How we see helps us make sense of the world. So when something seems off with our eyes, no wonder we get worried at the first signs of trouble. Experiencing blurry vision, redness, and other eye problems—even mild ones—can really disrupt our lives. What might be going on? 

Here, we’ve compiled a list of the most common eye diseases and disorders, including some helpful info about each so you can rest a little easier. Read on to learn about everything from refractive errors to those pesky floaters. (But please don’t use this list of eye conditions to diagnose yourself; see an eye doctor for that!)

Refractive Errors

Diagram of how light focuses in a normal eye, a nearsighted eye, and a farsighted eye

Refraction 101: How light focuses (or doesn’t) on the retina

If you need glasses or contact lenses to see clearly, then you most likely have a refractive error. A refractive error occurs when the shape or structure of your eye prevents light from focusing on your retina with precision. Without that pinpointed focus on your retina, you can’t see as sharply, and objects at certain distances can appear blurred.

Your eye doctor records the type and severity of any refractive errors you have on your eye prescription. The four most common types of refractive error are:  

Nearsightedness (Myopia) 

When you’re nearsighted, you have trouble seeing objects that are far away, like upcoming road signs. This is because the light passing through your eye focuses on a point in front of the retina, rather than on its surface. This eye condition is also called myopia, and it’s becoming increasingly common throughout the globe—in fact, it’s estimated that about half of the entire world will be nearsighted by the year 2050. 

Farsightedness (Hyperopia)

When you’re farsighted, you have trouble seeing objects that are close to you, like your computer screen or a book. Just as nearsighted eyes focus light too far in front of the retina, farsighted eyes focus light on a spot behind it.


Astigmatism is a kind of refractive error that can make objects at any distance appear blurry. It results when the curvature of the cornea or the lens of your eye is uneven instead of rounded. Due to this irregular curvature, light that passes through your eye focuses on two points instead of one. Fortunately, there are glasses and contacts for astigmatism, too! (Subtle, aren’t we?)


Presbyopia has many of the same symptoms as farsightedness, but the two are not the same. People with presbyopia have lost a degree of flexibility in the lens of their eye. 

Typically, as light passes through your eye, your lens adjusts its shape to focus the light on the retina. But as you get older, your lens tires out a bit. It isn’t as elastic as it once was, and may even be thicker, resulting in a harder time discerning text and objects that are close to your face. 

People with presbyopia can benefit from bifocal or multifocal glasses and contacts, which sharpen their vision at multiple distances. They may also wear reading glasses when they want to pick up a book.

Glasses sitting on a stack of books


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Eye Movement Disorders

Some eye disorders can impact the way that eyes move in their sockets, resulting in (often disrespectful, frankly!) nicknames that reference the eye’s behavior. 

Amblyopia, or “Lazy Eye”

Amblyopia is an inability to see clearly through one eye. This vision disorder most often arises during childhood, when the nerve pathway between the brain and affected eye develops abnormally. The eye doesn’t “learn” to see correctly, and the brain eventually starts to favor the other, stronger eye. 

Amblyopia is sometimes referred to as “lazy eye,” because the weaker eye can drift in an independent direction. But it’s not very nice to call anything “lazy,” including your eye. We prefer the scientific term.

Strabismus, or “Crossed Eyes”

Strabismus, often called “crossed eyes,” is a condition that causes both eyes to look in different directions. This may be due to a problem with the muscles surrounding the eyes or the brain’s ability to guide those muscles. 


Nystagmus refers to an uncontrollable and rapid movement of the eyes, often with a side-to-side pattern. It’s thought that nystagmus stems from neurological factors, but its exact cause can be hard to discern. 


Glaucoma refers to a group of eye diseases that cause damage to the optic nerve, which can result in vision loss and blindness. Although glaucoma’s exact cause is unknown, it seems to be closely associated with high intraocular pressure—which is why it’s so important to get your IOP tested at regular eye exams


A cataract is a portion of the lens of your eye that has become cloudy. The hazy appearance comes from proteins that have broken down inside the lens, which can happen naturally with age. Cataracts can impair your vision moderately to severely.

Conjunctivitis, or “Pink Eye”

Many people are familiar with Pink Eye. This colorful (sorry, couldn’t help it) moniker is another name for conjunctivitis, which is itself referencing the conjunctiva: the thin lining around your eye and inside your eyelids. When you have conjunctivitis, that lining is inflamed and itchy due to allergies or an infection—and if it’s the latter, it’s very contagious. 


Uveitis is an inflammatory disease that results in swelling of the uvea, which is the middle section of your eye. Left untreated, it can harm eye tissue so much that it causes all types of vision problems, including irreversible vision loss. 

Retinal Disorders

Many serious eye disorders involve the retina. This light-sensitive layer at the back of your eyeball is responsible for sending images to your brain, so it’s crucial to monitor its health! 

As you get older, your macula—the part of your retina that corresponds to seeing straight ahead—may thin or become damaged. When that happens, your central vision worsens, making it tougher to perform certain tasks such as driving and reading. 

Age-related macular degeneration is increasingly common in seniors, and is one of the leading causes of blindness in the elderly population. 

Diabetic Retinopathy 

Diabetic retinopathy is a concern for people with diabetes, and results when high blood sugar damages the blood vessels in your retina. This condition causes the vessels to swell, leak, or become blocked; it can also prompt the formation of new, less-functional vessels. 

If diabetic retinopathy goes unaddressed, it can lead to blindness. But studies have shown that keeping your blood sugar and blood pressure within recommended ranges can lower the risk of its progression. 

Retinal Detachment

In certain circumstances, the retina (or part of it) can become detached from the back of the eye. This usually occurs due to aging or injury, and is considered a medical emergency—surgery is needed to treat a detached retina. 

So, if you notice flashing lights intruding on your vision, a sudden, marked increase in those pesky eye floaters, or what seems like a dark shadow or “curtain” impinging on your sight, we recommend you get to a doctor post-haste. 

Corneal Diseases and Conditions

The cornea is the clear, outer covering at the very front of your eye that sort of looks (and functions) like a protective dome. It’s an open eye’s first line of defense, and also helps to focus light. Some common corneal conditions include: 


Keratitis is an inflammation of the cornea. The infectious version can be caused by bacteria, parasites, or even fungus; the noninfectious kind is usually caused by an injury or by wearing your contact lenses for too long. (One study found that daily-contact wearers who sometimes left their contacts in overnight were at 9 times greater risk of developing keratitis than wearers who took them out as advised!) 

Keratitis can result in an open sore on your cornea, also known as a corneal ulcer. It can also lead to permanent vision damage if it isn’t treated. 


Keratoconus occurs when the cornea thins out and protrudes into a more cone-like shape. This affects how light enters the eye and causes impaired vision. Mild cases can be corrected by glasses or contacts, whereas highly progressed cases may require surgery. 

Scratched Cornea

The clinical term for a scratch on your cornea is a corneal abrasion. Corneal abrasions happen when anything scrapes up against the surface of your cornea too hard. Irritants such as makeup brushes, grains of sand, and even fingernails can cause these scratches if they contact the cornea with enough force. Minor corneal abrasions heal in a matter of days, but severe ones can scar the eye and impact your vision.

Diagram of a corneal abrasion seen from the side and front

Corneal Dystrophies

There are many, many types of corneal dystrophies, and they’re all rare genetic eye diseases that involve the accumulation of abnormal material in your cornea. They tend to run in families and progress as you age. 

Vision Problems

Eye disorders—as well as the natural process of aging—can give rise to a host of vision problems. These aren’t exactly clinical diagnoses, but are often symptoms of an underlying eye condition. You already know what we’re going to recommend: if you’re experiencing any of these vision issues, see your eye doctor. 

Low Vision 

If you have low vision, then you’re having difficulty seeing clearly to the point where it affects your everyday life. Low vision can’t be fixed with glasses or contacts, and is commonly a symptom of some of the eye disorders we’ve talked about already, including cataracts, glaucoma, and age-related macular degeneration. 

Night Blindness

Night blindness, or nyctalopia, is an eye condition that makes it much harder to see in the dark. If you have night blindness, it doesn’t mean you’re completely blind at night, but navigating around a dark room or driving at night can be tough. 

Vision Changes

Some vision changes come naturally with age, and they usually have a slow, progressive onset. Presbyopia, for example, is extremely common in people 40 and older. But sudden vision changes—blurred vision, flashing lights, dark spots, etc.—can be signs of a serious problem, and should always be investigated by a professional ASAP. 

Color Blindness

Individuals with color blindness perceive colors differently from the way most of us do. The degree of color blindness can range from mild to severe—those with very mild color blindness might not even know that they have it. It’s usually a genetic condition, meaning you’re born with it. 

Because inherited color blindness is carried on the X chromosome, it affects more men than women. It is estimated that about 8% of all men and 0.5% of all women have some form of color blindness.

Other Common Eye Problems

Your eyes are seriously powerful seeing machines, but they’re also sensitive. Sometimes, they can react to the environment or other factors in inconvenient ways, resulting in various eye issues. 

Red Eyes

Red eyes are typically irritated eyes. If your eyes are red, the culprit could be anything from a burst blood vessel to allergies to excessive dryness, or even a bit of debris that’s gotten trapped. Redness could also be caused by an infection that requires treatment. 

If you have a red eye or eyes, watch for other symptoms, such as pain, tenderness, and discharge. And obviously, if your eyes are red and causing you discomfort without a clear explanation, seek medical attention. 

Dry Eyes

Although our eyes moisten themselves with blinking and tears, sometimes these lubricating mechanisms don’t work as well as they used to, and your eyes become dry. Dry eyes can be treated with artificial tears and other methods, including medications.

Watery Eyes

Teary, watery eyes are another symptom with a multitude of explanations. Illness and infection can prompt your eyes to tear up, but so can foreign material, allergies, and even certain medications. If you can’t identify the reason behind excess tears, consult your doctor. 

Eye Strain

Just like you might strain a muscle in your arm from carrying too much weight, you can strain your eyes from overuse! Strained eyes might be sore in their sockets, and experience greater difficulty focusing or seeing clearly. Any activity that heavily involves your eyes can cause eye strain, such as reading or driving for long periods. 

In recent years, as we spend more and more time each day in front of screens, digital eye strain (AKA computer vision syndrome) has also become a much more prominent eye problem.

Eye Floaters

Diagram of eye floaters inside an eye

A look (no pun intended) at eye floaters

You’ve probably noticed stringy, spotty shapes in your field of vision that move with your eyes when you try to focus on them. These are called eye floaters, and they’re perfectly normal. They appear because the fluid (or “vitreous”) inside of your eye sometimes clumps together and casts shadows on your retina. 

Floaters are no cause for concern, unless you’re seeing way more of them than usual (or they’re spelling out worrisome messages). In that case, call your eye doctor. 

Eye Allergies

Having allergies can bring some of the most annoying eye problems together: itchiness, tears, redness, tenderness, and more. Both indoor and outdoor allergens can trigger these reactions in eyes, but thankfully, allergy sufferers have options: you can take medications, avoid known irritants, and pursue other treatments if these first-step remedies don’t work. 

Additionally, if you wear contact lenses, switching from weekly or monthly lenses to daily disposable contacts can be enough to alleviate some allergy symptoms!

Eye(s) Bothering You? See Your Eye Doctor!

Although it’s long, this list of eye disorders is by no means exhaustive. The best advice we can always offer when your eyes are acting up is to see an eye doctor

Which type of eye doctor? You may ask. Probably an optometrist, but you can read up on the differences between an optometrist and ophthalmologist to decide which is best suited to your current needs.

In fact, you should see an optometrist regularly anyway, eye issues or no eye issues! It’s one of the best ways to keep your peepers healthy and spot eye disease symptoms before your vision becomes at risk. If you take care of your corneas (and everything under ‘em), you’ll up your chances of seeing clearly for years to come. 

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