Heavy metals are a group of toxic agents that can be toxic for nervous system including the optic nerve. Lead poisoning is a common cause of metal toxicity. There are several sources of lead exposure, such as paint, gasoline, cosmetic products, and batteries. Absorption of lead occurs via the respiratory and gastrointestinal tracts. 

In a study by Abri Aghdam et al, the investigators showed bilateral optic disc swelling due to lead toxicity in a patient with progressive blurred vision. The interesting finding in this patient was the source of toxicity. The patient was a chronic oral opium user, and recently, the opium used by him contained lead as a chemical impurity. Lead is occasionally added to opium products to increase its weight for higher profits. 

This interesting article emphasize in cases of chronic oral opium use, lead toxicity should be considered, as lead is occasionally added to the product. 

Reference:

Abri Aghdam K, Zand A, Soltan Sanjari M. Bilateral Optic Disc Edema in a Patient with Lead Poisoning. J Ophthalmic Vis Res. 2019;14(4):513-517. Published 2019 Oct 24. doi:10.18502/jovr.v14i4.5465

Link:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6825703/

Amin Zand, MD 

Eye Research Center, The Five Senses Institute, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran.