With the use of electronics that appeal to users through visual interfaces, it is a pleasure to find an iPhone and iPod application that has the capability to, 'check-up,' on certain aspects of a person's eyesight. The Vision application by AppZap has some different capabilities that can help you to check and preserve your eyesight. You might even have some fun in the meantime. Included with the Vision application are the:
Ishihara Color Vision Test
Retinal Function Test
Visual field Test
The Ishihara Color Vision Test assists you in finding out if you have a form of color blindness. Below is an example image from one of the screens from the test. There are several of these images included in the test. The results are provided so that you can determine your own level of color-awareness.
Astigmatism is something that a person experiences when their cornea is more football-shaped than spherical. Persons with astigmatism have eyes that cause light rays to focus on two points in the back of their eyes instead of on one point. Those who have a common form of astigmatism are easily treatable, while persons who have a less-common form have vision that is more difficult to correct. Astigmatism is usually something that is hereditary; a number of people are born with corneas that are oblong and resulting vision that worsens as time progresses. Astigmatism can also be caused by an injury to a person's eye which has caused scarring to their cornea. Eye surgery may cause astigmatism, as well as, 'Keratoconus,' a disease which causes a gradual thinning of the cornea.
The retina is a multi-layered sensory tissue lining the back of the eye; it contains millions of photoreceptors which capture light rays and convert them into electrical impulses. The electrical impulses then travel along the person's optic nerve to their brain, where they are translated into images. The retina contains two types of photoreceptors; rods and cones. There are about six-million cones in a person's retina. Cones are contained in the, 'Macula,' a portion of the retina that is responsible for central vision. Cones are what allow a person to appreciate color.
A person's, 'Visual Field,' is the entire area they can see when their eye is directed forward, to include what they can see using peripheral vision. A visual field test is used to measure both the extent and distribution of the field of vision. There are a number of diseases that can affect someone's visual field such as strokes, glaucoma, hypertension, multiple sclerosis, hyperthyroidism, and diabetes. Some medications may also affect a person's field of vision.
The Vision application provides some simple tests and exercises that can help people to test and preserve their vision while having fun doing it. The application includes some interesting optical illusions and stereograms as well. The Stereograms create the illusion of depth from a flat, two-dimensional image while helping to relax the viewer's eye muscles. There is a feature called, 'Stereo Pairs,' included in the application that also creates the illusion of depth. It uses a pair of two-dimensional images, viewed with a cross-eyed technique that trains the viewer's eye muscles.
Vision for iPhone and iPod: app-zap.com/2008/10/30/vision/