Why Do I See Halos Around Lights?


Have you ever seen a streetlamp at night and noticed a radiant circle around the light? This visual effect, known as a halo, is not just a photographic phenomenon. It is something many people experience in their vision. 

While often harmless, halos can sometimes signal underlying eye conditions like astigmatism. In this post, we’ll dive into the causes of halos around lights, explore treatment options, and discuss when it might be time to see your eye doctor.

What Are Halos Around Lights?


Imagine driving home on a dark, rainy night. As you glance at the streetlights or the headlights from oncoming traffic, you might notice each light source is encircled by a soft, glowing ring. This visual effect is what we call a halo. Halos are essentially circles of light that appear around luminous objects, often noticed in low-light conditions or when looking directly at bright lights.

The science behind halos is as fascinating as the phenomenon itself. In essence, halos occur when light rays entering the eye get scattered. This scattering can be due to various reasons, from natural variations in the eye’s structure to changes caused by eye conditions. Normally, the cornea (outermost, clear layer of the eye) and lens of the eye focus light directly onto the retina (the layer of cells lining the back wall inside the eye), creating clear, sharp images. But when light is scattered rather than neatly focused — whether due to irregularities in the eye’s surface or moisture or other factors — it results in these radiant circles.

Ultimately, understanding halos requires delving a bit into optics and eye anatomy. For instance, in people with astigmatism, the eye’s cornea or lens has an irregular shape, causing light to focus unevenly on the retina and leading to blurred vision and halos. Similarly, age-related changes or eye conditions that affect the clarity of the cornea or lens can also contribute to the scattering of light, making halos more prominent. While often a benign and temporary experience, persistent halos can be a cue to underlying issues worth a professional’s attention.

What Causes Halos Around Lights?

Halos around lights are a curious phenomenon that can stem from several causes, ranging from temporary conditions to more chronic eye disorders. Here are five common culprits.

1. Astigmatism

This is a refractive error caused by an irregular curvature of the cornea or lens. Instead of having a perfectly spherical shape, an eye with astigmatism has a more oval shape, causing light to be focused unevenly. This irregular focusing can lead to blurred vision, both near and far, and is often accompanied by halos around lights.

2. Cataracts

Cataracts develop when the lens of the eye, which is normally clear, becomes clouded. This cloudiness can scatter light as it passes through the lens, causing a halo effect around lights. Cataracts are most commonly related to aging but can also result from other risk factors, including diabetes, smoking, and prolonged exposure to sunlight.

3. Glaucoma

This group of eye conditions is characterized by increased pressure inside the eye, which can damage the optic nerve. One of the symptoms of glaucoma, especially acute angle-closure glaucoma, can be seeing halos around lights. This symptom requires immediate medical attention as it can indicate a rapid increase in eye pressure.

4. Dry Eye Syndrome

Dry eyes occur when the eyes don’t produce enough tears, or the tear quality is poor. This can lead to various symptoms, including a gritty sensation, discomfort, and the appearance of halos around lights. Dry eyes can be exacerbated by factors like computer use, air conditioning, and heating.

5. Corneal Abrasions or Erosions

The cornea is the clear, protective outer layer of the eye. When it’s scratched (abrasion) or wears away in certain areas (erosion), it can scatter light entering the eye, leading to halos. These conditions can be caused by injuries, foreign objects in the eye, or degenerative corneal diseases.

6. Refractive Surgery Complications

Procedures like LASIK (laser-assisted in situ keratomileusis) or PRK (photorefractive keratectomy), designed to correct vision, can sometimes result in side effects such as halos around lights. These effects are often temporary and diminish as the eye heals post-surgery.

Treating Causes of Halos Around Lights

Switching from glasses to contacts

Addressing the causes of halos involves a mix of medical treatments, corrective measures, and sometimes, lifestyle adjustments. Here’s how treatments align with the previously discussed causes.

  1. Astigmatism – Glasses or contact lenses are the most common treatments for astigmatism as they are designed to correct the uneven curvature of the cornea or lens. Procedures like LASIK or PRK can also permanently correct the shape of the cornea, eliminating the need for glasses or contacts.
  2. Cataracts – The only effective treatment for cataracts is surgical removal of the cloudy lens and its replacement with an artificial lens. This procedure is highly successful in restoring vision.
  3. Glaucoma – Eye drops or oral medications can reduce intraocular pressure, helping to manage glaucoma and prevent further optic nerve damage. Laser therapy or conventional surgery can also improve drainage of fluid from the eye, reducing pressure.
  4. Dry Eye Syndrome – Over-the-counter lubricating eye drops can alleviate the symptoms of dry eyes. Certain drugs can also increase tear production or reduce inflammation, and tiny devices inserted into tear ducts can block drainage and increase eye moisture.
  5. Corneal Abrasions or Erosions – Antibiotic drops or ointments can help prevent infection and facilitate the healing of corneal abrasions or erosions. There are also special lenses that protect the cornea and allow it to heal.
  6. Post-Refractive Surgery – Artificial tears can help manage dry eyes, a common temporary side effect of post-refractive surgery. Steroid eye drops can also help reduce inflammation and aid in the healing process.

Additionally, adjusting ambient lighting, avoiding driving at night, or using anti-glare glasses can help minimize the perception of halos. For eye conditions related to nutritional deficiencies, supplements such as omega-3 fatty acids may improve eye health and reduce symptoms. Finally, regularly taking comprehensive eye exams can help detect early signs of conditions that may lead to halos, allowing for timely intervention.

How to Prevent Seeing Halos Around Lights

While not all causes of halos around lights can be prevented, especially those related to congenital conditions or age, there are several strategies to manage symptoms or reduce the risk of developing conditions that lead to halos.

  1. Regular Eye Examinations – Annual or biannual check-ups can catch early signs of conditions like cataracts or glaucoma before they progress to more serious stages.
  2. Protect Your Eyes From UV Light – Wearing sunglasses that block UVA and UVB rays can protect your eyes from conditions exacerbated by sunlight, such as cataracts.
  3. Maintain a Healthy Lifestyle – Incorporate foods rich in vitamins C and E, zinc, lutein, and omega-3 fatty acids to support eye health. Regular physical activity can also reduce the risk of conditions like diabetes, which can lead to eye complications.
  4. Stay Hydrated – Adequate fluid intake supports tear production and can help prevent dry eye syndrome.
  5. Limit Screen Time – Reducing the amount of time spent in front of computer screens and smartphones can decrease eye strain and dryness.
  6. Use Proper Lighting – Ensure that your reading or work environment is well-lit to reduce eye strain, which can exacerbate the appearance of halos.
  7. Quit Smoking – Smoking increases the risk of developing cataracts and other eye diseases that can lead to halos.
  8. Eye Protection – Wear protective eyewear during activities that could lead to eye injuries or when exposed to potential irritants.
  9. Manage Chronic Conditions – Keeping systemic diseases like diabetes under control can help prevent eye complications.

When to See Your Eye Doctor

While occasional halos around lights may not always signify a serious problem, understanding when to seek professional advice is crucial for maintaining eye health. Here’s what you need to know about diagnosing this condition and determining when it’s time to see a doctor.

  • Persistent or Worsening Symptoms – If halos are persistent, seem to worsen over time, or are accompanied by other visual disturbances (like blurred vision or sensitivity to light), consult with an eye care professional (ECP).
  • Sudden Onset – A sudden appearance of halos, especially if it’s accompanied by pain or redness in the eyes, could indicate acute conditions like angle-closure glaucoma, which requires immediate medical attention.
  • After Eye Surgery – Patients who have recently undergone eye surgery, such as cataract removal or LASIK, should monitor for halos as part of their post-operative care. While halos are common during the healing process, persistent symptoms should be evaluated by a doctor.
  • Associated Symptoms – If halos around lights are accompanied by symptoms such as headaches, nausea, or visual field loss, seeing a doctor as soon as possible is crucial, as these could be signs of serious eye conditions.

What to Expect During an Eye Examination

When you visit an eye care professional for halos around lights, the examination may include:

  • Patient History – Discussing when the halos started, any associated symptoms, and your general health history.
  • Visual Acuity Test – Assessing your vision clarity at various distances to identify any changes.
  • Refraction Assessment – Determining if a refractive error like nearsightedness, farsightedness, or astigmatism is present.
  • Corneal Examination – Inspecting the cornea for abnormalities that could cause light scattering.
  • Intraocular Pressure (IOP) Measurement – Checking for elevated eye pressure, which could indicate glaucoma.
  • Dilated Eye Exam – Dilating the pupils to examine the retina and optic nerve for signs of damage or disease.

Wrapping Up

Experiencing halos around lights can range from a temporary nuisance to a sign of underlying eye health issues. While often harmless and transient, it’s crucial to pay attention to what your eyes are telling you. Understanding the causes behind this phenomenon and knowing when to seek professional advice are key steps in maintaining good vision and overall eye health.