Lenses - Are You Comparing Apples with Apples?
Why do lenses vary in price when they all look the same? Lenses are highly technical products that in many cases will require a greater investment than your frames. As the many built-in benefits are not visible at a glance, comparing like for like can be difficult.
Understanding the key features and benefits that can be built into your lenses will help you to confidently discuss with your optometrist those which are most important to you.
Lens Index (thickness and weight)
Determines the thickness and weight of lenses. 1.50 index (or CR39) is the base option and the one advertised in most package deals. As you increase the index (eg. 1.56, 1.60 and 1.67) lenses become thinner, lighter and more aesthetically pleasing. Higher indexes are especially useful for those with stronger prescriptions.
Lens Type (type of vision correction)
SINGLE VISION LENSES
Single Vision Lenses are the most commonly prescribed lens type and are included in most packages. They have the same focal power over the whole lens, meaning they will allow you to see either up close or at a distance, but not both. You can have single vision lenses for:
- Shortsightedness: if you have difficulties focusing on objects in the long distance (such as when driving or playing sport)
- Longsightedness: if you have trouble focusing on objects up close (commonly known as readers)
Multifocal lenses allow multiple distance correction with no visible lines, making them the most convenient solution for many viewing distances. While this lens type can be more costly due to their complexity, the latest sophisticated designs will deliver more seamless and natural vision, less distortion, and provide greater flexibility in frame choice over standard options. There are three types of Multifocal lenses:
- Progressive Lenses are made with two or three focal powers that gradually and smoothly change throughout the lens. This allows you to achieve natural vision up close, at arms length and at a long distance.
- Extended Readers are lenses designed to help you read both up-close and at arms lengths, such as the computer screen. This eliminates the need to constantly remove glasses to focus on objects in the intermediate distance.
- Bifocal Lenses are similar to progressive lenses except there is no gradual transition, but rather two separate focal powers splitting the lens into two distinct parts. Today bifocal lenses have been largely replaced by progressive lenses.
Basic lenses common to low-cost packages are typically spherical. They have steep curves that result in a thicker appearance. Aspheric lenses are a premium alternative, producing a flatter, thinner, more comfortable and appealing finish.
Lens Enhancements & Coatings
Lens options including Transitions, anti-reflective coatings and polarising technology will enhance your visual performance, safety and the look of your lenses. These are generally treated as package extras.
- Transition Lenses react to light and UV by changing the lenses from clear to dark and every shade in between. This allows for a smooth transition from indoors to outdoors without the need to change from spectacles into sunglasses.
- Anti-reflective Coatings enhance the visual performance, comfort and look of your lenses by minimising unwanted glare and reflection.
- Scratch Resistance Coatings are applied to plastic lenses for improved durability and greatly reduce the chance of lenses being scratched in everyday situations.
- UV Coatings can boost the UV protection already built into your lenses to 100% for even greater protection.
Your local ProVision optometrist will be able to explain the range of options mentioned above in more detail, and recommend the lenses that will best suit your lifestyle.