Your next trip to smooth out crow’s feet or fill in smile lines could look a little different. Experts are urging clinics to perform ultrasounds before injecting cosmetic fillers into patients’ faces — a step they say could make the popular procedure safer and more precise. The push follows new research raising concerns about a rare but serious complication linked to the treatment that can lead to skin loss, blindness or even stroke. The dangerous risk, called vascular occlusion , happens when