Eye Library
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CORNEA: Transparent front segment of the eye that covers iris, pupil, and anterior
chamber, and provides most of an eye's optical power.
PUPIL: Variable-sized, circular opening in center of iris; it appears as a
black circle and it regulates amount of light that enters the eye.
IRIS: Pigmented tissue lying behind cornea that (1) gives color to eye, and
(2) controls amount of light entering eye by varying size of black
pupillary opening; separates the anterior chamber from the posterior chamber.
LENS: Natural lens of eye; transparent intraocular tissue that helps bring
rays of light to focus on the retina.
RETINA: Part of the eye that converts images into electrical impulses sent
along the optic nerve for transmission back to the brain. Consists of
many named layers that include rods and cones.
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Amblyopia
Amblyopia, commonly called lazy eye, occurs when one eye develops differently than the other eye, causing one eye to be weaker than the other. Sometimes a difference in focusing ability causes one eye to be used more often. Other times, the eyes are misaligned, causing one eye to "shut off" to avoid double vision. Regardless of the cause, the result is a weakened, or amblyopic, eye.
Symptoms It's hard to spot amblyopia. Sometimes a child will noticeably favor one eye over the other. Another possible symptom is the child frequently bumping into things on one side. The best way to tell if your child has lazy eye is through a complete exam around six months and three years. Early diagnosis can prevent amblyopia from leading to more serious problems such as loss of the ability to see three dimensions or functional blindness in the amblyopic eye.
Treatment Most of the time amblyopia can't be entirely corrected. The amblyopic eye will always be a bit weaker than the other. However, with treatment, vision in the amblyopic eye can be improved to some extent. Treatment involves encouraging the weak eye to develop. This is done using eye patches, vision therapy, glasses, and usually a combination of the three. The strong eye may be patched to encourage the weak eye to develop. Vision therapy can help to correct improper use of the eyes. If a focusing error is at the root of the problem, then glasses may reduce the error. Most of the time the amblyopic eye will always require glasses.
Recommended Link National Eye Institute Amblyopia Resource Guidehttp://www.nei.nih.gov/health/amblyopia/index.asp
Astigmatism
Sometimes the cornea is irregularly shaped, causing the eye to focus an object on two different areas of the retina. This is known as astigmatism. For the cornea to bend light correctly, it should be dome-shaped, like a basketball. Astigmatic corneas are shaped more like a football. This causes a distorted view when looking at objects which are close-up and far away.
The cause of astigmatism is unknown. Astigmatism is often associated with myopia or hyperopia, and usually occurs from birth. It may be hereditary, or it may be caused by factors such as pressure on the cornea, incorrect posture, or increased use of the eyes for "near work."
Mild astigmatism usually doesn't need to be corrected. Eyeglasses, contact lenses, or refractive surgery can correct moderate to high degrees of astigmatism.
Recommended Link American Optometric Association: Astigmatism https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/astigmatism
Computer Vision Syndrome
Computer vision syndrome (CVS) affects three out of four computer users. It is a series of symptoms related to extended periods of computer usage. Though it is no cause for panic, measures can be taken to relieve symptoms of CVS.
Symptoms CVS can appear as a variety of symptoms. Headaches, eye strain, neck and back aches, sensitivity to light, blurred vision, double vision, and dry or irritated eyes are all possible problems related to CVS.
Risk Factors Any computer user can develop CVS. Your vision, your computer, and the environment where you use your computer are all factors which can lead to CVS.
Emmetropia
When an eye's optical power is perfectly matched to its length, the eye is said to be emmetropic. Emmetropia is the medical term for 20/20 vision needing no corrective lenses, contact lenses, or reading glasses. It occurs because the optical power of the eye can perfectly focus an image to the retina, giving them "perfect" vision.
The opposite of emmetropia is ametropia. With ametropia, the focal point of the eye is some distance in front of or behind the retina.
Hyperopia
Hyperopia is more commonly known as farsightedness. As the name suggests, people with farsightedness are able to focus on objects that are further away, but have difficulty focusing on objects which are very close. This is because the eyeball is shorter than normal, which prevents the crystalline lens in the eye from focusing correctly on the retina. About a fourth of the population are afflicted with hyperopia. Hyperopia can lead to chronic glaucoma, a more serious condition, later in life.
A family history of hyperopia is a risk factor for developing hyperopia. Often babies are born with hyperopia but they can usually outgrow the condition as the eye develops into the correct shape. Hyperopia can be corrected with eyeglasses or contact lenses. There are also new surgical procedures that can correct hyperopia.
Myopia
Myopia is the medical term for what most people call nearsightedness. It is a condition where you can see objects clearly only when they are closer, but when objects are further away you can't focus on them. Myopia usually develops in early childhood, though it sometimes develops in early adulthood. In rare cases, myopia can lead to more serious conditions such as retinal detachment.
Myopia is considered a genetic disorder. If your parents are nearsighted, you are at greater risk of also being nearsighted. Another risk factor is "near work" - work involving fine detail or focusing on close objects. Myopia can be accommodated and sometimes corrected with eyeglasses or contact lenses. Sometimes myopia continues to gradually worsen throughout life, a condition known as myopic creep. Myopia can also be corrected by LASIK surgery.
Presbyopia
As a people get older, usually when they hit their mid to late 40s, a condition called presbyopia can set in. Presbyopia is the inability to focus on objects near the eye. One usually notices that it is harder to read or use the computer. Bifocals or reading glasses are a way to remedy.
Presbyopia is a natural consequence of the aging process. There is no cure, though researchers are constantly looking for one. Even if a someone has never had vision problems before, they can still develop presbyopia. It may seem to occur suddenly, but actually occurs over a long period of time. Symptoms include having to hold things at arm's length to see them clearly, eye strain, fatigue, and headaches from near work.
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Blepharitis
There are two types of blepharitis. Seborrheic blepharitis is often part of an overall skin condition of seborrhea, which may also affect the scalp, chest, back and the area behind the ears. The second form of blepharitis - staph blepharitis - is a more severe condition, caused by bacteria, that begins in childhood and may continue through adulthood.
Causes
Hormones, nutrition, general physical condition, and even stress may contribute to seborrheic blepharitis. Build-ups of naturally occurring bacteria contribute to staph blepharitis.Symptoms
Blepharitis could be described as dandruff of the eyelids. Seborrheic blepharitis results in redness of the eyelids, flaking and scaling of eyelashes, and greasy, waxy scales caused by abnormal tear production. Staph blepharitis can cause small ulcers, loss of eyelashes, eyelid scarring, and even red eye.Treatment
Careful cleaning of the eyelids can reduce seborrheic blepharitis. Application of hot packs to the eyes for 20 minutes a day can also help. Staph blepharitis may require antibiotic drops and ointments.Cataracts
Cataracts are a cloudiness that occurs in the lens of the eye. The lens is made mostly of water and protein arranged to let light through. Sometimes the protein clumps, blocking light and making the lens appear cloudy.
Symptoms
A person with cataracts may encounter faded colors, problems with light (such as halos, or headlights that seem too bright), poor night vision, double vision, or multiple vision.Treatment
Your eye doctor can detect the presence of cataracts through a thorough eye exam, including a visual acuity test and dilation of the pupils. Treatment is available to prevent or reduce cataracts.Conjunctivitis
Conjunctivitis, commonly called pink eye, is a redness of the eye. It is often accompanied by a discharge (clear, yellow, or white) and itching in the eye.
Causes
Pink eye is most often a viral infection, but may also be caused by bacteria or allergic reaction. The viral pink eye is highly contagious.Prevention and Treatment
To avoid spreading conjunctivitis, wash your hands often, don't touch the infected area with your hands, don't share wash cloths or towels, and avoid using makeup which may become contaminated. A child with pink eye should be kept from school for a few days. Sometimes an eye doctor will need to prescribe antibiotic eye drops and ointments to remove conjunctivitis.Diabetic Retinopathy
Diabetic retinopathy is a condition associated with diabetes. High levels of blood sugar may damage tiny blood vessels in your eye. New vessels may form to replace the damaged vessels. The new vessels can burst, resulting in blurred vision or even blindness.
Symptoms
Symptoms of diabetic retinopathy include:
- "Floaters" - small specks that pass across your field of vision, made up of cells floating in the transparent gel of your eyeball
- Difficulty reading or seeing things close-up
- Sudden loss of vision
- Flashes
- Blurred or darkened visionRisk Factors and Treatment
If you have diabetes, make sure you control your blood sugar level. This will reduce your risk of getting diabetic retinopathy. If you are experiencing some of the symptoms listed above, give us a call. If diagnosed properly, diabetic retinopathy can be treated with a laser procedure or a vitrectomy.Dry Eye Syndrome
If your eyes are constantly itchy or dry, you may have dry eye syndrome, which affects almost 10 million Americans. Dry eye syndrome is caused by a lack of, or poor quality of, tears. Tears lubricate the outer layer of the eye, called the cornea. If the tears are not composed of a proper balance of mucous, water, and oil, the eye becomes irritated.
Symptoms
Dry eye syndrome leads to a number of symptoms, including itching, irritation, burning, excessive tearing, redness, blurred vision that improves with blinking, and discomfort after long periods of watching television, using a computer, or reading.Risk Factors
There are many factors that can contribute to dry eye syndrome. These include dry, hot, or windy climates, high altitudes, air-conditioned rooms, and cigarette smoke. Contact lens wearers, people with drier skin, and the elderly are more likely to develop dry eye syndrome. You may also be more at risk if you take certain medications, have a thyroid condition, a vitamin-A deficiency, Parkinson's or Sjorgen's disease, or if you are a woman going through menopause.Glaucoma
Glaucoma is a very common eye disorder affecting millions of Americans. It is caused by too much pressure on the inside of the eye. Fluid in your eyes helps to nourish and cleanse the inside of your eyes by constantly flowing in and out. When the fluid is prevented from flowing out, the intraocular pressure builds and damages the optic nerve. This causes a gradual loss in peripheral vision.
Symptoms
Those suffering from open-angle glaucoma experience a type of tunnel vision, where their field of vision gradually decreases. It can eventually lead to blindness. Narrow-angle glaucoma, which is rare, carries symptoms of sharp pain in the eyes, blurred vision, dilated pupils, and even nausea or vomiting. It can cause blindness in a matter of days, and requires immediate medical attention.Risk Factors
Heredity seems to be a risk factor. Also, you may be at greater risk if you are over 45, of African descent, near-sighted, or diabetic. Finally, if you have used steroids or cortizone for a long period of time, or if you have suffered an eye injury in the past, you have a greater chance of developing glaucoma.Macular Degeneration
Macular degeneration is a disease which affects a small area of the retina known as the macula. The macula is a specialized spot on the retina that allows us to see fine detail of whatever is directly in front of us. Macular degeneration occurs when the macula begins to deteriorate.
"Wet" vs. "Dry"
Most often, macular degeneration is accompanied by formation of yellow deposits called "drusen" under the macula, which dry out or thin the macula. This is called "dry" macular degeneration. In rare cases, abnormal blood vessels develop under the macula and leak fluid. This is called "wet" macular degeneration.Causes
A number of uncontrollable factors contribute to macular degeneration, including age, sex, eye color, farsightedness, and race. Risk factors you can control include smoking, high blood pressure, exposure to harmful sunlight, and diet.Symptoms
It is difficult to detect dry macular degeneration in early stages. The most common symptoms, when detected, include a spot of blurry vision, dark vision, or distorted vision. Wet macular degeneration acts much faster when it occurs. Both forms of macular degeneration can cause blindness.Treatment
Currently, there is no cure for macular degeneration, but treatment is available to slow the effects.Retinal Detachment
The part of the eye which collects light and transmits the light messages to the optic nerve and brain is the retina. It lines the inner back wall of the eye. When the retina separates from the back wall, it is known as retinal detachment. It is a serious condition which can cause permanent damage and vision loss if not treated quickly.
Symptoms
A retinal detachment will result in a sudden defect in your vision. It may just cause a blind spot too small to notice, or it may cause a noticeable shadow which obscures your vision. An increase in "floaters," which look like small particles or fine threads, may also be noticed. Finally, flashes of light are associated with retinal detachment.Risk Factors
Eye injuries, tumors, and cataract surgery can cause retinal detachment. Near-sighted individuals and the elderly are at greater risk for spontaneous detachment. Also, diabetic retinopathy, a condition associated with diabetes, can cause bleeding which leads to retinal detachment. -
The struggle between fashion and function is officially declared a tie! Never before have eyeglass frames been offered in so many stylish choices. Yet, you'll be amazed at how many options are at your fingertips to help you see well, and protect your vision.
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Vision is arguably the most important of the five senses; it plays a crucial role throughout childhood and beyond. Yet many parents don't understand how vision helps their children develop appropriately. Use these articles to proactively care for your childâs eyes, spot potential trouble, and maximize the opportunity for crisp, convenient and healthy vision.
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Today there are more convenient and healthy contact lens choices than ever before. Whatever your vision challenge, it can probably be met with an array of specialty contact lenses for individual vision needs.
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Whether or not you require vision correction, sunglasses can add an element of comfort and enhanced performance to your activities, while helping you look great.
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Seeing clearly is just one part of your overall eye health. It’s important to have regular eye exams whether or not you wear glasses or contacts, and even if your vision is sharp. The articles below explain what problems can be spotted with an eye exam, what’s involved in a comprehensive exam, and special considerations for kids and contacts.
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Tired of wearing glasses or contact lenses? Today, several surgical methods can correct your eyesight and, in most cases, give you the freedom of seeing well without corrective lenses.
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Eye problems can range from mild to severe; some are chronic, while others may resolve on their own, never to appear again. The articles below will give you a basic understanding of some of these problems and their implications. The cardinal rule is if your eyes don't look good, feel good or see well, you should visit your doctor.
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If you are among the 85 million Baby Boomers in the United States and Canada (born between 1946 and 1964), you've probably noticed your eyes have changed. Most notably, presbyopia - the normal, age-related loss of near focusing ability - usually becomes a problem in our 40's, requiring new vision correction solutions. Learn about measures you can take to keep seeing clearly for years to come.
As people get older, usually around their mid to late 40s, a condition called presbyopia can set in. Presbyopia is the inability to focus on objects near the eye. One usually notices that it is harder to read or use the computer. Bifocals or reading glasses are a way to remedy this condition.
Presbyopia is a natural consequence of the aging process. There is no cure, though researchers are constantly looking for one. Even if a person has never had vision problems before, he or she can still develop presbyopia. While symptoms can present suddenly, presbyopia usually occurs over a long period of time. Symptoms include having to hold things at arm's length to see them clearly, eye strain, fatigue and headaches from near work.
Computer Glasses
To reduce eye strain and fatigue, we carry specialized computer lenses. These lenses are perfect for computer users who spend a majority of their day working on a computer. And since three out of four computer users will suffer from Computer Vision Syndrome, computer lenses are a great way to keep your eyesight healthy.Reading Glasses
One of the first areas of your life where presbyopia becomes prominent is in your ability to read. There are a variety of styles available, with sleek designs that allow you to carry them anywhere.Progressive No-Line Lenses
For many presbyopes, bifocal lenses are a necessity. But it can be difficult to adjust to the harsh line that is found in bifocal lenses. Fortunately, there are no-line lenses which are also called progressive lenses. No more lines! Just a gradual change in focusing power which allows you to comfortably focus on any distance. Just like bifocals, distant objects are viewed through the top portion of the lenses, and near objects are viewed through the bottom portion of the lenses.Bifocal Contacts
If you need bifocals but can't stand wearing glasses, you need bifocal contact lenses. Now you can have all of the benefits of bifocal lenses in the convenience of contact lenses. Talk with your doctor about bifocal contacts today.Monovision Correction
For some of our emerging presybopes we offer another option to glasses, monovision. This is a method of fitting your dominant eye for distance vision and your non-dominant eye for near vision. Contacts are available in disposable, extended wear, and even daily disposable lenses to fit your lifestyle. Most patients require 2-4 weeks to make the adjustment from binocular vision to monovision. -
Just as our physical strength decreases with age, our eyes also exhibit an age-related decline in performance - particularly as we reach our 60's and beyond. Some age-related eye changes are perfectly normal, but others may signal a disease process. It's important to recognize signs and symptoms, and perhaps even more important to mitigate the effects of aging with some simple and common-sense strategies.
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Sports eyewear can give you the performance edge you're seeking for just about any sport. But make sure you get the eye protection you need as well. And after you're fit for the right eyewear, you might want to take your game up a notch with the same kind of vision training used by professional athletes.
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Low vision is the term used to describe reduced eyesight that cannot be fully corrected with eyeglasses, contact lenses or eye surgery. The primary causes of low vision are eye diseases, but low vision also can be inherited or caused by an eye or brain injury.
