The Best Eyeglasses: Materials and Lens Coatings for Your Glasses
The best eyeglasses are the right combination of materials and lens coatings. This the of 2 articles explaining the making of the great eyeglasses.
Eyeglass blank lenses, also known as uncut or semi-finished lenses, are the initial form of lenses before they are shaped and surfaced to match a specific prescription. These blank lenses come in various materials, each with its own unique properties and uses.
At the heart of best eyeglasses is the material chosen to make the lenses.Here are the common types of eyeglass blank lenses and their specific uses:
Glass Lenses:
Material: Glass lenses are made from regular glass.
Properties: Glass lenses offer excellent optical clarity but are heavier and more prone to breakage compared to plastic lenses.
Uses: Glass lenses are less common in modern eyewear due to their weight and safety concerns. They were more prevalent in the past before the popularity of plastic lens materials.
CR-39 (Regular Plastic) Lenses:
Material: CR-39 is a lightweight plastic material (allyl diglycol carbonate).
Properties: CR-39 lenses provide good optical clarity and are more comfortable to wear than crown glass due to their lighter weight.
Uses: CR-39 lenses are suitable for low to moderate prescriptions, offering an economical option for standard vision correction.
Polycarbonate Lenses:
Material: Polycarbonate is a durable and highly impact-resistant plastic material.
Properties: Polycarbonate lenses are significantly thinner and lighter than glass and CR-39 lenses, making them ideal for higher prescriptions and active individuals.
Uses: Polycarbonate lenses are commonly used for safety glasses, sports eyewear, and for those who need stronger prescriptions without the added weight.
High-Index Plastic Lenses:
Material: High-index plastic lenses are made from materials with a higher refractive index.
Properties: High-index lenses are thinner and lighter than crown glass, CR-39, and polycarbonate lenses, providing a more appealing option for strong prescriptions.
Uses: High-index lenses are suitable for individuals with moderate to high prescriptions who want thinner and lighter lenses.
Trivex Lenses:
Material: Trivex is a lightweight and impact-resistant plastic material.
Properties: Trivex lenses are thinner and lighter than polycarbonate lenses and offer good optical clarity. Trivex was developed during the “space race” of the late 1960’s. It was used for helmets and visors for astronauts. It was soon adapted for use in safety eyewear applications due to its superior impact resistance. Other benefits include resistance to chemicals and better light refraction. However, this lens material can be expensive and hard to find.
Uses: Trivex lenses are a versatile choice for a wide range of prescriptions and are often used as an alternative to polycarbonate for individuals seeking lightweight and impact-resistant lenses.
When choosing eyeglass blank lenses, the optician considers your prescription strength, lifestyle, and preferences to provide the most suitable material for optimal vision correction and comfort.
Best Eyeglasses and Lens Coatings
Coatings can be applied to all eyeglass lenses whether they are made from glass, plastic, or other materials. Coatings enhance lens performance, durability, and provide visual comfort.
Each type of coating serves specific purposes and opticians can apply them based on the wearer’s needs and preferences. Coatings can be combined to meet specific needs. For example, lenses can have both Anti-Reflective and UV coatings for improved visual clarity and UV protection.
Here are common coatings and how they are applied to various lens blanks:
Anti-Reflective (AR) Coating:
Purpose: AR coating reduces reflections on the lens surface, allowing more light to pass through the lenses. This reduces glare and improves visual clarity, especially in low-light conditions and when using digital devices.
Application: The coating is applied to the front and back surfaces of the lenses using a vacuum deposition process. This process involves evaporating and condensing multiple layers of metal oxides and other materials onto the lens surfaces to create the anti-reflective effect.
Scratch-Resistant Coating:
Purpose: Scratch-resistant coating helps protect the lens surfaces from minor scratches and abrasions that can occur during daily use.
Application: The coating is typically applied to the front and back surfaces of the lenses through a dip coating process. The lenses are immersed in a solution that contains the scratch-resistant material, and then they are cured to create a hard, protective layer.
UV-Protective Coating:
Purpose: UV-protective coating blocks harmful ultraviolet (UV) rays from reaching the eyes, helping to reduce the risk of eye damage caused by UV exposure.
Application: The UV coating is applied to the lens surfaces using a dip coating process or a vacuum deposition method, similar to the process used for AR coatings.
Hydrophobic and Oleophobic Coatings:
Purpose: Hydrophobic coatings repel water and prevent water droplets from clinging to the lens surface, while oleophobic coatings repel oils and grease, making the lenses easier to clean.
Application: These coatings are applied to the lens surfaces through a dip coating process or a spray-on method. They create a repellent surface that resists water and oil buildup.
Blue Light Filter Coating:
Purpose: Blue light filter coatings block a portion of blue light emitted by digital screens, helping to reduce eye strain and discomfort caused by prolonged screen use.
Application: Blue light filter coatings are typically applied to the front and back surfaces of the lenses, using the same methods as AR coatings.
Mirror Coating:
Purpose: Mirror coatings create a reflective, mirrored appearance on the lens surface, reducing the amount of visible light that passes through the lenses.
Application: Mirror coatings are applied through a vacuum deposition process, similar to AR coatings. Different colors and levels of reflection can be achieved with this coating.
Opticians work to understand your preferences and recommend coatings that enhance your eyewear’s performance and suit your lifestyle requirements.
Gregory Scimeca, M.D.
Ophthalmologist and Medical Director
The Eye Professionals
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