Imperfections in the focusing power of the eye are called refractive errors. There are three primary types of refractive errors: myopia, hyperopia and astigmatism. Combinations of myopia and astigmatism or hyperopia and astigmatism are common. With age, presbyopia and cataracts can also impair vision.
- Persons with myopia, or nearsightedness, have more difficulty seeing distant objects as clearly as near objects.
- Hyperopia, or farsightedness, have more difficulty seeing near objects as clearly as distant objects.
- Astigmatism is a distortion of the image on the retina caused by irregularities in the cornea or lens of the eye.
- People over the age of forty also suffer from increased difficulty in reading. This condition is called presbyopia.
- Cataracts form cloudy areas on the eye lens and reduce vision.
Short sightedness (Myopia)
Myopia is the most common refractive error, affecting one in five Australians. Myopic patients are nearsighted; they see close objects more clearly, but distant objects are blurry or even indistinguishable.
Myopia occurs when the eye is too long or the cornea is too steep. As a result, light rays entering the eye fall in front of the retina instead of directly on it. The condition can be inherited and usually starts in childhood and stabilizes in the late teens or early adulthood.
Traditionally, spectacles or contact lenses have been prescribed to refocus light entering the eye directly onto the retina. However refractive surgeries like LASIK Zyoptix Custom Eyes Epilasik or ICL lens surgery are delivering great results and permanent corrections.
A myopic eye may be longer than usual or the cornea too steep. Images fall in front of the retina, causing distant objects to appear blurry.
Far sightedness (Hyperopia)
Hyperopic patients are farsighted; they can focus on more distant objects, but close-up objects appear blurry.
Hyperopia occurs when the eye is shorter than normal or the cornea is too flat. As a result, light rays are not focused by the time they reach the retina.
In young people, the natural lens can sometimes correct the focus in hyperopic eyes. With aging, the natural lens loses this ability and the vision blurs. This is why many hyperopic patients do not become aware of their condition until they enter their 20s or 30s.
Once diagnosed and having lived a significant part of their lives without corrective lenses, many people instead choose permanent visual freedom with refractive surgery like LASIK.
A hyperopic eye may be shorter than usual or the cornea too flat. Images are not in focus when they reach the retina, causing close objects to appear blurry.
Astigmatism
Astigmatism occurs when the curve of the cornea, and sometimes the lens, is uneven-steeper in one direction than the other-like a football or the back of a spoon. Almost everyone has some small degree of astigmatism, but for some the uneven curve causes light rays to focus on many points in the eye and distorts both close and far vision.
Traditionally spectacles and contact lenses have been prescribed to correct the blurred image. Refractive procedures like Lasik & Custom Eyesnow offer excellent results and visual freedom.
An astigmatic eye has an unevenly curved cornea. Images fall in front of and beyond the retina, causing both close and distant objects to appear blurry.
Loss of Reading Vision (Presbyopia)
Presbyopia is the age-related loss of close-up focusing ability. When we are young, our eye's lens is soft and flexible and can change shape easily, allowing the eye to focus on objects both close and far away. As people enter their 40s, the lens becomes less flexible and is unable to focus on close-up objects.
Initially the blurring is worse in dim light, which is why many people first realise they have presbyopia when they have difficulty reading a menu. Later, the fine print in newspapers, magazines and phone books appears blurry.
Near vision is most often corrected with reading glasses or bifocals, now Lasik or Conductive Keroplasty can be used instead to allow people to continue enjoying life free from visual aids.
With presbyopia, the eye's lens can no longer change shape to focus on close objects. Images are not in focus by the time they reach the retina.
Cataracts
A cataract is a loss of clarity within the lens of the eye. A normal lens is clear and lets light pass to the back of the eye. When a cataract forms in the lens it blocks some of the light. As it develops, it becomes harder for a person to see.
Cataracts are a normal part of aging. About half of Australians aged between, 65 to 74 have some cataract. About 70 percent of those 75 and over have this condition.
Most people with cataracts have a cataract in both eyes. However, one eye may be worse than the other because each cataract develops at a different rate. Some people with cataract don't even know it. Their cataract may be small, or the changes in their vision may not bother them very much. Other people who have cataracts cannot see well enough to do the things they need or want to do.
What Are the Symptoms of a Cataract?
- Cloudy, fuzzy, foggy, or filmy vision.
- Changes in the way you see colors.
- Problems driving at night because of glare from car headlights.
- Problems with glare from lamps or the sun.
- Frequent changes in your glasses prescription (increasing shortsightedness).
- Double vision
These symptoms may also be signs of other eye problems.
Find out more about cataract symptoms and surgery.