Allergic conjunctivitis
Allergic conjunctivitis occurs when the outer part of the eye becomes swollen or irritated in a reaction to pollen, dander, mold, or other substances that trigger allergies.
Allergy-causing substances release a chemical called histamine into the eyes, which causes the blood vessels in the outer layer of the eye to become swollen. The eyes may quickly become red, itchy, and watery. Other symptoms of allergic conjunctivitis include:
- burning eyes
- puffy eyelids, especially in the morning
- stringy discharge in the eyes
- widened blood vessels in the outer layer of the eye
How to prevent it
The best way to avoid allergic conjunctivitis is to avoid the substances that trigger your symptoms. But researchers have also found eye drops to be helpful in preventing allergic conjunctivitis in those who are prone to allergic reactions. The antihistamines emedastine and levocabastine are helpful in preventing the condition. Use these after you have been exposed to a trigger, such as a day with high air pollen levels.
The eye depends on the flow of tears to provide constant moisture and lubrication to maintain vision and comfort. Tears are a combination of water, for moisture; oils, for lubrication; mucus, for even spreading; and antibodies and special proteins, for resistance to infection. These components are secreted by special glands located around the eye. When there is an imbalance in this tear system, a person may experience dry eyes
When tears do not adequately lubricate the a person may experience:
- Pain
- Light sensitivity
- A gritty sensation
- A feeling of a foreign body or sand in the eye
- Itching
- Redness
- Blurring of vison
Presbyopia
Presbyopia usually occurs beginning at around age 40, when people experience blurred near vision when reading, sewing or working at the computer.
You can’t escape presbyopia, even if you’ve never had a vision problem before. Even people who are nearsighted will notice that their near vision blurs when they wear their usual eyeglasses or contact lenses to correct distance vision.
Presbyopia Symptoms and Signs
When people develop presbyopia, they find they need to hold books, magazines, newspapers, menus and other reading materials at arm’s length in order to focus properly. When they perform near work, such as embroidery or handwriting, they may develop headaches, eye strain or feel fatigued.
What Causes Presbyopia?
Presbyopia is caused by an age-related process. This differs from astigmatism, nearsightedness and farsightedness, which are related to the shape of the eyeball and are caused by genetic and environmental factors. Presbyopia generally is believed to stem from a gradual thickening and loss of flexibility of the natural lens inside your eye.
These age-related changes occur within the proteins in the lens, making the lens harder and less elastic over time. Age-related changes also take place in the muscle fibers surrounding the lens. With less elasticity, the eye has a harder time focusing up close. Other, less popular theories exist as well.
Presbyopia Treatment: Eyeglasses
Eyeglasses with bifocal or progressive addition lenses (PALs) are the most common correction for presbyopia. Bifocal means two points of focus: the main part of the spectacle lens contains a prescription for distance vision, while the lower portion of the lens holds the stronger near prescription for close work.
Progressive addition lenses are similar to bifocal lenses, but they offer a more gradual visual transition between the two prescriptions, with no visible line between them.
Reading glasses are another choice. Unlike bifocals and PALs, which most people wear all day, reading glasses typically are worn just during close work.
If you wear contact lenses, your eye doctor can prescribe reading glasses that you wear while your contacts are in. You may purchase readers over-the-counter at a retail store, or you can get higher-quality versions prescribed by your eye doctor.
What Is Astigmatism?
Astigmatism is an imperfection in the curvature of your cornea — the clear, round dome covering the eye’s iris and pupil — or in the shape of the eye’s lens. Normally, the cornea and lens are smooth and curved equally in all directions, helping to focus light rays sharply onto the retina at the back of your eye. However, if your cornea or lens isn’t smooth and evenly curved, light rays aren’t refracted properly. This is called a refractive error.
When the cornea has an irregular shape, it is called corneal astigmatism. When the shape of the lens is distorted, you have lenticular astigmatism. As a result of either type of astigmatism, your vision for both near and far objects appears blurry or distorted. It’s almost like looking into a fun house mirror in which you appear too tall, too wide or too thin.
In a normal eye, the cornea and lens focus light rays on the retina.
In astigmatism, images focus in front of and beyond the retina, causing both close and distant objects to appear blurry.
People can be born with astigmatism — in fact, most people probably are born with some degree of astigmatism — and they may have it along with other refractive errors: nearsightedness (myopia) or farsightedness (hyperopia).
While adults with a higher degree of astigmatism may realize their vision isn’t as good as it should be, children who have astigmatism symptoms may not be aware they have this condition, and are unlikely to complain about blurred or distorted vision. But uncorrected astigmatism can seriously impact a child’s ability to achieve in school and sports. And some forms of astigmatism can be a sign of keratoconus, a cone-like bulge of the cornea, which can distort vision. That’s why it is crucial that children have regular eye exams to detect astigmatism or other vision problems as early as possible.
Eye floaters are small spots that drift through your field of vision. They may stand out when you look at something bright, like white paper or a blue sky. They might annoy you, but they shouldn’t interfere with your sight.
If you have a large floater, it can cast a slight shadow over your vision. But this tends to happen only in certain types of light.
You can learn to live with floaters and ignore them. You may notice them less as time passes. Only rarely do they get bad enough to require treatment.
What Are the Symptoms?
Floaters earn their name by moving around in your eye. They tend to dart away when you try to focus on them.
They come in many different shapes:
- Black or gray dots
- Squiggly lines
- Threadlike strands, which can be knobby and almost see-through
- Cobwebs
- Rings
Once you get them, they usually don’t go away. But they might get better over time.
What Causes Them?
Most floaters are small flecks of a protein called collagen. They’re part of a gel-like substance in the back of your eye called the vitreous.
As you age, the protein fibers that make up the vitreous shrink down to little shreds that clump together. The shadows they cast on your retina are floaters. If you see a flash, it’s because the vitreous has pulled away from the retina. If that happens, see your eye doctor ASAP.
These changes can happen at any age, but usually occur between 50 and 75. You’re more likely to have them if you’re nearsighted or have had cataract surgery.
It’s rare, but floaters can also result from:
- Eye disease
- Eye injury
- Diabetic retinopathy
- Crystal-like deposits that form in the vitreous
- Eye tumors
Serious eye disorders associated with floaters include:
- Detached retina
- Torn retina
- Bleeding in your vitreous
- Inflamed vitreous or retina caused by infections or an autoimmune condition
- Eye tumors
Glaucoma
Glaucoma is a set of eye conditions that together damage the optic nerve, which is important for good vision. This damage is often caused by unusually high pressure in the eye or eyes. Over time, glaucoma can lead to blindness that can’t be reversed. Glaucoma tends to be hereditary, but can also be caused by diabetes, eye injuries, and lack of exercise.
The symptoms of glaucoma include:
- patchy blind spots in your side (peripheral) or central vision, often in both eyes
- tunnel vision
- bad headaches
- eye pain
- nausea
- vomiting
- blurry vision
- seeing halos around lights
- eye redness
How to prevent it
Not all cases of glaucoma can be prevented, but there are steps you can take to prevent your glaucoma from worsening. Glaucoma treatment is most effective when given early. Experts agree that the best preventive step for glaucoma is to get frequent eye care and eye screenings, especially if you have diabetes.
You can prevent glaucoma by exercising regularly and safely, which reduces eye pressure. It’s also important to wear protective eye gear when working with power tools or playing sports that may cause injury to your eyes.
Symptoms
If you are nearsighted, you typically will have difficulty reading road signs and seeing distant objects clearly, but will be able to see well for close-up tasks such as reading and computer use.
Other signs and symptoms of myopia include squinting, eye strain and headaches. Feeling fatigued when driving or playing sports also can be a symptom of uncorrected nearsightedness.
If you experience these signs or symptoms while wearing your glasses or contact lenses, schedule a comprehensive eye examination with your optometrist or ophthalmologist to see if you need a stronger prescription.
What Causes Myopia?
Myopia occurs when the eyeball is too long, relative to the focusing power of the cornea and lens of the eye. This causes light rays to focus at a point in front of the retina, rather than directly on its surface.
Nearsightedness also can be caused by the cornea and/or lens being too curved for the length of the eyeball. In some cases, myopia is due to a combination of these factors.
Myopia typically begins in childhood and you may have a higher risk if your parents are nearsighted. In most cases, nearsightedness stabilizes in early adulthood but sometimes it continues to progress with age.
Myopia Treatment
Nearsightedness can be corrected with glasses, contact lenses or refractive surgery. Depending on the degree of your myopia, you may need to wear your glasses or contact lenses all the time or only when you need very clear distance vision, like when driving, seeing a chalkboard or watching a movie.
If you’re nearsighted, the first number (“sphere”) on your eyeglasses prescription or contact lens prescription will be preceded by a minus sign (–). The higher the number, the more nearsighted you are.
Refractive surgery can reduce or even eliminate your need for glasses or contacts. The most common procedures are performed with an excimer laser.