Both of these lenses are high-index lenses, making them thinner and lighter compared to regular lenses (like those with a 1.50 index). They provide better visual clarity and comfort.
If your SPH (spherical) prescription is 500 or below, we typically use 1.60 index lenses. For prescriptions over 500, we use 1.67 index lenses.
However, if you have a personal preference, feel free to contact our customer service center.