In this article, we’ll be discussing one of the most important areas of vision correction– the optical lens. Whether you are seeking a better understanding of your own vision issues, or are simply looking to know more about eyeglasses or contact lenses, learning more about the optical lens is a fantastic place to start.
We’re going to run through all the basics. We’ll explain what an optical lens is and then jump into the different types of lenses. We’ll also look at different materials and coatings that make up opticals lenses. Our hope is that this article will provide you with a comprehensive resource for understanding this area of eyewear.
What Is an Optical Lens?
To begin, let’s look at what exactly an optical lens is, and how it helps with vision.
An optical lens is a lens that is used for vision correction. Typically, it is worn in front of the eye (such as with eyeglasses or contact lenses). The optical glass (more accurately plastic these days) will typically make refractive adjustments that address a certain problem and allow a person to see more clearly. Optical lenses differ depending on the vision problem addressed and are capable of assisting a wide variety of vision issues.
Common vision problems that are helped with a corrective lens include myopia (nearsightedness), hypermetropia (farsightedness), astigmatism, and presbyopia. The exact science behind each of these conditions is quite complex and outside of the scope of this article. All you need to know is that each type of prescription lens is built in accordance with specific engineering to correct a specific issue.
Types of Optical Lenses
Now that we’ve covered the basics, we can outline the various types of optical lenses. Each type of optical lens is designed to address a certain vision problem. A vision specialist (such as an optometrist) will first examine a person’s eyes in order to figure out what type of vision correction is needed and then determine which type of optical lens is best suited to perform the correction.
Here are some of the most common types of optical lenses:
Single Vision Lenses
Single vision lenses have the same prescription across the entire lens and are used to correct the entire field of vision. They are designed for people who have been diagnosed with only one type of vision problem. For example, they can be built to address nearsightedness or farsightedness.
Because these lenses tend to be the simplest in construction, they are also generally the least expensive.
Bifocal lenses have different “sections” for correcting different vision problems. The lens itself is actually divided into different areas with different prescriptions. For example, there could be a section to correct nearsightedness and another section to correct farsightedness. These lenses are often used in eyeglasses to assist people with more than one vision issue.
Generally, the upper part of the lens is used to correct distance vision, while the lower part of the lens is used for “presbyopia.” However, the exact design and construction of the lenses are adjusted to each person. The shape of the lens is determined based on different functional requirements and the type of vision correction is unique to the patient.
The different types of vision issues are corrected by the user looking through different parts of the lens. The corrective lens used to correct Presbyopia is often located toward the bottom of the glasses, as people tend to look down when focusing on something nearby (such as a book or a phone). Since bifocals require the user to adjust their vision manually through moving their eyes, these lenses can take some getting used to.
Trifocal lenses are an extension of bifocal lenses. Trifocals add a third section to the lens for yet another type of vision correction. Each section is separated with a line, and the user trains their eyes to see through each section depending on the type of assistance required.
For example, a set of trifocals can have three “sections” with correction for near, far, and intermediate vision. As with bifocals, the construction of these glasses will differ based on functional preferences, and the vision specifications of the user.
Progressive, or multifocal, lenses are yet another advancement in optical lens technology. These lenses are designed to rectify many of the inconveniences associated with the bifocal, or trifocal lens.
Like bifocal and trifocal lenses, these lenses also have various “sections” which are dedicated to correcting different types of vision problems, however the transition between the areas is meant to be more seamless, allowing for a more natural progression and a more comfortable user experience. These lenses don’t have the dividing lines that are seen in bifocals and trifocals, as the different segments are blended into the lens.
These glasses do require some getting used to, but are often preferred to bifocals because there is not as sharp a contrast between the different “sections” of the lens.
Transition lenses are another type of optical lens, but address a different type of issue than the previous mentioned lens. Transition lenses will darken on their own in response to harshening UV rays, essentially adjusting themselves to perform the same function as sunglasses.
Transition lenses can be designed in any type of optical lens, meaning you can get transitions in lenses such as single vision, bifocal and trifocal.
Transitions are a consideration if you want to keep your eyes protected from UV rays, and want to make vision easier in strong sunlight.
Plano lenses are lenses that are not designed for vision correction (ie. they do not refract light). This type of lens can be useful if only one eye requires vision correction. In this case the one eye will need a corrective lens, and the other eye will use a plano lens. A lens is used for both eyes so that the glasses do not appear odd or asymmetrical.
Of course, these glasses are also useful for people that enjoy wearing glasses for stylistic appeal!
Lens coatings are special treatments that can be applied to any lens to add special features and increase functionality. There are various coatings available, and they can be categorized by the different functions they perform. Here are some of the more popular coatings you can consider adding to your optical lens:
Scratch Resistant: A popular lens treatment – scratch resistant treatments increase the strength and durability of the lens and make the lens more resistant to scratches that may occur during regular use.
Anti-Reflective Coating: AR coating is meant to eliminate reflection on a lens which can result in “glare.” Glare can be quite distracting, and adding an AR coating allows for clearer vision without the distracting glare of the sun and other light sources.
Blue Light Blocking (Screen Coating): Screen coating is designed to offset the negative implications caused by looking at screens (ex. computers, TVs, phones) for long periods of time. Because screens are such an important part of our daily life, screen coating has been developed to protect our eyes against the harsh blue light that screens emit. Blue light is particularly hard on our eyes, and this coating acts to filter it out of our vision. This helps to minimize eye strain, and allows us to look at these screens for longer periods of time without fatigue.
Polarization: A popular feature in sunglasses, polarization can actually be applied to many different types of lenses. Polarization simply means that the lens eliminates glare from shiny surfaces and reflected light. Essentially, this eliminates distractions and allows for a clearer field of view.
How to Find the Right Optical Lens For You?
There are a variety of issues that may be indicative of vision problems. There are obvious ones, like near or farsightedness or struggling to read small print in newspapers, screens, or books.
However, there are other, less obvious indications of vision troubles as well. Sometimes it is the case that vision loss is a slow process, to the extent where your vision may be less than perfect, but it seems normal to you. Things such as headaches and nausea might also indicate vision problems.
So, what do you do if you are having trouble seeing, and how do you know which corrective lens is best for you? There are a few steps you should follow:
See a Doctor or an Eye Doctor
To begin, if you think you might require vision correction, then you’ll need to consult with a professional. The optometrist will perform a detailed examination of your eyes. The specialist will examine the specific problems with your vision, and also look at your overall eye health to spot any underlying issues.
If a corrective lens is necessary, then the eye doctor will establish the type of corrective lens you require. This is a process that must be done by a optometrist.
Finally, picking a lens isn’t all about function. A lot of the fun of getting a new pair of glasses is picking a style. Much of the style that comes from a pair of glasses is derived from the frame itself.
There are many popular types of frames, and they can differ based on aspects such as shape, size, material, thickness. Popular frame shapes include rectangular, round, horn, wayfarer, aviator, to name a few. The most important part of this decision is settling on a frame that you like and that looks good on you.
While you can certainly buy a pair of glasses sight-unseen, it is recommended to try on a pair of glasses before you purchase them. This will allow you to see if the frames suit your face. A good sales associate can help to make recommendations based on the shape of your face, and the particular style you are looking for.
Glasses are ideal for correcting your vision, but they are a stylistic choice as well!
Thanks very much for reading our comprehensive guide to optical lenses. We hope that this guide not only helped you to understand this aspect of vision correction, but to understand how it is relevant to you.
If you think you require optical lenses, your first step should be to see an optometrist. An eye doctor can point you in the right direction to get a proper prescription, and to find a pair of optical lenses that addresses your unique needs.