Why is Optical Glass Lenses Better?

Eyeglasses date back to the 13th century when glass blown lenses were placed into leather or wooden frames and held in front of the eyes or perched on the nose.

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Thankfully, nowadays, with the advancement of technology, not only do we have temples on our frames to keep our glasses in place and a wide variety of optical lenses and frame styles, but the lenses themselves are also being manufactured with plastic materials to make up for qualities glass lenses cannot provide.

Glass or plastic?

Plastic lenses are generally made from a strong material called CR-39, but also are available in a range of hi-index lenses, which are thinner and lighter. While most people prefer the newer plastic lenses, there are still a number of people who continue to prefer glass. Each material has its own advantages and disadvantages, and the lens material you choose is really a personal choice.

To help you make a more informed decision, we have provided the advantages and disadvantages of each type of lens below. 

If you have any questions, you can always ask your optometrist for advice. Optometrists are aware of all the latest optical lens choices and understand your specific needs.

Glass lenses

While plastic has become the most popular choice of lens material in recent years, glass lenses are still preferred by some for the following reasons: 

Clarity. Glass lenses provide the clearest vision with the smallest amount of distortion.

Scratch resistance. Glass lenses are almost impossible to scratch, while plastic lenses can be scratched easily if you are not careful.

Thin and attractive. Glass lenses are typically manufactured with a higher index, which gives them a thinner, more attractive appearance.

However, keep the following factors in mind before purchasing a new pair of glass lenses:

Heavier than plastic. The weight of glass lenses can get uncomfortable, especially if you plan to wear them all day. Their heaviness can also cause them to frequently slide down your face, which can become irritating over time.

Limited frame options. The weight of the glass lens makes them incompatible with semi-rimless and rimless frames. This can be quite limiting when choosing a frame style.

Delicate. Glass frames, though scratch resistant, are more delicate than plastic frames and can easily crack or even shatter upon impact. This is an important deciding factor if you lead an active lifestyle, have young children at home that may try to pull your glasses off your face, or if you are choosing a lens material for a child's eyeglasses.

Difficult to tint. If you were hoping to add a colored tint to your lenses, you may want to rethink purchasing glass lenses. Since glass is a hard, non-absorbent material, applying a tint is difficult and is generally not recommended.

Limited transition (photochromic) options. If you are interested in transition (photochromic) lenses, it is important to be aware that glass lenses cannot accommodate all of the different transition options, and are only available in two colors: Photo Grey Extra (PGX) and Photo Brown Extra (PBX).

Contact an eye doctor near you to discuss how to achieve the best vision possible.

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Plastic lenses

It is undeniable that plastic has become widely popular in recent years, and there is definitely a good reason for this change:

Lightweight. Plastic lenses are by nature much lighter and more comfortable than glass lenses. This is an important consideration if you plan to wear your glasses all day. Their light weight also helps them to stay in place longer, with less of a chance that they will slip down your nose multiple times per day.

Durable. Plastic lenses are very difficult to crack or break and are much more durable than glass lenses' making them a great choice for both kids and adults.

Reduce glare. Plastic lenses are less likely to cause problems with glare since they are naturally less reflective than glass.

Large variety. Plastic lenses are compatible with a large variety of frames that come in all different shapes, sizes, thickness and colors. This means you will have a much larger selection of frames to choose from when choosing plastic lenses over glass lenses.

Easy to tint. If you are looking to add a colored tint to your lenses, plastic lenses are the way to go. Due to its absorbent nature, plastic lenses can be easily tinted in a large variety of colors and shades.

Wide variety of transition lens options. If you are interested in purchasing transition (photochromic) lenses, plastic lenses are a great choice for you. Most plastic lenses are able to accommodate a large variety of transition lens options.

However, while plastic lenses are the preferred choice, there may be one drawback to choosing plastic over glass'

Easily scratched. This is the main reason why some people choose glass lenses over plastic lenses.

Keep in mind though, that while this factor may have been a cause for concern in the past, nowadays, the option to add an anti-scratch coating to your lenses eliminates the worry that your lenses will get scratched easily.

Which type of lens is right for you?

When deciding between glass and plastic, think about what you are looking for in a lens and which type of lens will suit your lifestyle best. If you have any questions or concerns, ask your optometrist or optician for advice.

LEARN MORE:  Optical and Contact Lenses

Schedule an appointment with an eye doctor to discuss how to achieve the best vision possible.

Glass lenses ' lenses made from natural mineral glass, according to their professional classification ' used to be the norm. They still have their place in optometry today thanks to their exceptional scratch resistance. Consumers will also like the fact that they are less expensive than comparable plastics. In cases of severe ametropia, they can also provide the correction needed with relatively thin lenses - an aesthetic aspect that is not to be underestimated.

Natural glass is also recommended for bifocal or trifocal lenses because various materials can be melted together without forming a noticeable cutting edge. In principle, the increased thickness of the material makes it optically purer; the glasses appear cleaner and are free from disruptive color fringes (so-called dispersion). When light strikes an eyeglass lens, it is broken down into its component parts and dispersed. This creates a disruptive visible color spectrum, similar to a prism. The intensity of this effect, known as dispersion, depends on the condition of the material used: high-quality material means minimal dispersion. The color fringe effect is measured based on what is known as the Abbe number: The higher the Abbe number for an eyeglass lens material, the lower the dispersion.

The advantage of natural glass: It produces considerably weaker color fringes even when the refractive index is identical to that of plastic lenses.

The greater the refractive index range (also called the refraction index) of the eyeglass lens material, the thinner the finished glass. For high dioptric values, it is therefore advisable to use a lens material with a high refractive index, as this will reduce the thickness of the lenses and thus the weight of the glasses. For example: A lens with a refraction index of 1.6 is always thinner than one with a refraction index of 1.5 for an identical dioptric value. Natural glass has a clear advantage here: Its refractive index range extends from 1.5 to 1.9, while the refractive index range of organic glass (= plastic) is only 1.5 to 1.74. Natural glass also has a greater density than plastic.

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