Eyewear, explained
The Designer Glasses Editorial Team 
What Is a High-Index Lens? A high-index lens is made from a material that bends light more efficiently than standard plastic, which means it can be made thinner and flatter for the same prescription strength. The trade-off is that this material handles colour less faithfully, so light can split slightly at the edges — a … Read more
An occupational or office lens is a prescription lens built specifically for the distances that matter at a desk — arm’s length to a monitor and closer for paperwork or a phone — rather than for driving distance or the far horizon. It trades away long-distance clarity to give a wider, more comfortable zone for … Read more
A bifocal has two distinct zones of correction — usually distance up top and near vision in a segment at the bottom, separated by a visible line. A progressive does the same job of covering multiple distances, but blends them into one lens with no line at all. The difference is as much about how … Read more
A progressive lens is a single lens that blends several focusing powers into one smooth surface, letting the wearer see clearly at distance, at arm’s length and up close without switching glasses or looking through a visible line. Most people need a few days to two weeks to adapt, though how the lens fits your … Read more
A single-vision lens corrects for one distance only — near, intermediate, or far — across its entire surface. That’s the whole definition. There’s no blending of powers, no zones, no transition line. It’s the simplest lens construction available, and for a large share of prescriptions, it’s also the one with the fewest visual and cosmetic … Read more
Abbe value is a number that describes how much a lens material bends different colours of light by different amounts. A low Abbe value means more colour separation and softer, fringier vision at the edges of a lens. It matters for thick prescriptions because the materials used to make strong lenses thinner tend to have … Read more
Lens index (or refractive index) is a number that describes how strongly a lens material bends light. A higher index bends light more per millimetre of thickness, so the lens can be made thinner and flatter for the same prescription — at a cost in weight, price, and sometimes optical clarity. What does lens index … Read more
An anti-reflective coating is a microscopically thin layer applied to the front and back of a lens that stops light bouncing straight back off the glass or plastic. Less light reflects, so more of it passes through to the eye — the lens looks clearer, and other people can actually see your eyes rather than … Read more
You tell by the label, not the lens. Genuine UV protection is stated explicitly — as “UV400” or “100% UVA/UVB protection” — printed on the lens, the arm, or the swing tag. If that wording isn’t there, the tint tells you nothing about UV filtering at all, no matter how dark or expensive the sunglasses … Read more
Prescription sunglasses are a single lens, ground to your prescription and tinted or coated at the factory, sitting in one frame you wear on their own. A clip-on is a second, separate tinted lens that attaches to the front of glasses you already own. The correction lives in your everyday glasses; the clip-on only adds … Read more
About what you read here. Everything on The Designer Glasses is general information and our own editorial opinion. We research carefully and we say when the evidence is unclear, but we can be wrong, things change, and no article can know your particular situation. Please do your own research and make your own judgement rather than treating anything here as the final word. This is not medical advice, not a diagnosis, and not a substitute for speaking to an optometrist, optician or eye doctor about your own eyes, vision and eyewear. We are writers and researchers, not clinicians. We do not recommend prescription treatments or give doses. If something is painful, getting worse, or worrying you, please talk to a professional — going early is not an overreaction.