Age Related Macular Degeneration (AMD)
AMD is one of the most common causes of poor vision after age 60. It is a deterioration or breakdown of the macula. The macula is a small area at the center of the retina that is responsible for our straight-ahead central vision. This area allows us to see fine details clearly and perform activities such as driving, reading, crafting or recognizing faces. The visual symptoms of AMD involve loss of part or all of one’s central vision, while peripheral vision remains unaffected. Although a specific cause for development of AMD has yet to be determined, aging is one of the most significant risk factors. Other risk factors include heredity, blue eyes, high blood pressure, cardiovascular disease, exposure to UV light, and smoking.
There are two different types of AMD. Dry (or atrophic) AMD is the more common form. Approximately 90% of AMD patients have the dry form. This results in a thinning of the macula, which may take years to develop. Currently there is no treatment for dry AMD. However, studies have shown ocular vitamins with Lutein can help to slow the progression of AMD. The other form of AMD is wet (exudative) AMD. This is the more serious, but fortunately less common form. In wet AMD, abnormal blood vessels grow in the layer beneath the retina, leaking blood and fluid into the macula through “cracks” in the layers of the retina. This will cause permanent distortion or a large blind spot in the central vision. Laser treatment or injections into the eye can help to seal off the leaky vessels to help prevent further vision loss.
Amblyopia, or lazy eye, is the lack of development of vision in one eye that is not correctable with lenses. It is often associated with crossed-eyes (strabismus) or a large difference in the degree of nearsightedness or farsightedness (anisometropia) between the two eyes. It usually develops before the age of 6. Symptoms are not always obvious, but may include a tendency to favor one eye or bumping into objects on one side. Most often amblyopia is detected during a comprehensive eye examination. Treatment for amblyopia is most effective if diagnosed before 7 years old and can include a combination of glasses and patching of the non-amblyopic eye. Patching the better seeing eye forces the brain to use the amblyopic eye. This process allows the amblyopic eye to achieve better vision potential. Lazy eye will not resolve on its own. If detected only in teenage or adult years, treatment is non-effective. Therefore, it is important that all young children receive a comprehensive eye examination to make sure vision can develop normally.
Blepharitis is a common, persistent inflammation of the eyelids. This is usually caused by an excess growth of bacteria that is normally found on the skin, blockage of the eyelid’s oil glands, and occasionally allergies. It frequently occurs in people who have a tendency towards oily skin, dandruff or dry eyes.
Symptoms include redness, irritation, itching and burning. Because blepharitis is a chronic condition, it cannot be cured. However, it can be controlled with simple daily hygiene. First, a warm wet washcloth placed over the eyes at least once daily for a few minutes will help to loosen the debris on the lashes. This also helps to liquefy the oily secretion from the eyelid’s oil glands. Secondly, washing the eyelids with baby shampoo and rinsing with water will keep the eyelids clean and eyelashes free from debris. Thirdly, over-the-counter artificial tears (Refresh, Systane, TheraTears, etc.) can be used as needed to moisturize the eyes.
Sometime prescription eye drops are necessary, and can be used short-term, in conjunction with the lid hygiene.
A cataract is a loss of transparency, or clouding, of the normally clear lens inside the eye. The most common cause of a cataract is aging. Other causes include trauma, medications, systemic diseases and prolonged exposure to UV light. Occasionally, babies are born with a cataract. Reducing the amount of UV light exposure by wearing a wide-brimmed hat and sunglasses may reduce your risk of developing a visually-significant cataract, but once a cataract develops there is no cure other than to have it surgically removed. Glasses or contact lenses cannot sharpen your vision if a visually-significant cataract is present.
On examination, a cataract is graded on a scale of 0 to 4. Zero means no cataract development while 4 describes a very advanced cataract. A cataract may be removed at any point, but should be removed once the cloudiness affects the quality of vision and a person’s ability to perform daily activities, such as reading, driving, or working on a computer.
If you have diabetes mellitus, your body does not use and store sugar properly. Over time, this can damage the blood vessels in the retina. Non-proliferative diabetic retinopathy (NPDR) is an early stage of retinopathy in which tiny blood vessels within the retina leak blood or fluid. This can cause deposits in the retina called exudates or result in swelling within the layers of the retina. In many cases, mild to moderate NPDR will have no effect on vision unless it is accompanied with macular edema and/or macular ischemia.
Macular edema is caused by blood vessels leaking fluid in the center area of the retina. Because the macula is responsible for central vision, this part of the vision will be compromised. Laser treatment may help to control some vision loss; however some of the vision may be permanently lost.
Macular ischemia occurs when the small blood vessels that nourish this area of the retina close off. The vision blurs because the macula no longer receives adequate blood supply to function properly. Unfortunately, there are no effective treatments for macular ischemia.
Proliferative diabetic retinopathy (PDR) is advanced stage diabetic retinopathy. In PDR, the retinal blood vessels are so damaged that they close off. In response to lack of nourishment, the retina grows new, fragile blood vessels. These abnormal blood vessels grow on the surface of the retina so they don’t actually supply the retina with the nourishment that is needed. Occasionally, these blood vessels leak and cause a vitreous hemorrhage. A small amount of blood in this gel-like substance will cause dark floaters, while a large hemorrhage might block all vision. These new blood vessels can also cause scar tissue to grow. As the scar tissue shrinks, it can cause wrinkling and pulling on the retina which will distort vision. If the pulling is severe, the macula can detach from its normal position and cause vision loss.
Laser surgery may be used to shrink the abnormal blood vessels and reduce the risk of bleeding. The body may absorb the blood from a vitreous hemorrhage, but it may take time. A vitrectomy, removal of the gel substance from the eye, can be performed in the hemorrhage does not clear or if a retinal detachment is detected.
If you have diabetes, early detection of diabetic retinopathy is the best protection against vision loss. Because those with NPDR and PDR may have no symptoms until it’s too late for treatment, it is important to have a yearly diabetic eye examination. Also, strict control of blood sugar may significantly lower the risk of permanent vision loss.
Dry Eye Syndrome (DES)
Dry eye is a common, chronic condition in which there is insufficient tears to lubricate and nourish the eye. Tears are necessary for maintaining the health of the front surface of the eye in order to provide clear, comfortable vision. Those who suffer from dry eye either do not produce an adequate amount of tears or have poor quality tears. Symptoms of dry eye may include irritation, gritty feeling, scratchiness, burning, feeling that something is in the eye, excess watering or blurred vision. Risk factors for dry eye include:
Age – dry eye is a natural part of the aging process. A majority of people over 65 years old experience some symptoms.
Gender – dry eye is more common in women due to pregnancy, oral contraceptives and menopause.
Medications – antihistamines, decongestants, blood pressure medications and antidepressants can reduce the amount of tears produced in the eyes.
Medical conditions – those with rheumatoid arthritis, allergies, diabetes and thyroid problems are more likely to have DES.
Other factors – Exposure to smoke, wind and dry climates will increase tear evaporation causing dry eye symptoms. Staring at a computer screen or extended near vision tasks will reduce the amount of blinking which can contribute to eye dryness. Also contact lens wear and LASIK can lead to DES. Treatment for DES depends on the severity of the condition. Over-the-counter artificial tears can be used to supplement natural tear production in mild dry eye. Punctal plugs, small semi-permanent silicone plugs used to block the tear duct drainage system, can be used to keep natural tears in contact with the eye longer. Omega-3 fatty acid nutritional supplements or prescription Restasis can be used in more moderate dry eye to increase the production of the tears.
Floaters and Flashes
Floaters are a natural part of the aging process within the eye. The vitreous, a clear-like gel substance that fills the inside of the eye, tends to shrink slightly and detach from the retina, forming clumps within the vitreous. A floater is the shadow that these clumps cast on the retina. Floaters have been described as looking like a cobwebs, squiggly lines, floating bugs or clouds moving in the vision. Most people have some floaters normally, but do not notice them until they become more prominent.
Flashes, or the appearance of flashing lights, come from the traction of the vitreous gel on the retina at the time of vitreous separation. Flashes have been described as twinkles or lightning streaks.
Floaters and flashes are sometimes associated with a retinal tear. As the vitreous shrinks, it can pull on the retina causing a tear or detachment. If a new floater or flash of light appears suddenly, a dilated eye examination should be performed as soon as possible.
Glaucoma is the leading cause of blindness in the United States. It occurs over time as elevated intraocular pressure inside the eye causes damage to the individual fibers of the optic nerve. The optic nerve, located in the back of the eye, carries the images we see from the eye to the brain. The damage to the optic nerve results in loss of peripheral (side) vision or blind spots in the vision. If glaucoma goes undiagnosed for a long period of time, the loss of peripheral vision may be severe enough to affect one’s ability to perform daily activities, such as driving. Once the vision is lost due to glaucoma, treatment will not gain that vision back, but it can keep it from progressing further. Treatment for glaucoma includes various eye drops, selective laser trabeculoplasty, trabeculectomy and various other surgical procedures.
The most common form of glaucoma is primary open angle glaucoma (POAG). In this form, the aqueous humor fluid that normally circulates in the front portion of the eye is blocked from flowing out of the eye through the tiny drainage system known as the trabecular meshwork. This leads to the increase in intraocular pressure which can damage the optic nerve. Most people with POAG do not notice any symptoms until their vision is impaired.
Angle closure glaucoma (ACG) is caused when the iris (colored part of the eye) drops over and completely closes off the drainage angle, abruptly blocking the flow of aqueous humor fluid leading to increased intraocular pressure or optic nerve damage. In acute ACG, there is a sudden spike in intraocular pressure due to the buildup of the aqueous humor fluid. Symptoms may include eye pain, light sensitivity, nausea and vomiting. This condition is considered an emergency because vision loss and/or optic nerve damage can occur within hours. Normal or Low tension glaucoma is optic nerve damage and vision loss with “normal” intraocular pressure. Lowering the intraocular pressure further, using eye drops to decrease the amount of aqueous humor fluid in the eye, has shown to slow the progression of this type of glaucoma.
Childhood glaucoma is rare. It can start in infancy, childhood or adolescence. There are typically no symptoms of glaucoma in this early age. Blindness can result if left untreated. Like most forms of glaucoma, childhood glaucoma tends to run in families.
Posterior Vitreous Detachment (PVD)
The vitreous is a clear gel-like fluid that comprises two-thirds of the volume and weight of the eye. It fills much of the inside “hollow” space of the eyeball. Overtime, the vitreous becomes increasingly prone to a degenerative process known as syneresis. Syneresis is a contracting of the gel with loss of water which creates fluid filled cavities. This affects at least 65% of persons over 60 years of age, but can happen at a much earlier age. Those who are nearsighted are especially susceptible, even in childhood.
As a PVD is occurring, symptoms of this collapse and detachment of the vitreous may be evident as floaters and flashing lights. These floaters or flashing lights can also be associated with a retinal tear or detachment, which is a far more serious condition. It is for this reason that every new case of floaters or flashes requires a careful assessment of the vitreous and retina to identify the nature and origin of the problem. No tear may be found on the initial examination, but may occur later, so another examination is usually required within 4-6 weeks.
Strabismus refers to misaligned eyes. If the eye(s) turn inward, it is called esotropia. If the eye(s) turn outward, it is called exotropia. If one eye is higher than the other, it is called hypertropia. Hypotropia refers to the lower eye. Strabismus can be constant or intermittent and in one eye or alternate between the eyes. Strabismus usually begins in infancy or childhood. In some children, the eyes cross due to accommodative esotropia. In this case, the child is farsighted and requires glasses to correct the focusing issue which helps to straighten the eyes. Other cases of strabismus may not have a cause, although a positive family history does play a role. Acquired strabismus later in life can be due to a problem in the brain, an injury to the eye socket or thyroid eye disease. Symptoms of strabismus are often minor in children. Often a child may tilt his or her head in one direction, cover or squint with the eye that deviates. Adults, however, will have more debilitating symptoms such as double vision or loss of depth perception.
Early diagnosis and treatment is necessary in children to prevent amblyopia. Amblyopia is reduced vision in the eye that is turned. A patch may need to be worn over the good eye in order to force the lesser seeing eye to work better. Glasses may also be worn. Once both eyes are corrected to the best vision potential, eye surgery may be required to adjust the tension on the eye muscles to straighten the eye. The goal of surgery is to get the eyes close enough to perfectly straight that it is hard to see any residual eye turn. Surgery will improve the condition, although results are rarely perfect, and could be repeated in needed.
**This list is not inclusive of all eye conditions.**