Eyeglass Lens Types Explained: Index, Coatings and Costs
Two frames can look identical and cost triple the difference — the money is almost always in the lens. Here is what each option does, and when it is worth it.
A lens decision has three parts, and they are independent of each other: what the lens corrects, how thin it is, and what is coated onto its surface. Getting clear on those three makes every price list readable.
1. What the lens corrects
Single vision
One power across the whole lens, correcting either distance or near vision. This is what the overwhelming majority of people need, and it is the cheapest and optically cleanest option.
Bifocal
Two powers with a visible line between them — distance on top, reading below. Cheaper than progressives and easier to adapt to, at the cost of a visible line and a hard jump between the two zones.
Progressive (varifocal)
Distance, intermediate and reading blended into one lens with no visible line. Most people need one to two weeks to adapt. Progressives are unforgiving of a poor fit: they only work if the optical centres line up with your pupils, which is why they must be measured on the frame you actually chose.
2. Lens index — why thinner costs more
The index number is how strongly the material bends light. A higher index bends light more, so less material is needed for the same correction, so the lens is thinner and lighter. Nothing else about your vision changes.
| Index | Best for | Notes |
|---|---|---|
| 1.50 standard | Up to about ±2.00 | Cheapest, thickest. Fine on low powers. |
| 1.59 polycarbonate | Kids, sport, rimless | Impact-resistant, built-in UV. Slightly softer surface. |
| 1.60 | ±2.00 to ±4.00 | The usual sweet spot for price and thickness. |
| 1.67 | ±4.00 to ±7.00 | Noticeably thinner edges on strong minus powers. |
| 1.74 | Above ±7.00 | Thinnest available. Always pair with anti-reflective. |
3. Coatings — which ones actually earn their price
- Anti-reflective (AR) — the one coating worth buying every time. It removes the ghost reflections that tire your eyes at night, and it lets people see your eyes instead of two white discs.
- Scratch-resistant — standard on most lenses now, and worth confirming is included rather than paying extra for.
- UV protection — essential in Egypt, and already built into polycarbonate and most high-index materials. Ask rather than assume.
- Blue light filter — useful if you work long hours on screens, mainly for comfort. Treat the stronger claims with caution.
- Photochromic — clear indoors, darkening outdoors. Genuinely convenient under Egyptian sun, though they darken less inside a car because windscreens block the UV that triggers them.
- Polarised — for sunglasses, not clear lenses. Cuts glare off roads, water and car bonnets. Note it makes some phone and dashboard screens go dark at certain angles.
What a fair quote looks like
A trustworthy quote separates the frame price from the lens price, states the index, and lists the coatings by name. If you are handed one number for "glasses", ask for the breakdown — that is a completely normal request and any real optician will give it.
Lenses are cut, coated and fitted in-house, so the index and coatings you pick are the ones you get.
See our lens labFrequently asked questions
What does lens index mean?
It is how strongly the lens material bends light. A higher index bends light more, so less material is needed for the same prescription, producing a thinner, lighter lens. It does not change how well you see — only the thickness, weight and price.
Is an anti-reflective coating worth it?
Yes — it is the single coating we would recommend on every pair. It cuts the reflections that cause halos around headlights at night, reduces eye fatigue on screens, and makes the lenses look almost invisible in photos and in person.
How long do progressive lenses take to get used to?
Usually one to two weeks. Wear them full-time during that period rather than switching back and forth, and move your head towards what you are looking at rather than only your eyes. If they still feel wrong after two weeks, the fitting measurements should be rechecked.
Do I need high-index lenses?
Only if your prescription is strong enough for thickness to be visible — roughly above ±2.00, and clearly worth it above ±4.00. Below that the difference is fractions of a millimetre and the extra cost buys you nothing you can see.
Are photochromic lenses good enough to replace sunglasses?
For walking around, mostly yes. For driving, no — car windscreens block most of the UV that activates them, so they stay lighter than you want. Anyone who drives regularly in Egyptian daylight is better served by a dedicated pair of prescription sunglasses.