Check lipid profile.
The next best step in this case would be to obtain a lipid profile, because the results from this panel are likely to indicate hypertriglyceridemia.
The findings in the Figure indicate that he has lipemia retinalis, which causes a creamy white appearance to the retinal arteries and veins. The condition is associated with severe hypertriglyceridemia.
Reference:
Baron RB. Lipid disorders. >In: Papadakis MA, McPhee SJ, Rabow MW, eds, et al. Current Medical Diagnosis & Treatment. 2016.