Disclaimer: The information and reference materials provided are intended solely for the general educational purposes and discussion with patient’s own physician. Information presented here is not intended to diagnose or treat health problems or take the place of professional medical care.
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Anatomy Of A Human Eye
- Nearsightedness (myopia) is a vision condition that causes blurred distance vision but near vision is often clear. Blurred distance vision is most often noticed with tasks such as seeing the whiteboard at school, watching the television, or driving. The eyeball is too long or the cornea has more curvature than needed to focus light precisely on the back of the eye. This condition affects approximately 1/3 of the U.S. population. Nearsightedness can be corrected with spectacles, contact lenses, or other refractive procedures.
- Farsightedness (hyperopia) is a vision condition that often allows distant objects to be seen clearly but near vision is blurry. The eyeball is too short or the cornea has too little curvature to focus light precisely on the back of the eye. This can lead to difficulty eye strain, headaches, concentrating, and intermittent blurred vision. In mild cases of farsightedness, the eye can compensate for this by accommodating but it can sometimes cause eyestrain. This can be corrected with spectacles, contact lenses, or other refractive procedures.
- Astigmatism is a vision condition that causes blurred vision. The curvature of the cornea and lens bends light to focus it precisely on the back of the eye. With astigmatism the lens or cornea may have a different curvature in one direction causing light to be focused in two different places on the retina. This leads to blurry or distorted vision. Small amounts of astigmatism are common and may not have a large effect on vision. Astigmatism can be corrected with spectacles, contact lenses, or other refractive procedures.
Presbyopia is a change in the crystalline lens that causes a decrease in the eyes accommodative ability. This decrease in accommodation makes near vision more difficult causing small print to become blurred and can often lead to eye strain. This change typically becomes noticeable in the early to mid 40’s and poor lighting conditions often exacerbate the problem. This can be corrected for with several different types of spectacles or contact lenses.
Ocular Disease Management
As our population ages, vision loss from eye diseases is increasing. According to the National Eye institute (NEI) the most common eye diseases in people over the age of 40 are:
A condition in which the eye's normally clear lens becomes cloudy. It eventually occurs in both eyes but may be more noticeable in one eye first. Since less light passes through a cloudy lens, vision blurs. Cataracts are small at first and may not affect vision. But the denser they grow, the more they affect your vision. Most cataracts are due to aging. Other risk factors include: Diseases like diabetes, eye injury or trauma, eye surgery for another problem, inheritance or pregnancy-related causes (Babies can be born with cataracts or develop them in childhood.), overexposure of eyes to the sun's damaging ultraviolet (UV) rays, smoking, and certain medications.
AMD damages, then destroys central vision, which is our fine detailed vision. This eye disease takes two forms, dry and wet. About 90% of AMD cases are dry. The remaining 10% are wet, a more advanced form. Wet AMD is more damaging causing about 90% of serious vision loss.
- An Amsler grid is a tool used to detect vision changes at home.
- While wearing your glasses used for near, hold the Amsler grid at approximately 33 cm or 13 inches.
- Cover one eye and stay focused on the black dot in the center.
- Look for any wavy, squiggly, or missing lines in the grid. If you detect a change in your vision contact your eyecare provider right away.
Diabetics are at risk for developing several eye diseases: Diabetic retinopathy, glaucoma, and cataracts. Diabetic retinopathy is the most common eye disease in people with diabetes. It affects over 5 million Americans ages 18 and older. Usually both eyes develop the disease. Diabetic retinopathy progresses in four stages. The most severe is proliferative retinopathy. More than a third of people with diabetes don't get proper vision care. This puts them at higher risk for blindness. If you have diabetes, be vigilant about eye and vision care. People with diabetes, even those without diagnosed eye disease, need to see their eye doctor once a year. Those with diabetic changes in their eyes need to be seen more frequently.
A group of related eye diseases that can cause blindness. Many people who have it don't know it. Symptoms don't appear until glaucoma has already damaged the optic nerve. This nerve carries images from the eye to the brain. Glaucoma is usually associated with an elevated pressure inside the eye (intraocular pressure). The most common type of glaucoma is primary open-angle glaucoma. Its causes are not yet clearly understood. Glaucoma can also develop without an increase in eye pressure, called low-tension or normal-tension glaucoma.
Floaters are commonly described as small dots, squiggly lines, clouds or cobwebs moving in your field of vision. Floaters are tiny clumps of the vitreous gel that fills the back of the eye. These clumps cast a shadow on the retina causing them to appear as if they are in your field of vision. They are often seen more frequently when looking at plain background such as the blue sky, water, white paper, or a blank wall.
Dry eye is a disease where the ocular surface is affected by an imbalance of the layers of tear film which include the lipid layer, aqueous layer, and mucin layer. This can be due to several different causes including: ocular surface inflammation, hyperosmolarity, and tear film instability. Good quality tears are important to lubricate and nourish the eye to provide comfortable, stable, and clear vision. Symptoms may include: irritation, burning, stinging, scratchy sensation, excess tearing, fluctuations in vision, sensitivity to fans, A/C, wind or smoke.
- Meibomian Gland Dysfunction can also contribute to dry eye symptoms and is a condition where the oil glands in the eyelid become clogged or congested and do not secrete good quality lipids or oils on the ocular surface. This leads to a poor quality tear film and many of the above dry eyes symptoms.
- Blepharitis is inflammation of the eyelid commonly caused by bacteria and oil accumulation at the base of the eyelashes. Symptoms can include eyelid irritation, redness, and itching and burning.
Also known as an eye turn, strabismus is a condition where the two eyes do not always align. This is often due to an imbalance of the extraocular muscles. Proper eye alignment is important to avoid seeing double, have good depth perception and to allow for proper development of both eyes.
Also known as a “lazy eye", amblyopia is caused by a lack of neural development of central vision in one or both eyes. This can be associated with an eye turn or can be caused by a refractive difference between the two eyes leading one eye to do most of the work. Symptoms may include favoring one eye but often symptoms are not evident.
Click here to find more resources about amblyopia and register your child in the Ohio amblyopia registry.
Computer Vision Syndrome
Also known as digital eye strain, computer vision syndrome is a group of eye and vision related problems that results from extended computer, tablet, or cell phone use. The average American worker spends 7 hours on a computer in the office or at home. The most common symptoms include eyestrain, headaches, blurred vision, dry eyes, and neck and shoulder pain. These symptoms can be exacerbated by poor lighting, glare on screens, improper viewing distance, poor seating posture, or uncorrected vision problems. One simple tip to help alleviate digital eye strain is to follow the 20-20-20 rule, take a 20 second break to look at something 20 feet away every 20 minutes.
Smoking and Eye Disease
People who smoke are at an increased risk for developing many eye disease including: cataracts, age-related macular degeneration, dry eye, and increased susceptibility to damage to the optic nerve. Contact your primary care doctor for resources to help with smoking cessation.
There's no substitute for the quality of life good vision offers. Adding certain nutrients to your daily diet—either through foods or supplements—can help preserve your vision. Researchers have linked eye-friendly nutrients, such as lutein and zeaxanthin, vitamin C, vitamin E and zinc, to reducing the risk of certain eye diseases.
Lutein & Zeaxanthin are important nutrients found in green leafy vegetables, as well as other foods, such as eggs. Many studies show that lutein and zeaxanthin reduce the risk of chronic eye diseases, including age-related macular degeneration and cataracts.
Vitamin C (ascorbic acid) is an antioxidant found in fruits and vegetables. Scientific evidence suggests vitamin C lowers the risk of developing cataracts. Also, when taken in combination with other essential nutrients, it can slow the progression of age-related macular degeneration and visual acuity loss.
Vitamin E is a powerful antioxidant found in nuts, fortified cereals and sweet potatoes. Research indicates it protects cells in the eyes from unstable molecules called free radicals, which break down healthy tissue.
Essential Fatty Acids are a necessary part of the human diet. They maintain the integrity of the nervous system, fuel cells and boost the immune system. Research shows omega-3 fatty acids are important for proper visual development and retinal function.
- Zinc is an essential trace mineral or "helper molecule." It plays a vital role in bringing vitamin A from the liver to the retina in order to produce melanin, a protective pigment in the eyes. Zinc is highly concentrated in the eye, mostly in the retina and choroid, the vascular tissue layer lying under the retina.
At the end of the day, eating to maintain eye health isn’t all that different from regular healthy eating.