Besides its physical size, the focal length defines the critical property of a lens or mirror. We will discuss the importance of the focal length a bit later, but first let us look at the mathematical definition that directly affects how these lenses/mirrors are made. The focal length turns out to be:

Note that the magnification is not a property of the lens by itself, but is instead a function of how far the object is placed from the lens.

Progressive lenses are a type of multifocal lens that corrects multiple viewing distances seamlessly, without visible lines. The correction gradually transitions from reading correction at the bottom to computer-distance vision correction in the middle and no correction at the top.

Contact lenses can be a great option if you don’t want to wear glasses. You may have heard that dry eye can prevent you from wearing contacts, so it’s reasonable to wonder if another eye disease like glaucoma could pose the same difficulties.  Fortunately, you can often wear contact lenses with glaucoma. Glaucoma isn’t a […]

In the past, eyeglasses were made of glass. Today, they are mostly made of high-tech plastics. Here are different types of lens materials with added technology for better visual acuity and lens treatments:

Many people rely on glasses or contact lenses to correct their vision and thus experience the world with clarity. However, for some, the discomfort, maintenance, or aesthetic concerns associated with these traditional vision correction methods may lead them to search for alternatives.  Advances in technology and medical research have introduced other options that can offer […]

where "n" is the index of refraction of the lens glass, f is the focal length and r is the radius of curvature of the lens, which is positive in the case of a convex lens (negative in the case of concave mirrors, which we will not cover in detail). This radius of curvature can be seen clearly below for a biconvex lens geometry (the "bi" denotes the lenses are double sided with the same curvature).

Blepharitis is a common eye condition caused by inflammation in your eyelids. The condition can cause many uncomfortable symptoms, but fortunately, it is not contagious. Blepharitis is most commonly caused by a buildup of bacteria at the base of your eyelashes and cannot be spread from person to person.  While blepharitis typically does not cause […]

Choosing the frame for your glasses is important, but selecting the right lenses is crucial. Eyeglasses have long been a popular choice for vision correction, even with the availability of alternatives such as contact lenses or eye surgery. For many individuals, eyeglasses remain the preferred option due to their ease of use, convenience, and versatility in correcting various visual impairments.

The world is a tapestry of colors, and all of us deserve to see it clearly. Whether we’re navigating bustling city streets or curling up with a good book, having the right pair of glasses is essential for comfort and style. But how often do we need to get new glasses? Many optometrists recommend replacing […]

Dr. Christopher Bettner has been serving the optometric needs of Colorado Springs since 1995. He is trained in ocular pathology with an emphasis in the treatment and management of ocular disease, including diabetic retinopathy, glaucoma, and pre- and post-operative care.

Optical Lenses price

Dry eye disease can cause a burning or gritty sensation in the eyes, among other symptoms. There are many different causes of dry eye, but fortunately, there are also many options available for dry eye therapy. One of these options is getting prescription glasses with special qualities that can help address the causes of dry […]

Vision problems can significantly impact daily life. Difficulties with eye coordination and focusing make reading and comprehending written material challenging, leading to eye strain, headaches, and fatigue. Problems with depth perception and spatial awareness hinder safe navigation and participation in sports. Untreated vision issues affect children’s learning and academic performance, impairing their ability to write, […]

In addition to reducing glare and enhancing clarity, sunglasses act as a shield for your eyes, guarding against potential harm from elements such as sand, dust, wind, and debris.

Now we define the common nomenclature used in geometrical optics. For the convex lens seen in the image below, we see the parameters do, di, and f . All of these are lengths measured with respect to the lens/mirror, where do is the "object distance", di is the "image distance", and f is the focal length. The diagram below is known as a ray diagram, where the object is the physical item we wish to focus using a lens/mirror, and the image is the place where the light would yield a crisp replica of the actual object. A solid line runs through the center of lens/mirror and is the optical axis along which the focal points lie. Note that the image appears inverted about the optical axis. Also note that this particular ray diagram is only true while the object remains farther from the lens than the focal point.

Dry eye syndrome is a common eye condition that many people experience at some point. It’s caused by a problem with your tears–either you don’t produce enough tears or the ones you do produce are of poor quality. This results in your eyes not getting enough lubrication, leading to discomfort and sometimes, blurry vision. Can […]

When deciding on eyeglass lenses, you’ll want to consider your prescription, the coating, and lifestyle. Here are different glasses lenses to suit almost all your needs:

Types oflens optics

To focus images, the majority of telescopes encountered in optical astronomy use convex lenses that work through refraction, or concave mirrors that reflect light. Contrary to popular belief, the main purpose of a telescope is NOT to magnify objects, but to collect a larger amount of light by using lenses/mirrors that have a much larger area than the human eye.

Different glasses lens types include progressive, bifocals, polarized, readers, and blue-blockers. Glasses lenses can provide a multitude of benefits depending on their features, such as protecting your eyes from damage, preventing eye strain while reading or doing close-up work, providing clarity by reducing glare, and correcting vision deficiencies.

Bettner Vision is conveniently located in the Marketplace at Briargate, on the corner of North Union Boulevard and Family Place. You can find us beside Sushi Rakkyo and the T-Mobile store.

As you age, changes in your vision are common, such as presbyopia which can occur in your 40s. The natural lens in your eye loses flexibility, causing difficulty in quickly focusing on nearby objects.

Prescription eyeglasses and contact lenses are two correction methods for myopia, but neither is really better than the other. Rather, each has its advantages and disadvantages. For example, contact lenses could make a good option for someone with a job requiring safety eyewear. Alternatively, eyeglasses will likely be the better choice for someone with chronically […]

Using our convex lens diagram, we can construct a simple mathematical relationship between do, di, and f by looking at various similar triangles we can see in the diagram below.

Keratoconus is an eye disease affecting the eye’s cornea and, ultimately, vision. Keratoconus can be partly genetic and partly epigenetic, meaning that it’s hereditary, though environmental and behavioral factors also play a role. Regular comprehensive eye exams can help monitor eye health, detect early signs of vision problems, and help monitor vision changes so they […]

by combining equations (2a) and (3) (I suggest you all do this step on your own to work your algebra muscles). The term $\frac{1}{f}$ is known as the optical power and is generally given in units of diopters, which are simply inverse meters. These are the units optometrists use to prescribe corrective lenses or contacts (in addition to other key numbers, such as the distance between your pupils if you are getting eye glasses).

If you’ve recently noticed your vision becoming cloudier or more sensitive to bright lights, you may have developed cataracts. Cataracts are something that almost everyone will deal with at some point in their life. Cataracts are a cloudy buildup in your eye that can obscure your vision, making it more difficult to see things clearly, […]

GoogleLens

Your comprehensive eye exam is often the first touchpoint we have to gain insights into your eye health and make recommendations to ensure you have clear and comfortable vision. During your exam, we can make recommendations based on your unique personalized eye care needs. An eye exam is crucial to evaluating your fit for contact […]

For those of us reliant on eyeglasses for clear vision, the choice of frame material might be dictated more by fashion or budget than by how it interacts with our skin. However, an increasing number of lens wearers are discovering that their choice in frames, particularly plastic ones, can lead to unexpected skin irritation such […]

6 types of lenses

Now let us create another pair of similar triangles in the image below. We can see that triangles Δ{123} and Δ{425} are similar triangles since the angle at point 2 for both triangles are clearly the same, while lines |13| and |45| are again parallel. The line |42| is equivalent to the object height and the line |12| is the sum of the object height and image height. Now we get the relationship,

Your glasses may be providing you with clear vision right now, but when should you be visiting your optometrist for a new prescription?  Continue reading to learn more about your glasses prescription, including how often you should change it.  Understanding Your Eyeglass Prescription Approximately 3 out of 4 Americans need corrective lenses, requiring them to […]

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If your vision is not impaired in any other way, non-prescription reading glasses can help with the correct strength. If you notice the following signs of presbyopia, you may need reading glasses or reading glasses:

Vision therapy is a noninvasive, personalized program that addresses various visual problems, such as strabismus (crossed or turned eyes), amblyopia (lazy eye), and convergence insufficiency (eye coordination issues).  Once you’ve completed a vision therapy program, which typically takes 6 to 8 months, depending on your condition, you won’t need to repeat it because the changes […]

Vision problems can significantly impact our lives, leading to difficulties in school, at work, and in our everyday activities—but not all vision problems have the same solution. Vision therapy is one solution for visual challenges that involves a noninvasive, individualized program of exercises and activities intended to strengthen a person’s visual skills. Vision therapy is […]

What islensclass 10

If you’re on the hunt for eyewear that combines style, durability, and comfort, then acetate eyeglasses could be the perfect choice for you. The flexibility of acetate means you can get sunglasses with acetate frames, too! Acetate is a type of plastic material often used in eyeglass frames. Its popularity has surged in recent years, […]

We can see that the triangles Δ{ABC} (this denotes the triangle that has vertices at points A, B, and C) and Δ{ADE} must be similar because they are both right triangles, and the angle at point C in Δ{ABC}, is the same as the angle at point E in Δ{ADE} since the lines |BC| (which denotes the line that runs from vertex B to vertex C) and |DE| are parallel. The line |AB| is equivalent to the object height, and the line |AD| is equivalent to the image height. Since we know that the triangles are similar, the ratios of corresponding sides must be equal. So we get,

If you spend extended periods of time in front of digital devices like a computer, phone, or tablet, you may want to consider wearing blue-light-blocking glasses. Blue light, which is found in sunlight, is also emitted from screens of digital devices and can cause overexposure.

You may have received your first eyeglasses prescription when you were a kid or as recently as a few years ago. Your optometrist will have tested your eyes to fully understand your vision needs and how they can help you manage them. If it’s been a few years since your last visit, you may be […]

Lensformula

It’s best to have the right glasses lens for you according to your needs and preferences. Bettner Vision offers a wide range of frames that can provide comfort and functionality with whatever your purpose of glasses is—readers, blue light blockers, sunglasses, or progressives.

where ho is the object height and hi is the image height. Similarly we can manipulate equation (2a) by defining the magnification of the lens as:

Wearing glasses can be a life-changing way to address your vision concerns. With how essential your vision is to your day-to-day life, allowing you to see the world with perfect clarity and precision, utilizing any form of vision protection can make your life much easier. However, what happens if your glasses are too strong? How […]

1. Rays that leave the object parallel to the optical axis will pass through the focal point on the image side of the lens.

Choosing the frame for your glasses is important, but selecting the right lenses is crucial. Eyeglasses have long been a popular choice for vision correction, even with the availability of alternatives such as contact lenses or eye surgery. For many individuals, eyeglasses remain the preferred option due to their ease of use, convenience, and versatility […]

Finding the perfect lens from different lens types can be confusing or overwhelming. But it doesn’t have to be when you understand their functions and match them to your visual needs.

Bifocals help with distant and near vision. If your eyes can’t focus well due to presbyopia, these lenses help prevent eye strain when switching from far vision to close-up.

Convexlens

Polarized sunglasses provide eye protection against sun damage, regardless of the season, through polarized lenses that block UV rays and decrease glare from reflective surfaces.

In the realm of eye care, the debate about whether retinal imaging or dilation is the more effective method for examining the retina has been ongoing.  Digital retinal imaging is a great option for people who aren’t fans of eyedrops. And while digital retinal imaging is a bit more costly than traditional methods, it’s a […]

Cylindricallens Optics

If your eyes are constantly irritated and you feel like something is stuck inside them no matter how much you rub, you may have dry eye disease. Although dry eye can be painful, it’s also manageable if you understand what’s causing your dry eye. If left untreated, dry eye can reduce your quality of life, […]

Contact lenses are an excellent alternative to glasses. A frequently overlooked fact is that not all patients use contact lenses as their primary means of vision correction. Each patient is unique, with some only wearing contact lenses on weekends, special occasions, or for sports. That is the allure of contact lens wear: the freedom it […]

The use of technology is in an upwards trend in our modern world—and so is digital eye strain. With many Americans spending more than 2 hours per day on digital devices, many people are developing uncomfortable and irritating eye strain symptoms. While technology isn’t the only cause of eye strain, it is a contributing factor […]

While dry eyes and eye allergies were once thought of as separate conditions, data has shown there is a seasonal link between allergies and dry eyes.  Researchers have found 3 interesting details linking seasonal allergies and dry eyes: Both pollen levels and dry eye cases reach a yearly peak in April Seasonal spikes of dry […]

3. A ray that passes from the object thought the focal point on the object side of the lens, will be parallel to the optical axis as it leaves the lens to form an image.

Since we are now looking at ray diagrams, let us talk about the rules of how the rays work. We choose to show all rays leaving the head of the object (arrow seen in red above), although any other position on the object would work just as well.

The advancements in vision care have shown themselves in many ways, from specialty lenses for your glasses to specialized contact lenses for your unique visual needs. Laser eye surgery is another option that can help clear up your vision and addresses refractive errors. Laser eye surgery can serve several functions, including correcting refractive errors.  Let’s […]

Children’s Eye Exams A child’s first anything can be an exciting event. First tooth, first haircut, first steps—but what about their first eye exam? Many childhood milestones can be achieved at the child’s pace—but health checkups usually have recommended timelines to help ensure the child’s success. A child’s first comprehensive eye exam is more than […]

Vision is a crucial part of a child’s development. From learning to read to playing sports, clear eyesight plays a vital role in your child’s growth and success. But how do you know if your child needs glasses? A comprehensive eye exam is the best way to know your child needs glasses. Regular eye exams […]

If you or your child is experiencing myopia, you’re not alone. Many parents share concerns about their child’s vision, especially if they notice them squinting to see distant objects or straining to read from afar. You might find yourself wondering if this is just a phase, or something more significant.  Unfortunately, there is currently no […]

This can lead to issues such as computer vision syndrome, headaches, eyestrain, and visual fatigue. Blue light blocking glasses are designed to reduce these risks with a special coating that reflects or blocks the blue light from reaching your eyes, providing added visual health protection.

Are you tired of having to switch between reading and distance glasses constantly? Multifocal contact lenses may be the solution for you. These specialized lenses offer the convenience of both near and far vision correction in one pair, eliminating the need for multiple pairs. But how exactly do these multifocal contact lenses work?  They work […]