A patient presented with diminished vision and neuropsychiatric manifestations and with hepatic dysfunction. His eyes on general examination and slit lamp examination appeared as shown in the Figure below. What investigation you will do next?

Ref. API Textbook of Medicine. Pg. 870   Image represents “Kayser-Fleischer” ring -  KF ring is golden brown ring due to deposition of copper in Descement’s membrane of cornea.   Wilson’s Disease: Rare autosomal recessive disease. Characterized by abnormal copper metabolism Sternlieb's criteria: Presence of KF rings Decreased serum ceruloplasmin (copper containing enzyme / ferroxidase) levels Measuring hepatic copper levels in liver biopsy 24-Hr urine copper excretion ● Kayser Fleischer ring: Excess circulating copper deposits in descemet’s membrane. Usually golden brown located in peripheral cornea, beginning at schwalbe’s line upto 5 mm into cornea. Detected via Gonioscopy in earlier stage & seen by naked eyes in advanced stage.