When buying a new pair of glasses, I always find that patients put a lot of thought into the frame and never think about the lenses. Patients will spend hours (and even days!) looking for the right frame for them but never spend any time considering what lenses are best for them. The lenses are actually the most functional part of the glasses, they provide you with clear vision.
Lens Materials
When choosing lenses for your glasses, it's good to know what lens material is most suitable for your lifestyle and most importantly, your vision. There are 3 main types of premium lens materials you will come across when buying prescription eyeglasses, these are:
1. High-index plastics
High index plastics make thinner and lighter lenses. They are highly recommended if you have a strong eyeglasses prescription for nearsightedness, farsightedness or astigmatism.
2. Polycarbonate
Lightweight lenses that are extremely impact resistant and also offer UV protection. It’s a suitable choice for both children’s glasses and safety glasses.
3. CR-39 plastic
These lenses are half the weight of glass lenses and still provide excellent optics and vision correction; however they are generally thicker than the other lens materials listed above.
Lens Index
“What does lens index mean?” I get a lot of patients asking that question when buying new lenses.
Lens index is a number that describes how thick or thin your lenses are. The higher a lens' index is, the thinner it becomes. Higher prescriptions require higher index lenses, while lower prescriptions require lower index lenses. Lens indices range from standard plastic lenses, thin and light, ultra-light, and super ultra-light.
1.5 - Standard Plastic Lens
20% lighter than glass lenses and made from high grade plastic - an affordable choice for daily use.
1.61 - Thin and Light
Up to 20% thinner than normal plastic lenses and extremely durable - ideal for stronger prescription strengths.
1.67 - Ultra Thin
Around 30% thinner than 1.61 and are recommended for stronger prescriptions - ideal for those seeking a thinner frame.
1.74 – Super Ultra-Thin
High Index 1.74 lenses are the thinnest, flattest, and most cosmetically appealing lens ever developed. These ultra-thin lenses are nearly 50% thinner than plastic and 5% thinner than 1.67 high index lenses, offering you the ultimate in technology and cosmetics.
Lens material and index are just one aspect to consider when buying lenses. Coatings and the type of prescription lenses will also be covered in my blog in later posts.