Multiple visual aids provided by bifocal eyeglasses have been known by people across the world for many decades. The advanced functionality and convenience brought by bifocal reading glasses have definitely helped millions of presbyopic patients. Supposed to offer two kinds of visual correction, a bifocal lens has to be equipped with two focal points. This involves really unique design and skills. Some people may have the thought that a bifocal lens should be larger than a single vision lens, because there are two different powers that must be fused together. If this idea is proven, bifocal eyeglass frames should also be made in a relatively larger size. Only in this way can the users get clear visual fields that are wide enough. However, this is not the truth.
Lens technological advancements have enabled lens manufacturers to incorporate two or three different powers in a single lens easily. When it comes to progressive lenses, there are even dozens of focal points made into a single lens. So, it is absolutely unnecessary to worry about the inappropriate frame size caused by bifocals’ lens design that is a little complex. It is equally understandable to say that bifocal eyeglass frames do not have noticeable differences from most of the regular, single vision prescription eyeglasses.
When it comes to frame material, bifocal eyeglasses are now available in nearly all possible options, like plastics, metals and even mixed materials. Their special lens functionality will not exert extra requirements on the frame design. Another factor is frame style. All of the three styles including full frame, semi-rimless and rimless can be seen in bifocal eyeglass frames. Each type will bring similar advantages as regular eyeglasses. Moreover, bifocal reading glasses have no additional requirements on frame color. This element is completely dependent on the customers’ personal preference. Furthermore, some brands even provide bifocal reading eyeglasses that are compatible with clip-on sunshades.
Thursday, June 10, 2010
The development of bifocal glasses
In the history of bifocal glasses, Benjamin Franklin has been generally credited with these glasses’ invention. Even if there are still historians doubting about whether he was the first to invent bifocal reading glasses, Benjamin wrote in his letters of correspondence that he invented these glasses independently. And this great man was surely among the first to use bifocal lenses. At the beginning of the 20th century, two separate lenses were cut in half and combined together in the rim of the frame. This is typical and traditional bifocal design which is called Franklin or Executive bifocal. The basic feature of these bifocals is that there is a line going all the way across the entire width of the lens. Not so long ago, all presbyopic patients had to wear this original version of bifocal reading glasses. Of course, these glasses have helped them a lot.
Lens technology has never stopped its progression. This is also the case in the world of bifocal reading glasses. As a typical and the most common type of multifocal eyeglasses, bifocal glasses are now available in a few of lens designs. Some of them are designed for special occupational use. As the name shows, a bifocal lens has never changed its nature that there are basically two different lens powers or two focal points. The typical design involves one power for distance and the other for near. These glasses are really needed by people who require some visual correction in order to read or see things nearly.
Nowadays, bifocal glasses that mold a reading segment into a primary lens are the majority in the market. The Franklin style can be seldom seen now. The commonest design is D segment, which is also called half-moon, flat-top or straight-top. The added reading segment can be in other shapes, like round and narrow rectangle. All these modern designs actually work in the same way. Different shapes or positions of the reading segment are generally aimed to provide customized visual correction for people with particular occupations.
Lens technology has never stopped its progression. This is also the case in the world of bifocal reading glasses. As a typical and the most common type of multifocal eyeglasses, bifocal glasses are now available in a few of lens designs. Some of them are designed for special occupational use. As the name shows, a bifocal lens has never changed its nature that there are basically two different lens powers or two focal points. The typical design involves one power for distance and the other for near. These glasses are really needed by people who require some visual correction in order to read or see things nearly.
Nowadays, bifocal glasses that mold a reading segment into a primary lens are the majority in the market. The Franklin style can be seldom seen now. The commonest design is D segment, which is also called half-moon, flat-top or straight-top. The added reading segment can be in other shapes, like round and narrow rectangle. All these modern designs actually work in the same way. Different shapes or positions of the reading segment are generally aimed to provide customized visual correction for people with particular occupations.
The basic lens design of bifocal safety eyewear
As the name reflects, a pair of bifocal safety eyewear can serve as either bifocal reading glasses or safety eyeglasses. The reason is that this special kind of spectacles combines the functionalities of traditional bifocals and protective eyewear together. A single pair of bifocal safety glasses can provide a user with both visual need while reading and eye protection against dangerous sources in the environment. In fact, safety goggles or protective eyeglasses are needed by a large number of jobs and hobbies. And people who are operating most power tools are highly encouraged to wear protective goggles. However, traditional goggles or protective eyeglasses are refused by some people who still need visual aids. Regular prescription goggles are then introduced to flatter a special group of people who regularly manage power tools and suffer nearsightedness or farsightedness.
Nevertheless, for people who have presbyopia and have occupations associated with certain power tools, regular prescription goggles are not enough. The reason is that the vision correction provided by regular prescription goggles will not help in viewing close up objects. Near vision for presbyopic people is to some extent very important when they try to deal with precise operation on some objects. In this case, bifocal safety eyewear is a perfect solution. This type of eyewear can meet the needs of the mentioned group of people and the others in a similar situation. The bifocal effect of visual aid marks the difference between a pair of bifocal safety glasses and another pair of regular prescription spectacles.
The lens design of bifocal safety eyewear may be slightly different from most of the bifocal reading glasses. Lenses of the former type usually come with only a reading power in the bottom part, while the upper section is Plano or non-prescription. Most people know that a regular bifocal lens deals with both presbyopia and nearsightedness or hyperopia. But this is not the case of the majority of bifocal safety eyeglasses.
Nevertheless, for people who have presbyopia and have occupations associated with certain power tools, regular prescription goggles are not enough. The reason is that the vision correction provided by regular prescription goggles will not help in viewing close up objects. Near vision for presbyopic people is to some extent very important when they try to deal with precise operation on some objects. In this case, bifocal safety eyewear is a perfect solution. This type of eyewear can meet the needs of the mentioned group of people and the others in a similar situation. The bifocal effect of visual aid marks the difference between a pair of bifocal safety glasses and another pair of regular prescription spectacles.
The lens design of bifocal safety eyewear may be slightly different from most of the bifocal reading glasses. Lenses of the former type usually come with only a reading power in the bottom part, while the upper section is Plano or non-prescription. Most people know that a regular bifocal lens deals with both presbyopia and nearsightedness or hyperopia. But this is not the case of the majority of bifocal safety eyeglasses.
Lens powers of bifocal safety reading glasses
Also called bifocal safety eyewear or bifocal safety glasses, bifocal safety reading glasses are among the most creative combinations in the industry of eyeglasses. For those types of eyeglasses with a single function such as regular prescription eyeglasses, regular sunglasses and traditional protective goggles, it is easy to tell which is the most important element associated with them. Fashionable elements that are added to these spectacles are truly additional. They will never replace the basic or primary functionalities. However, it is hard to tell a single importance when it comes to those combinational eyewear products, like prescription sunglasses, prescription goggles and more advanced bifocal safety glasses. To be exactly, there are two equally important elements within each type of these combinational spectacles.
Prescription sunglasses and prescription goggles will hardly cause any confusion in the public in term of their functionalities. Considering the function of vision aid, they both provide simply a single form of vision correction. It is no longer simple when we try to interpret bifocal safety reading glasses. It is widely known that bifocal reading glasses alone involve quite complex designs and variations. Their functional combinations include presbyopia/myopia and presbyopia/hyperopia. These are the original driven forces behind the invention of bifocal reading glasses. However, this analysis is not applicable to the more advanced type of product called bifocal safety glasses.
In the vast majority of cases, bifocal safety reading glasses provide only “reading aids” while evaluating its function of vision correction. Only the lower part of a lens is made with a reading power, leaving the upper section to be Plano or non-prescription. This mainstream design explains why bifocal safety glasses are sold with a single dimension of lens power, like +1.00, +2.00 and so forth. While the bottom section will help in seeing close-up things, the top section will provide uncorrected vision.
Prescription sunglasses and prescription goggles will hardly cause any confusion in the public in term of their functionalities. Considering the function of vision aid, they both provide simply a single form of vision correction. It is no longer simple when we try to interpret bifocal safety reading glasses. It is widely known that bifocal reading glasses alone involve quite complex designs and variations. Their functional combinations include presbyopia/myopia and presbyopia/hyperopia. These are the original driven forces behind the invention of bifocal reading glasses. However, this analysis is not applicable to the more advanced type of product called bifocal safety glasses.
In the vast majority of cases, bifocal safety reading glasses provide only “reading aids” while evaluating its function of vision correction. Only the lower part of a lens is made with a reading power, leaving the upper section to be Plano or non-prescription. This mainstream design explains why bifocal safety glasses are sold with a single dimension of lens power, like +1.00, +2.00 and so forth. While the bottom section will help in seeing close-up things, the top section will provide uncorrected vision.
The popularity of progressive prescription eyeglasses
The number of presbyopic patients in the world is very huge. This eye problem happens to the overwhelming majority of individuals age 40 and above. The reason is that presbyopia is not a refractive visual error, but is caused by the eyes’ natural aging. Knowing this, most people can understand that presbyopia is unavoidable in some degrees. Creative human beings can always find solutions to any problems bothering their lives. Dealing with presbyopia, the earliest form of corrective eyeglasses is reading glasses which are single vision. Regular reading glasses with a prescription can enable presbyopic patients to perform normal visual tasks. This visual aid is particular needed for people who spend a long time on close up work every day.
The second type of visual aid for presbyopic patients is bifocal reading glasses. These are especially for people who still have nearsightedness or farsightedness. The upper section of the lens will be incorporated with another power. In this way, both of the two visual problems can be solved. For a special group who does not need vision correction at the distance, there are even no prescription bifocal reading glasses. However, there is another fact in the field of presbyopia correction. Nowadays, very few people still have several pairs of glasses, one for each task or distance, with different lenses for reading, computer use and television watching. The vast majority of presbyopic patients have already switched to different forms of multifocal reading glasses. An important point is that progressive eyeglass prescription is the most popular among all types.
Progressive prescription eyeglasses use progressive lenses that are significantly superior to bifocals and trifocals. They bring smooth visual transition from a distance to another. No visible segment lines will be present, making wearers to be natural in the eyes. Nowadays, there are even progressive sunglasses provided by Ray Ban, Bolle, Serengeti and Vogue and so on.
The second type of visual aid for presbyopic patients is bifocal reading glasses. These are especially for people who still have nearsightedness or farsightedness. The upper section of the lens will be incorporated with another power. In this way, both of the two visual problems can be solved. For a special group who does not need vision correction at the distance, there are even no prescription bifocal reading glasses. However, there is another fact in the field of presbyopia correction. Nowadays, very few people still have several pairs of glasses, one for each task or distance, with different lenses for reading, computer use and television watching. The vast majority of presbyopic patients have already switched to different forms of multifocal reading glasses. An important point is that progressive eyeglass prescription is the most popular among all types.
Progressive prescription eyeglasses use progressive lenses that are significantly superior to bifocals and trifocals. They bring smooth visual transition from a distance to another. No visible segment lines will be present, making wearers to be natural in the eyes. Nowadays, there are even progressive sunglasses provided by Ray Ban, Bolle, Serengeti and Vogue and so on.
Get a comfortable and attractive pair of varifocal glasses online
No one will deny that the most important factor of varifocal eyeglasses is accurate lens fitting and clear vision provision. But it is also important to get satisfied in other aspects, like comfort and attractiveness. The first aspect is quite basic because a well fitted pair of spectacles will not bring satisfactory experience if the frame is too large or too small. The second aspect means even more for some fashion-aware users even if they have entered their 40s or 50s. Buying varifocal or progressive reading glasses from a traditional optical shop makes it relatively easy to meet these two needs. However, it is considerably more challenging when a presbyopic person tries to buy a pair of varifocal glasses online. The reason is that the products showed by online retailers are untouchable. So, the customer can not have a try of a favorable pair and get a real feeling. Realizing this natural shortcoming, nearly all online retailers feel obliged to satisfy customers in these aspects.
Dealing with frame comfort associated with different sizes, providers of varifocal glasses online offer tips. A simplest tip is to select a pair of progressive glasses in a size that is close to the customer’s current glasses. It is also feasible to measure one’s head with a measuring tape or use his or her hat size as a reference. In some cases, there are some other measurements involved. They include lens width, bridge distance, lens height, total width as well as temple length. All these factors may affect the comfort of eyeglasses. For sure, it is quite hard for the customer to get these tasks done without others’ help. It is advisable to take the current glasses to an optician and ask for these measurements. Most online sellers will provide exact figures of their products in these measurements.
Renowned sellers of varifocal glasses online pay even more attention to the work of enabling their potential customers to get a chance to try on their favorable glasses. A common solution is to provide a virtual try-on system on the website. A typical system comes with some model faces as well as an interface for customers to upload person pictures. Using a virtual try on system, purchasers can place target eyeglasses on a model face or personal picture. This way is really effective for customers to get an approximate feeling of their appearance with the glasses.
Dealing with frame comfort associated with different sizes, providers of varifocal glasses online offer tips. A simplest tip is to select a pair of progressive glasses in a size that is close to the customer’s current glasses. It is also feasible to measure one’s head with a measuring tape or use his or her hat size as a reference. In some cases, there are some other measurements involved. They include lens width, bridge distance, lens height, total width as well as temple length. All these factors may affect the comfort of eyeglasses. For sure, it is quite hard for the customer to get these tasks done without others’ help. It is advisable to take the current glasses to an optician and ask for these measurements. Most online sellers will provide exact figures of their products in these measurements.
Renowned sellers of varifocal glasses online pay even more attention to the work of enabling their potential customers to get a chance to try on their favorable glasses. A common solution is to provide a virtual try-on system on the website. A typical system comes with some model faces as well as an interface for customers to upload person pictures. Using a virtual try on system, purchasers can place target eyeglasses on a model face or personal picture. This way is really effective for customers to get an approximate feeling of their appearance with the glasses.
Trifocal Safety Glasses Protects Your Eyes
First of all, do you know what are trifocal safety glasses? According to the words, eyeglasses with three divisions of correction in the lenses are called trifocals. These are considered to be better to protect your eyes than bifocals, although it sounds harder to see through.
The implying principle is simple – when a person is progressing from one step to another, an intermediate step between the two steps makes it easier for the person. So do not think that having three different corrections will make tougher to see through.
Trifocals are similar to bifocal glasses. The only difference is that they are equipped with a three level vision correction lens on each lens instead of two level vision correction lenses.
People with acute presbyopia are usually prescribed trifocals. These people require vision correction at all three steps – long distance, intermediate and near/reading distance. The calculation for the intermediate correction is usually made by halving the reading addition. For example, if a presbyopia patient has -4 diopters with a +3 reading addition; the net power is -1 and hence the intermediate correction would be -2.5 diopters.
In addition to the distance vision correction and near/reading vision correction like in bifocal lenses, trifocals have an intermediate correction field in each lens to give a better viewing experience.
As can be understood, trifocals are different from bifocals. Bifocals only have two different corrections on each lens. Trifocals on the other hand have three different vision correction stages. So, trifocals offer more clarity in vision and less strain on the eye.
The trifocals have the usual semi-circular area with the reading addition like bifocals. There is also the area for seeing things in the distance. And in addition to these two, there is a narrow band of intermediate correction viewing area in the middle of the lens for seeing things that aren’t very far but are further than the reading distance. This is immensely useful for many people. For those who need this area more, like those who are constantly working on computers, it can be made bigger on demand.
But sometimes these measures are not enough and the person develops a condition where all three stages of vision need corrective glasses. So instead of using three different pairs of glasses all the time, people go for trifocals.
People who suffer from acute presbyopia are usually prescribed trifocals. The term has been derived from Latin and it means ‘ageing eyes’. This means that has the body ages, the eyes lose their capacity to adjust and focus on different things. This usually happens after a person reaches 40. Usually this can be countered with corrective glasses, refractive surgery or contact lenses.
Now there are progressive lenses that have no lines to distinguish them from the usual lenses. These are called PALs (progressive addition lenses), progressive power lenses, graduated lenses, no-line bifocals and varifocal lenses.
The calculation for the intermediate area is simple enough. Let’s say that a person has been found to have a power of -4 diopters and +3 addition for reading correction. With these numbers, we know that the net power is -1. The rule for finding out the intermediate is halving the reading addition. So with the given numbers, it would be -2.5 diopters.
The implying principle is simple – when a person is progressing from one step to another, an intermediate step between the two steps makes it easier for the person. So do not think that having three different corrections will make tougher to see through.
Trifocals are similar to bifocal glasses. The only difference is that they are equipped with a three level vision correction lens on each lens instead of two level vision correction lenses.
People with acute presbyopia are usually prescribed trifocals. These people require vision correction at all three steps – long distance, intermediate and near/reading distance. The calculation for the intermediate correction is usually made by halving the reading addition. For example, if a presbyopia patient has -4 diopters with a +3 reading addition; the net power is -1 and hence the intermediate correction would be -2.5 diopters.
In addition to the distance vision correction and near/reading vision correction like in bifocal lenses, trifocals have an intermediate correction field in each lens to give a better viewing experience.
As can be understood, trifocals are different from bifocals. Bifocals only have two different corrections on each lens. Trifocals on the other hand have three different vision correction stages. So, trifocals offer more clarity in vision and less strain on the eye.
The trifocals have the usual semi-circular area with the reading addition like bifocals. There is also the area for seeing things in the distance. And in addition to these two, there is a narrow band of intermediate correction viewing area in the middle of the lens for seeing things that aren’t very far but are further than the reading distance. This is immensely useful for many people. For those who need this area more, like those who are constantly working on computers, it can be made bigger on demand.
But sometimes these measures are not enough and the person develops a condition where all three stages of vision need corrective glasses. So instead of using three different pairs of glasses all the time, people go for trifocals.
People who suffer from acute presbyopia are usually prescribed trifocals. The term has been derived from Latin and it means ‘ageing eyes’. This means that has the body ages, the eyes lose their capacity to adjust and focus on different things. This usually happens after a person reaches 40. Usually this can be countered with corrective glasses, refractive surgery or contact lenses.
Now there are progressive lenses that have no lines to distinguish them from the usual lenses. These are called PALs (progressive addition lenses), progressive power lenses, graduated lenses, no-line bifocals and varifocal lenses.
The calculation for the intermediate area is simple enough. Let’s say that a person has been found to have a power of -4 diopters and +3 addition for reading correction. With these numbers, we know that the net power is -1. The rule for finding out the intermediate is halving the reading addition. So with the given numbers, it would be -2.5 diopters.
Subscribe to:
Posts (Atom)