Meniscus, equiconcave, and flat concave are types of what?

Meniscus, equiconcave, and flat concave refer specifically to variations in lens shapes that are primarily associated with minus lenses.

Minus lenses, which are designed to correct nearsightedness (myopia), are characterized by their concave shape. The meniscus lens has a surface that curves inward, which helps in diverging light rays. Equiconcave lenses have two equally concave surfaces, providing uniform power across the lens. Flat concave lenses, as the name suggests, feature a flat surface on one side and a concave shape on the other. All these types are designed to achieve various optical effects required for the correction of vision in individuals with myopia.

Understanding these specific types of lenses is crucial for opticians as they determine how light interacts with the lens and consequently how it affects vision correction.