Types of spectacle lenses explained: single vision, bifocal, progressive and coatings
The main types of spectacle lenses are single vision, bifocal and progressive, made in CR-39, polycarbonate, high-index or glass, and finished with coatings such as ARC, blue-cut and photochromic. Lenses are where most of the value in a pair of glasses is, and where customers are most confused. This guide explains lens designs, materials and coatings in words you can use at the counter.
Spectacle lens types by design
| Design | What it does | Who it suits |
|---|---|---|
| Single vision | One power across the whole lens. | Distance-only or reading-only glasses. The most common lens. |
| Bifocal | Two zones: distance on top, a visible reading segment below (often D-shaped or round, sometimes called Kryptok). | Customers who want two clear zones and a lower price than progressives. |
| Progressive (PAL) | Power changes gradually from distance at the top through intermediate to reading at the bottom, with no visible line. | Customers over about 40 who want one pair for everything and a line-free look. |
| Office / computer lenses | Wider intermediate and near zones for desk work. | People who spend long hours at a screen or desk. |
Progressives take a few days to get used to. Measure monocular PD and fitting height carefully, and tell the customer to move their head, not just their eyes, while adapting. Our progressive lens fitting height guide shows how.
Spectacle lens materials
| Material | Refractive index | Notes |
|---|---|---|
| CR-39 (plastic) | 1.50 | Light, good optics and affordable. Often called "fiber" or "hard resin" at the counter. |
| Polycarbonate | 1.59 | Very impact-resistant and thinner than CR-39. A good choice for children, sports and rimless frames. |
| Mid and high index | 1.56, 1.60, 1.67, 1.74 | The higher the index, the thinner and lighter the lens for the same power. Worth it for stronger prescriptions. |
| Glass | 1.52 and above | Very scratch-resistant but heavy and can shatter. Rarely used now. |
Coatings and treatments
- Hard coat: makes plastic lenses more scratch-resistant. Usually included.
- Anti-reflective coating (ARC): cuts reflections so the wearer sees more clearly, especially at night, and others see their eyes instead of glare. "ARC fiber" at the counter usually means a CR-39 lens with anti-reflective coating.
- Blue-cut / blue-light filter: reduces some blue light from screens and adds a faint tint or reflection. Many customers like them for screen comfort, but avoid promising they protect eye health: major eye-care bodies have not found strong evidence for that.
- Photochromic (often called photogray): darkens in sunlight and clears indoors. Note that many photochromic lenses darken less inside a car, because windscreens block much of the UV that triggers them.
- Hydrophobic and oleophobic layers: repel water and fingerprints, making lenses easier to clean.
- UV protection: blocks ultraviolet light. Polycarbonate and high-index materials block UV on their own.
Explaining lens choices to customers
- Start from the prescription: strong powers need higher-index material. If the numbers are unclear, see how to read an eye prescription.
- Ask how they spend their day: driving, screens, outdoor work, reading.
- Offer two or three clear options (good, better, best) instead of a long list.
- Write the lens details on the bill, so the next pair can be made the same way.
Opticdigit keeps the lens type, coating and eye power on each bill, so when a customer comes back you can see exactly what they bought last time. On Premium and above it also tracks lens orders from prescription to lab to delivery. See the plans.
Frequently asked questions
What are the types of spectacle lenses?
By design: single vision, bifocal, progressive and office (computer) lenses. By material: CR-39 plastic, polycarbonate, mid and high index, and glass. On top of that come coatings such as hard coat, anti-reflective (ARC), blue-cut, photochromic and UV protection.
Which spectacle lens is thinnest?
The higher the refractive index, the thinner the lens for the same power. A 1.74 high-index lens is thinner than 1.67, 1.60 or 1.56, and all are thinner than a 1.50 CR-39 lens. High index is most worth it for stronger prescriptions.
What is the difference between ARC and blue-cut spectacle lenses?
ARC (anti-reflective coating) cuts reflections so vision is clearer, especially at night. Blue-cut lenses filter some blue light from screens. Avoid promising that blue-cut protects eye health; major eye-care bodies have not found strong evidence for that.
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