In the normal eye, light rays pass through the cornea, pupil, and lens and focus directly on the retina. When the cornea fails to focus light rays directly on the retina, refractive errors such as myopia, hyperopia, and astigmatism occur.
Myopia, or nearsightedness, occurs when the curvature of the cornea is too steep or the eyeball is too long. Therefore, light rays entering the eye focus in front of the retina. This results in blurred vision at distance.
Hyperopia, or farsightedness, occurs when the curvature of the cornea is too flat or the eyeball is too short. Therefore, light rays entering the eye focus in back of the retina. This results in blurred vision at near.
Astigmatism occurs when the curvature of the cornea is irregularly shaped, like the shape of a football. Therefore, light rays entering the eye focus at two different foci, causing blurred or distorted vision at distance and near. Astigmatism can occur alone or in conjunction with myopia and hyperopia.
Presbyopia is a vision condition in which the crystalline lens loses its flexibility or elasticity, making it difficult to focus on near objects. Generally, presbyopia becomes noticeable in the early to mid-40s. Presbyopia is an unpreventable age-related process. To help alleviate symptoms of presbyopia, reading glasses, bifocals, progressive lenses, and multifocal contact lenses can be prescribed.
Dry Eye Syndrome
Dry eye syndrome is a physical condition in which the front of the eye becomes dry. Symptoms of dry eyes will affect the majority of people at some time. Patients with dry eyes often report feelings of sandy, gritty, burning, tearing, and itchiness in the eye. Other symptoms include fluctuation in vision, contact lens intolerance and recurrent infections. Symptoms may worsen in hot and dry climates and can become more irritated by smoke, wind, and air conditioned environments.
Achieving relief from the symptoms of dry eye is easy with dry eye therapy. Therapy may be as simple as using over the counter artificial tears, but may be complex to involve the use of prescription medications and/or punctal plugs. A dry eye therapy plan is covered by most major medical insurances and can be easily implemented to help relieve the pesky ailments of dry eyes.
Allergy and Infections
Red eyes that itch and burn are commonly related to an allergy or in worse cases, an infection. Allergies are common and often present symptoms similar to those of dry eyes, but will definitely become more prevalent during hay fever season. Irritations caused by allergies can be alleviated with prescription eye drops.
When allergy-like symptoms are accompanied with pain or discomfort, eye secretions, vision loss, and light sensitivity, it may be due to an eye infection. Infections of the eyes may result from many scenarios, such as eye abrasions from injuries, foreign bodies, or contact lens wear. Symptoms of an emerging infection can be easily dismissed for an allergy or dry eye, hence it is important that all patients seek immediate care for any suspicious redness, pain, or sudden loss of vision.
Cataract is the clouding of the eye's natural crystalline lens. This loss of transparency decreases the amount of light that can reach the retina, resulting in overall blurriness of images. Signs and symptoms of cataract include: blurry, hazy vision, reduced intensity of colors, increased sensitivity to glare, increased difficulty with night vision, and changes in the eye's refractive error. Cataracts are typically due to age-related changes in the natural lens. Other precipitating factors may include: ultraviolet radiation exposure, diabetes, corticosteroid use, smoking, high alcohol consumption, and certain nutrient deficiency. Recent studies have shown that antioxidants (e.g. vitamin C, vitamin E, carotenoids) may decrease cataract formation.
Glaucoma is an eye disease caused by an increased pressure in the eye. This can damage the optic nerve that transmits visual information to the brain, resulting in the loss of vision. Glaucoma is the second leading cause of blindness in the U.S. Individuals over the age of 40, individuals with a family history of glaucoma, and African Americans are at an increased risk of developing glaucoma. Other risk factors for the development of glaucoma include: thinner corneas, systemic vascular conditions (e.g. diabetes, hypertension, heart disease), prolong corticosteriod use, high myopia, chronic ocular inflammation, and ocular trauma.
Macular degeneration (MD) is the leading cause of blindness in Americans over the age of 55. MD causes a deterioration and loss of photoreceptors and other cells in the macula, the part of the retina responsible for sharp, clear central vision. Because only central vision is usually affected, people rarely go blind from the disease. However, MD can sometimes make it difficult to read, drive, or perform other daily activities that require fine, central vision. Most people with MD have the dry form, for which there is no known treatment. The less common wet form may respond to laser procedures, if diagnosed and treated early. A major National Eye Institute study (AREDS) indicates that certain nutrients such as beta carotene (vitamin A) and vitamins C and E may help prevent or slow progression of MD.
The retina is the light-sensitive tissue that lines the inside back wall of the eye. In retinal detachment, the retina is separated from its underlying supportive tissue, depriving it from nutrients and oxygen. The longer the retina is detached, the greater the risk of permanent vision loss. Retinal detachment, thus, is a medical emergency requiring prompt surgical treatment to preserve vision. Warning signs of retinal detachment include: floaters, flashes of light, a sudden decrease in vision, and a shadow or curtain over the vision. Risk factors for retinal detachment include: high myopia, previous severe eye injury/trauma, family history of retinal detachment, and previous history of retinal detachment in the other eye.