You should replace your shooting glasses whenever they show signs of damage or deterioration that may affect their protection or performance. For example, you should replace your glasses if they have cracks, chips, scratches, or dents on the lenses or frames. You should also replace your glasses if they have loose hinges, screws, or nose pads that may compromise their fit or stability. You should also replace your glasses if they have faded colors, peeling coatings, or distorted vision that may impair their clarity or quality.