increases of melanin production aggravates the discoloration due to a reduction in the silver deposits. Physical examination and silver exposure in the anamnesis can be highly suggestive of the diagnosis, but a histopathological analysis with Energy-Dispersive X-ray Spectroscopy is required to unequivocally determine the discoloration etiology. Safe and effective treatment has only been accomplished with laser techniques, though only a few cases have been reported and with limited follow-up time. In conclusion, argyria typically has an occupational or iatrogenic etiology. It should be suspected when a patient presents with typical skin or eye lesions. A seemingly viable treatment modality, with laser technology, is finally within the horizon.

Review on Metal-Based Nanoparticles: Role of Reactive Oxygen Species in Renal Toxicity

The rapidly emerging field of nanotechnology has offered innovative discoveries. Due to a wide variety of nanotechnology applications in the industrial, medical, and consumptive products, the application of nanotechnology has received considerable attention in the past decades. Metal-based nanoparticles including metal and metal oxide nanoparticles are now widely utilized in different areas of nanotechnology, leading to an increase in human exposure to nonmaterial. Since the kidney is one of the major organs to remove a variety of potentially harmful substances, including nanoparticles (NPs), from living organisms and a large proportion of cardiac output reaches the kidney, this organ is susceptible to the toxin-induced renal injury. However, despite the extensive use of NPs, there is still a limited understanding of NP-mediated toxicity. The unique physicochemical properties of metal-based NPs not only make them highly desirable in a variety of applications but also enable them to induce changes at biological levels of cellular activities, including reactive oxygen species (ROS) generation. Since oxidative stress is a key factor of NP-induced injury, it is urgent to characterize the ROS response resulting from metal-based NPs. This review summarizes an assessment of the signaling pathways that are involved in the metal-based NP-induced nephrotoxicity, with a particular focus on ROS production along with the potential oxidative stress-dependent mechanism. However, available data show that metal-based NPs may have a severe impact on the renal system, but the exact molecular mechanism of nephrotoxicity is not fully understood. A highly effective strategy for a better understanding of the mechanism would be to collect an increasing volume of information about the exposure time, physicochemical characteristics of the engineered NPs, and the cellular effects. In order to achieve a thorough knowledge of ROS-dependent renal toxicity, both in vitro and in vivo studies should be considered.

Safety Assessment of Nanomaterials to Eyes: An Important but Neglected Issue

The production and application of nanomaterials have grown tremendously during last few decades. The widespread exposure of nanoparticles to the public is provoking great concerns regarding their toxicity to the human body. However, in comparison with the extensive studies carried out to examine nanoparticle toxicity to the human body/organs, one especially vulnerable organ, the eye, is always neglected. Although it is a small part of the body, 90% of outside information is obtained via the ocular system. In addition, eyes usually directly interact with the surrounding environment, which may get severer damage from toxic nanoparticles compared to inner organs. Therefore, the study of assessing the potential nanoparticle toxicity to the eyes is of great importance. Here, the recent advance of some representative manufactured nanomaterials on ocular toxicity is summarized. First, a brief introduction of ocular anatomy and disorders related to particulate matter exposure is presented. Following, the factors that may influence toxicity of nanoparticles to the eye are emphasized. Next, the studies of representative manufactured nanoparticles on eye toxicity are summarized and classified. Finally, the limitations that are associated with current nanoparticle-eye toxicity research are proposed.

Antimicrobial and physicomechanical natures of silver nanoparticles incorporated into silicone-hydrogel films

PURPOSE

The effects of silver nanoparticles (AgNPs) incorporated in silicone-hydrogel films on their physicochemical properties and microbial activity were investigated.

METHODS

Silicone-hydrogel composite films (SiHCFs) were prepared by in-situ chemical reduction of silver ions added in different concentrations (0, 10, 20, 30, 40, 60, and 80 ppm) followed by ultraviolet (UV) casting. The reduction of silver ions into AgNPs was confirmed by transmission electron microscopy (TEM) and absorption spectroscopy over ultraviolet and visible (UV-vis) wavelengths. Incorporation of AgNPs into SiHCFs was confirmed by UV-vis absorption spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopic mapping. The physico- mechanical properties of the SiHCFs were evaluated. Antimicrobial activity and biofilm formation of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were assessed.

RESULTS

TEM, UV-vis absorption, SEM, and EDX mapping showed that silver ions were reduced in the mixture of co-polymerizing monomers and incorporation of AgNPs into SiHCFs was achieved. Mechanical properties of the SiHCFs were enhanced with increasing AgNPs concentration without affecting their chemical and thermal properties. SiHCFs exhibited transmittance greater than 90% at a wavelength 600 nm. Bacterial growths in the solutions bathing the SiHCFs with increasing silver concentration were 95, 78, 4, 2, 0, 0, 0% respectively, for Escherichia coli; 95, 82, 4, 0.6, 0, 0, 0% for Pseudomonas aeruginosa; and 93, 79, 4, 0.5, 0, 0, 0% for Staphylococcus aureus.

CONCLUSIONS

Incorporation of AgNPs into SiHCFs demonstrated sufficient release of AgNPs to inhibit bacterial growth and reduce biofilm formation, with collateral enhancement of some mechanical properties of SiHCFs.

Pigmented Deposits in the Skin

Pigmented deposits can occur in the skin due to many and varied causes. Some of them are systemic conditions accompanied by involvement of internal organs. Others have serious prognostic implications, and early diagnosis can help in the correct and adequate management of the diseases. In addition, some of them are quite innocuous and the correct diagnosis avoids unnecessary treatments. In this article, we review the morphologic features of some of the most common and some of the less usual pigmented deposits in skin other than tattoos.

Case Report: In Vivo Confocal Microscopic Appearance of Corneal Argyrosis

SIGNIFICANCE

This report details the natural history of corneal argyrosis over 3 years using in vivo confocal microscopy to document regression of hyperreflective deposits, as well as effects on corneal nerves and endothelial cell morphology.

PURPOSE

To report the in vivo confocal microscopic features and clinical characteristics of a case of bilateral corneal argyrosis.

CASE REPORT

A 52-year-old man referred to us 3 months following cautery of the palpebral conjunctiva of both eyes with a silver nitrate stick was observed over the course of 3 years, during which slit-lamp photography and in vivo confocal microscopy were performed. At the first visit, slit-lamp examination showed a light blue-green discoloration and a thick, yellow, oval discoloration in the right and left cornea, respectively. One year later, under slit-lamp examination, the right cornea appeared nearly transparent, and the discoloration in the left cornea had remarkably regressed. In vivo confocal microscopy done at that time showed highly reflective deposits in Descemet membrane of the right cornea and throughout Bowman layer, the stroma, and Descemet membrane of the left cornea. Three years later, no accumulation of silver was observed during slit-lamp examination of either eye. In vivo confocal microscopy of the right cornea did not reveal any silver deposits, and the corneal structure appeared normal. In the left cornea, some silver deposits were still evident in Descemet membrane, and alterations of corneal nerve and endothelial cell morphology were also evident.

CONCLUSIONS

This report reviews the 3-year natural history of a patient with corneal argyrosis. In vivo confocal microscopy demonstrates that over time the corneal argyrosis gradually resolves without any treatment. However, the presence of silver in the cornea may impact the corneal nerves and endothelial cells.

Synthesis and characterization of nanosilver-silicone hydrogel composites for inhibition of bacteria growth

PURPOSE

Nanosilver-silicone hydrogel (NAgSiH) composites for contact lenses were synthesized to asses the antimicrobial effects.

METHODS

Silicone hydrogel (SiH) films were synthesized followed by impregnation in silver nitrate solutions (10, 20, 30, 40, 60, 80ppm) and in-situ chemical reduction of silver ions using sodium borohydride (NaBH₄). The silver nano particles (AgNPS) were identified by UV-vis absorption spectroscopy, Energy-dispersive X-ray spectroscopy (EDX) mapping and EDX spectrum. Physico-mechanical and chemical properties of NAgSIH films were studied. The antimicrobial effect of the hydrogels against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus was evaluated. The numbers of viable bacterial cells on NAgSiH surface or in solution compared to control SiH were examined.

RESULTS

The NAgSiH films were successfully synthesized. FTIR results indicated that AgNPS had no effect on the bulk structure of the prepared SiH films. From TGA analysis, NAgSiH(R80) and SiH(R0) films had the same maximum decomposition temperature (404°C). UV-vis absorption spectroscopy and EDX mapping and spectrum emphasized that AgNPS were in spherical shape. The maximum absorption wavelength of NAgSiH films were around 400nm. The light transmittance decreased as the concentration of AgNPS increased, but still greater than 90% at wavelength around 555nm. The Young's modulus increased gradually from 1.06MPa of SiH(R0) to highest value 1.38MPa of NAgSiH(R80). AgNPS incorporated into SiH films reduced the bacterial cell growth and prevented colonization. Groups NAgSiH(R60,R80) demonstrated an excellent reduction in bacterial viability in solution and on the SiH surface.

CONCLUSIONS

NAgSiH composites were successfully synthesized and possessed an excellent antimicrobial effects.

Diagnostic methods in ocular argyrosis: case report

Purpose

The aim of this report is to present a case of a patient, metal foundry worker, who had been exposed to industrial silver salts for over 20 years. It is well established that chronic exposure to silver compounds can cause accumulation of silver deposits in various tissues. This condition is referred to as argyrosis or argyria, whereas changes related to eye tissues are defined as ocular argyrosis.

Methods

A complete eye examination, corneal confocal microscopy, kinetic and static visual field test, posterior segment optical coherent tomography, pattern visual evoked potentials (PVEP), flash visual evoked potentials, multifocal electroretinogram, pattern electroretinogram (PERG), full-field electroretinography (FERG) and electrooculogram were all performed.

Results

Eye examination revealed decreased visual acuity, corneal deposits and drusenoid changes within the macula. Although electrophysiology tests did not show changes in the function of retinal pigment epithelium, they revealed abnormal function of photoreceptors in the central and peripheral retina. PERG abnormalities and delayed latency of P100 wave in PVEP confirmed impaired function of the inner layers of the retina in the macular region.

Conclusions

Corneal confocal microscopy and electrophysiological tests may help confirm the diagnosis of ocular argyrosis.

Confocal microscopy in biopsy proven argyrosis

Purpose. To evaluate the confocal microscopy findings of a 46-year-old male with bilateral biopsy proven argyrosis. Materials and Methods. Besides routine ophthalmologic examination, anterior segment photography and confocal microscopy with cornea Rostoch module attached to HRT II (Heidelberg Engineering GmbH, Heidelberg, Germany) were performed. Findings. Squamous metaplastic changes on conjunctival epithelium and intense highly reflective extracellular punctiform deposits in conjunctival substantia propria were detected. Corneal epithelium was normal. Highly reflective punctiform deposits starting from anterior to mid-stroma and increasing through Descemet's membrane were evident. Corneal endothelium could not be evaluated due to intense stromal deposits. Conclusion. Confocal microscopy not only supports diagnosis in ocular argyrosis, but also demonstrates the intensity of the deposition in these patients.

A Case of Bilateral Descemet's Membrane and Subepithelial Opacity: In vivo Laser Confocal Microscopic Study

Purpose

To report the in vivo laser confocal microscopy findings from a patient with Descemet's membrane and subepithelial opacity OU.

Case Report

A healthy 41-year-old male with Descemet's membrane and subepithelial opacity OU was studied. Routine ophthalmic examination, standard slit-lamp biomicroscopy, and in vivo laser confocal microscopic analysis of the entire corneal layer were performed. Slit-lamp biomicroscopy revealed subepithelial opacity in the mid-peripheral to peripheral cornea and numerous opacities located at the level of Descemet's membrane. It was difficult to distinguish the precise histological location of the opacity. In vivo laser confocal microscopy showed numerous hyperreflective particles in the subepithelium to superficial stroma and hyperreflectivity of Descemet's membrane. No abnormalities could be detected in the epithelial cell layer, midstromal layer, deep stromal layer, or endothelial cell layer.

Conclusion

Although the origin of the corneal opacities was unclear, in vivo laser confocal microscopy was useful for observing microstructural abnormalities in a case of Descemet's membrane and subepithelial opacity.

Ocular argyrosis secondary to long-term ingestion of silver nitrate salts

This case report describes the clinical, autofluorescence, and optical coherent tomography findings in a patient with panocular argyrosis secondary to chronic intake of diluted silver nitrate salts in his water supply. An 86-year-old Caucasian male with a distinctive gray-bluish hue of the skin presented to our clinic, having developed a slow decrease in visual acuity in both eyes and nyctalopia for the past 2 years. Based on the patient’s history of chronic intake of silver nitrate salts and a positive skin biopsy (performed by the dermatology department, data not shown), a diagnosis of panocular argyrosis was made. Fluorescein angiography showed choroidal blockage with a completely dark choroid. Fundus autofluorescence was within normal limits. Optical coherent tomography showed multiple excrescences of retinal pigment epithelium in both eyes. Although the drusen-like changes on fundus examination and retinal pigment epithelium changes may account for the diminished vision, the presence of concomitant nyctalopia suggests underlying damage of the photoreceptors.

Intrinsic therapeutic applications of noble metal nanoparticles: past, present and future

Biomedical nanotechnology is an evolving field having enormous potential to positively impact the health care system. Important biomedical applications of nanotechnology that may have potential clinical applications include targeted drug delivery, detection/diagnosis and imaging. Basic understanding of how nanomaterials, the building blocks of nanotechnology, interact with the cells and their biological consequences are beginning to evolve. Noble metal nanoparticles such as gold, silver and platinum are particularly interesting due to their size and shape dependent unique optoelectronic properties. These noble metal nanoparticles, particularly of gold, have elicited a lot of interest for important biomedical applications because of their ease of synthesis, characterization and surface functionalization. Furthermore, recent investigations are demonstrating another promising application of these nanomaterials as self-therapeutics. To realize the potential promise of these unique inorganic nanomaterials for future clinical translation, it is of utmost importance to understand a few critical parameters; (i) how these nanomaterials interact with the cells at the molecular level; (ii) how their biodistribution and pharmacokinetics influenced by their surface and routes of administration; (iii) mechanism of their detoxification and clearance and (iv) their therapeutic efficacy in appropriate disease model. Thus in this critical review, we will discuss the various clinical applications of gold, silver and platinum nanoparticles with relevance to above parameters. We will also mention various routes of synthesis of these noble metal nanoparticles. However, before we discuss present research, we will also look into the past. We need to understand the discoveries made before us in order to further our knowledge and technological development (318 references).

Acute pulmonary toxicity and body distribution of inhaled metallic silver nanoparticles

The purpose of this study was to determine the acute pulmonary toxicity of metallic silver nanoparticles (MSNPs, 20.30 nm in diameter). Acute pulmonary toxicity and body distribution of inhaled MSNPs in mice were evaluated using a nose-only exposure chamber (NOEC) system. Bronchoalveolar lavage (BAL) fluid analysis, Western blotting, histopathological changes, and silver burdens in various organs were determined in mice. Mice were exposed to MSNPs for 6 hrs. The mean concentration, total surface area, volume and mass concentrations in the NOEC were maintained at 1.93 × 10(7) particles/cm(3), 1.09 × 10(10) nm(2)/cm(3), 2.72 × 10(11) nm(3)/cm(3), and 2854.62 μg/m(3), respectively. Inhalation of MSPNs caused mild pulmonary toxicity with distribution of silver in various organs but the silver burdens decreased rapidly at 24-hrs post-exposure in the lung. Furthermore, inhaled MSNPs induced activation of mitogen-activated protein kinase (MAPK) signaling in the lung. In summary, single inhaled MSNPs caused mild pulmonary toxicity, which was associated with activated MAPK signaling. Taken together, our results suggest that the inhalation toxicity of MSNPs should be carefully considered at the molecular level.

Acute and subchronic dermal toxicity of nanosilver in guinea pig

Silver has been used as an antimicrobial agent for a long time in different forms, but silver nanoparticles (nanosilver) have recently been recognized as potent antimicrobial agents. Although nanosilver is finding diverse medical applications such as silver-based dressings and silver-coated medical devices, its dermal and systemic toxicity via dermal use has not yet been identified. In this study, we analyzed the potential toxicity of colloidal nanosilver in acute and subchronic guinea pigs. Before toxicity assessments, the size of colloidal nanosilver was recorded in sizes <100 nm by X-ray diffraction and transmission electron microscopy. For toxicological assessments, male guinea pigs weighing 350 to 400 g were exposed to two different concentrations of nanosilver (1000 and 10,000 μg/mL) in an acute study and three concentrations of nanosilver (100, 1000, and 10,000 μg/mL) in a subchronic study. Toxic responses were assessed by clinical and histopathologic parameters. In all experimental animals the sites of exposure were scored for any type of dermal toxicity and compared with negative control and positive control groups. In autopsy studies during the acute test, no significant changes in organ weight or major macroscopic changes were detected, but dose-dependent histopathologic abnormalities were seen in skin, liver, and spleen of all test groups. In addition, experimental animals subjected to subchronic tests showed greater tissue abnormalities than the subjects of acute tests. It seems that colloidal nanosilver has the potential to provide target organ toxicities in a dose- and time-dependent manner.

A pharmacological and toxicological profile of silver as an antimicrobial agent in medical devices

Silver is used widely in wound dressings and medical devices as a broad-spectrum antibiotic. Metallic silver and most inorganic silver compounds ionise in moisture, body fluids, and secretions to release biologically active Ag(+). The ion is absorbed into the systemic circulation from the diet and drinking water, by inhalation and through intraparenteral administration. Percutaneous absorption of Ag(+) through intact or damaged skin is low. Ag(+) binds strongly to metallothionein, albumins, and macroglobulins and is metabolised to all tissues other than the brain and the central nervous system. Silver sulphide or silver selenide precipitates, bound lysosomally in soft tissues, are inert and not associated with an irreversible toxic change. Argyria and argyrosis are the principle effects associated with heavy deposition of insoluble silver precipitates in the dermis and cornea/conjunctiva. Whilst these changes may be profoundly disfiguring and persistent, they are not associated with pathological damage in any tissue. The present paper discusses the mechanisms of absorption and metabolism of silver in the human body, presumed mechanisms of argyria and argyrosis, and the elimination of silver-protein complexes in the bile and urine. Minimum blood silver levels consistent with early signs of argyria or argyrosis are not known. Silver allergy does occur but the extent of the problem is not known. Reference values for silver exposure are discussed.

Ability of silver-impregnated contact lenses to control microbial growth and colonisation

Purpose

To examine the ability of silver nano-particles to prevent the growth of Pseudomonas aeruginosa and Staphylococcus aureus in solution or when adsorbed into contact lenses. To examine the ability of silver nano-particles to prevent the growth of Acanthamoeba castellanii.

Methods

Etafilcon A lenses were soaked in various concentrations of silver nano-particles. Bacterial cells were then exposed to these lenses, and numbers of viable cells on lens surface or in solution compared to etafilcon A lenses not soaked in silver. Acanthamoeba trophozoites were exposed to silver nano-particles and their ability to form tracks was examined.

Results

Silver nano-particle containing lenses reduced bacterial viability and adhesion. There was a dose-dependent response curve, with 10 ppm or 20 ppm silver showing > 5 log reduction in bacterial viability in solution or on the lens surface. For Acanthamoeba, 20 ppm silver reduced the ability to form tracks by approximately 1 log unit.

Conclusions

Silver nanoparticles are effective antimicrobial agents, and can reduce the ability of viable bacterial cells to colonise contact lenses once incorporated into the lens.

Confocal microscopy in ocular argyrosis

PURPOSE

To identify the presence of silver deposits in the cornea using a new-generation confocal microscopy technique.

METHODS

Case report.

RESULTS

A 70-year-old man, who had been a jeweler for many years, was referred to our center for assessment of corneal opacity and ocular pigmentation. Slit-lamp examination revealed grayish, dense confluent deposits in the central and peripheral cornea, deep stroma, and Descemet's membrane. On confocal microscopy, we observed typical images of hyperreflective keratocytes across the entire stromal surface and two hyperreflective plaques coinciding with areas of metal deposition, one at Descemet's membrane and the other at Bowman's membrane. This last deposition site has not been previously identified in vivo by confocal microscopy.

CONCLUSIONS

Confocal microscopy is a useful tool for the diagnosis of corneal argyrosis because it allows the in vivo visualization of silver deposits at different corneal levels.

Critical Observations on the Neurotoxicity of Silver

Silver is a xenobiotic element with no recognized trace metal value in the human body. It is absorbed into the body through the lungs, gastrointestinal tract, mucus membranes of the urinogenital tract, and through the skin, mainly in the form of silver protein complexes. Although silver is metabolized throughout the soft tissues, available evidence from experimental animal studies and human clinical reports has failed to unequivocally establish that it enters tissues of the central nervous system or is a cause of neurotoxic damage. Argyria characterized by deposition of particles of silver sulfide or silver selenide is the principle contraindication for using silver in medical devices or occupationally. This presents discoloration of the skin but is not regarded as a health risk or manifestation of toxicity. No evidence is available to demonstrate the toxic risk of silver to the peripheral nervous system, although silver sulfide deposits have been identified in the region of cutaneous nerves. Transitory silver sulfide deposits seen in the tissues of the blood-brain and blood-CSF barriers are mostly lysosomally bound or deposited on basement membranes or collagen without toxic effect. Silver is mostly excreted from the body in the urine and feces. Further research is indicated to evaluate the role of metal binding proteins including metallothioneins as cytoprotectants for neurological tissue.

Ocular argyrosis after long-term self-application of eyelash tint

PURPOSE

To report cases of ocular argyrosis that developed after long-term self-application of commercially available eyelash tint.

DESIGN

Observational case series.

METHODS

Case review, clinicopathologic analysis, and literature review.

RESULTS

Three patients developed ocular argyrosis after the long-term self-application of Revlon Professional Roux Lash and Brow Tint (Colomer USA Corp, New York, New York, USA). Clinical evaluation revealed various degrees of silver deposition on the upper eyelid, lid margin, caruncle and conjunctiva, and diffuse Descemet's membrane deposits. In one case, histologic examination demonstrated silver deposition in the basement membrane and superficial substantia propria of the conjunctiva.

CONCLUSIONS

Argyrosis can occur after long-term application of readily available eyelash tints, and the deposition of silver may be permanent. In certain circumstances, conjunctival argyrosis may simulate benign and malignant lesions, including conjunctival melanoma. These products should only be applied by trained cosmetologists.

An in vitro assessment of the antibacterial properties and cytotoxicity of nanoparticulate silver bone cement

Infections with multiresistant bacteria have become a serious problem in joint arthroplasty. This study reports about in vitro antibacterial activity against multiresistant bacteria and in vitro cytotoxicity of polymethylmetacrylate bone cement loaded with metallic silver particles with a size of 5-50 nm called NanoSilver. In vitro antibacterial activity against S. epidermidis, methicillin-resistant S. epidermidis (MRSE), and methicillin-resistant S. aureus (MRSA) was studied by microplate proliferation tests. Quantitative elution testing and qualitative ongrowth of human osteoblasts was done to study in vitro cytotoxicity. Only NanoSilver cement showed high-antibacterial activity against all strains, including MRSE and MRSA. Gentamicin cement was not effective against MRSA and MRSE due to the high-level gentamicin resistance of the tested strains. Plain cement did not inhibit proliferation of any strains. There was no significant difference regarding in vitro cytotoxicity between NanoSilver and the non-toxic control. Cytotoxicity of cement loaded with silver salts made this kind of silver unsuitable for all day clinical use in the past. This new form of silver called NanoSilver was free of in vitro cytotoxicity and showed high effectiveness against multiresistant bacteria. If the results can be confirmed in vivo NanoSilver may have a high interest in joint arthroplasty.

How safe is silver in wound care?

Use of silver in burns, chronic ulcers and diabetic ulcers can lead to circulatory absorption and deposits in wound sites, liver, kidney and other organs. Despite this, the risks of lasting tissue damage or functional disorders are low.

Occupational corneal argyrosis in art silver solderers

PURPOSE

To determine the value of confocal and specular microscopy in the examination of corneal argyrosis in art silver solderers.

METHODS

Six patients with corneal argyrosis underwent a complete physical and ophthalmologic examination. Specular microscopy was performed in three cases, and in vivo confocal microscopy in four cases. Ultrasound biomicroscopy and corneal topography were performed in three cases. A conjunctival specimen of one patient was examined histologically in paraffin sections.

RESULTS

Slit-lamp examination showed gray, diffuse opacities in the deep corneal stroma. Confocal microscopy showed highly reflective deposits with a granular pattern anterior to the corneal endothelium and hypereflective keratocyte nuclei with visible cytoplasm in the anterior stroma. Specular microscopy demonstrated round white bodies anterior to the corneal endothelium. Silver deposits were not found histologically.

CONCLUSIONS

Silver solderers with long-term exposure to silver compounds are at high risk of developing corneal argyrosis. We conclude that specular microscopy and in vivo confocal microscopy provided important information for the diagnosis of corneal argyrosis.

Multifocal corneal argyrosis after an explosion injury

PURPOSE

To document the clinical and histopathologic corneal features of a patient who developed multifocal corneal argyrosis after a chemical explosion injury with unusual involvement of the corneal stroma and keratocytes.

METHODS

The corneal button was investigated by light and transmission electron microscopy and scanning electron microscopy combined with energy-dispersive x-ray microanalysis.

RESULTS

Clinically, the patient showed dark discoloration of the lids, periocular skin, episclera, and conjunctiva and had multiple brown dots in the superficial layers of the cornea. Microscopic examination of the cornea showed diffuse deposition of silver particles in the epithelial basement membrane, Bowman's layer, and Descemet's membrane. In the corneal stroma, silver granules accumulated intracellularly within lysosomal structures of degenerative keratocytes and extracellularly in association with collagen fibers and cellular debris. Energy-dispersive x-ray analysis showed peaks of silver and sulfur.

CONCLUSION

The toxic influence of intracellular accumulation of silver in stromal keratocytes may lead to cell damage and necrosis and result in visual impairment.

Unexplained blindness after a major burn

A 43-year-old woman experienced the sudden onset of unexplained bilateral blindness 42 days after a 55 per cent total body surface area burn. Possible causes are examined, and a comparison with cases previously reported in the literature is made.

Argyrosis of the lacrimal sac

Silver deposition in the wall of the lacrimal sac after prolonged application of mild silver protein (Argyrol) eye drops is documented at the light and electron microscopical level. Silver granules were found in the extracellular matrix predominantly on elastic fibres and within cells forming conglomerates in secondary lysosomes. Most of the silver-containing cells showed a prominent rough endoplasmic reticulum, suggesting their fibroblastic origin. Investigation by energy-dispersive analysis of X-rays (EDAX) indicated the precipitation of silver as selenide.

Potential nephrotoxic effects of exposure to silver

A cross sectional study was conducted on workers engaged in manufacturing precious metal powder. Of the 27 workers, 96% had raised urine silver concentrations (range 0.5-52.0 micrograms/l, mean 11.3 micrograms/l) and 92% had raised blood silver concentrations (range 0.05-6.2 micrograms/100 ml, mean 1.0 microgram/100 ml). Nineteen per cent also had raised urine cadmium concentrations (range 1.9-76.0 micrograms/l, mean 11.8 micrograms/l). Most workers had symptoms of respiratory irritation and nose bleeds were reported in eight (30%) of the 27 workers. Deposition of silver in the cornea of the eye was detected in five of eight (63%) of the long term workers. Although not statistically significant, corneal deposition was associated with complaints of decreased night vision. The urinary enzyme N-acetyl-B-D glucosaminidase (NAG) was significantly raised in four individuals and was correlated with blood silver concentrations and age. In addition, the group's average NAG concentration was significantly higher than that found in a control population. No association between age and urinary NAG was found in the control group. Estimated creatinine clearance was also significantly lower in the group exposed to silver than in the control group. Kidney function appears to have been adversely affected by exposures at work but because of the exposure to cadmium the role of silver in causing the decrement in kidney function could not be definitely determined.

Peripheral corneal disorders

The peripheral cornea is anatomically and physiologically distinct from its central counterpart. The major differences relate to the gradual transition of corneal tissues to those of the conjunctiva, episclera, and sclera; furthermore, the vascular structures, lymphatics, and inflammatory cells from these neighboring structures are intimately associated with the limbus and periphery of the cornea. The peripheral cornea is thereby predisposed to three main classes of disorders which do not normally involve the central cornea. First, local conditions affecting the sclera and conjunctiva may secondarily spread to involve the limbus and peripheral cornea. These include several infectious diseases, as well as hypersensitivity conditions, mass lesions, and degenerations. Second, due to the associated blood vessels and lymphatics, the peripheral cornea may be involved in a variety of systemic diseases, including vasculitides, autoimmune disorders, and abnormal metabolic conditions. Finally, there are several conditions, such as the noninflammatory peripheral degenerations, which primarily affect the peripheral cornea without associated ocular or systemic changes. In this review, we present a classification and discussion of the various disorders which may involve the peripheral cornea.

Biologic monitoring of workers exposed to silver

The smelting and refining of silver and the preparation of silver salts for use in photosensitized products can lead to occupational exposures to silver. Our objectives in this study were to determine the absorption and elimination of silver by workers exposed to different species of silver, to estimate the body burden of silver and to relate these findings to the potential development of argyria. Workers potentially exposed to silver (n = 37) and a similar number of controls (n = 35) participated in this study. Blood, urine, feces and hair samples were collected and were analyzed for total silver content by atomic absorption spectroscopy. The mean concentration of silver in the blood, urine and feces of silver workers was 0.011 microgram/ml, less than 0.005 microgram/g and 15 microgram/g, respectively; and of controls was less than 0.005 microgram/ml, less than 0.005 microgram/g and 1.5 microgram/g, respectively. The concentration of silver in hair was markedly higher for the silver workers than for controls (130 +/- 160 vs 0.57 +/- 0.56 microgram/g, respectively). The importance of these latter findings was questionable since airborne particles of silver can bind to hair and lead to apparent high values. Since silver is eliminated predominantly in the feces, fecal measurements were used as an index of exposure and as a means of calculating body burdens. Human exposure to metallic silver at the TLV (0.1 mg/m3) is expected to lead to a fecal excretion of about 1 mg of silver per day.(ABSTRACT TRUNCATED AT 250 WORDS)