Eye Diseases

Medical science knows of hundreds of eye diseases, and they’re some of the most common conditions in the world. Many are treatable, especially when caught early.


Eye diseases have many potential causes, and they can also be idiopathic, meaning their cause is unknown.
Eye diseases can happen due to factors you can manage, factors outside your control, or even for unknown reasons.

What are eye diseases?

Eye diseases are conditions that affect any part of your eye, and include conditions that affect the structures immediately around your eyes. These conditions can be acute (meaning they develop quickly) or chronic (meaning they develop more slowly and last a long time).

Your eyeball itself is where most eye diseases happen, but it isn’t the only place. Eye diseases also include conditions that can affect your eye muscles, eye socket, eyelids, or the skin and muscles immediately around your eyes.


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How common are eye diseases?

In general, eye diseases and vision disorders are extremely common. The World Health Organization estimates that over 2.2 billion people have some form of vision impairment or blindness.

One reason that eye diseases are so common is that your eyes don’t exist in isolation from the rest of your body. In fact, the opposite is true. Many conditions that affect your eyes happen because of or in connection with conditions affecting other body systems. That’s why there are hundreds of different conditions that can affect your eyes.

What are the most common eye diseases?

The most common eye diseases worldwide are:

Eye injuries are also a leading cause of vision loss and blindness. Experts track and research them like diseases to find better ways to prevent and treat eye injuries.

Eye cancers and tumors, while rare, do sometimes happen, but often they’re detectable with regular eye exams. Fortunately, many eye tumors are benign (noncancerous). These benign growths may still need removal to prevent them from affecting nearby tissues, but aren’t a greater threat.


What are the different types of eye diseases?

There are many types of eye diseases, but there are a few main ways to organize them:

  • Structure. What specific part(s) of the eye do they affect?
  • Underlying cause. Primary eye diseases start in your eye. Secondary eye diseases happen because of a condition elsewhere in your body that later affects your eye.
  • Effect. What symptoms do they cause, or what functions do they affect or disrupt?
  • Duration. Acute eye diseases, like eye infections, are very short-lived. But chronic eye conditions can last months, years or even your entire lifetime.

When talking about eye diseases, it’s also important to know the difference between sight and vision.

  • Sight: This starts when light enters through the cornea and ends when light lands on the retina.
  • Vision: This covers every step that’s part of your visual sense, including sight. It also includes how your nervous system handles and processes visual signals and turns them into what you see.

While many people — experts included — frequently use “vision” and “sight” interchangeably, they aren’t always the same thing. Sight-related diseases are specific to your eyes, while vision-related diseases can involve your brain and optic nerves, too. That’s why some diseases can cause vision loss even though your eyes work just fine.

Symptoms and Causes

What are the symptoms of eye diseases?

There are many possible symptoms of eye diseases. Those symptoms usually happen in a few key ways:

  • Symptoms you can feel. Examples include pain, irritation or eye tiredness or strain.
  • Changes in eye functions. Examples include watery eyes (epiphora) and trouble controlling how you blink your eyes.
  • Changes in the appearance of your eyes. These changes include yellowing of the white of your eyes (scleral icterus), red eyes and pupils that are too narrow (miosis).
  • Changes in eye movement or alignment. Examples include exotropia or esotropia.
  • Changes in how you see. Some common examples are double vision (diplopia), blurred vision or tunnel vision.


What causes eye diseases?

Eye diseases can happen for many, many reasons. Some are direct causes while others are contributing or risk factors.

  • Genetics. Your DNA is a key part of how your eyes develop and work, and DNA changes (mutations) can cause many eye conditions. The genetic form of color blindness is an example.
  • Differences in how your eyes form and develop. These differences could have started while you were a developing fetus, or at some point during your childhood.
  • Environmental factors. Some eye conditions develop because of things happening to or around you. Ultraviolet light exposure, humidity and temperature, dust or particles in the air, and many other variables can be a part of this.
  • Infectious diseases. Many types of germs and microbes (pathogens) can cause eye diseases. They include viruses, bacteria, fungi and parasites. These can infect your eyes directly or spread from elsewhere in your body.
  • Other chronic conditions. Your eyes are vulnerable to many conditions that affect your whole body. Examples include high blood pressure (hypertension), Type 2 diabetes and several types of thyroid disease.
  • Previous eye injuries. Some events that damage your eye can make you more prone to developing certain eye diseases or issues.
  • Idiopathic causes. “Idiopathic” means the cause is unknown. That means there’s no cause that experts can identify (though this can sometimes change over time).

Diagnosis and Tests

How are eye diseases diagnosed?

An eye care specialist or other healthcare provider can diagnose eye diseases using a combination of methods. The first and foremost tool for diagnosing these diseases is an eye exam. While most people think of these as just checking how well you see (visual acuity), that’s not always the case.

Eye exams can be routine and happen every one to two years like a regular wellness check. Providers can also do exams in a more specific way when you have signs or symptoms of an eye condition. Certain parts of an eye exam, like pupil dilation and a slit lamp exam, can be especially useful.

Your eye specialist may also recommend more specific eye tests. These include:

Many other tests that aren’t eye-specific can help, too. They include:

Your eye care specialist or other healthcare provider can tell you more about any other tests they recommend, including how those tests work and how they may help you.

Management and Treatment

How are eye diseases treated?

Eye disease treatments can vary even more than the conditions they treat. Some treatments can help with many conditions. Others are very specific, meaning they won’t help with anything but the conditions they’re meant to treat.

Refractive errors are some of the most common eye conditions. They’re also usually easier to treat, with corrective lenses like eyeglasses or contact lenses helping to adjust eyesight and improve visual acuity.

Other common treatments for eye conditions include:

Because the treatments can vary so widely and be so specific, your eye care specialist is the best source of information about treatments for your specific needs. They can also tell you about possible side effects, complications and more.


Can eye diseases be prevented?

Some eye diseases are completely preventable, and you can at least reduce your risk of developing others. But many eye diseases happen unpredictably, making it impossible to prevent or lower the odds of having them.

Some general steps you can take to help maintain your eye health include:

  • Get regular eye exams. Everyone, even people who don’t wear corrective lenses, should get an eye exam at least every one to two years (or more often if you have conditions that increase your risk of eye issues).
  • Wear eye protection. Injuries to your eyes, face or head can cause long-term eye issues and damage. Wearing eye protection specifically meant for that purpose (not just treating eyeglasses like they can do the same job) can prevent eye injuries or make them less severe.
  • Avoid nicotine use. Smoking, vaping and smokeless tobacco usage can all affect your circulatory system. That’s especially true for the blood vessels that supply your eyes.
  • Don’t ignore infections. If you have what feels like an eye infection for more than a few days, see a healthcare provider. Eye infections that go untreated for too long can become bigger issues and cause lasting damage or other complications.
  • Don’t ignore eye symptoms. Gradual vision changes are a sign that you need to see an eye care specialist for an eye exam. And sudden, unexpected vision changes — especially vision loss — are medical emergencies that need immediate care.
  • Make proper nutrition a priority. Your eyes need specific vitamins and minerals to do their best.
  • Reach and maintain a weight that’s healthy for you. Your overall health can have a big impact on eye health. Your eye specialist or primary care provider can guide you on the best ways to manage your overall health for the benefit of your eyes.

Additional Common Questions

What are some common children’s eye conditions?

Children can have many eye conditions that adults have. Some of the most common include:

An important detail about many childhood eye diseases like strabismus and lazy eye is that they’re much easier to treat during early childhood. If you have concerns about whether a child you care for has an eye condition like this, talk to their pediatrician or another healthcare provider. The child’s provider can offer suggestions and guidance on checking for those conditions and what needs to happen next if they think further investigation or treatment is necessary.

A note from Cleveland Clinic

Eye diseases are common, but it’s still normal to experience difficult or unpleasant feelings when you learn you have one of these conditions. The type and severity of these conditions vary widely, but most are treatable, and many are curable. Regular eye exams are essential and can help catch these conditions early, when it’s more likely they’ll be easier to treat.

If you have concerns about your vision, talk to an eye care specialist. They can offer guidance, support and reassurance as you work together to manage any conditions you face.

Medically Reviewed

Last reviewed on 05/02/2024.

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