Retinal lead toxicity

Presumed retinal lead poisoning: a case report

PURPOSE

To describe a case of presumed retinal lead poisoning.

METHODS

Clinical examination, optical coherence tomography, fundus autofluorescence, fluorescein angiography, and electroretinography were used to study a 42-year-old male with the complaint of bilateral reduced vision following systemic lead poisoning.

RESULTS

The fundus examination showed venous tortuosity, as well as macular atrophy, and pigmentary changes in his both eyes. Optical coherence tomography revealed retinal thinning, outer retinal and retinal pigment epithelium atrophy, as well as foveal schitic changes. Blue autofluorescence showed moderately hypoautofluorescence in peripapillary area of both eyes. Fluorescein angiogram showed a leopard-like pattern of hypo- and hyperfluorescence in the posterior pole. Electroretinogram showed a moderate reduction in photopic and scotopic responses.

CONCLUSIONS

The most probable diagnosis of this case is early onset retinal lead poisoning.

Dose and Time Response Study to Develop Retinal Degenerative Model of Zebrafish with Lead Acetate

Animal models are the silent scouts that help to understand the complex biological processes and gather data that aid our understanding of how organisms function. Various animal models are being sacrificed to assess the impact of toxic chemicals. Mortality calculations should be minimized and much data should be collected on the basis of clinical signs that can contribute to identifying robust humane endpoints linked to mortality. This study was designed to calculate the lowest possible dose of PbAc (lead acetate), a neurotoxicant, that can have a toxicological impact on the zebrafish retina and to minimize animal usage. Dose and time-dependent changes were observed in the zebrafish retina following PbAc exposure with zero mortality. Vision and visual behavior response are the foremost indicators that can be recorded to mark the risk assessment of any chemical. Therefore, the present study aims at dose and time response to find the lowest dose of PbAc affecting the zebrafish retina and its visual behavior. Zebrafish were treated for 3 weeks with four concentrations of 0.04, 0.06, 0.08, and 0.1 mg/L of PbAc for a dose-response study. Then for the time response study, two doses 0.08 and 0.1 mg/L were selected and zebrafish were exposed to those concentrations for 2 and 4 weeks. The results of qualitative and quantitative analyses of retinal histology showed that 15 days of treatment with 0.08mg/L concentration can cause appropriate damage to the photoreceptor layer. At the ultrastructural level, it was further observed that PbAc induces damage to the photoreceptors, especially the rod cells. Escape response behavior showed a significant decrease in visual response to changing contrasts in an increasing dose-dependent manner.

Bilateral Optic Disc Edema in a Patient with Lead Poisoning

Purpose

Heavy metals, such as lead can cause optic neuropathy. Optic disc neuropathy due to lead intoxication has previously been reported. We report a rare case of lead toxicity-induced optic neuropathy presenting with bilateral hemorrhagic optic disc swelling.

Case Report

The patient was a 42-year-old man with a history of chronic oral opium use, who had a gradually progressing blurred vision in both eyes over 40 days, with ataxia, paresthesia, and a toxic level of serum lead. He had been treated with lead chelators for lead poisoning. His color vision was impaired in both eyes. Humphrey's visual field test revealed double arcuate scotoma with enlargement of the blind spot. Funduscopy revealed bilateral optic disc swelling, which was confirmed on optical coherence tomography and fluorescein angiography.

Conclusion

In cases of optic disc edema, a comprehensive history should be taken to detect the cause. Further, in cases of chronic oral opium use, lead toxicity should be considered.

Morphological, biochemical, and histopathological postmortem ocular indices following subchronic exposure to cadmium and/or lead in a rabbit model

Cadmium (Cd) and lead (Pb) are ubiquitous environmental pollutants. There is a dearth of information on the mutual interaction between the antemortem metal intoxication and the postmortem changes of the eye. Thus, this study aimed to follow the morphological, biochemical, histopathological ocular perturbations and the retinal DNA damage up to 8 h postmortem (PM) in Cd and/or Pb intoxicated rabbits. The animals orally received 5 mg Cd Cl₂/kg bw and/or 12.5 mg lead acetate/kg bw for 30 consecutive days. At time of death, eye pupil of different groups had a normal diameter except Pb-intoxicated group had marked myosis. After 8 h of death, different rabbit's eye corneas appeared wrinkled and covered with thin white cloud while the pupils were in the mydriatic stage. Up to 8 h PM, the individual exposure to Cd or Pb resulted in a significant elevation in GGT, urea, K, DNA damage and obvious retinal lesions. However, their co-exposure evoked an antagonistic outcome. The eye of Cd and/or Pb intoxicated rabbit showed mildly degenerated tissue of cornea and sclera and the presence of irregular eosinophilic droplets of variably size in the lens with a gradual degeneration and vacuolization in the different cell layers of retina especially ganglion up to 8 h PM. Also, by increasing post mortem interval (PMI), retinal DNA damage in Cd and/or Pb intoxicated group significantly decreased. It is concluded that Cd and/or Pb intoxication induced ocular alterations which retain the same trend in correlation with PMI as natural deaths except for the retinal DNA damage. Also, the simultaneous exposure to Cd and Pb evoked an antagonistic outcome in the eye. The findings of the current study should be taken into consideration when estimating PMI in areas with high Cd and/or Pb contamination.

Hip-implant related chorio-retinal cobalt toxicity

A 39-year-old female with elevated serum cobalt levels from her bilateral hip prostheses presented with a 3-week history of blurred vision in her left eye. Optical coherence tomography revealed patchy degeneration of the photoreceptor-retinal pigment epithelium (RPE) complex. The lesions were hypofluorescent on indocyanine green angiography. We postulate that this is a case of implant-related chorio-retinal cobalt toxicity.

P53 and Bcl2 apoptosis proteins in meso-2,3-dimercaptosuccinic acid treated lead-intoxicated rabbits

Lead (Pb) toxicity is one of the commonest environmental problems in our life; it causes many reversible and irreversible changes in our tissues. This study was carried out to investigate the effect of meso-2,3-dimercaptosuccinic acid (DMSA) on treatment of oxidative stress caused by lead poisoning in rabbits. Lead acetate (Pb(Ac)(2)) was orally administrated to rabbits for 21 days and then treated by DMSA for another 21 days. The effect of this treatment was investigated by measuring 2 of the apoptosis proteins p53 and Bcl2. Also, the auto-oxidation rate and their histopathological changes in brain, bone and liver were investigated. Hemoglobin auto-oxidation rate is measured as well as histopathological study of liver. Our data indicate that exposure to rabbits to Pb(Ac)(2) caused a significant increase of apoptosis protein p53 and decrease in the antiapoptotic BCl2 proteins.