Optical Index of Prescription Lenses: Understanding the Basics

by | Apr 12, 2023

The optical index of prescription lenses is an important factor to consider when choosing the right pair of glasses for your needs.

Prescription lenses are an essential tool for people with vision problems, helping them see clearly and comfortably. However, not all prescription lenses are created equal. 

Have you ever wondered what the optical index of your prescription lenses means? 

It can have a significant impact on the quality and comfort of your vision. 

In this post, we’ll explain what the optical index is, and how it affects the thickness, weight, and clarity of your lenses.

What is an Optical Index of a Prescription Lens

The optical index is a measure of the refractive index of a lens material. 

It refers to the speed of light as it travels through the material and as it enters and exits the lens. 

The higher the optical index, the faster light travels through the material, and the less it is bent, leading to a thinner, lighter lens with less distortion.

There are several optical indexes available for prescription lenses, including 1.50, 1.57, 1.59, 1.60, 1.67, and 1.74. 

The most common optical indexes are 1.50, 1.60, and 1.67.

Optical index 1.50 lenses are the thickest and heaviest of the options. 

They are typically made of a plastic material and are the most affordable option. However, they are also the least aesthetically appealing, making them a less popular choice among people who value style.

Optical index 1.60 lenses are a popular option for many people. They offer a balance of affordability and style and are often made of a material that is lighter and thinner than 1.50 lenses. They provide good vision correction and are suitable for most prescription needs.

Optical index 1.67 lenses are the thinnest and lightest of the options and are made of a high-tech material that allows for maximum light transmission. They are often the most expensive option, but are also the most attractive, making them the top choice for people who want a sleek and stylish look.


How Does the Optical Index Affect the Lenses?

The optical index has a direct impact on several important factors that affect the quality and comfort of your vision while using your glasses. 

Here are some of the ways it can impact your lenses:


The lower the optical index the thicker the lens meanwhile, the higher the optical index, the thinner the lens will be. This is because the faster light travels through the material, the less it is bent and distorted. Thinner lenses not only look more aesthetically pleasing, but they also reduce the thickness of your glasses, making them fit into most frames and more comfortable to wear for long periods of time.


Lenses with a higher optical index are also lighter, as they require less material to achieve the same degree of correction. This makes them ideal for those who need stronger prescriptions, as heavier lenses can cause discomfort and strain on the nose and ears.


High-index lenses have less internal distortion and aberrations, resulting in clearer vision and improved image quality. They also have a lower surface reflection, which reduces glare and improves contrast sensitivity.


High-index lenses are typically more expensive than lower-index lenses, as they require more advanced materials and technology to manufacture. However, the benefits of thinner, lighter, and clearer lenses often outweigh the additional cost for many people.


How to Choose the Right Optical Index for Your Lenses?

When choosing the right lenses for your glasses, it’s important to consider the optical index along with other factors, such as your prescription strength, frame style, and lifestyle needs. Here are some tips to help you make the right choice:

Consider your prescription strength: 

The higher your prescription strength, the more benefit you’ll see from high-index lenses. If your prescription is weaker, you may not notice as much of a difference, and a lower-index lens may be sufficient.


Consider the frame style: 

High-index lenses are ideal for smaller, rimless frames, as they allow you to maximize the visual area while minimizing the thickness of the lens.

Consider your lifestyle: 

If you are active and engage in sports or other physical activities, you may want to consider high-index lenses, as they are more impact-resistant and less likely to shatter.


In conclusion: 

The optical index of your lenses is an important factor to consider when choosing the right lenses for your glasses. 

A higher optical index can lead to thinner, lighter, and clearer lenses with less distortion, but it also comes at a higher cost. 

When making your decision, It’s important to weigh the benefits against your budget, prescription, strength, frame style, and lifestyle needs, also don’t forget to consult with your eye doctor to determine the best choice for your specific needs.

Remember, your eyes are an important part of your overall health, and having the right lenses can greatly improve your quality of life. 

Whether you need lenses for reading, driving, or playing sports, choosing the right optical index can make a significant difference in your vision and comfort.

So, take the time to get the right information about the different options available, and make an informed decision about your lenses. 

With the right optical index, you can enjoy clear and comfortable vision for years to come especially when complimented with the right lens coating. You are welcome to visit us at our optometry eye clinic in Port Harcourt, Nigeria. For any enquiries, feel free to contact us.

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