Common eye conditions
Common eye conditions
Short sightedness, or myopia, is a common focusing error of the eye, and it has become more prevalent in recent years. In fact, a recent studies shows the prevalence of myopia grew from 25 percent of the population in 1971-1972, to 41.6 percent in 1999-2004.
Though the exact cause for this increase in myopia is still being studied, recent research shows it may be an adaptation of the visual system due to excessive near work and other extended near vision tasks, with less outside exposure to sunlight, coupled with a genetic predisposition for myopia.
Myopia Symptoms and Signs.
If you are short sighted, you typically will have difficulty reading road signs and seeing distant objects clearly, but will be able to see well for close-up tasks such as reading and computer use. Other signs and symptoms of myopia include squinting, eye strain and headaches. Feeling fatigued when driving or playing sports also can be a symptom of uncorrected short sightedness.
If you experience these signs or symptoms while wearing your glasses or contact lenses, schedule a comprehensive eye examination to see if you need a stronger prescription.
What Causes Myopia?
Myopia occurs when the eyeball is too long, relative to the focusing power of the cornea and lens of the eye. This causes light rays to focus at a point in front of the retina, rather than directly on its surface.
Myopia also can be caused by the cornea and/or lens being too curved for the length of the eyeball. In some cases, myopia is due to a combination of these factors.
Myopia typically begins in childhood and you may have a higher risk if your parents are short sighted . In most cases, nearsightedness stabilizes in early adulthood but sometimes it continues to progress with age.
We offer correction of myopia with glasses and contact lenses. Depending on the degree of your myopia, you may need to wear your glasses or contact lenses all the time or only when you need very clear distance vision, like when driving, seeing a chalkboard or watching a movie.
How do we slow down the progression of myopia?
Certain treatments have been shown to slow down the progression of myopia. Higher levels of myopia increase the risk of retinal detchments and macula degeneration related to myopia. Myopia control is the treatment of myopia that may keep the myopia at low levels.
Contact lenses have been shown to have a positive effect on the control of myopia.
- Ortho-K uses contact lenses that are worn overnight to flatten the cornea.
- Certain designs of multifocal contact lenses that have a centre distance prescription and a peripheral reading prescription have been shown to slow down myopia. These lenses are available in a daily disposable lens known as Misight, easy to use and look after for younger myopes.
- Glasses – glasses can have positive effect only in certain cases, usually when the myopia is low and associated with binocular vision problems at near working distances. Often by treating the cause of the early myopia with glasses before the eye changes shape and becomes more permanently myopic, we may be able to keep myopia from progressing.
- Vision therapy – myopia control is one of the areas that we work with in our vision therapy clinic, Vision Advantage. During the vision therapy program, visual efficiency skills that are reduced will be explored so that more flexibility is built into the focus system, eye alignment and peripheral vision. A flexible visual system that can relax and look out at far working distances is what we require to keep our vision clear and comfortable.
Like short sightedness and farsightedness, astigmatism is a focussing error, meaning it is not an eye health problem; it simply is a problem with how the eye focuses light.
In an eye with astigmatism, light fails to come to a single focus on the retina to produce clear vision. Instead, multiple focus points occur, either in front of or behind the retina (or both).
Astigmatism usually causes vision to be blurred or distorted to some degree at all distances. Symptoms of uncorrected astigmatism are eye strain and headaches, especially after reading or other prolonged visual tasks. Squinting also is a very common symptom of uncorrected astigmatism.
What Causes Astigmatism?
Astigmatism usually is caused by an irregularly shaped cornea. Instead of the cornea having a symmetrically round shape (like a soccerball), it is shaped more like a football, with one meridian being significantly more curved than the meridian perpendicular to it.
How Common is Astigmatism?
Astigmatism often occurs early in life, so it is important to schedule an eye exam for your child to avoid vision problems in school from uncorrected astigmatism.
We offer correction of myopia with glasses, contact lenses.
Presbyopia usually occurs beginning at around age 40, when people experience blurred near vision when reading, sewing or working at the computer.
You can’t escape presbyopia, even if you’ve never had a vision problem before. Even people who are short sighted will notice that their near vision blurs when they wear their usual glasses or contact lenses to correct distance vision.
Presbyopia Symptoms and Signs.
When people develop presbyopia, they find they need to hold books, magazines, newspapers, menus and other reading materials at arm’s length in order to focus properly. When they perform near work, such as craft work or handwriting, they may develop headaches, eye strain or feel fatigued.
What Causes Presbyopia?
Presbyopia is caused by an age-related process. This differs from astigmatism, nearsightedness and long sightedness, which are related to the shape of the eyeball and are caused by genetic and environmental factors. Presbyopia stems from a gradual thickening and loss of flexibility of the natural lens inside your eye.
Glasses with multifocal lenses are the most common correction for presbyopia, although multifocal contact lenses are becoming more prevalent.. Multifocal progressive glasses offer a more gradual visual transition between the distance and reading prescription, with no visible line between them.
Reading glasses are another choice, and are typically are worn just during close work.
Amblyopia, also known as lazy eye, is a vision development disorder in which an eye fails to achieve normal visual acuity, even with prescription glasses or contact lenses. Amblyopia begins during infancy and early childhood. In most cases, only one eye is affected. But in some cases, reduced visual acuity can occur in both eyes.
Particularly if lazy eye is detected early in life and promptly treated, reduced vision can be avoided. But if left untreated, lazy eye can cause severe visual disability in the affected eye, including legal blindness.
Amblyopia Signs and Symptoms.
Because amblyopia typically is a problem of very young children, symptoms of the condition can be difficult to detect. However, a common cause of amblyopia is strabismus ( turned eye) . So if you notice your baby or young child has crossed eyes or some other apparent eye misalignment, schedule an appointment for a children’s eye exam immediately.
Another clue that your child may have amblyopia is if he or she cries, fusses or becomes agitated when you cover one eye. This may suggest that the eye you have covered is the “good” eye, and that the uncovered eye is amblyopic, causing blurred vision.
What Causes Amblyopia?
Strabismus is the most common cause of amblyopia. To avoid double vision caused by poorly aligned eyes, the brain ignores the visual input from the misaligned eye, leading to amblyopia in that eye (the “lazy eye”). This type of amblyopia is called strabismic amblyopia.
Sometimes, amblyopia is caused by unequal focussing in the two eyes, despite perfect eye alignment. For example, one eye may have significant uncorrected short sightedness or long sightedness, while the other eye does not. Or one eye may have significant astigmatism and the other eye does not.
In such cases, the brain relies on the eye that has less uncorrected refractive error and ignores the blurred vision from the other eye, causing amblyopia in that eye from disuse.
Ultimately amblyopia and strabismus are problems of the brain’s visual system using the 2 eyes together well. The brain uses the main input of vision through the dominant eye, with weaker input from the other eye.
In some cases of amblyopia, normal vision can be achieved simply by fully correcting the focussing errors in both eyes with glasses or contact lenses. Often, however, vision therapy is required to retrain the brain to use the 2 eyes together. It may also involve some part time patching of the “good” eye to help the brain to pay attention to the visual input from the amblyopic eye and enable normal vision development to occur in that eye.
Treatment of strabismic amblyopia is more involved and may occasionally involve strabismus surgery to straighten the eyes. Appropriate glasses as well as vision therapy and some patching is most likely required to help the visual system align the 2 eyes.
Hyperopia, or longsightedness, is a common vision problem, affecting about a fourth of the population. People with hyperopia can see distant objects very well, but have difficulty focusing on objects that are up close.
Hyperopia Symptoms and Signs
Longsighted people sometimes have headaches or eye strain and may squint or feel fatigued when performing work at close range. If you get these symptoms while wearing your glasses or contact lenses, you may need an eye examination and a new prescription.
What Causes Hyperopia?
This vision problem occurs when light rays entering the eye focus behind the retina, rather than directly on it. The eyeball of a farsighted person is shorter than normal.
Most children have mild hyperopia. In fact it’s considered normal to have a low level of hyperopia.. It’s only necessary to treat hyperopia in children if it is a higher level than normal or the child finds it difficult to focus even with lower levels of hyperopia.
Hyperopia outside normal levels has been found to have an impact on learning ability. Attention is given to the visual system and keeping the vision clear, rather than to the task at hand.
Sometimes people confuse hyperopia with presbyopia, which also causes near vision problems but for different reasons.
Longsightedness can be corrected with glasses or contact lenses to change the way light rays bend into the eyes. You may need to wear your glasses or contacts all the time or only when reading, working on a computer or doing other close-up work.
Diabetic Retinopathy is damage to the retina caused by complications of diabetes mellitus, and can often lead to blindness. It often has no early warning signs, so early detection is very important.
Small blood vessels – such as those in the eye – are especially vulnerable to poor blood sugar (blood glucose) control. An over-accumulation of glucose and/or fructose damages the tiny blood vessels in the retina. During the initial stage, called non-proliferative diabetic retinopathy (NPDR), most people do not notice any change in their vision.
Some people develop a condition called macular edema. It occurs when the damaged blood vessels leak fluid and lipids onto the macula, the part of the retina that lets us see detail. The fluid makes the macula swell, which blurs vision.
As the disease progresses, the lack of oxygen in the retina causes fragile new blood vessels to grow along the retina and in the clear, gel-like vitreous humour that fills the inside of the eye. Without timely treatment, these new blood vessels can bleed, cloud vision, and destroy the retina.
Macular Degeneration (MD) is a disease associated with aging that gradually destroys central vision. Central vision occurs at the macula on the retina, at the back of the eye. Because it is the central part of vision, it is needed for seeing objects clearly and for common everyday tasks such as reading and driving.
In some cases, MD advances so slowly that people fail to notice the gradual deterioration of their vision. In others, the disease progresses faster and may lead to a permanent loss of central vision.
While there is presently no cure for Macular Degeneration, there are steps that you can take to prevent or slow the progress of the disease.
MD is present in 15% of people between the ages of 70-75 and is now the leading cause of blindness and severe vision loss in Australia.
Symptoms of Macular Degeneration
- The first signs of MD involve distortion of vision where straight lines appear wavy or bent, rather than loss of sight.
- Difficulty reading.
- Difficulty distinguishing faces.
- Need for increased illumination.
- Sensitivity to glare.
- Decreased night vision.
- Reduced colour sensitivity.
- In many cases, MD progresses so slowly that people don’t notice changes until their vision has already been significantly compromised.
Risks for developing MD:
- Ageing is the greatest risk factor. The prevalence trebles with each decade over 40 years.
- Smokers have a 3 times greater risk of developing MD. They also develop the disease approximately 10 years earlier than non-smokers.
- Women have slightly higher risk than men.
- Family history is a risk factor. Genes have been identified and linked with MD. There is a 50% chance of developing MD if there is a family history of the disease.
Defense against MD:
- Early detection of MD is crucial as some forms of the disease may be arrested with early treatment.
- Regular eye examinations are the key to early detection before vision loss occurs.
- Eat a healthy diet. (See more details below).
- Consider taking a zinc and anti-oxidant supplement.
- Eye protection against UV damage. This is especially important before MD develops.
- Maintain a healthy weight and get some regular exercise (minimum of a 30 minute walk, three times a week).
- Don’t smoke.
Diet and MD
Diet can help with good eye health and there is a recommended eating program that can lower the risk of Macular Degeneration. Scientific studies have shown that MD responds to anti-oxidants and other nutrients. This is not an unpleasant diet, but simply emphasizes the benefits of vegetables, fruit and fish.
- Anti-oxidants benefit our health by neutralisng “free radicals” in the body. The most important anti-oxidants are:
- Lutein – Found in especially high levels in leafy dark green vegetables (eg spinach)
- Vitamin C – Found in citrus fruits, papaya and rockmelon. Or vegetables like capsicum, peas and broccoli.
- Vitamin E – Found in nuts (almonds, pine nuts, brazil nuts), whole grains, leafy green vegetables, broccoli and carrots.
- Zinc – Found in meat, seafood (especially oysters), nuts (cashews, pine nuts, brazil nuts, pecans, almonds) and whole grains.
Eat a healthy well-balanced diet. Include fish at least two times a week and include dark green leafy vegetables. Eat fresh fruit every day, a handful of nuts each week and avoid fatty foods.
Glaucoma is a disease where the pressure within the eye is typically increased (although not always). This can damage parts of the eye, and if left untreated may result in blindness.
Many times the symptoms are not noticeable until damage to the eye has already occurred. Diagnosis consists of having regular eye examinations which include a pressure measurement and visual field assessment (usually every 2 years for patients over 40), to enable early detection of possible problems.