Author: nowyouseeme

You’ve just had an eye exam and your optometrist or ophthalmologist has given you an eyeglass prescription, but what do all those numbers on your eyeglass prescription mean?

And what about all those abbreviated terms, such as OD, OS, SPH and CYL?

This article will help you decipher all parts of your prescription and discuss it knowledgeably with an optician or when you buy eyeglasses online.

What OD and OS mean

The first thing to understand your eyeglass prescription is knowing what “OD” and OS” means. They are abbreviations for oculus dexter and oculus sinister, which are Latin terms for right eye and left eye.

Your eyeglass prescription also may have a column labeled “OU.” This is the abbreviation for the Latin term oculus uterque, which means “both eyes.”

Though the use of these abbreviated Latin terms is traditional for prescriptions written for eyeglasses, contact lenses and eye medicines, some doctors and clinics have opted to modernize their prescriptions and use RE (right eye) and LE (left eye) instead of OD and OS.

On your eyeglasses prescription, the information for your right eye (OD) comes before the information for your left eye (OS). Eye doctors write prescriptions this way because when they come face to face with you, they see your right eye on their left (first) and your left eye on their right (second).

Other terms on your eyeglass prescription

Your eyeglass prescription contains other terms and abbreviations as well. These include:

Sphere (SPH)

Sphere indicates the amount of lens power, measured in diopters (D), prescribed to correct nearsightedness or farsightedness. If the number appearing under this heading has a minus sign (–), you are nearsighted; if the number has a plus sign (+) or is not preceded by a plus sign or a minus sign, you are farsighted.

Cylinder (CYL)

Cylinder indicates the amount of lens power for astigmatism. If nothing appears in this column, either you have no astigmatism, or your astigmatism is so slight that it is not really necessary to correct it with your eyeglass lenses.

The number in the cylinder column may be preceded with a minus sign (for the correction of nearsighted astigmatism) or a plus sign (for farsighted astigmatism). Cylinder power is always written after sphere power in an eyeglass prescription.

Add

Add is the added magnifying power applied to the bottom part of multifocal lenses to correct presbyopia. The number appearing in this section of the prescription is always a “plus” power, even if it is not preceded by a plus sign. Generally, it will range from +0.75 to +3.00 D and will be the same power for both eyes.

Prism

This is the amount of prismatic power, measured in prism diopters (“p.d.” or a superscript triangle when written freehand), prescribed to compensate for eye alignment problems. Only a small percentage of eyeglass prescriptions include prism.

Lens types and coatings 

Your eye doctor also might write specific lens recommendations on your eyeglass prescription — such as anti-reflective coating, photochromic lenses and/or progressive lenses — to give you the most comfortable vision correction possible.

An example of an eyeglass prescription

Did you get confused? Let’s use an example to understand things better.

Here is a sample eyeglass prescription:

OD -2.00 SPH +2.00 add 0.5 p.d.

OS -1.00 -0.50 x 180 +2.00 add 0.5 p.d.

In this case, the eye doctor has prescribed -2.00 D sphere for the correction of myopia in the right eye (OD). There is no astigmatism correction for this eye, so no cylinder power or axis is noted. This doctor has elected to add “SPH,” to confirm the right eye is being prescribed only spherical power. (Some doctors will add “DS” for “diopters sphere;” others will leave this area blank.)

The left eye (OS) is being prescribed -1.00 D sphere for myopia plus -0.50 D cylinder for the correction of astigmatism. The cyl power has its axis at the 180 meridian, meaning the horizontal (180-degree) meridian of the eye has no added power for astigmatism and the vertical (90-degree) meridian gets the added -0.50 D.

Both eyes are being prescribed an “add power” of +2.00 D for the correction of presbyopia, and this eyeglass prescription includes a prismatic correction of 0.5 prism diopter in each eye. In the right eye, the prism is base down (BD); in the left eye, it’s base up (BU).

Now you know the ABCs and the ODs and OSs of your eyeglass prescription, so you can make sense of your eyeglass prescription.

A stye is a painful red lump in the eyelid (near the base of the eyelashes) caused by infected gland.

Most styes are harmless and will heal on their own in about a week.

Here are two home remedies that may help you get rid of it a little faster — or at least reduce some of the swelling and discomfort caused by it.

Stye treatment 1: Clean your eyelids

• The first thing you should do if you develop a stye is cleanse your eyelids. You can use diluted baby shampoo on a clean washcloth. Then rinse your eyelids with warm water and gently pat them dry.
• Also, be sure to wash your hands before and after touching the stye, and don’t share your towels or washcloths with others.
• Pre-moistened eyelid cleansing pads are another option. You can purchase these in many drugstores.
• It’s wise to stop wearing eye makeup when you have a stye. Also, discard old makeup or applicators that could be contaminated.
• If you need vision correction, wear glasses rather than contact lenses until your stye heals.

Stye treatment 2: Apply warm, moist compresses

• You can help a stye to heal faster by applying warm compresses for 10 to 15 minutes, three or four times a day.
• To do this, soak a clean washcloth in warm water. Then wring the cloth (so it’s not dripping) and place it over your closed eyelid.
• Warm compresses will help bring the stye to a head, like you see on a pimple. But do not squeeze or “pop” a stye! Allow the stye to open, drain and heal on its own. Squeezing a stye can cause the infection to spread and worsen.

Ease the discomfort

• Over-the-counter painkillers like acetaminophen and ibuprofen probably won’t do much to speed healing, but these medications may ease discomfort if a stye is particularly bothersome.
• Your eye doctor can also address pain associated with styes. Sometimes, your eye doctor may choose to surgically open a large stye to relieve discomfort and prevent a serious infection.

Seek professional help

These tips usually will help most styes clear up fairly quickly. But don’t hesitate to contact your eye doctor for additional advice. Your doctor might prescribe a medicated ointment or other stye treatment to help the condition resolve more quickly.

If your stye worsens, affects your vision or doesn’t go away within a week or so, contact your eye doctor. In some cases, stubborn styes may require surgical treatment by your doctor, followed by application of a prescription medicine.

Preventing future styes

Proper eyelid hygiene can significantly reduce the risk of styes. Clean your eyelids thoroughly before bedtime, especially if you wear eye makeup.

Also, if you sometimes have problems with blepharitis, taking steps to quickly treat this eyelid problem also will help prevent styes.

Dry eyes or dry eye syndrome is a condition in which the eyes do not produce enough tears. It is one of the major reasons people visit an eye doctor. Here’s what you need to know about dry eye syndrome: its causes, symptoms and treatments:

What causes dry eyes?

An adequate and consistent layer of tears on the surface of the eye is essential to keep your eyes healthy, comfortable and well. Dry eye syndrome is caused by a chronic lack of sufficient lubrication and moisture on the surface of the eye. Consequences of dry eyes range from subtle but constant eye irritation to significant inflammation and even scarring of the front surface of the eye.

Dry eyes can become red and irritated, causing a feeling of scratchiness.

Dry eye symptoms

Symptoms of dry eyes and dry eye syndrome include:

• Burning sensation
• Itchy eyes
• Aching sensations
• Heavy eyes
• Fatigued eyes

• Sore eyes
• Dryness sensation
• Red eyes
• Photophobia
• Blurred vision

Another common symptom is a foreign body sensation — the feeling that grit or some other object or material is “in” your eye.

And as odd as it may sound, watery eyes also can be a symptom of dry eye syndrome. This is because dryness on the eye’s surface sometimes will over-stimulate production of the watery component of your tears as a protective mechanism. But this “reflex tearing” does not stay on the eye long enough to correct the underlying dry eye condition.

In addition to these symptoms, dry eyes can cause inflammation and (sometimes permanent) damage to the surface of the eye.

Dry eye syndrome also can affect the outcomes of LASIK and cataract surgery.

Dry eye treatment and prevention

Thankfully, there are effective treatment options if you suffer from chronic dry eye.

In many cases, routine use of artificial tears and minor behavioral modifications (taking frequent breaks during computer use, for example) can significantly reduce dry eye symptoms.

In other cases, your eye doctor might recommend prescription eye medications to help your body create and secrete more tears and to decrease eye irritation and inflammation

Blue light is the visible light spectrum with the shortest wavelength and highest energy, and similar to ultraviolet rays, blue light has both benefits and dangers. Here are seven important things you should know about blue light:

Blue light is the visible light spectrum with the shortest wavelength and highest energy, and similar to ultraviolet rays, blue light has both benefits and dangers. Here are seven important things you should know about blue light:

1. Blue light is everywhere

Sunlight is the main source of blue light, and being outdoors during daylight is where most of us get maximum exposure to blue light. But there are also many man-made, indoor sources of blue light, including fluorescent and LED lighting and flat-screen televisions.

Most notably, the display screens of computers, electronic notebooks, smartphones and other digital devices emit significant amounts of blue light.

The amount of HEV light these devices emit is only a fraction of that emitted by the sun. But the amount of time people spend using these devices and the proximity of these screens to the user’s eyes, is a cause of concern for many eye doctors and other health care professionals.

2. HEV light rays make the sky look blue

The short-wavelength, high-energy light rays on the blue end of the visible light spectrum scatter more easily than other visible light rays when they strike air and water molecules in the atmosphere. The higher degree of scattering of these rays makes the cloudless sky look blue.

3. The eye is not very good at blocking blue light

Anterior structures of the adult human eye (the cornea and lens) are very effective at blocking UV rays from reaching the light-sensitive retina at the back of the eyeball. In fact, less than one percent of UV radiation from the sun reaches the retina, if you aren’t wearing sunglasses.

(Remember, that sunglasses that block 100 percent of UV are essential to protect these and other parts of the eye from damage that could lead to cataracts and even cancer.)

On the other hand, virtually all visible blue light passes through the cornea and lens and reaches the retina.

4. Blue light exposure may increase the risk of macular degeneration

The fact that blue light penetrates all the way to the retina (the inner lining of the back of the eye) is important, because laboratory studies have shown that too much exposure to blue light can damage light-sensitive cells in the retina.

This causes changes that resemble those of macular degeneration, which can lead to permanent vision loss.

Many eye care providers are concerned that the added blue light exposure from computer screens, smartphones and other digital devices might increase a person’s risk of macular degeneration later in life. More research is needed, though, to determine how much natural and man-made blue light is “too much blue light” for the retina.

5. Blue light contributes to digital eye strain

Because short-wavelength, high energy blue light scatters more easily than other visible light, it is not as easily focused. When you’re looking at computer screens and other digital devices that emit significant amounts of blue light, this unfocused visual “noise” reduces contrast and can contribute to digital eye strain.

Research has shown that lenses that block blue light with wavelengths less than 450 nm (blue-violet light) increase contrast significantly. Therefore, computer glasses with yellow-tinted lenses may increase comfort when you’re viewing digital devices for extended periods of time.

6. Blue light protection may be even more important after cataract surgery

If you have cataracts and are about to have cataract surgery, ask your surgeon what type of intraocular lens (IOL) will be used to replace your cloudy natural lens, and how much blue light protection the IOL provides.

After cataract surgery you might benefit from eyeglasses that have lenses with a special blue light filter — especially if you spend long hours in front of a computer screen or using other digital devices.

7. Not all blue light is bad

So, is all blue light bad for you?

It’s well documented that some blue light exposure is essential for good health. Research has shown that high-energy visible light boosts alertness, helps memory and cognitive function and elevates mood.

In fact, light therapy is used to treat seasonal effective disorder — which is a type of depression that’s related to changes in seasons. Its symptoms usually begin in autumn and continue through winter. The light sources for this therapy emit bright white light that contains a significant amount of HEV blue light rays.

Also, blue light is very important in regulating circadian rhythm — the body’s natural wakefulness and sleep cycle.

Exposure to blue light during daytime hours helps maintain a healthful circadian rhythm. But too much blue light late at night (reading a novel on a tablet computer or e-reader at bedtime, for example) can disrupt this cycle, potentially causing sleepless nights and daytime fatigue.

Blue light filters and protective eyewear

If you are using your phone constantly — especially if you use it primarily for texting, emailing and web browsing — a convenient way to reduce your blue light exposure is to use a blue light filter.

Digital electronic devices emit blue light that can cause eye strain and may lead to eye problems over time.

These filters are available for smartphones, tablets, and computer screens and prevent significant amounts of blue light emitted from these devices from reaching your eyes without affecting the visibility of the display. Some are made with thin tempered glass that also protects your device’s screen from scratches. As mentioned above, computer glasses also can be helpful to reduce blue light exposure from computers and other digital devices.

Also, a number of lens manufacturers have introduced special glare-reducing anti-reflective coatings that also block blue light from both natural sunlight and digital devices.

Ask your eye doctor or optician about which type of vision correction and lens features best suit your needs for viewing your computer and other digital devices and protecting your eyes from blue light.

Blue light filters and protective eyewear

If you are using your phone constantly — especially if you use it primarily for texting, emailing and web browsing — a convenient way to reduce your blue light exposure is to use a blue light filter.

Digital electronic devices emit blue light that can cause eye strain and may lead to eye problems over time.

These filters are available for smartphones, tablets, and computer screens and prevent significant amounts of blue light emitted from these devices from reaching your eyes without affecting the visibility of the display. Some are made with thin tempered glass that also protects your device’s screen from scratches. As mentioned above, computer glasses also can be helpful to reduce blue light exposure from computers and other digital devices.

Also, a number of lens manufacturers have introduced special glare-reducing anti-reflective coatings that also block blue light from both natural sunlight and digital devices.

Ask your eye doctor or optician about which type of vision correction and lens features best suit your needs for viewing your computer and other digital devices and protecting your eyes from blue light.