Vision Conditions

Nearsightedness (Myopia)

1. What is Nearsightedness?
   1. Nearsightedness, or myopia, as it is medically termed, is a vision condition in which near objects are generally seen clearly, but distant objects are blurred and do not come in proper focus.
2. Why Does Nearsightedness Occur?
   1. When your eyeball is too long or the cornea has too much curvature, light entering the eye is not focused properly. Hereditary factors often control the growth and development of the eye. However, some evidence supports the theory that nearsightedness may also be caused by the stress of too much close vision work.
3. How Common is Nearsightedness?
   1. Nearsightedness is a very common vision condition that affects nearly 30 percent of the American population. It normally first occurs in school age children. Since the eye continues to grow during childhood, nearsightedness generally develops before the individual reaches age 20.
4. How is Nearsightedness Diagnosed?
   1. Nearsighted children are usually easy to identify because they often squint or have trouble seeing the chalkboard, the movie screen, the television or other distant objects. A comprehensive examination with Dr. Cantrell will include testing for nearsightedness.
5. How is Nearsightedness Treated?
   1. Eyeglasses or contact lenses can be prescribed to optically correct nearsightedness and enable you to see more clearly. These devices alter the way the light images are focused in your eyes, but they do not cure nearsightedness. You may only need them for certain activities, like watching television, going to a movie or driving a car.

In recent years, a number of options such as LASIK, to surgically alter the shape of the cornea, the eye’s clear front surface, to reduce nearsightedness have been developed. These surgical procedures are not recommended until the eye has stopped growing and your prescription has stabilized. There is also a procedure called orthokeratology which uses a series of rigid contact lenses to alter the curvature of the cornea to provide improved vision for significant periods of time for some people with nearsightedness. Dr. Cantrell can help you decide which procedure, if any, is right for you.

1. Farsightedness (Hyperopia)
   1. What is Farsightedness?
      1. Farsightedness, or hyperopia, as it is medically termed, is a vision condition in which distant objects are usually seen clearly, but, close ones are not brought into proper focus.
   2. Why Does Farsightedness Occur?
      1. If the length of your eyeball is too short or the cornea has too little curvature, near objects cannot be brought into sharp and clearly focused images. Hereditary factors often control the growth and development of the eye. However, environmental factors also contribute to the development of farsightedness.
   3. How Common is Farsightedness?
      1. Many people have some degree of farsightedness. The condition is only a problem if it significantly affects a person’s ability to see or they develop symptoms such as tired eyes, eye strain, or headaches. It is estimated that over half the people who wear glasses are wearing them because of a focusing problem due to farsightedness or presbyopia, a natural decrease in the eye’s focusing ability at near distance.
   4. What Are Signs/ Symptoms of Farsightedness?
      1. Common signs and symptoms of farsightedness include difficulty in concentrating and maintaining a clear focus on near objects, blurred vision, eye strain, fatigue and/or headaches after close work.
   5. How is Farsightedness Diagnosed?
      1. Farsightedness can be effectively diagnosed in a comprehensive examination with Dr. Cantrell. Common vision screenings, often done in schools, are generally ineffective in detecting farsighted people. This is because these individuals can identify letters on an eye chart with little difficulty.
   6. How Does Farsightedness Affect Vision?
      1. If you are farsighted, you involuntarily exert extra effort to maintain clear distance vision and even greater effort to see clearly at close range. This extra effort can cause fatigue, tension and discomfort. If the crystalline lens of the eye cannot bring the object being viewed into focus, blurred vision occurs.
   7. How is Farsightedness Treated?
      1. In mild cases, your eyes may be able to compensate adequately without the need for corrective lenses. In moderate or severe cases, Dr. Cantrell may recommend glasses or contact lenses.
2. Astigmatism
   1. What is Astigmatism?
      1. Astigmatism is a vision condition in which light entering the eye is unable to be brought into a single focus, resulting in vision being blurred at all distances. Astigmatism is not a disease, but rather, a vision condition that is quite common. It often occurs in conjunction with other refractive errors like nearsightedness and farsightedness.
   2. Why Does Astigmatism Occur?
      1. Typically, astigmatism is caused by the front of your eye (the cornea) being more oval than round, and not allowing light to focus properly on the back of your eye (the retina). The causes of this irregular shape vary.
   3. How Common is Astigmatism?
      1. Most people have some degree of astigmatism. However, only individuals with moderate to highly astigmatic eyes usually need corrective lenses.
   4. What Are Signs/Symptoms of Astigmatism?
      1. People with significant amount of astigmatism will usually have blurred or distorted vision. Those with mild astigmatism may experience headaches, eye strain, fatigue or blurred vision at only certain distances.
   5. How is Astigmatism Diagnosed?
      1. A comprehensive eye examination with Dr. Cantrell will include testing for astigmatism.
   6. How is Astigmatism Treated?
      1. Astigmatism can generally be optically corrected with properly prescribed and fitted eyeglasses or contact lenses. In recent years, a number of options to surgically alter the shape of the cornea have been developed. Corneal modification (orthokeratology) is also a treatment option for some patients.
   7. Does Astigmatism Get Progressively Worse?
      1. Astigmatism may change slowly. Regular optometric care with Dr. Cantrell can, however, help to ensure that proper vision is maintained.
3. Presbyopia
   1. What is Presbyopia?
      1. Presbyopia is a vision condition in which the crystalline lens of your eye loses its flexibility, which makes it difficult for you to focus on close objects.
   2. What Causes Presbyopia?
      1. Your eye stops growing in your early teens. The lens, however, continues to produce more and more cells. This continued growth eventually causes the lens to harden and lose some of its elasticity and therefore some focusing ability.
   3. At What Age Does Presbyopia Occur?
      1. Presbyopia may seem to occur suddenly, but the actual loss of flexibility takes place over a number of years. Presbyopia usually becomes noticeable in the early to mid-40s.
   4. What Are Signs/Symptoms of Presbyopia?
      1. Some signs/symptoms of presbyopia include the tendency to hold reading materials at arm’s length, blurred vision at normal reading distance and eye fatigue along with headaches when doing close work.
   5. Can Presbyopia Be Prevented?
      1. Presbyopia is a natural part of the aging process of the eye. It is not a disease, and it cannot be prevented.
   6. How is Presbyopia Diagnosed?
      1. A comprehensive examination with Dr. Cantrell will include testing for presbyopia.
   7. How is Presbyopia Treated?
      1. To help you compensate for presbyopia, Dr. Cantrell can prescribe reading glasses, bifocals, trifocals, or contact lenses. Because presbyopia can complicate other common vision conditions like nearsightedness, farsightedness and astigmatism, Dr. Cantrell will determine the specific lenses to allow you to see clearly and comfortably. Dr. Cantrell will also ask specific questions about your occupational and recreational activities. This information will aid in determining what type of lenses you need.
   8. Will I have to Wear Glasses All the Time?
      1. This will depend on a number of factors, including any other vision conditions you have. You may only need to wear your glasses for reading, working at your computer, sewing or other close work. However you may find that wearing them all the time is more convenient and beneficial for your vision needs.
   9. Can I Still Wear Contact Lenses?
      1. Great strides continue to be made in contact lenses. There are many more options available for doctors of optometry to correct presbyopia with contact lenses, in both rigid and soft contact lenses, that in the past. You and Dr. Cantrell can decide whether contact lenses are right for you.
   10. Why Are Frequent Lens Changes Necessary After 40?
       1. Because the effects of presbyopia continue to change the ability of the crystalline lens to focus properly, periodic changes in your eyewear may be necessary to maintain clear and comfortable vision.
4. Amblyopia (Lazy Eyes)
   1. What is Amblyopia?
      1. Lazy eye, or amblyopia, is the loss or lack of development of central vision in one eye that is unrelated to any eye health problem. The brain does not acknowledge the images seen by the amblyopic eye. Reduced vision due to amblyopia is not correctable with lenses.
   2. Who is Likely to Develop Amblyopia?
      1. Amblyopia is generally the result of poor early visual development, and as such, usually occurs before the age of 6. Infants born prematurely or with low birth weight are at a greater risk for the development of the condition. It is estimated that two to four percent of children have amblyopia. The chance of amblyopia developing during adulthood is very small.
   3. What Causes Amblyopia?
      1. Amblyopia can result from a failure to use both eyes together. Lazy eye is often associated with crossed-eyes (strabismus) or a large difference in the degree of nearsightedness or farsightedness between the two eyes. Amblyopia can also be caused by a physical obstruction such as a congenital cataract. It usually develops before the age of 6, and it does not affect side vision.
   4. How Does Amblyopia Affect Vision?
      1. Normally, the images sent by each eye to the brain are identical. When they differ too much, the brain learns to ignore the poor image sent by one eye and “sees” only with the good eye. The vision of the eye that is ignored becomes weaker from disuse.
   5. Is the Amblyopic Eye Blind?
      1. The amblyopic eye is never blind in the sense of being entirely without sight. Amblyopia affects only the central vision of the affected eye. Peripheral awareness will remain the same.
   6. What Are Signs/Symptoms of Amblyopia?
      1. Amblyopia usually produces few symptoms. Symptoms may include noticeably favoring one eye or a tendency to bump into objects on one side. Symptoms are not always obvious.
   7. How is Amblyopia Diagnosed?
      1. Since amblyopia occurs in only one eye, the good eye takes over and the individual is generally unaware of the condition. Early diagnosis increases the change for a complete recover. This is one reason why the American Optometric Association and Dr. Cantrell recommend that children have a comprehensive optometric examination by the age of 6 months and again at age 3. Lazy eye will not go away on its own. If not diagnosed until the pre-teen, teen or adult years, treatment takes longer and is often less effective.
   8. How is Amblyopia Treated?
      1. Treatment for lazy eye may include a combination of prescription lenses, prisms, vision therapy and eye patching. Vision therapy teaches the two eyes how to work together, which helps prevent lazy eye from reoccurring.
   9. Does Amblyopia Get Worse?
      1. Vision in the amblyopic eye may continue to decrease if left untreated. The brain simply pays less and less attention to the images sent by the amblyopic eye. Eventually, the condition stabilized and the eye becomes virtually unused. It is quite difficult to effectively treat amblyopia at this point.
   10. How Will Amblyopia Affect My Lifestyle?
       1. Amblyopia can limit the occupational and leisure activities you can do. Activities requiring good depth perception may be difficult or impossible to perform. In addition, should your good eye become injured or develop vision problems, you may have difficulty maintaining your normal activities.
5. Strabismus (Crossed Eyes)
   1. What is Strabismus?
      1. Strabismus occurs when one or both of your eyes turns in, out, up or down, and is usually caused by poor eye muscle control. Newborns often appear to have an eye turn. By the age of 2 months, the eye muscles become more developed and begin to work together. Misalignment often first appears before age 21 months but may develop as late as age 6. This is one reason why the American Optometric Association and Dr. Cantrell recommend a comprehensive optometric examination before 6 months and again at age 3.
   2. How is Strabismus Diagnosed?
      1. A comprehensive examination with Dr. Cantrell will include testing for strabismus.
   3. Can My Child Outgrow Strabismus?
      1. There is a common misconception that a child will outgrow strabismus. In most cases this is not true. In fact, the condition may get worse without treatment.
   4. How is Strabismus Treated?
      1. Treatment for strabismus may include single vision or bifocal eyeglasses, prisms, vision therapy, and in some cases, surgery. Vision therapy helps align your eyes and solves the underlying cause of strabismus by teaching your two eyes to work together. Surgery alone may straighten your eyes, but unless your eye muscle control is improved, your eyes may not remain straight. If detected and treated early, strabismus can often be corrected with excellent results. If left untreated amblyopia may develop.
6. Spots and Floaters
   1. What Are Spots and Floaters?
      1. Spots (often called floaters) are small, semi-transparent, or cloudy specks or particles within the vitreous, which is the clear, jelly-like fluid that fills the inside of your eyes. They appear as specks of various shapes and sizes, threadlike strands or cobwebs. Because they are within your eyes, they move as your eyes move and seem to dart away when you try to look at them directly.
   2. Does Everyone Have Spots?
      1. Almost everyone sees a few spots at one time or another. They can occur more frequently and become more noticeable as you grow older. If you notice a sudden change in the number or size of the spots, you should contact Dr. Cantrell right away for an examination to be sure they are not the result of a more serious problem.
   3. What Causes Spots?
      1. Spots are often caused by small flecks of protein or other matter trapped during the formation of your eyes before birth. They can also result from deterioration of the vitreous fluid, due to aging, or from certain eye diseases or injuries.
   4. Can These Spots Cause Blindness?
      1. Most spots are not harmful and rarely limit vision. However, spots can be an indication of more serious problems. You should see Dr. Cantrell for a comprehensive eye examination when you notice a flash or flashes of light associated with new floaters.
   5. How Are Spots Diagnosed?
      1. By looking in your eyes with special instruments, Dr. Cantrell can examine the health of your eyes and determine if what you are seeing is harmless or the symptom of a more serious problem that requires treatment.
7. Color Deficiency
   1. What is Color Deficiency?
      1. Color vision deficiency means that your ability to distinguish some colors and shades is less than normal. The term “color blind” is often used, but usually incorrectly. About eight percent of men and one percent of women are color deficient. Only a very small number of people are completely unable to identify any colors.
   2. What Causes Color Deficiency?
      1. Color deficiency is usually inherited, but can also result from certain diseases, trauma or as a side effect of certain medications. It occurs when the color-sensitive cone cells in your eyes do not properly pick up or send the proper color signals to your brain.
   3. What Types of Color Deficiency Exist?
      1. Red-green deficiency is by far the most common form and it results in the inability to distinguish certain shades of red and green. Those with a less common type have difficulty distinguishing blue and yellow. In very rare cases, color deficiency exists to an extent that no colors can be detected, only shades of black, white and grey.
   4. When Should a Person Be Tested for Color Deficiency?
      1. Because many learning materials are color-coded, it is important to diagnose color vision deficiency early in life. This is why the American Optometric Association and Dr. Cantrell recommend a comprehensive optometric examination before a child begins school.
   5. Can Color Deficiency Be Cured?
      1. Color vision deficiency is usually inherited and cannot be cured, but those affected can often be taught to adapt to the inability to distinguish colors. In some cases, a special red-tinted contact lens is used in one eye to aid people with certain color deficiencies.