Types of Contact Lenses

There are two principal types of contact lenses in use today. Soft contact lenses are those that are made of hydrophilic plastics and absorb liquid and must be kept moist for softness and easier moulding to the corneal surface. They are extremely comfortable and are used by majority of contact lens users. The other type in use is the gas permeable (RPG) or rigid contact lenses, which are composed of durable and flexible plastics, which permit oxygen to pass through to the cornea and are easier to maintain. The original hard lenses, or PMMAs, used earlier did not allow oxygen to pass to the eye and have been replaced by the RPGs.

If a person desires to use contact lenses, he or she should do so only after consultation with an ophthalmologist. He/she will advise whether contact lenses would be suitable for a person to use or which kind of lenses, soft or gas permeable, should be used in a particular case. It is imperative that a yearly examination be done after the initial use of contact lenses.

Courtesy- contactlensdoctor.com/

Contact Lense -A brief History

Contact Lense -A brief History
A contact lens (also known simply as a contact) is a corrective, cosmetic, or therapeutic lens usually placed on the cornea of the eye. Leonardo da Vinci is credited with describing and sketching the first ideas for contact lenses in 1508, but it was more than 300 years later before contact lenses were actually fabricated and worn on the eye. Modern soft contact lenses were invented by the Czech chemist Otto Wichterle and his assistant Drahoslav Lím, who also invented the first gel used for their production.

Contact lenses usually serve the same corrective purpose as glasses, but are lightweight and virtually invisible—many commercial lenses are tinted a faint blue to make them more visible when immersed in cleaning and storage solutions. Some cosmetic lenses are deliberately colored to alter the appearance of the eye. Some lenses now have a thin surface treatment which is a UV coating; this helps to reduce UV damage to the eye's natural lens.
It has been estimated that 125 million people use contact lenses worldwide (2%), including 28 to 38 million in the United States 13 million in Japan. types of lenses used and prescribed vary markedly between countries, with rigid lenses accounting for over 20% of currently-prescribed lenses in Japan, the Netherlands and Germany but less than 5% in Scandinavia.

People choose to wear contact lenses for many reasons, often due to their appearance and practicality. When compared with spectacles, contact lenses are less affected by wet weather, do not steam up, and provide a wider field of vision. They are more suitable for a number of sporting activities. Additionally, ophthalmological conditions such as keratoconus and aniseikonia may not be accurately corrected with glasses.

Courtesy - wikipedia.org/

How does the eye see and common vision problems.

To better understand the science of vision correction techniques, let’s first take a look at perfect vision that doesn’t need correction. Perfect vision comes when light beams meet at a point directly on the retina. If light rays fail to come to that point at exactly the same point, then sight becomes blurry. And so the purpose of restorative lenses/techniques is to refocus light rays so they do meet at that point on the retina.

Let’s look at faulty vision - what happens when those light rays do not arrive at that spot on the retina. There are a number of common eye/ visual disorders. Two of the most common are myopia, or short-sightedness, and hyperopia, or long-sightedness. People with myopia can see clearly up close but not at a distance. Those with hyperopia see better at a distance than at close range and occasionally experience difficulty bringing their vision into sharp, clear focus for reading and other near sight activities.

A few other well-known irregular eye conditions are astigmatism and presbyopia. A person with astigmatism has an irregularly-shaped cornea, which causes light rays to focus on two separate points in the eye. Presbyopia is commonly known as an “ageing eye”. In this condition the eye loses its ability to shift focus between far and near objects.
So these are the most common problems that could arise with individual’s sight. However, with advancing contact lens technology with many more options including eye exercises have been made available for treating each kind of problem.

Relaxation Is A Key For Better Vision And Improved Memory

You will be surprised learning that vision is intricately related to memory and vision maintenance is important for sharp memory. Vision and mental focus go hand by hand and both don’t work perfectly under stress and strain condition. When relaxation is a factor to maintain vision similarly inner peace and relaxed mind is also necessary for remembering things.

Try a great way to test the condition of your eye; it is related to mental memory. In this process, your goal is to maintain a visual image for as long as possible. Start with one of your eye, cover the other one and have a quick look at a letter or number on a page. Close your eyes and try to hold the image in your mind as long as possible. Note down the time the image stays in your mind before fade out. Do the same exercise with your other eye and compare the result.

Now try above exercise again after relaxing the eyes. Here is a way to relax your eye, close them and concentrate on good memories or pleasant thought. Let your eyes to focus on darkness and empty your mind, forget your surrounding. Open your eyes and try once again the visual image exercise given above. Hopefully now the results are different and images stayed longer, if not your eyes are yet to be relaxed more to remove the strain.

Vision affects memory, more clearly we see the image we recall it more efficiently later. Focusing on the positive events helps us to have relaxed mind and strain free eyes. Here is another exercise that helps to relax and improve memory. While lying in the bed at night focus on all positive events and happy moments of that very day. Try to picture the events in as much as possible in detail and color. Focusing on the positive not only clear mind also relax body and gives better night sleep too.

Try to remove strain from your eye to ensure better memory.

Eye Is Not Only For Vision

It is now proved that light has much more effect on human body as we imagine and scientist has come to this decision after discovering an optical nerve that responses to light and dark but not connected to vision.

scientists at Brigham and Women's Hospital and Harvard Medical School during studying of blind subjects has found that eye detect light for other functions too like resetting body’s internal clock, when exposed to bright day light the subjects exhibit different biological responses such as change in hormone levels, pupil constriction and change in brain function.

Most surprising is the finding that the stimulation of eye’s retinal ganglion cells that are most sensitive to short-wavelength blue light brings visual awareness of light in blind subjects and raises the question against the traditional view that rods and cons are only responsible for visual response.

Here is a quote of Dr.Steven Locleky from Brigham and Women’s Hospital’s Division of Sleep Medicine-"People have been studying the eyes for hundreds of years and thought that they knew everything. ... [But] in the past five to 10 years, we've discovered a whole new photoreceptor system, a whole new way of detecting light in the eye which isn't in the parts of the eye which we were traditionally used to seeing. So we have to start to rethink all of our concepts about how light affects the brain, about how our eyes see light, what our eyes are designed to do. Because this whole new approach to a photoreceptor system isn't related to vision and is there entirely to tell us what time of day it is essentially in the outside world."

The implication of this discovery for human health is immense and wide-ranging. This could be used to design office building to allow more light to enter so to reduce electrical lighting and reducing power consumption to finding possible link between light pollution and cancer. Another use of the result of Brigham and Women's Hospital study is blue light therapy for the patients of circadian rhythm disorders.
Experiment showed that lower-intensity, short-wavelength blue light is more effective than the most visible kind of light to treat people having disturbed circadian rhythm. In test compares subjects exposed to blue light were less sleepy and more alert with quicker reaction time and fewer lapses in attention than those who were exposed to green light. Dr Lockely said” With the advent of new, more controllable lighting technologies, we can begin to develop ‘smart’ lighting systems designed to maximize the beneficial effects of light for human health."