Vision loss can be caused by many factors, such as:
• Abnormalities of the retina
• Abnormalities of the nerves
• Clouding of normally transparent eye structures
Second to our brains, the eyes are one of the most complex parts of our bodies, which is why at Crossroads Optometry we pride ourselves on giving proper eye exams and general information about your eyes. To explain loss of vision we have to explain how our eyes actually absorb light to see.
Light rays enter the eye through the cornea. The cornea’s refractive power bends the light rays. The light rays then pass freely through the pupil in the center of the iris. Once the light passes through the iris, the light rays pass through the crystalline lens. Light rays then pass through the vitreous (a gel like substance). This refractive process is carried by electrical impulses by the optic nerve to the brain.
The cornea is the last functioning part of an eye, being a protective clear barrier that not only keeps foreign particles from entering the eye but also admits light to begin the refractive process. This means that that smallest irregularity or scar in the cornea’s shape can cause vision to be affected (even if the rest of the eye is functioning properly). Understanding the importance of all the eye’s “moving parts” can help you “see” how they can be affected by particular diseases. Diseases like Macular Degeneration, Glaucoma, and Cataracts can cause different types of sight loss.
According to Macular.org, there is no cure for Macular Degeneration. The intrusive eye disease is caused by the deterioration of the central portion of the retina, which controls our ability to read, recognize faces or colors, drive a car, and even see objects in fine detail. Here’s an example of what people see when they have Macular Degeneration.
There are two types of Macular Degeneration:
• Dry: The atropic type is related to age. In fact, approximately 85% to 90% of the Macular Degeneration cases are the “dry” type. This form has people suffering with functional limitations (even if they have good central vision) that include fluctuating vision, difficulty with reading, and limited vision during reduced light (common at night). Drusen (the formation of small yellow deposits) is associated with the deterioration of the retina. This leads to the thinning and drying out of the macula, which in turn causes it to lose its function.
• Wet: The exudative type affects 10-15% of the cases of Macular Degeneration. During this type, abnormal blood vessels grow under the retina and macula. Theses blood vessels bleed and leak fluid, which causes the macula to bulge or “lift up” from its naturally flat position. This causes the central vision to be distorted or even be destroyed.
This condition is usually caused by damage to your eye’s optic nerve. Usually people who suffer from Glaucoma feel a buildup of pressure inside their eye. The increased pressure can actually damage the optic nerve. If the optic nerve (mentioned earlier as the part of the eye that carries electrical pulses to the brain) is damaged than it becomes increasingly harder for your eyes to have sight. If the damage continues (as it does in some cases) Glaucoma can lead to permanent vision loss. According to Web MD “without treatment, Glaucoma can cause total permanent blindness within a few years.”
Glaucoma is caused by the result of high fluid pressure inside the eyes. The liquid that’s in front part of the eye, ends up not circulating the way that it should. Usually the liquid flows in and out of your eyes through a “mesh-like channel.” Liquid builds up when that channel gets blocked. As of yet, doctors haven’t been able to find out a reason for the blockage. But treatment is necessary and advised!
There are two types of Glaucoma:
• Open-angle Glaucoma: The Trabecular meshwork (drain structure in your eye) looks normal, however fluid doesn’t flow out of it.
• Angle-closure Glaucoma: The eye doesn’t drain right due to the angle between your iris and cornea being too narrow. Since your iris is in the way, it can cause a buildup of pressure in your eye.
Cataracts are another leading cause of vision loss. Cataracts are a clouding of the eye’s natural lens, which lies behind the iris and the pupil. According to All About Vision, this is the most common cause of vision loss in people over age 40. Typically Cataracts start with your vision slightly blurred. Your vision looks as if you’re looking through foggy glasses. Cataracts might also make light seem too bright (during the day with the sun, as well as at night with headlights). For some, colors may even look more dull than they had been before.
There are three types of Cataracts:
• Subcapsular Cataract: This occurs at the back of the lens. People who are more susceptible to this type of Cataract is usually people with diabetes or those taking high doses of steroid medications.
• Nuclear Cataract: This occurs deep in the nucleus of the lens. This is usually associated with aging.
• Cortical Cataract: This occurs in the lens cortex, which surrounds the nucleus. It starts in the periphery of the lens and works its way to the center.
Macular Degeneration, Glaucoma, and Cataracts can cause major problems for your eyes including complete vision loss. Often these diseases (and others) can be spotted early on with regular eye exams. Stopping by Crossroads Optometry can help you keep your eye sight. Our trained and friendly optometrists can even help diagnosis and offer treatment methods, especially for the three leading causes of vision loss.