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Understanding Vision Problems: Symptoms & Prevention

Dr. Melody Huang

Written By:

Dr. Melody Huang

Updated: 23 July 2024 •  
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Many conditions can affect your vision and eye health. While some are easily treated, others cause permanent vision loss and damage to eye structures.
In this article, we’ll be taking you through the most common vision problems, and their common symptoms.

Understanding the eye

Our eyes are incredibly complex organs. Over half of the cortex (which is the outermost layer of the brain) is dedicated to processing vision – that’s more than our sense of sound, smell, taste, and touch combined!
The eye contains many structures, but the primary ones responsible for clear vision include the cornea, lens, and retina.
eye structure

The eye is a complex structure.


Common refractive errors

Refractive errors are very common and affect over half of the adult population in the United States. These occur when the eyes cannot focus light properly onto the retina (that’s the light-sensing tissue in the back of the eye).
Here are a few different signs that might suggest you have a refractive error:

  • Blurred vision (distance or near)
  • Squinting
  • Headaches
  • Eyestrain
  • Light sensitivity
  • Glare
  • Difficulty seeing at night

There are multiple types of refractive error:

  • MyopiaAKA nearsightedness, which means you have trouble seeing far away. Your eye’s focusing power is too strong, so light falls in front of your retina (instead of on your retina). The more myopic you are, the closer you need to hold something to see it.

  • HyperopiaAKA farsightedness, which means you have difficulty seeing up close because your eye’s focusing power is too weak. Hyperopic people may have good distance vision, but if the hyperopia is severe enough, they may see blurry at all distances.

  • AstigmatismIt occurs when the cornea (clear covering in front of the eye) takes on an irregular, egg-like shape instead of a spherical form. The irregular shape causes your eye to have problems focusing light into a single image. People with astigmatism may complain that their vision seems to fluctuate between clear and blurry, or they see starbursts and halos around lights.

  • PresbyopiaThis is an age-related change in which the near vision becomes progressively blurry. The natural lens inside the eye is flexible and alters its shape to focus light properly. Over time, this lens becomes stiffer and thicker, making it difficult to focus on objects up close. Presbyopia begins after age 40, when many people need reading glasses.

Most refractive errors are corrected with eyeglasses or contact lenses. However, if you prefer not to wear glasses or contacts, your eye doctor can evaluate your eyes to see if you are a candidate for laser refractive surgery (such as LASIK).

Common non-refractive vision problems

Vision issues can also be related to eye health conditions as opposed to refractive errors.
Some of the most common eye health issues include:

1. Cataracts

Cataracts result from the ageing process of the natural lens. Gradually, the lens becomes hazy and yellowed. Most people develop cataracts after their fifties, and approximately 40 to 50 percent of Americans have cataracts by the age of 75.
In the earlier stages, you can have cataracts without symptoms. As they progress, you may notice vision problems such as:

  • Blurred vision
  • Light sensitivity
  • Glare
  • Changes in color vision
  • Difficulty with night vision
  • Double vision (out of one eye)

The primary treatment for cataracts is surgical removal, although most cataracts don’t require surgery unless they are significantly affecting your vision or causing other eye health issues. During cataract surgery, you receive an artificial lens implant that restores your vision. The benefit of this procedure is that you may not need to use glasses afterward!

2. Glaucoma

Glaucoma is a leading cause of blindness globally, affecting over 50 million adults aged 40 to 80. The primary eye structure that’s affected in glaucoma is the optic nerve, which transmits visual information from the retina to the brain. In some cases of glaucoma, high eye pressure causes damage to the optic nerve.
The damage is not painful and occurs gradually, so most people with glaucoma do not have symptoms. However, as the disease progresses, you may have issues such as:

  • Loss of peripheral (side) vision
  • Poor contrast sensitivity
  • Blindness (in advanced glaucoma)

In a less common form of glaucoma called angle-closure glaucoma, the eye pressure increases quickly and dramatically, resulting in:

  • Eye pain
  • Cloudy vision
  • Eye redness
  • Halos around lights

Angle-closure glaucoma is considered an eye emergency and requires prompt medical attention. If you have these symptoms, see your eye doctor immediately.
Glaucoma treatments prevent further damage by lowering eye pressure, but they cannot cure the disease completely. Therapies include:

  • Glaucoma eye drops
  • Oral medications
  • Laser treatments (such as selective laser trabeculoplasty)
  • Minimally invasive glaucoma surgeries
  • Glaucoma drainage devices
  • Trabeculectomy surgery

Keep in mind that any optic nerve damage is permanent, so early prevention is the best treatment strategy.

3. Age-related macular degeneration

Macular degeneration (abbreviated as AMD) is a disease that affects the macula, the structure in the retina responsible for your central vision and fine, detailed vision. Several genes that influence AMD have been identified, so it’s important to know if you have a family history of this disease.
Additionally, there are environmental factors that may contribute to your risk level, such as:

  • Older age (above 60 years)
  • Smoking
  • Obesity
  • Heart disease
  • High blood pressure

Depending on the type of AMD, you may experience different visual symptoms:

  • Dry AMDoccurs in the early stages of AMD. During this stage, the macula becomes thinned and collects yellowish deposits called drusen. Many people with dry AMD maintain good vision. However, there is an advanced type of dry AMD called geographic atrophy, in which severe thinning of the macula occurs. This thinning results in significant vision loss and a blind spot in the center of the vision.

  • Wet AMDis an advanced form of AMD in which abnormal blood vessels develop and leak underneath the retina. Some patients develop distortions in the vision, such as wavy spots or blind spots. Vision loss occurs more rapidly in wet AMD, and if left untreated, can cause blindness.

Wet AMD is treated with eye injections called anti-vascular endothelial growth factor (anti-VEGF) therapy. This medication reduces abnormal blood vessel growth. Currently, there are no approved treatments for dry AMD, although researchers are developing new therapies for geographic atrophy.
Typically, eye doctors prescribe nutritional supplements for people with dry AMD, which may include lutein, zeaxanthin, zinc, vitamin C, and other ingredients.

4. Diabetic retinopathy

Diabetic retinopathy is an eye complication occurring in approximately one out of every three people with diabetes. In diabetes, high blood sugar causes damage to blood vessels throughout the body, including the eyes.
There are different stages of diabetic retinopathy:

  • Nonproliferativediabetic retinopathy can be mild, moderate, or severe. Once blood vessels in your retina are damaged from diabetes, they can start leaking blood (hemorrhages). Other fluid and cellular materials also accumulate within the retina (exudates). Depending on the severity, your vision can remain relatively normal during this stage. However, if you develop diabetic macular edema, fluid and exudates in the macula can cause blurry and distorted vision.

  • Proliferativediabetic retinopathy is the most advanced stage. This type is a leading cause of severe vision loss. In the proliferative stage, abnormal blood vessel growth leads to extensive bleeding and scarring in the retina and vitreous (clear gel filling the cavity of the eyeball).

Other signs of diabetic retinopathy include:

  • Fluctuations in the vision (i.e. your eyeglass prescription keeps changing)
  • Sudden loss of vision
  • Dark or red spots in the vision
  • Distortions in the vision
  • Shadows or flashes in the field of vision

More severe cases of diabetic retinopathy are treated with anti-VEGF therapy, laser treatments, and a surgery called vitrectomy.

5. Amblyopia (or ‘lazy eye’)

Amblyopia is a common vision problem in children. Some people call this condition “lazy eye” because the vision in one eye is poorer than the other. However, both eyes can have amblyopia. Most cases of amblyopia develop before age 8, which is a critical period of visual development.
In amblyopia, the brain does not receive normal visual signals and favors the better-seeing eye. The brain may suppress vision in the poorer-seeing eye to avoid seeing blurry or double. As a result, the poorer-seeing eye has decreased vision, ranging from mild to severe.
There are a few causes of amblyopia:

  • Refractive errorsare a common cause of amblyopia. For example, if one eye has high hyperopia and the other eye sees normally, the eye with hyperopia may become amblyopic. The greater the difference between both eyes, the higher the risk for amblyopia. If both eyes have a significant refractive error, amblyopia can develop in each eye.

  • Strabismusis an eye misalignment, which we will discuss in the next section.

  • Deprivationis a rare cause of amblyopia that involves a physical obstruction of the vision. Cataracts, droopy eyelids, or corneal scarring are some conditions that can block the vision and prevent normal visual development.

The child may not show any apparent symptoms since the better eye can compensate for the weaker eye. However, a parent can look for signs of amblyopia such as:

  • Eye turns
  • Squinting
  • Closing one eye
  • Head tilt
  • Difficulty reading or learning in school
  • Headaches
  • Poor depth perception

Amblyopia can cause permanent vision loss if not treated early enough (before the eye fully develops). Refractive amblyopia is treated with eyeglasses and contacts. The eye doctor may add an eye patch to force the weaker eye to see. Deprivation amblyopia may require surgery to remove whatever is obstructing the vision.

6. Strabismus

This type of eye misalignment prevents the brain from seeing out of both eyes simultaneously.
The brain suppresses the eye with an eye turn to avoid double vision. As a result, that eye can have decreased vision.
The eye turn may be up, down, in, or out and may be present constantly or occasionally. Strabismus may appear as a “cross-eyed” or “wall-eyed” look. Although strabismus can develop at any age, most cases present within the first three years.
Sometimes, the eyes can straighten out on their own or improve with glasses and patching.
However, strabismus surgery may be necessary to realign the eyes and ensure normal visual development. If the surgery is performed after the visual system has developed (such as in adulthood), the eye will be realigned, but the vision remains decreased.

When to visit your doctor about vision problems

Differentiating between mild vision problems and severe eye health issues can be tricky since symptoms may be similar. Some signs should increase your level of concern:

  • Sudden change in vision
  • Double vision (especially if sudden)
  • Blacking out of vision
  • Dark or red spots in the vision
  • Shadows or flashes in the field of vision
  • Distortions in the vision

Consult your eye doctor promptly if you have any of the symptoms listed above.

How often should you have eye exams?

Photo of trial frame
Regular eye exams from an ophthalmologist or optometrist are essential to healthy vision and eyes. Experts recommend having a comprehensive eye health exam by age 40, if not earlier.
If you are in good health and don’t have any eye symptoms, experts recommend an eye exam every 2 to 4 years if you are 40 to 54 years old. Over 55 years of age, you should aim for an exam every 1 to 2 years. If your eye doctor uncovers any problems or you have risk factors such as diabetes, they may recommend more frequent exams.

Tips to prevent eye and vision problems

Not all eye issues are entirely preventable, but you can reduce your risk for many eye diseases by following these recommendations:

  • Don’t smokeSmoking damages your eye health in many ways by promoting inflammation and blood vessel damage (such as in macular degeneration). It also increases your risk for many systemic conditions such as diabetes, high blood pressure, and heart disease. All of these diseases can also affect your eyes.

  • Exercise regularlyExercise lowers your risk for many systemic diseases that can harm your eyes and vision. For example, regular physical activity helps maintain your blood sugar and blood pressure.

  • Eat a healthy dietSome of the essential nutrients for eye health include vitamin A, vitamin C, lutein, zeaxanthin, omega-3 fatty acids, zinc, and flavonoids. Eating foods with these nutrients promotes antioxidant activity and helps combat diseases like AMD, cataracts, and glaucoma.

  • Wear sunglassesExcessive ultraviolet exposure can accelerate cataracts and may play a role in AMD. The sun can also damage the front of your eye (cornea and conjunctiva) and even cause sunburns in your eye!

Remember to see your eye care provider for your annual eye exam. Take care of your eyes to ensure a lifetime of healthy, clear vision!


  • University of Rochester – ‘The Mind’s Eye’

  • National Centre For Biotechnology Information – ‘Prevalence of refractive error in the United States, 1999-2004’, 2008

  • National Eye Institute ‘Cataract Data and Statistics’, 2019

  • Scientific Reports ‘Prevalence of primary open angle glaucoma in the last 20 years: a meta-analysis and systematic review’, 2021

  • Clinical Ophthalmology (Auckland, N.Z.) – ‘Genetics and age-related macular degeneration: a practical review for the clinician’, 2016

  • BMC Ophthalmol – ‘Clinical risk factors for age-related macular degeneration: a systematic review and meta-analysis’, 2010

  • Eye and Vision – ‘Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss’, 2015

  • Unnati V. Shukla; Koushik Tripathy, ‘Diabetic Retinopathy’, 2021

  • BMJ Clinical Evidence, ‘Amblyopia in children (aged 7 years or less)’, 2016

  • Venkata M. Kanukollu; Gitanjli Sood, ‘Strabismus’, 2021

  • AAO Hoskins Center for Quality Eye Care, ‘Frequency of Ocular Examinations’, 2015
Dr. Melody Huang
Melody Huang is an O.D. and medical writer with over ten years of expertise. As an optometric physician licensed with the California State Board of Optometry, Melody currently practices in the Los Angeles area.