The Lasik Blog

Have you ever been gazing up at the sky and noticed strange little shapes floating around in your vision? When you try to examine one of them, it darts away and continues to drift lazily around, maybe shimmering or vibrating a little. They may gradually change their shape and may disappear, or not. This drifting behavior occurs because they exist in fluid.

Floaters Related to Aging and Usually Not a Danger

Our eyes are filled with fluid -- aqueous fluid in the anterior chamber (in front of the lens) and vitreous fluid in the much larger posterior chamber, behind the lens. As we age the vitreous fluid (often referred to as just "the vitreous"), starts to shrink, with cells clumping together here and there and casting little shadows on the retina, the light-sensitive cells at the back of the eye. These shadows are floaters.

You are more likely to develop floaters if you:

• Have diabetes
• Have had a cataract surgery
• Are very myopic (nearsighted)

Floaters can arise because of an infection, eye injury, inflammation, bleeding in the eye, or tears in the retina. These causes will have consequences more damaging than just floaters.

Vitreous Detachment May Require Immediate Care

In some older people (over about 50), the vitreous can abruptly pull away from the retina. You may notice this by a sudden increase in the numbers of floaters, or by light flashes at the side of your vision. It usually does not need any treatment, as it does not threaten vision. If it happens in one eye, it will likely happen in the other eye too, although perhaps not for a few years.

However, in some cases, vitreous detachment pulls hard enough on the retina that it can pull the retina itself out of position -- known as retinal detachment, and definitely sight-threatening. Or it can cause damage to the macula, which is the central area of the retina where the fovea centralis is. The fovea is the small area that gives us our clearest visual focus.

If you experience any sudden increase in light flashes at the sides of your vision, or in floaters, do contact your eye doctor immediately. Your vision could be in danger. Retinal detachment can cause blindness, and any tears or breaks in the retina can lead to retinal detachment. So it's better not to delay in seeking advice and care.

There are several types of glaucoma and the most common one is open-angle glaucoma. Glaucoma is detectable damage to the optic nerve caused by high intraocular pressure and its causes are not well understood. The fluid inside the eye always exerts a certain amount of pressure outwards, and in a normal eye, the cornea (front clear part) holds its curvature steady, the lens, iris, and sclera are not damaged by the pressure, and the optic nerve and retina remain healthy.

However, in a glaucomatous eye, the pressure is too high and causes eye tissue damage. When the optic nerve is damaged, our sight is compromised. Glaucoma is a progressive disease, and if not treated will cause blindness.

The retina is made up largely of light-sensitive cells which receive the image information in light rays entering the eyes. They convert it to electrical energy. The optic nerve is connected to the retina and carries this electrical (neural) energy to the brain, which interprets it. When the optic nerve is damaged, it is less able to carry that vision information to the brain, which gradually reduces our visual field until it becomes zero.

Diagnostic Tests

Traditionally, glaucoma is diagnosed through several tests. Two are tests of intraocular pressure:

• The 'puff test' -- where a puff of air is sent to the eye and gives a measurement of how much intraoculat pressure that eye has
• The visual field test -- where tiny lights flashing for a moment are the stimulus for you to press a button at each light. The testing system converts this into a map of each eye, with black areas where lights flashed but you didn't press the button because you didn't see them.

A third is an examination of the optic nerve:

• Stereoscopic photographs are taken of the optic nerve

Newer tests attempt to measure the thickness of nerve fibers in the retina. Glaucoma reduces their thickness until they are lost. By measuring any changes in the thickness of these fibers, these tests detect the glaucoma progression.

A Recent Mayo Clinic Study

Using Mayo Clinic records, a team of ophthalmologists (all members of the American Academy of Ophthalmology) and others recently compared intraocular fluid pressures to cerebrospinal fluid (CSF) pressures. CSF surrounds the spinal cord and brain, extending to the area of the optic nerve.

They chose 28 glaucoma patients and 49 control group patients without glaucoma. Both groups had received eye examinations, and had had CSF samples taken through a lumbar puncture between 1996 and 2007.

The researchers found that CSF pressures were significantly lower in all glaucoma patients than they were in any of the control group patients. This was independent of any patient's age, or the reason he or she had had the lumbar puncture done.

In other words, they found that in the glaucoma patients, lower CSF pressures were combined with higher intraocular pressures. Further studies are now planned, to learn more about the role of CSF pressure in the development of glaucoma.

If you are approaching age 40 or so, and have not had any glaucoma testing, it is strongly urged that you do so. Glaucoma can creep up silently on a person, and you may not notice anything is amiss until you have permanently lost a significant amount of vision. If you are in the Bloomington or Peoria areas in Illinois, please visit the Gailey Eye clinic, where any of six highly-trained ophthalmologists can help you keep your eyesight intact.

The National Eye Institute and Prevent Blindness America joined forces recently to do a Study on Vision Problems in The U.S., updating one they did back in 2002. The Study gathered information from leading ophthalmologic epidemiologists and found that four causes of blindness are increasing:

1. Incidence of AMD (Age-Related Macular Degeneration) rose by 25% and at present, about two million Americans are diagnosed with AMD.

What is it? -- Gradual loss of function in the eye's macula. This is the part of the retina (the "camera film" of the eye) which allows clear images of fine detail in the center of our field of vision. There is no pain as it progresses.

2. Diabetic Retinopathy in increasing and now affects over 3.6 million Americans.

What is it? -- Damage to the retinal blood vessels, which swell and leak. The body tries to counter this lack of effective blood circulation in the eye by building new blood vessels, but they are usually just as weak and prone to leaking. The leaks can cause blindness.

3. Glaucoma is diagnosed in about 2.29 million, and the Study estimates that about two million more people have it but don’t know.

What is it? -- Elevated pressure within the eye which damages the optic nerve. This is a large nerve at the back of each eye which carries image information from the retina to the brain. Vision is lost gradually as the nerve is increasingly damaged.

4. About 22.3 million Americans have cataracts, many of whom cannot afford to obtain eye care for it

What is it? -- Cloudy areas in the eye's lens which block vision by blocking incoming light. Over time they grow larger until the entire lens has lost is translucency and blindness occurs.

The Study estimates that as the baby boomers continue aging, the incidence of these four conditions will double. They all develop gradually, so that for some time a person does not notice their presence. Vision loss happens slowly enough that one becomes used to each small loss before the next increment happens.

However, the Study notes too that early diagnosis and treatment can minimize vision loss, and it urges people to see their eye care professional today so as to protect their vision.

Persistent squinting can make you feel tired and eventually cause wrinkles. For some it becomes a matter of habit, but it can be an early sign of vision problems or an eye condition.

If your vision is less than adequate you may have begun squinting without really noticing that your vision has declined. You may not even notice that you are squinting until someone point it out to you. Nearsightedness and farsightedness are common refractive errors that may cause you to squint. More often the inability to adjust between near and far vision is the problem. Vergence disorders affect your eyes' ability to turn outward or inward and work together properly.

Light sensitivity also causes squinting and can be a sign of more serious underlying problems including cataracts, corneal abrasions, retinal detachment, and central nervous system disorders.

To learn more about vision disorders, click here to visit The LASIK Directory.

A drooping eyelid can be caused by excess skin or a problem with the muscle which controls the eyelid. Birth defects, tumors, surgery, and some diseases can also cause the eyelids to droop. It can occur in one or both eyes and can be so severe as to impair vision.

Excess skin is common in older people as the skin loses its elasticity. Connective tissue diseases which cause the skin to lose its elasticity are collectively referred to as dermatochalasis. Blepharochalasis is excess eyelid skin caused by recurring swelling, and is common in young people.

Levators are the muscles which lift the eyelids. When drooping eyelids impair vision, eyelid surgery to tighten or bypass these muscles may be necessary.

To learn more about eyelid drooping and corrective procedures, click here to visit the website of the Carter Eye Center in Dallas, Texas.

After being outside in bright sunlight, we often experience a brief moment of dim vision when we first come inside. When our eyes have had a few seconds to adjust, the problem corrects itself because our pupils dilate to take in more light, and the pigment in the rods of our eyes regenerates.

Pupils which do not dilate, or which contract when they should not, can cause persistent or sudden and inappropriate dim vision. Pupil dilation and contraction problems can be caused by glaucoma, inflammation of the optic nerve, certain medications, recreational drugs, toxins, Horner's syndrome, and certain diseases, such as syphilis.

Rods are the photoreceptors used to see in dim light. Certain conditions of the eye, such as retinitis pigmentosa and macular degeneration cause degeneration of the rods and therefore cause dim vision and difficulty seeing in low light. Vitamin A deficiency can also cause degeneration of the rods.

Clouding of the lens of the eye can prevent enough light from getting in. Cataracts and other conditions of the eye can cloud the lens.

To learn more about vision disorders, click here to visit The LASIK Directory.

Eye pain is very difficult to ignore, and can be the symptom of something fairly minor such as eye strain, or it can mean that you are experiencing an eye or health emergency.

Cornea problems, including abrasions or scratches, an infected abrasion (called a corneal ulcer), swelling (corneal edema), corneal dystrophies, and erosion of the cornea can cause eye pain. If you suspect that you may have an infected scratch or abrasion of the cornea, you should seek immediate medical attention.

Paralysis of the eye muscle can be extremely painful and may be cause by health problems such as a stroke, thyroid disease, multiple sclerosis, a tumor, and some palsies.

Vascular problems including blood clots, aneurysm, and high blood pressure, often cause eye pain, and sometimes a bulging eye or blurred vision.

When eye pain is accompanied by floaters, light sensitivity, a red or pink eye, or vision loss, you should seek immediate medical attention. Causes can include inflammation inside of the eye (often as a result of trauma or surgery), a tumor, fungal infections such as fungal keratitis or mucormycosis, glaucoma, Graves' ophthalmology, low pressure inside of the eye, inflammation of the optic nerve, and inflammation of the retina.

To learn more about vision disorders, click here to read Vision Disorder articles on The LASIK Directory.