Patient Education Center
Glaucoma is a disease that damages your eye’s optic nerve. It usually happens when fluid builds up in the front part of your eye. That extra fluid increases the pressure in your eye, damaging the optic nerve.
Primary open-angle glaucoma
This is the most common type of glaucoma. It happens gradually, where the eye does not drain fluid as well as it should (like a clogged drain). As a result, eye pressure builds and starts to damage the optic nerve. This type of glaucoma is painless and causes no vision changes at first. Some people can have optic nerves that are sensitive to normal eye pressure. This means their risk of getting glaucoma is higher than normal. Regular eye exams are important to find early signs of damage to their optic nerve.
Angle-closure glaucoma (also called “closed-angle glaucoma” or “narrow-angle glaucoma”)
This type happens when someone’s iris is very close to the drainage angle in their eye. The iris can end up blocking the drainage angle. You can think of it like a piece of paper sliding over a sink drain. When the drainage angle gets completely blocked, eye pressure rises very quickly. This is called an acute attack. It is a true eye emergency, and you should call your ophthalmologist right away or you might go blind.
Here are the signs of an acute angle-closure glaucoma attack:
Your vision is suddenly blurry
You have severe eye pain
You have a headache
You feel sick to your stomach (nausea)
You throw up (vomit)
You see rainbow-colored rings or halos around lights
Many people with angle-closure glaucoma develop it slowly. This is called chronic angle-closure glaucoma. There are no symptoms at first, so they don’t know they have it until the damage is severe or they have an attack.
Angle-closure glaucoma can cause blindness if not treated right away.
Inside our eyes, we have a natural lens. The lens bends (refracts) light rays that come into the eye to help us see. The lens should be clear, like the top lens in the illustration.
The top lens is clear. The bottom lens shows clouding by cataract.
Vision problems with cataracts
If you have a cataract, your lens has become cloudy, like the bottom lens in the illustration. It is like looking through a foggy or dusty car windshield. Things look blurry, hazy or less colorful with a cataract.
LASIK - (Laser Assisted in situ keratomileusis)
LASIK is an outpatient refractive surgery procedure used to treat nearsightedness, farsightedness and asti-gmatism. A laser is used to reshape the cornea — the clear, round dome at the front of the eye — to improve the way the eye focuses light rays onto the retina at the back of the eye.
With LASIK, an ophthalmologist creates a thin flap in the cornea using either a blade or a laser. The surgeon folds back the flap and precisely removes a very specific amount of corneal tissue under the flap using an excimer laser. The flap is then laid back into its original position where it heals in place.
For people who are nearsighted, LASIK is used to flatten a cornea that is too steep. Farsighted people will have LASIK to achieve a steeper cornea. LASIK can also correct astigmatism by shaping an irregular cornea into a more normal shape.
It is important that anyone considering LASIK have realistic expectations. LASIK allows people to perform most of their everyday tasks without corrective lenses. However, people looking for perfect vision without glasses or contacts run the risk of being disappointed. More than 90 percent of people who have LASIK achieve somewhere between 20/20 and 20/40 vision without glasses or contact lenses. If sharp, detailed 20/20 vision is essential for your job or leisure activities, consider whether 20/40 vision would be good enough for you.
You should be comfortable with the possibility that you may need a second surgery (called a retreatment or enhancement) or that you might need to wear glasses for certain activities, such as reading or driving at night. Also, you should be aware that LASIK cannot correct presbyopia, the age-related loss of close-up focusing power.
LASIK risks and side effects
LASIK, like any surgery, has potential risks and complications that should be carefully considered. Since it was approved by the FDA in 1998, LASIK is has become a popular treatment in the United States and the overall complication rate is low. Infection and inflammation are possibilities, as with any surgical procedure, and usually can be cleared up with medications.
Problems with the corneal flap after surgery sometimes make further treatment necessary. There is a chance, though small, that vision will not be as good after the surgery as before, even with glasses or contacts.
Some people experience side effects after LASIK that usually disappear over time. These side effects may include hazy or blurry vision; difficulty with night vision and/or driving at night; scratchiness, dryness and other symptoms of the condition called "dry eye"; glare, halos or starbursts around lights; light sensitivity; discomfort or pain; or small pink or red patches on the white of the eye. In a small minority of patients, some of these effects may be permanent.
Sometimes a second surgery, called a retreatment or enhancement, may be needed to achieve the desired vision correction. This is more likely for people who were more nearsighted, farsighted, or had higher astigmatism before LASIK — those whose vision originally needed more intensive correction. Approximately 10.5 percent of LASIK patients in the United States require a retreatment.
Age-Related Macular Degeneration
Age-related macular degeneration (AMD) is a problem with your retina. It happens when a part of the retina called the macula is damaged. With AMD you lose your central vision. You cannot see fine details, whether you are looking at something close or far. But your peripheral (side) vision will still be normal. For instance, imagine you are looking at a clock with hands. With AMD, you might see the clock’s numbers but not the hands.
Two types of AMD
This form is quite common. About 80% (8 out of 10) people who have AMD have the dry form. Dry AMD is when parts of the macula get thinner with age and tiny clumps of protein called drusen grow. You slowly lose central vision. There is no way to treat dry AMD yet.
This form is less common but much more serious. Wet AMD is when new, abnormal blood vessels grow under the retina. These vessels may leak blood or other fluids, causing scarring of the macula. You lose vision faster with wet AMD than with dry AMD.
Many people don’t realize they have AMD until their vision is very blurry. This is why it is important to have regular visits to an ophthalmologist. He or she can look for early signs of AMD before you have any vision problems.
Dry Eyes Syndrome
Our eyes need tears to stay healthy and comfortable. If your eyes do not produce enough tears, it is called dry eye. Dry eye is also when your eyes do not make the right type of tears.
How do tears work?
When you blink, a film of tears spreads over the eye. This keeps the eye’s surface smooth and clear. The tear film is important for good vision.
The tear film is made of three layers:
An oily layer
A watery layer
A mucus layer
Each layer of the tear film serves a purpose.
The oily layer is the outside of the tear film. It makes the tear surface smooth and keeps tears from drying up too quickly. This layer is made in the eye’s meibomian glands.
The watery layer is the middle of the tear film. It makes up most of what we see as tears. This layer cleans the eye, washing away particles that do not belong in the eye. This layer comes from the lacrimal glands in the eyelids.
The mucus layer is the inner layer of the tear film. This helps spread the watery layer over the eye’s surface, keeping it moist. Without mucus, tears would not stick to the eye. Mucus is made in the conjunctiva. This is the clear tissue covering the white of your eye and inside your eyelids.
Normally, our eyes constantly make tears to stay moist. If our eyes are irritated, or we cry, our eyes make a lot of tears. But, sometimes the eyes don’t make enough tears or something affects one or more layers of the tear films. In those cases, we end up with dry eyes.
People with diabetes can have an eye disease called diabetic retinopathy. This is when high blood sugar levels cause damage to blood vessels in the retina. These blood vessels can swell and leak, or they can close, stopping blood from passing through. Sometimes, abnormal new blood vessels grow on the retina. All of these changes can steal your vision.
NPDR (non-proliferative diabetic retinopathy)
This is the early stage of diabetic eye disease. Many people with diabetes have it. With NPDR, tiny blood vessels leak, making the retina swell. When the macula swells, it is called macular edema. This is the most common reason why people with diabetes lose their vision.
Also with NPDR, blood vessels in the retina can close off. This is called macular ischemia. When that happens, blood cannot reach the macula. Sometimes tiny particles called exudates can form in the retina. These can affect your vision too.
If you have NPDR, your vision will be blurry.
PDR (proliferative diabetic retinopathy)
PDR is the more advanced stage of diabetic eye disease. It happens when the retina starts growing new blood vessels. This is called neovascularization. These fragile new vessels often bleed into the vitreous. If they only bleed a little, you might see a few dark floaters. If they bleed a lot, it might block all vision.
These new blood vessels can form scar tissue. Scar tissue can cause problems with the macula or lead to a detached retina.
PDR is very serious, and can steal both your central and peripheral (side) vision.
Your cornea is the clear, dome-shaped window at the front of your eye. It focuses light into your eye. Keratoconus is when the cornea thins out and bulges like a cone. Changing the shape of the cornea brings light rays out of focus. As a result, your vision is blurry and distorted, making daily tasks like reading or driving difficult. Mild keratoconus can be corrected with glasses or contact lenses; however, as the disease advances, you may require corneal crosslinking or corneal transplant to improve vision.
The retina is the light-sensitive tissue lining the back of our eye. Light rays are focused onto the retina through our cornea, pupil and lens. The retina converts the light rays into impulses that travel through the optic nerve to our brain, where they are interpreted as the images we see. A healthy, intact retina is key to clear vision.
The middle of our eye is filled with a clear gel called vitreous (vi-tree-us) that is attached to the retina. Sometimes tiny clumps of gel or cells inside the vitreous will cast shadows on the retina, and you may sometimes see small dots, specks, strings or clouds moving in your field of vision. These are called floaters. You can often see them when looking at a plain, light background, like a blank wall or blue sky.
As we get older, the vitreous may shrink and pull on the retina. When this happens, you may notice what look like flashing lights, lightning streaks or the sensation of seeing “stars.” These are called flashes.
Usually, the vitreous moves away from the retina without causing problems. But sometimes the vitreous pulls hard enough to tear the retina in one or more places. Fluid may pass through a retinal tear, lifting the retina off the back of the eye — much as wallpaper can peel off a wall. When the retina is pulled away from the back of the eye like this, it is called a retinal detachment.
The retina does not work when it is detached and vision becomes blurry. A retinal detachment is a very serious problem that almost always causes blindness unless it is treated with detached retina surgery.
Posterior Vitreous Detachment
American Academy of Ophthalmology