Gilman & Vorster Optometry provides this information to help you better understand some of the more common and not so common vision related subjects.
Nearsightedness, or myopia, as it is medically termed, is a vision condition in which near objects are seen clearly, but distant objects do not come into proper focus. Nearsightedness occurs if your eyeball is too long or the cornea has too much curvature, so the light entering your eye is not focused correctly.
Farsightedness, or hyperopia, as it is medically termed, is a vision condition in which distant objects are usually seen clearly, but close ones do not come into proper focus. Farsightedness occurs if your eyeball is too short or the cornea has too little curvature, so light entering your eye is not focused correctly.
Astigmatism is a vision condition that occurs when the front surface of your eye, the cornea, is slightly irregular in shape. This irregular shape prevents light from focusing properly on the back of your eye, the retina. As a result, your vision may be blurred at all distances. People with severe astigmatism will usually have blurred or distorted vision, while those with mild astigmatism may experience headaches, eye strain, fatigue or blurred vision at certain distances.
Presbyopia is a vision condition in which the crystalline lens of your eye loses its flexibility, which makes it difficult for you to focus on close objects. Presbyopia usually becomes noticeable in the early to mid-forties. Presbyopia is a natural part of the aging process of the eye. It is not a disease and it cannot be prevented.
Lazy eye, or amblyopia, is the loss or lack of development of central vision in one eye that is unrelated to any eye health problem and is not correctable with lenses. It can result from a failure to use both eyes together. Lazy eye is often associated with crossed-eyes or a large difference in the degree of nearsightedness or farsightedness between the two eyes. It usually develops before age six and it does not affect side vision.
Symptoms may include noticeably favoring one eye or a tendency to bump into objects on one side. Symptoms are not always obvious.
Treatment for lazy eye may include a combination of prescription lenses, prisms, vision therapy and eye patching. Vision therapy teaches the two eyes how to work together, which helps prevent lazy eye from reoccurring.
Diabetic retinopathy is a complication of diabetes and a leading cause of blindness. It occurs when diabetes damages the tiny blood vessels inside the retina, the light-sensitive tissue at the back of the eye. A healthy retina is necessary for good vision.
If you have diabetic retinopathy, at first you may notice no changes to your vision. But over time, diabetic retinopathy can get worse and cause vision loss. Diabetic retinopathy usually affects both eyes. Annual dilated eye examinations can help detect the onset of diabetic retinopathy.
Age-Related Macula Degeneration
Macular degeneration is caused by the deterioration of the central portion of the retina, the inside back layer of the eye that records the images we see and sends them via the optic nerve from the eye to the brain. The retina’s central portion, known as the macula, is responsible for capturing the central vision in the eye It controls our ability to read, drive a car, recognize faces or colors, and see objects in fine detail.
A cataract is a clouding of the eye’s natural lens, which lies behind the iris and the pupil. The lens works much like a camera lens, focusing light onto the retina at the back of the eye. The lens also adjusts the eye’s focus, letting us see things clearly both up close and far away. Although most common in the elderly, cataracts can affect young children, with disastrous consequences
Retinoblastoma is a relatively uncommon tumor of childhood that accounts for about 3% of the cancers in children under the age of 15. The tumors originate in the retina, the light sensitive layer of the eye. When the tumors are present in one eye, it is referred to as unilateral retinoblastoma, and when it occurs in both eyes it is referred to as bilateral retinoblastoma. 60% of the cases involve only one eye (unilateral); the rest affect both eyes (bilateral). 90% of retinoblastoma patients have no family history of the disease and only 10% of newly diagnosed patients have other family members with retinoblastoma.
Choroidal melanoma is a primary cancer of the eye. It arises from the pigmented cells of the choroid of the eye and is not a tumor that started somewhere else and spread to the eye. Malignant means that the tumor is a cancer which may metastasize, that is, spread to other parts of the body. Although some choroidal melanomas are more life-threatening than others, almost all should be treated as if they were malignant.
Retinal Detachment and Retinal Tears
A retinal detachment occurs when the retina’s sensory and pigment layers separate. Because it can cause devastating damage to the vision if left untreated, retinal detachment is considered an ocular emergency that requires immediate medical attention and surgery. It is a problem that occurs most frequently in the middle-aged and elderly and can be associated with high nearsightedness.
Retinitis Pigmentosa is the name given to a group of inherited eye diseases that affect the retina. Retinitis pigmentosa causes the degeneration of photoreceptor cells in the retina. Photoreceptor cells capture and process light helping us to see. As these cells degenerate and die, patients experience progressive vision loss.
As the disease progresses and more rod cells degenerate, patients lose their peripheral vision. Patients with Retinitis Pigmentosa often experience a ring of vision loss in their mid-periphery with small islands of vision in the very far periphery. Others report the sensation of tunnel vision, as though they see the world through a straw. Many patients with Retinitis Pigmentosa retain a small degree of central vision throughout their life.
Ocular albinism in an inherited condition in which the eyes lack melanin pigment, while the skin and hair show normal or near-normal coloration.
Glaucoma is a group of eye diseases that gradually steal sight without warning. In the early stages of the disease, there may be no symptoms. Vision loss is caused by damage to the optic nerve. There is no cure for glaucoma. However, medication, laser or surgery can slow or prevent further vision loss. The appropriate treatment depends upon the type of glaucoma among other factors. Early detection is vital to stopping the progress of the disease.It was once thought that high pressure within the eye, also known as intraocular pressure or IOP, is the main cause of this optic nerve damage. Although IOP is clearly a risk factor, we now know that other factors must also be involved because even people with “normal” levels of pressure can experience vision loss from glaucoma.
Central retinal vein occlusion (CRVO) presents with mild to severe, sudden, painless, visual loss. The majority of patients will either have systemic hypertension, chronic open-angle glaucoma, or significant atherosclerosis.
A retinal artery occlusion occurs when the central retinal artery or one of the arteries that branch off of it becomes blocked. This blockage is typically caused by a tiny embolus (clot) in the blood stream. The occlusion decreases the oxygen supply to the area of the retina nourished by the affected artery, causing permanent vision loss.
Toxoplasmosis is an infectious condition caused by the parasite Toxoplasma gondii. The classic and most common ocular presentation is a retinal infection and associated inflammatory response, characterized by retinitis and uveitis of the eye. The condition is potentially blinding, though one eye is typically more severely affected than the other. About 98% of cases are congenital, being passed via the placenta to the unborn fetus. The domesticated cat is the definitive host of the Toxoplasma organism.