Advantages and Disadvantages of the Main Types of Vision Correction

Photo Credit: Peretz Partensky

Our eyes represent an optical system through which we view the world around us. As the most sophisticated camera, they consist of several lenses, or even two: the cornea (the clear covering of the front of the eye) and the lens inside our eyes. There are different vision defects and there will be relevant applicable methods of their correction.

Glasses: they are composed of two main elements – lenses and frames that holding them in front of our eyes. The lenses must match the features of our face and certain geometrical parameters, such as center distance, vertex distance, angle, etc.

Advantages of vision correction using glasses:

• Creating an image of smart person;
• Wide availability of different frames in all possible price categories;
• Wide availability of lenses, each designed to correct a specific defect;
• The possibility of combining the optical and sun lenses;
• Ease of use and maintenance.

Disadvantages of vision correction with glasses:

• Incorrect spatial perception and narrowing of the field of view;
• Evidence of “physical disability” to others;
• Unacceptable change in appearance;
• Risk of injury to the face and eyes in some situations;
• Restrictions on the choice of leisure activities and sports.

Contact lenses are worn directly on the cornea of the eye and form with it a single optical system similar to tightly coupled lenses in the lens of the camera.

Advantages of vision correction using contact lenses:

• No destruction of spatial perception and normal viewing angle;
• Invisible to others;
• Ability to change the color of eyes;
• No restrictions on the choice of activities and sports;

Disadvantages of vision correction using contact lenses:

• Direct contact with the eyes and the related risk;
• A need for adherence to strict hygiene and wear;
• Frequent money expenditure on new lenses and care products;
• Inconvenience in certain circumstances;
• Limitation of usage with certain diseases (colds, allergies, etc.)

Surgical vision correction is done either by a special diamond scalpel, which makes incisions in the cornea of the eye or with a laser, which gives the cornea a new form. Both interventions provide for a change in the optical power of the cornea.

The advantages of surgical and laser vision correction:

• Reducing dependence on optical means of vision correction;
• Quick and painless procedure of correction;
• A short recovery period.

Disadvantages of surgical and laser vision correction:

• A risk of serious and irreversible complications to the eyes;
• A likelihood of further deterioration of vision;
• Set of contraindications.

As you can see, there is no ideal method of vision correction, therefore try to find a balance between life and work and pay attention to eye health.

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Hassle Free Glasses Refunds And Replacements

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You do need to keep in mind that there is a line between defective frames and lenses and those that have obviously been abused or have gone through an accident. Generally speaking, the seller and the manufacturer aren’t obliged to replace your glasses in those cases, though some stores may provide warranty or insurance plans for them.

If you got the right prescription, but still aren’t comfortable with the vision that your new eyeglasses provide, you can just get your eyes rechecked and have your prescription fixed as needed.

The majority of optical stores out there won’t mind remaking the lenses for you free free after the first adjustment that your doctor makes on your prescription. In the majority of cases, one change is all that is needed to give you comfortable vision all throughout anyway.

Choose Reputable Optical Stores!

Most of the time, you can expect a complete refund or a replacement from an optical store if you buy an item with a manufacturer’s defect, like a broken frame brought about by weak solder joints; or the wrong prescription, coming about from the way that the lenses were fabricated or the way that your eyes were measured. By law, you can also ask for a complete cash refund, if the item was already broken when you bought it.

Anyway, reputable optical stores generally won’t mind providing you with a replacement since the majority of eyewear manufacturers will stick to their products and give out free replacements to retailers in cases of manufacturing defects. Plus, both the manufacturers of eyeglass frames and lenses and the optical stores tend to place their reputation on a pedestal because they don’t want their customers to think they have inferior eyewear available.

Can You Simply Change Your Mind?

A grey area will come into play if you are hoping to return your glasses just because you aren’t fond of them after taking them home. If your prescription is right, then not being happy with your glasses could come about because of the heaviness of the eyewear that makes it slip down your nose all the time; the unflattering lenses and frames; or just a poor style choice, in general.

Depending on your overall objection, optical stores will have policies in place. These policies may differ from store to store, though, so your success in getting a refund or getting your eyeglasses exchanged will depend on the store that you bought them from to begin with.

Some eyewear manufacturers are just sweet! Warby Parker made it clear via their youtube channel that should you have any problems, doubts or change of mind you can easily return you pair of glasses hassle-free!

Uncovering the Latest Technologies in Eye Care Optics

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Today we will be discussing progressive lenses – this particular term is applied to the most advanced type of lenses for the correction of vision with a smooth change of the focal distance between the “far” and “near” bands.

The farsightedness – the eye’s ability to focus on close object only is forcing us to use lenses. For majority, diopters are needed when looking at close objects, while using other lenses for distanced items. People can certainly use two different types of glasses with conventional lenses – one pair specifically for reading, while others, if they are needed – to look into the distance.

When we use reading glasses and suddenly need to look at more distanced objects, we have to look above the lens of our glasses. Thus, there are special frames for reading, so-called “half-moon glasses” designed for this purpose, which are narrow and cover only the lower part of the field of our vision. But still, it is much more convenient to be able to have glasses equally good for all distances.

So, in order to use the same lens to see both near and far objects, the lenses should combine different diopters. Such lenses are called multifocal optics – various diopters mean a different focal length, hence the name. Our usual lenses are, therefore, called monofocal, or “single vision lenses” – they have only one specific diopter.

The opportunity to combine a single lens for both functions comes from the fact that we look differently at close and far objects. When we read, our eyes look down, and the directions of the left and right eyes converge with each other very close, so pupils are shifted towards the nose. When we look into the distance, our eyes are pushed down slightly, and the pupils are in their normal position. When we first look at the book, and after – into the distance, the direction of our vision goes through different parts of the lens. Therefore it is possible to make the lens sections with different prescriptions.

First multifocal lenses have historically been bifocals. These lenses, as you might have guessed by their name, combine two specific fixed diopters. Basic diopter – for general view, and an additional diopter for close vision – a special segment, located in the lower portion of the lens, and shifted to the nose. The shape and size of the segments may vary. Most often, segments have a horseshoe shape with a flat or arcuate top and a width of 25 to 35 mm. There are also circular segments of the same size.

Bifocal lenses allow us to use the same points, whether we look into the distance, or at close objects. However, they have a set of drawbacks. In terms of comfort, they deliver quite an abrupt change in the optical power of the lens when you turn your sight from distant objects to close. In addition, it often turns out that you need some intermediate diopters between “close” and “distant” bands.

From an aesthetic point of view, the border’s segment is clearly visible from the outside. As reading glasses are associated with old people, bifocals frankly scream about your age. Furthermore, the segments are seen from outside, working as small magnifier, increasing your lower eyelids and the region under the eyes – not a favorable visual effect. Despite these numerous shortcomings, bifocal lenses are still being produced in large quantities.

There is another group of lenses called trifocal, where intermediate segment has smaller additional diopters than basic, providing a clear vision for medium-length distances. The rest of the trifocal lenses suffer from the same drawbacks as bifocals.

Most modern lenses that are replacing outdated bifocals and trifocals are progressive lenses. Their main difference is a smooth, or “progressive” increase of the optical power as we turn our sight from remote objects to those that are located in the middle distance, and then – to the closest. Progressive lenses have no segments with fixed different prescriptions and their optical features are based on complex geometry of their surfaces. The design of progressive lenses and their respective production are the most recent achievements of applied science and optical technology.

There is a huge variety of lenses available on the market – both of early designs and more modern (with a wide channel). In general, millions of customers today are more than satisfied with progressive lenses, especially when compared with bifocals. Progressives with a wide channel are more “tolerant” to small movements relative to the lenses of our eyes, and therefore provide for even greater level of comfort.

Progressive lenses have specific requirements for how and where you buy your glasses. Any lenses require a proper placement after the frame is assembled, but in the case of progressive lenses, this requirement becomes an absolute imperative, and technology to ensure this requirement is very specific. Therefore, the correct production of glasses with progressive lenses can be carried out only by professional optometrists who have undergone a special training, and constantly improve their skills in this area.

Choosing the Right Lens Material For Your Glasses

Photo Credit: Ken Teegardin

Plastic CR-39 Lenses

Plastic CR-39 is basically just regular plastic, which is what the majority of lenses out there consist of. Plastic CR-39 is usually used in clear lens glasses and can cover the mid-range of practically every prescription possible. Glass aside, it is also known to have the best clarity out of all of the other lens materials and is known to be the cheapest lens material out there. Aside from that, it is also very lightweight, easy to tint and less likely to break compared to glass.

The downside of Plastic CR-38 would be that it is a bit more fragile compared to trivex and polycarbonate. Also, the plastic will be thicker the higher your prescription is. However, if your prescription is still relatively low, or if you don’t need prescription lenses at all, then plastic CR-39 would be a great option for you. Plus, you will be able to save money with it at the same time. Naturally, this only counts if you don’t add any extra features, such as UV protection or scratch resistance, though.

Polycarbonate Lenses

Polycarbonate refers to a kind of plastic that is lighter, thinner and more durable compared to other lens materials. It also happens to so soft that it is considered to be one of the most shatter-resistant materials out there next to trivex. This is actually why polycarbonate is used for all sorts of eyeglasses and why it would be such a great match for most people out there. Polycarbonate would generally be highly recommended for anybody under 18 years old, as well as athletes, active kids and those who work in labor-intensive environments. Also, polycarbonate lenses usually already come with UV protection and scratch resistance included in their price tags.

The downside is that polycarbonate may scratch a bit easier compared to plastic CR-39. It is also a bit more expensive and isn’t as clear as plastic CR-39 or trivex overall. While the majority of people don’t really notice these disadvantages, those who are more sensitive to them may want to opt for plastic CR-39 or trivex instead. Polycarbonate cannot hold dark tint, either, and people with high astigmatism might experience additional distortion, as well.

Trivex Lenses

Trivex is relatively new and has all of the traits that polycarbonate has. However, it is much more stable, clearer and lighter in weight for rimless and semi-rimless glasses.

However, trivex does cost a bit more money and is a bit thicker compared to polycarbonate overall. It doesn’t have as many design options as polycarbonate, either.

Glass Lenses

Glass is the original material that was used for every lens back in the day and is the one with the best clarity and optical quality to this day. It is also more scratch-resistant and stable, and doesn’t flex or distort in any way. This is why people who work in mechanical fields or farms still prefer glass over any other lens material out there.

However, because of how heavy and expensive glass is, more and more frame lenses are now using plastic materials. This has made glass much less available in the market and has made it more expensive, as well. Its weight happens to put too much pressure onto the nose and even leaves skin marks sometimes. Plus, it requires special equipment for its production and it takes longer to produce, too.

High Index Lenses

High index refers to the type of plastic that is considered to be made of the topmost quality out of any of the other plastic materials used for lenses. Because of this, it provides the best clarity for prescription lenses. This material would be perfect for those who have high prescriptions because it stays thin, no matter how high the prescriptions may get.

However, high index is very expensive and tends to be oversold and overprescribed to people who don’t even need its quality for their glasses overall. Insurance companies usually won’t cover the upgrades of this material, either, so you may end up paying more than expected in the end.

Conclusion

Let me assure you that choosing the right lenses for your glasses is the most important step. You can still spend plenty of time deciding on specific shape, but i advise you to pay special attention to lens material and be aware of their pros and cons. You may be interested in checking how the lenses are being created and fitted. This process is not easy and requires highly-skilled professional work.

Why It’s Important to Choose Glasses Properly

Photo Credit: Adrian Sampson

Eyeglasses happen to be very important parts of certain people’s lives because they can help them see things more clearly in the world. This would be especially true if the people in question have to wear their glasses all day and everyday.

If this is the case with you and you are not simply following the trend of hipster glasses, then you have to make sure that you choose comfortable eyeglasses with a precise prescription to last you a long time. After all, ill-fitting, uncomfortable or inaccurate glasses could cause problems, such as blurred vision and headaches that can make things harder for you in the long run. This is why it would be so vital to purchase to quality glasses from a reliable and experienced lab from the beginning.

Problems Associated with Wearing Unsuitable Glasses

Some of the most obvious problems associated with wearing the wrong prescription would be fuzzed or blurred vision. While you might not notice a wrong prescription if there is only a minor difference involved, a bigger difference could cause dizziness, vertigo, nausea and headaches from eye strain.

Fortunately, using glasses with the wrong prescription won’t bring about any long-term side effects. In other words, your vision won’t get worse if you keep wearing them nor will your eyes get damaged in the process. However, if you don’t correct your vision properly, you could risk certain injuries at work or while driving.

There are several kinds of eyeglasses, like bifocal lenses, that will require a certain adjustment period before you can get used to them. This may last a few days or even a few months. Some signs that you are having trouble adjusting to your lenses include disorientation and headaches.

How to Choose Glasses for Computer

People are spending more and more time with their computers, tablets, smart phones and other technology. No wonder this is a very big burden for the human eyes. The question is – are there any special “magic” computer glasses that ensure our eyes are not getting tires while using our gadgets?

Problem may be related not to the computers and gadgets (though some time ago, there were myths about harmful monitor radiation), but the general problem for our eyes working “at close range.”

The myths about the harmful monitors have disappeared. Experts agree to the fact that the only way to facilitate the health of our eyes when working with different monitors is to use the yellow coat on the surface. Such coating cuts the blue-violet component of the color spectrum of monitors, which is the most annoying for our eyes (although there is no scientific evidence on this point and the conclusion comes from general considerations).

What happens with our eyes when working at close range? Let’s review three different case scenarios:

1. Normal vision (or vision already corrected with contact lenses): experts recommend using lenses up to +2 diopters;
2. Nearsightedness: it is strongly recommended to use glasses for distanced objects;
3. Farsightedness: people are advised to wear glasses with progressive lenses.

In any case, don’t forget about simple yet effective recommendations when working at your computer:

• It is important to organize the optimal lighting of the workplace;
• Make sure you do regular breaks and relaxation exercises for your eyes;
• Carry out regular checks to maintain vision health.

The 21st century is full of different gadgets, each of those are putting an excessive pressure on our sight. So, the combination of healthy nutrition, exercises and maintenance will pay off well at later stage!

Choosing The Right Food For Your Eyes

Without exception, all probably heard that carrots are one of the top products that improve vision, and its use in the diet plays a huge role in maintaining good eye health, so the benefit of this vegetable, as well as the benefit of carrot juice cannot be underestimated. But what other useful products can be used to improve our eyesight? What can we eat to maintain our eye health and reduce the risk of various diseases?

Answers to these questions are simple yet many people don’t pay enough attention to procedures that must be followed in order to look after such a complicated part of our body. As for improving vision, and for maintaining the general health of the whole organism, it is necessary to use nutritious and vitamin-rich foods. Here is the list of the top selected products that will help you get rid of your glasses if not for the rest of your life, but at least for some time if you so wish.

Kale

The substance called carotenoids was found in green leafy vegetables such as spinach chard, kale and others and proved to be important for your eyesight. These products – ordinary antioxidants – act as natural sunglasses to protect the eyes from ultraviolet radiation, as well as protecting cells from the harmful damage.

Wild Berries

You will be pleased to hear that various berries are here to correct your vision. Scientists have shown that the antioxidants contained in the berries reduce the risk of cataracts and other sight issues. Summer is the perfect time to stock up on vitamins – starting with fresh strawberries, followed by blueberries and raspberries. It is so easy to make desserts or add the fruits to salads!

Milk

Milk is also considered as one of the top health-improving products. Cheese, eggs and milk are a good source of vitamin A that is considered to be the best for our vision.

Fish

Omega-3 fats, which are found in oily fish, play a key role in the health of the retina. Eating at least once a week a fatty fish such as salmon, trout, mackerel, sardines, herring and others will reduce the risk of sight problems and the development of cataracts.

Nuts

Another group of products ideal for sight are nuts. They contain vitamin E, which is very important for normal eye condition. Almonds more likely to contain this vitamin, so eat them alone, or cook your meals using almond oil – your eyes will always be healthy.

So, we have introduced you the healthiest food products that will help you maintain your perfect vision. But there are some other things you can do for the same purpose in conjunction with the diet: make sure you do some eye exercise from time to time, especially when your work involves long hours in front of computer!