MEASURING VERTEX DISTANCE (MM RULER) 

When wearing glasses, the distance from the front of the cornea to the back surface of a lens is called the Vertex Distance. Why is this measurement important?

Prescription lenses in eyeglass frames have different effective powers at different distances, tilts and wrap angles from the eye. That means that the same prescription on two different people, one wearing lenses farther than the other would actually have different powers. Lenses become more plus (less minus) when moved away from the eye (increasing the vertex) and less plus (more minus) when closer. That explains why telling a progressive or bifocal wearer to slide their glasses to the tip of their nose provides a stronger add to read the phone book or a medicine bottle.

TO MEASURE VERTEX DISTANCE - Using a mm ruler, measure from the back of the lens to the front of the cornea 

or....

If you can’t see the back of the lens - measure from the front of the lens to the front of the cornea (then subtract lens thickness).

Lasik Laser Surgery...Advantage And Disadvatage for your eyes...!!!

LASIK, which stands for laser in-situ keratomileusis, is a popular surgery used to correct vision in people who are nearsighted, farsighted, or have astigmatism.

All laser vision correction surgeries work by reshaping the cornea, the clear front part of the eye, so that light traveling through it is properly focused onto the retina located in the back of the eye. LASIK is one of a number of different surgical techniques used to reshape the cornea.

What Are the Advantages of LASIK Eye Surgery?

LASIK has many benefits, including:

• It works! It corrects vision. Around 96% of patients will have their desired vision after LASIK. An enhancement can further increase this number.
• LASIK is associated with very little pain due to the numbing drops that are used.
• Vision is corrected nearly immediately or by the day after LASIK.
• No bandages or stitches are required after LASIK.
• Adjustments can be made years after LASIK to further correct vision if vision changes while you age.
• After having LASIK, most patients have a dramatic reduction in eyeglass or contact lens dependence and many patients no longer need them at all.

What Are the Disadvantages of LASIK Eye Surgery?

Despite the pluses, there are some disadvantages to LASIK eye surgery:

• Changes made to the cornea cannot be reversed after LASIK.
• LASIK is technically complex. Problems may occur when the doctor creates the flap, which can permanently affect vision.
• LASIK can rarely cause a loss of "best" vision. Your best vision is the highest degree of vision that you achieved while wearing your contacts or eyeglasses.

What Are the Potential Side Effects of LASIK Eye Surgery?

Some patients experience discomfort in the first 24 to 48 hours after LASIK eye surgery. Other side effects, although rare, may include:

• Glare
• Seeing halos around images
• Difficulty driving at night
• Fluctuating vision
• Dry eyes

How Should I Prepare for LASIK Eye Surgery?

Before LASIK eye surgery, you will meet with a coordinator or eye surgeon who will discuss what to expect during and after the procedure. During this session, your medical history will be evaluated and your eyes will be fully examined. Likely initial tests include measuring corneal thickness, refraction, corneal mapping, air pressure, and pupil dilation. Once you have gone through the initial evaluation, you will meet the surgeon, who will answer any questions you may have. Afterwards, you can schedule an appointment for the procedure.

If you wear rigid gas permeable contact lenses, you should not wear them for at least three weeks before your evaluation. Other types of contact lenses shouldn't be worn for at least three days prior to the evaluation. Be sure to bring your eyeglasses to the surgeon so your prescription can be reviewed.

On the day of your surgery, eat a light meal before going to the doctor and take all of your prescribed medications. Do not wear eye makeup or have any bulky accessories in your hair that will interfere with positioning your head under the laser. If you are not feeling well that morning, call the doctor's office to determine whether the procedure needs to be postponed

WHAT IS COMPUTER VISION SYNDROM [CVS].

Computer vision syndrome (CVS) is strain on the eyes that happens when you use a computer for prolonged periods of time. Anyone who has spent a few hours on the computer has probably felt some of the effects of prolonged use of the computer or other digital technology. It is temporary, and usually goes away on its own – however, the discomfort it causes can be minimized by following a few simple practices.

What Causes Computer Vision Syndrome?

There are a number of factors that determine the amount of strain your body feels as you work on a computer, including lighting in the room, distance from the screen, glare on the screen, seating posture, and the angle of your head – not to mention any existing vision problems you may have. One or all of these may combine to cause an uncomfortable amount of strain on your eyes.

Symptoms of Computer Vision Syndrome

Your eye care professional can diagnose computer vision syndrome through an eye exam, with special attention paid to how the eye works and responds at computer distance.

You probably have experienced at least one of the common symptoms of computer vision syndrome which include:

• Eyestrain
• Headaches
• Blurred vision
• Dry eyes
• Neck and shoulder pain

These symptoms may be caused by other factors such as uncorrected vision needs, glare, poor lighting, improper posture, etc.

Treatment for Computer Vision Syndrome

With these simple practices, you can reduce, or even prevent the effects of computer vision syndrome:

• Make sure the lighting in the room is comfortable on the eyes, and prevents you from staring into glare on the computer screen
• Position the computer screen so that your head is in a naturally comfortable position while working
• Take breaks. A few minutes away from the computer can go a long way when it comes to your eyes. Think of it similarly to the way you take stretch breaks for your arms and back.
• Make sure your seat is comfortable. A comfortable chair with support for your neck and back will help you avoid neck and shoulder strain commonly associated with computer vision syndrome.

WHAT IS HUMAN EYE.....

A clear fluid called the aqueous humor fills the space between the cornea and the iris.
Situated behind the pupil is a colorless, transparent structure called the crystalline lens. Ciliary muscles surround the lens. The muscles hold the lens in place but they also play an important role in vision.
When the muscles relax, they pull on and flatten the lens, allowing the eye to see objects that are far away. To see closer objects clearly, the ciliary muscle must contract in order to thicken the lens.
The interior chamber of the eyeball is filled with a jelly-like tissue called the vitreous humor. After passing through the lens, light must travel through this humor before striking the sensitive layer of cells called the retina.
The retina is the innermost of three tissue layers that make up the eye. The outermost layer, called the sclera, is what gives most of the eyeball its white color. The cornea is also a part of outer layer.
The middle layer between the retina and sclera is called the choroid. The choroid contains blood vessels that supply the retina with nutrients and oxygen and removes its waste products.
Embedded in the retina are millions of light sensitive cells, which come in two main varieties: rods and cones.
Rods are good for monochrome vision in poor light, while cones are used for color and for the detection of fine detail. Cones are packed into a part of the retina directly behind the retina called the fovea.
When light strikes either the rods or the cones of the retina, it's converted into an electric signal that is relayed to the brain via the optic nerve. The brain then translates the electrical signals into the images we see.

WELCOME...

WELCOME IN MY NEW BLOG ''I CARE EYES''...