Color Contacts\ Color Contacts lenses| Benefits & Types of CC

Color Contacts - Brief Description

What are the Color Contacts? What are the Benefits of color contacts lenses? Types of Color contacts lenses?  This article will helps to answer your question on color contacts.

What are the Color Contacts: - Contacts that do not have a corrective or powered lens. They are only meant for fashionable purposes and mainly aim to change the physical appearance of a person. Non Prescription Colored Contacts are very affordable and therefore you can get or collect different colors to be able to combine or match it with your daily outfit. The Non Prescription Colored Contacts are available in many colors which will surely suit whatever your mood is.

For people with vision problems, contact lenses remain an effective, almost invisible tool. The thin plastic or glass lenses are fitted over the cornea of the eye to correct vision problems such as nearsightedness, farsightedness or astigmatism. These days you can wear contact lenses even if you have presbyopia and need bifocals. You can buy color contacts as frequent replacement lenses or even as disposable lenses.

There are four Major types of colored contact lenses, each offering a slightly different benefit:

• Visibility tint: -  These colored contact lenses are lightly tinted so you can find your lens if you drop it. Visibility tints don't affect the color of your eyes. A visibility tint allows you to see your lens better while inserting it or during removal. It is a very light tint, usually in light blue or green thus does not influence your eye color. The purpose of this visibility tint is to allow you to quickly find the lens in the lens case or if you dropped the lens on the counter of floor. Since visibility tinted lenses do not change eye color they are typically only worn by those with eye problems needing vision correction.
• Enhancement tint. These colored contact lenses have a translucent tint that's meant to enhance your natural eye color. Enhancement tints are slightly darker than a visibility tint. An enhancement tint is a solid tint that is darker than a visibility tint and does influence your eye color. Enhancement tints intensify your existing eye color, thus "enhancing" your already either green or blue eyes to perhaps a different shade. For example you might enhance your blue eyes to an aquamarine color using this type of lens. These tints do not work on dark irises.
• Color tint. Darker, opaque tints that change the color of your eyes. Color tints come in a wide array of specialty colors, including amethyst, violet and green. The center of this colored contact lens is clear so you can see. Color tints offer the most dramatic color change for eyes. If you want to completely change the color of your eyes, from blue for example to green, you can use a color tint to achieve the desired outcome. A color tint lens is necessary for people with dark eyes to change their eye color.
• Light-Filtering tint. These colored contact lenses are designed for athletes and sports fans. They enhance certain colors and mute others to make balls stand out. For instance contact lenses for tennis players would enhance optic yellow, the color of tennis balls. This is a newer type of color tint that many are using for sports. Light-filtering tints help enhance some colors while muting others. Let's say for example you are a soccer player. A light-filtering tint can enhance the color of the ball you are using so it is easier to find and take advantage of while playing. This type of tint is increasingly popular among golfers, allowing them to tell the difference between various shades of green while on the golf course.

Other Types of Color Contact Lenses

Each type of colored contact lens will create different eye color effects. Let's look at a few of the types of available:

• Opaque - Color tints offer the most dramatic color change for eyes. If you want to completely change the color of your eyes, (for example brown to blue), choose an opaque lens. A color tint lens is necessary for people with dark eyes to change their eye color.

• Costume - Costume color lenses are for those that want to dramatically change the color and shape of their eye either to enhance a costume or for theatrical performances. The color is painted on to the contact lens to add special effects to your eyes. If you want to go for a cat eye appearance, then costume lenses will provide you just the look you need!

• Non Prescription Colored Contacts: -  do not need prescription from a doctor therefore anyone can surely get unlimited numbers of Non Prescription Colored Contacts. Non Prescription Colored Contacts can last for about three months and therefore you do not need to change your contacts every month thus you can save money.

Will You Need A Prescription To Take Advantage of Colored Lenses?

Even if you don't need a vision correction prescription, you will need a prescription for colored contact lenses. Getting a prescription will ensure a good fit for your lenses and will help you to avoid many problems associated with wearing contacts.

Know that you should never buy colored contact lenses from a supplier who doesn't require a proper fitting or prescription. Chances are they are being sold illegally. Fortunately, it doesn't take long for an optometrist to fit you for contact lenses.

Contact Lenses -1.75 | What does it stand for

Contact Lenses -1.75 - What Does It Stand For

Contact Lenses -1.75 >> It is the power of the contact lenses you are going to buy for your eyes. This is done by the Contact lenses Prescription. It is done by the EYE Doctor. There are Few Tests, measurements & Calculation while contact lenses Prescription test takes place. It is measured to get the right selection of the contact lenses with right power which one's eyes need for correcting the visionary effects.

First of all, just take a look at the simple chart below. Since we already know that lens power of 4.00 D or greater requires vertexing at each meridian, so we start with 4.00 D = add vertex factor of +0.25 D. For every 2 D power change, you will require a vertex factor change of +0.25 D.
Power of lens Vertex Factor (VF)
4.00 D +0.25 D
6.00 D +0.50 D
8.00 D +0.75 D
10.00 D +1.00 D
12.00 D +1.25 D
14.00 D +1.50 D
16.00 D +1.75 D
Example #1:
OD: -10.00 – 5.00 x 180
OS: +5.00 – 1.00 x 180
Given: Spectacle Rx for OD: -10.00 – 5.00 x 180. What’s the contact lens Rx?
1) Sphere power = -10.00 D –> -10.00 + vertex factor of +1.00 D = -9.00 D at 180th meridian
2) Sphere + Cylinder power = -10.00 – 5.00 = -15.00 D –> -15.00 + VF of +1.50 = -13.50 D at 90th meridian
3) Adjusted Cylinder power = -5.00 D + VF of +1.50 = -3.50 D
4) Estimated Rx = -9.00 – 3.50 x 180 (Need to ADD -0.25 to cylinder power to obtain the Final Rx)
5) Final Rx = -9.00 – 3.75 x 180

Given: Spectacle Rx for OS: +5.00 – 1.00 x 180. What’s the contact lens Rx?
1) Sphere power = +5.00 D –> +5.00 + vertex factor of +0.25 D = +5.25 D at 180th meridian
2) Sphere + Cylinder power = +5.00 – 1.00 = +4.00 D –> +4.00 + VF of +0.25 = +4.25 D at 90th meridian
3) Adjusted Cylinder power = -1.00 D + VF of +0.25 = -0.75 D
4) Estimated Rx = +5.25 – 0.75 x 180 (Need to ADD -0.25 to cylinder power to obtain the Final Rx)
5) Final Rx = +5.25 – 1.00 x 180

Useful Notes:
a) Spectacle plane –> Contact lens plane
(Remember: “CAP” = Closer ADD Plus!!!)
b) Minus spectacle Rx –> contact lens Rx (CLRx) = expect contact lens Rx to be LESS minus.
Ex: SRx = -4.50 D –> CL Rx = -4.25 D
c) Plus spectacle Rx –> contact lens Rx = expect contact lens Rx to be MORE plus.
Ex: SRx = +5.00 D –> CLRx = +5.25 D
- See more at: http://www.optometrystudents.com/pearl/how-to-rapidly-determine-a-contact-lens-prescription/#sthash.vWKP6NKA.dpuf

The formula for a contact lens prescription describes the amount of refractive error from normal vision. This article will show you how to read a contact lens prescription.

O.D. : -  This stands for Oculus Dexter, a Latin term for right eye. All of the numbers next to this row or column indicate the strength of correction needed for your right eye.

O.S. : - This stands for Oculus Sinister, a Latin term for left eye. All of the numbers following this row or column indicate the strength of correction needed for your left eye.

Power (PWR) or Sphere. They are usually the first set of numbers listed in the OD and OS rows/columns. It is common for the correction to differ between the right and left eyes. If you find the term PL, this stands for Plano, and it means the number is 0 and no correction is needed .

A negative number in this field indicates myopia, otherwise known as nearsightedness or the ability to see things clearly when they are close to you, but not when they are far away. For example, if the field under OD reads -1.75 D, this indicates the person has  diopters of nearsightedness in the right eye.

A positive number in this field indicates hyperopia, otherwise known as farsightedness, or the ability to see well in the distance, but not nearby. For example, if the field under OD reads +1.75, this indicates the person has 1.75 diopters of farsightedness in the right eye.

CYL and AXIS. These numbers indicate astigmatism, a common condition. It is usually caused by an irregularly shaped cornea, but can also be caused by an irregularly shaped lens inside the eye.

CLY stands for cylinder and it is the measure of astigmatism in diopters. Most doctors use a positive number, but if a negative number is given, a lens store may need to convert to a positive number.

AXIS is the degree measurement that is required to bend light to correct the irregular shape of the cornea.

All of the above calculation are taken place before prescribing for contact lenses for particular eyes. There are some other factors which also necessary for the right prescription of the contact lenses. 

First of all, just take a look at the simple chart below. Since we already know that lens power of 4.00 D or greater requires vertexing at each meridian, so we start with 4.00 D = add vertex factor of +0.25 D. For every 2 D power change, you will require a vertex factor change of +0.25 D.
Power of lens Vertex Factor (VF)
4.00 D +0.25 D
6.00 D +0.50 D
8.00 D +0.75 D
10.00 D +1.00 D
12.00 D +1.25 D
14.00 D +1.50 D
16.00 D +1.75 D
Example #1:
OD: -10.00 – 5.00 x 180
OS: +5.00 – 1.00 x 180
Given: Spectacle Rx for OD: -10.00 – 5.00 x 180. What’s the contact lens Rx?
1) Sphere power = -10.00 D –> -10.00 + vertex factor of +1.00 D = -9.00 D at 180th meridian
2) Sphere + Cylinder power = -10.00 – 5.00 = -15.00 D –> -15.00 + VF of +1.50 = -13.50 D at 90th meridian
3) Adjusted Cylinder power = -5.00 D + VF of +1.50 = -3.50 D
4) Estimated Rx = -9.00 – 3.50 x 180 (Need to ADD -0.25 to cylinder power to obtain the Final Rx)
5) Final Rx = -9.00 – 3.75 x 180

Given: Spectacle Rx for OS: +5.00 – 1.00 x 180. What’s the contact lens Rx?
1) Sphere power = +5.00 D –> +5.00 + vertex factor of +0.25 D = +5.25 D at 180th meridian
2) Sphere + Cylinder power = +5.00 – 1.00 = +4.00 D –> +4.00 + VF of +0.25 = +4.25 D at 90th meridian
3) Adjusted Cylinder power = -1.00 D + VF of +0.25 = -0.75 D
4) Estimated Rx = +5.25 – 0.75 x 180 (Need to ADD -0.25 to cylinder power to obtain the Final Rx)
5) Final Rx = +5.25 – 1.00 x 180

Useful Notes:
a) Spectacle plane –> Contact lens plane
(Remember: “CAP” = Closer ADD Plus!!!)
b) Minus spectacle Rx –> contact lens Rx (CLRx) = expect contact lens Rx to be LESS minus.
Ex: SRx = -4.50 D –> CL Rx = -4.25 D
c) Plus spectacle Rx –> contact lens Rx = expect contact lens Rx to be MORE plus.
Ex: SRx = +5.00 D –> CLRx = +5.25 D
- See more at: http://www.optometrystudents.com/pearl/how-to-rapidly-determine-a-contact-lens-prescription/#sthash.vWKP6NKA.dpuf

Human Eye Structure| Eye Parts & Their functions

Human Eye Anatomy

To understand how the human eye works, first imagine a photographic camera – since cameras were developed very much with the human eye in mind. The eye is a wonderful and the most complex organ of the human body. It is strange to learn that such a small organ has so many parts. The following account provides you information on the parts of the human eye and its function along with the particular functions assigned to each part of it.

The main parts of the human eye & Their Functions

• Cornea: transparent tissue covering the front of the eye that lets light travel through. It is composed of 5 layers of tissue. Its outer layer (the epithelium) provides protection for the eye. The epithelium is made up of highly regenerative cells that have the ability to grow back within 3 days, allowing for fast healing of superficial injuries. Most of the inner layers of the cornea provide strength to the eye.
• Ciliary Muscles: The eye lens is held by ciliary muscles. Ciliary muscles help the eye lens to change its focal length. The ciliary muscle changes the shape of the lens - (this is called accommodation). It relaxes to flatten the lens for distance vision; for close work it contracts rounding out the lens. Everyone will develop an eye condition called presbyopia. As we age, the ciliary muscle and crystalline lens lose their elasticity. This is why most people need reading glasses by their 40’s.
• Conjunctiva:  The conjunctiva is a thin, clear membrane covering the front of the eye and inner eyelids. Cells in this lining produce mucous that helps to lubricate the eye. This is the eyes first layer of protection against infection. Inflammation of this membrane is called conjunctivitis, or pink eye.
• Iris: A ring of muscles in the colored part surrounding the pupil of the eye. The primary function of the iris is to control the size of the pupil. This is achieved through contraction or expansion of the muscles of the iris.
• Pupil: An opening in the center of the iris that changes size to control how much light is entering the eye. This is the black circle in the middle of the eye. When you're in a bright environment, the pupil becomes smaller to allow less light through. When it's dark, the pupil expands to allow more light to reach the back of the eye.
• Sclera: The white part of the eye that is composed of fibrous tissue that protects the inner workings of the eye. The sclera's purpose is to provide structure, strength, and protection to the eye.
• Lens: located directly behind the pupil, it focuses light rays onto the retina. The lens is the clear structure located behind the pupil. Its primary function is to provide fine-tuning for focusing and reading. The lens performs this function by altering its shape. At about the age of 45, the lens becomes less flexible. At about the age of 65, the lens becomes cloudy and hard, preventing light from entering the eye.
• Retina: Membrane at the back of the eye that changes light into nerve signals. The retina consists of fine nerve tissue which lines the inside wall of the eyes and acts like the film in a camera. Its primary function is to transmit images to the brain.
• The Uvea: The uvea forms the center of the eyeball. It is made up of three parts, choroid, ciliary body and iris. The choroid is a thin membrane that is placed between the outer protective sclera and retina. Its function is to prevent the rays of light from bouncing off on the back side of the eye. Malfunctioning of the choroid may cause the formation of confusing images. The role of ciliary body is to assist in the adjustment of the shape of the lens. The iris is described as a separate part in this section of the article.
• Fovea: a tiny spot in the center of the retina that contains only cone cells. It allows us to see things sharply. The fovea is an indentation in the center of the macula. Its diameter is only 1.5 mm or about 1/16 inch. This small part of our retina is responsible for our highest visual acuity. It is the center of our central vision.
• Optic Nerve: a bundle of nerve fibers that carries messages from the eyes to the brain. The optic nerve emerges from the back of the eye, travels through the skull and stops inside the skull bone. From the skull bone, the nerves move through the lateral geniculate body, the internal capsule and ends up at the back of the brain. This part of the brain is known as visual cortex. It is responsible for receiving information from the eyes and interpreting it.
• Macula: a small and highly sensitive part of the retina responsible for central vision, which allows a person to see shapes, colors, and details clearly and sharply. This part of the retina is the most sensitive. Its diameter is only 7 mm or about 1/4 inch. It is responsible for our central, or reading vision. This part of the retina gives us 20/20 vision. Without the macula, you would be blind - Legally blind that is. People with eye diseases like Macular Degeneration have vision from 20/200 to 20/800.
•  Vitreous Cavity: The space between the lens and retina filled with the gel like Vitreous Humor.

How Human Eye works

Light reflects off of objects and enters the eyeball through a transparent layer of tissue at the front of the eye called the cornea. The cornea accepts widely divergent light rays and bends them through the pupil – the dark opening in the center of the colored portion of the eye.

The pupil appears to expand or contract automatically based on the intensity of the light entering the eye. In truth, this action is controlled by the iris – a ring of muscles within the colored portion of the eye that adjusts the pupil opening based on the intensity of light. 

The adjusted light passes through the lens of the eye. Located behind the pupil, the lens automatically adjusts the path of the light and brings it into sharp focus onto the receiving area at back of the eye – the retina.

An amazing membrane full of photoreceptors "rods and cones", the retina converts the light rays into electrical impulses. These then travel through the optic nerve at the back of the eye to the brain, where an image is finally perceived.

Since both the eyes are separated by the nose, they have different fields of vision. Due to the difference in the visual fields, each eye sees at different angles of the object, and so gives different information to the brain. Along the way at the optic chiasma, some of the nerves from each optic nerve cross over so as to separately collect the information from the left and right side of the field of vision. 
The swapping of information takes place one more time at the cell station. This connection works in accordance with the reflexes of the pupils. The information is now received by the visual cortex, which interprets the image at this point.