Leica, Nikon, Trifocal, Optics, Oculars, and Irises are all big names in lenses. Leica is a German camera and optics manufacturer that produces high-end cameras and lenses. Nikon is a Japanese multinational corporation specializing in optics and imaging products. Trifocal lenses are eyeglasses with three distinct optical powers, allowing for clear vision at near, intermediate, and far distances. Optics is the branch of physics that studies the behavior and properties of light and its interaction with matter. Oculars are lenses used in microscopes and telescopes to magnify images. Irises are the colored part of the eye that controls the amount of light entering the eye.