Common Eye Diseases
Age-related macular degeneration — also called macular degeneration, AMD or ARMD — is deterioration of the macula, which a small area in the centre of the retina of the eye that controls visual acuity.
The retina is the light sensitive tissue located in the back of the eye. It is like the film in a camera, recording the images we see and sending them to the brain via the optic nerve. The retina almost instantly converts light images into electrical impulses through a chemical reaction and then sends these impulses to the brain, where we interpret what we see, process the visual information, and relate what we see to the rest of our environment.
The macula is a small portion of the retina located in the central portion of the retina. The macula is responsible for central vision (straight-ahead vision) and provides the ability to see fine detail in your direct line of sight. We use the macula of each eye to have the clear vision that allows us to read, drive a car, and recognize faces or colours. The non-macular areas of the retina provide us with our side and night vision.
While there are many causes of macular degeneration, including genetic abnormalities such as Stargardt disease, age-related macular degeneration (AMD or ARMD) is by far the most common type. AMD is a disease associated with aging, that gradually destroys the sharp central vision that is needed for seeing objects clearly and for common daily tasks such as reading and driving. In some cases, AMD advances so slowly that people notice little change in their vision. In others, the disease progresses faster and may lead to a loss of vision in one or both eyes.
AMD occurs in two forms. “Wet” age-related macular degeneration is less common but more aggressive in its progression to severe central vision loss. “Dry” age-related macular degeneration is the more common type and is more slowly progressive in causing visual loss.
Wet AMD occurs when abnormal blood vessels grow under and into the macular portion of the retina. These new blood vessels (known as choroidal neovascularization or CNV) tend to be very fragile and often leak blood and fluid. The blood and fluid raise the macula from its normal place at the back of the eye and cause the central vision to blur. Under these circumstances, vision loss may be rapid and severe. Some patients, however, do not notice visual changes despite the onset of CNV so regular eye examinations are very important for patients at risk for CNV.
Once CNV has developed in one eye, whether there is a visual loss or not, the other eye is at high risk for the same change.
In dry AMD, the light sensitive cells in the macula slowly break down. With less of the macula functioning, central vision diminishes.
Dry AMD has three stages (early, intermediate, or advanced), all of which may occur in one or both eyes. These are defined by the amount and characteristics of the drusen that are present.
Retinal drusen are yellow deposits under the retina. Dr Zondi can detect drusen during a comprehensive dilated eye exam.
In addition to drusen, people with advanced dry AMD have a breakdown of light-sensitive cells and supporting tissue in the central retinal area. This breakdown can cause a blurred spot in the center of your vision. Over time, the blurred spot may get bigger and darker, taking more of your central vision. You may have difficulty reading or recognizing faces until they are very close to you.
Age-Related Macular Degeneration is a serious condition that requires consistent monitoring. If you suspect AMD, please contact Dr Zondi to schedule a comprehensive eye examination to assess the degree of degeneration and help you prevent further vision loss.
A cataract is a clouding of the eye’s natural lens, which lies behind the iris and the pupil.
They usually begin when proteins in the eye form clumps that prevent the lens from sending clear images to the retina. The retina works by converting the light that comes through the lens into signals. It sends the signals to the optic nerve, which carries them to the brain.
Cataracts usually develop slowly and eventually interfere with your vision. You may form cataracts in both eyes, but they usually don’t form at the same time. Cataracts are common in people over 40 years old.
Types of cataracts include:
- A subcapsular cataract occurs at the back of the lens. People with diabetes or those taking high doses of steroid medications have a greater risk of developing a subcapsular cataract.
- A nuclear cataract forms deep in the central zone (nucleus) of the lens. Nuclear cataracts usually are associated with aging.
- A cortical cataract is characterized by white, wedge-like opacities that start in the periphery of the lens and work their way to the centre in a spoke-like fashion. This type of cataract occurs in the lens cortex, which is the part of the lens that surrounds the central nucleus.
Cataracts usually start out small, and don’t affect your vision too much initially. You may begin noticing blurriness in your vision, which may get worse over time. You also notice sensitivity to light, or colours seeming duller than normal.
The type of cataract you have will affect exactly which symptoms you experience and how soon they will occur. When a nuclear cataract first develops, it can bring about a temporary improvement in your near vision, called “second sight.”
Unfortunately, the improved vision is short-lived and will disappear as the cataract worsens. On the other hand, a subcapsular cataract may not produce any symptoms until it’s well-developed.
Diabetic eye disease — known by its medical term, diabetic retinopathy — is an eye issue that specifically affects people who have diabetes. If you are diabetic, you should receive specialized screenings on a regular basis. Dr Zondi offers comprehensive Diabetic Eye Exams for patients who suffer with Diabetes.
Diabetic eye disease affects blood vessels in your retina, which is located in the back of your eyeball. The disease is the most common cause of permanent vision loss for people who suffer with diabetes, and it’s the leading cause of blindness among adults over the age of 20.
Cataracts and glaucoma may also develop as a result of diabetic eye disease. A cataract is a hazing or clouding of the eye’s lens caused by a buildup of protein within the lens that obscures vision. Adults who have diabetes are two to five times more likely to develop cataracts than those people who don’t have diabetes. Cataracts may also form among younger-aged people with diabetes.
Diabetic Retinopathy is a result of high blood sugar damaging the tiny blood vessels in your retina. The function of the retina is to receive the focused light that’s projected from the lens of the eye, and convert it to impulses that are sent to your brain through the optic nerve.
The blood vessels that are weakened by the high sugar levels from diabetes can haemorrhage (bleed) or leak fluid, which results in distorted vision. In severe cases, the blood vessels in the retina can accumulate on the surface of the retina, which can lead to cell loss in the retina, permanent scarring and ultimately vision loss.
Diabetic retinopathy typically progresses through four phases:
Mild nonproliferative retinopathy: The first phase occurs when small areas of swelling called micro aneurysms bloom in the blood vessels of the retina. These balloon-like areas of swelling may leak blood into your eye or fluid into your retina, obscuring your vision.
Moderate nonproliferative retinopathy: The next phase of diabetic retinopathy occurs when the swelling blood vessels begin to distort and lose their ability to transport blood. This phase may start to change the appearance of your retina.
Severe nonproliferative retinopathy: In this phase, the swelling, blood and fluid blocks even more blood vessels. By this point, the blood has begun to clot, preventing nutrients from reaching certain areas of your retina. These blood-deprived areas begin to secrete growths that signal the retina to grow new blood vessels to replace the blocked and damaged ones.
Proliferative diabetic retinopathy (PDR): The final phase of diabetic retinopathy occurs when the new blood vessels formed in severe nonproliferative retinopathy become weak and fragile, at which time they also can leak and bleed. Additionally, the scar tissue from the old blood vessels that are blocked can contract and tear the retina, which causes retinal detachment, the separation of the retina from underlying tissue at the back of your eyeball. Retinal detachment may result in permanent blindness.
The onset of diabetic retinopathy may not present any symptoms at all. Symptoms usually only appear when the disease progresses to the state that it affects your vision. This is why it’s so important to get regular eye exams, especially if you know you have diabetes.
The blood and other fluid that leaks from blood vessels can cause eye floaters, also called blood spots in the eye. Floaters are not necessarily signs of diabetic eye disease and they can go away on their own, but without treating the issue promptly, you increase the risk of permanent vision loss. If you are having any visual abnormalities you should always be evaluated with a thorough consultation and examination by an ophthalmologists as it may be a symptom or sign of a serious illness or condition.
If you are having any abnormal visual symptoms, give Dr Zondi a call and schedule a thorough consultation. Our patients are our number one priority and we strive to ensure that each patient leaves our practice with the best results possible.
Most common vision problems are caused by refractive errors – which means that the shape of your eye does not bend light correctly, resulting in a blurred image. Refractive disorders are usually the result of an eyeball that is too short or too long, a cornea (the clear front part of your eye) that is irregularly shaped, or a lens that is curved too much or too little.
The main types of refractive errors are myopia (nearsightedness), hyperopia (farsightedness), presbyopia (loss of near vision with age), and astigmatism.
Myopia (close objects are clear, and distant objects are blurry) – Also known as nearsightedness, myopia is usually inherited and often discovered in childhood. Myopia often progresses throughout the teenage years when the body is growing rapidly.
Hyperopia (close objects are more blurry than distant objects) – Also known as farsightedness, hyperopia can also be inherited. Children often have hyperopia, which may lessen in adulthood. In mild hyperopia, distance vision is clear while near vision is blurry. In more advanced hyperopia, vision can be blurred at all distances.
Presbyopia (aging of the lens in the eye) – After age 40, the lens of the eye becomes more rigid and does not flex as easily. As a result, the eye loses its focusing ability and it becomes more difficult to read at close range. This normal aging process of the lens can also be combined with myopia, hyperopia or astigmatism.
Astigmatism – Astigmatism usually occurs when the front surface of the eye, the cornea, has an asymmetric curvature. Normally the cornea is smooth and equally curved in all directions, and light entering the cornea is focused equally on all planes, or in all directions. In astigmatism, the front surface of the cornea is curved more in one direction than in another. This abnormality may result in vision that is much like looking into a distorted, wavy mirror. Usually, astigmatism causes blurred vision at all distances.
A refractive error is usually diagnosed during a routine eye examinations. Testing usually consists of asking the patient to read a vision chart while testing an assortment of lenses to maximize a patient’s vision. Special imaging or other testing is rarely necessary, but Dr Zondi is able to provide all the tests necessary to accurately diagnose any refractive errors you may have.
Glaucoma is an eye condition that damages the optic nerve, the nerve which supplies visual information to your brain from your eyes. Glaucoma is usually a result of abnormally high pressure inside your eye.
The back of your eye continuously makes a clear fluid called aqueous humour. As this fluid is made, it fills the front part of your eye. Then, it leaves your eye through channels in your cornea and iris. If these channels are blocked or partially obstructed, the natural pressure in your eye, which is called the intraocular pressure (IOP), may increase. As your IOP increases, your optic nerve may become damaged. As damage to your nerve progresses, you may begin losing sight in your eye.
What causes the pressure in your eye to increase isn’t always known.
However, doctors believe one or more of these factors may play a role:
- dilating eye drops
- blocked or restricted drainage in your eye
- medications, such as corticosteroids
- poor or reduced blood flow to your optic nerve
- high or elevated blood pressure
Over time, the increased pressure can erode your optic nerve tissue, which may lead to vision loss or even blindness. If it’s caught early, you may be able to prevent additional vision loss.
There are 5 major types of Glaucoma, and these types are categorised as follows:
- Primary open-angle glaucoma. This is the most common form of glaucoma. Damage to the optic nerve is slow and painless but those affected can lose a large portion of vision before they notice any vision problems.
- Angle-closure glaucoma. This type of glaucoma, also called closed-angle glaucoma or narrow-angle glaucoma, is a less common form of the disease. It is a medical emergency that can cause vision loss within a day of its onset, and it occurs when the drainage angle in the eye (formed by the cornea and the iris) closes or becomes blocked. Many people who develop this type of glaucoma are born with a very narrow drainage angle. With age, the lens in the eye becomes larger, pushing the iris forward and narrowing the space between the iris and the cornea. As this angle narrows, the fluid in the eye is blocked from the drainage system. So the fluid builds up and eye pressure increases. Angle-closure glaucoma can be chronic (progressing gradually) or acute (appearing suddenly). The acute form occurs when the iris completely blocks fluid drainage. When people with a narrow drainage angle have their pupils dilated, the angle may close and cause a sudden increase in eye pressure.
- Secondary glaucoma. This type of glaucoma forms as a result from trauma or disease. It may be caused by a variety of medical conditions, medications, physical injuries and eye abnormalities. Sometimes eye surgery can also lead to secondary glaucoma.
- Normal-tension or low-tension glaucoma. In this form of glaucoma, eye pressure remains within the “normal” range, but the optic nerve is damaged nevertheless. The cause of this form of glaucoma remains a mystery, but advances in Ophthalmology may provide us with answers in the near future.
- Congenital Glaucoma. Children born with congenital glaucoma have a defect in the angle of their eye, which slows or prevents normal fluid drainage. Congenital glaucoma usually presents with symptoms, such as cloudy eyes, excessive tearing, or sensitivity to light. Congenital glaucoma can be hereditary.
The most common type of glaucoma is primary open-angle glaucoma. It has no signs or symptoms except gradual vision loss. For that reason, it’s important that you schedule comprehensive eye examinations annually so that Dr Zondi can monitor any changes to your eyes or vision.
Acute-angle closure glaucoma, which is also known as narrow-angle glaucoma, is a medical emergency.
See your doctor immediately if you experience any of the following symptoms:
- severe eye pain
- redness in your eye
- sudden vision disturbances
- seeing coloured rings around lights
- sudden blurred vision
If you’ve experienced loss of vision, please give Dr Zondi a call to schedule a comprehensive eye examination. Treating Glaucoma early could prevent additional vision loss and possibly save your eyesight so it is vital that you see an Ophthalmologist as quickly as possible.
Keratoconus occurs when the cornea, the top clear tissue covering the eye, becomes less spherical and more cone-like in shape and structure. This affects how light is focused, in turn creating vision problems. Most instances of keratoconus are diagnosed in a patient’s teens or early 20s. The condition can occur in one or both eyes.
Your LASIK doctor may notice symptoms during your annual eye exam, but common signs of keratoconus are:
- Constantly changing of vision in one or both eyes
- Blurred vision at both near and far distances
- Seeing halos or ghost images
- Double vision
Spectacles often do not correct the vision satisfactorily.
There is no proven cause for keratoconus, but a family history of the condition is believed to be a major factor. If you are experiencing any of these symptoms, you should schedule an appointment with your ophthalmologist.
Presbyopia is a condition in which the eye’s lens is no longer able to properly focus on objects that are up close. As the eye ages, its lens loses elasticity and the muscles used to adjust the lens weaken. The lens then becomes unable to change shape as easily as when it was younger.
Most patients begin to notice these changes in their vision around 45 years old and can be diagnosed with presbyopia during a general eye exam. Since the main cause is aging, it generally affects everyone at some point in their lives.
Dr Zondi offers premium intraocular lenses (IOLs) such as multifocal lenses to correct presbyopia without the use of contacts or glasses. These are also often used as lens replacements for cataract surgery patients. With the Zeiss Trifocal premium intraocular lens, Dr Zondi can achieve true living vision for his patients after lens replacement.
Strabismus is a condition that causes the eyes to point in different directions. Typically, strabismus occurs in people who are very farsighted or have weak eye muscle control. Strabismus is also referred to as squint or squint eye. The irregular eye turning of strabismus may occur all the time or only when you are ill, tired or have done a lot of reading or focused work. The same eye may irregularly turn consistently, or your eyes may alternate in abnormal turning.
Correct eye alignment is vital for seeing good depth perception. When misalignment occurs, your brain receives two different images, which can cause confusion and double vision. Over time, your brain conditions itself to ignore that abnormal vision from the turned eye. When strabismus is untreated, it can lead to permanently degraded vision in the turned eye. This condition is known as lazy eye or amblyopia.
The exact cause of squint is not really known. Your eye movement is controlled by six muscles that receive signals from your brain, telling your eye to look up, down, left and right. Your eyes typically work together so they point in the same direction at the same time. Problems arise when one or more of the six muscles aren’t functioning properly or aren’t receiving the signals to tell the eye where to turn.
Sometimes a refractive error hypermetropia (farsightedness) may lead to inward deviation of the eye. Poor vision in an eye because of some other eye disease like cataract, etc. may also cause the eye to deviate. Therefore it is important in all the cases of squint, especially in children, to have a thorough eye checkup to rule out any other cause of loss of vision.
Risk factors that can lead to the development of strabismus include:
Refractive error: People who have severe hyperopia (farsightedness) are at risk to develop crossed eyes because of the additional eye focusing required to see clearly. Eye focusing can strain the eye muscles and cause strabismus.
Family history: Children of parents with strabismus are likely to develop the condition themselves.
Medical conditions: Those who struggle with medical conditions such as cerebral palsy or Down syndrome or those who’ve suffered a head injury or stroke are at a higher risk of developing crossed eyes
The squint is diagnosed by an experienced ophthalmologist such as Dr Zondi. He would do a few special tests to confirm the squint, to try and find out the cause and to quantify the amount of deviation. In some cases there may be a false appearance of squint due to broad nasal bridge in a child.
If you are having any abnormal visual symptoms, you should always be evaluated with a thorough consultation and examination by a physician for an accurate diagnosis and treatment plan as it may be a symptom or sign of a serious illness or condition. Our practice is fully equipped to thoroughly assess any vision issues you may be having.