Halos around lights are bright, often colorful, circles or rings that appear to surround sources of light, such as streetlights or car headlights. This visual phenomenon is frequently observed in low-light conditions or at night, potentially affecting vision clarity. While seeing halos can sometimes be a normal response of the eye to light, it can also signal an underlying issue that requires attention. This article explores the various reasons why halos appear around lights, from common occurrences to more serious medical conditions.
Why Halos Appear
Halos appear due to how light interacts with the eye’s structures, scattering or diffracting as it enters. In dimly lit environments, pupils naturally dilate, allowing more light to enter and scatter more noticeably. This scattering can create the perception of halos.
A common benign cause is dry eye syndrome, where an uneven tear film on the eye’s surface can scatter incoming light. Individuals recovering from refractive surgeries like LASIK may experience temporary halos as their eyes heal. New glasses or contact lenses can also lead to a temporary adjustment period.
Aging contributes as the eye’s natural lens undergoes changes over time. Conditions like astigmatism, which involves an irregularly shaped cornea or lens, cause light to scatter incorrectly, leading to halos and blurred vision. These instances are generally not serious and may resolve on their own or be managed with simple interventions.
Medical Conditions Associated with Halos
While often harmless, halos can also be a symptom of underlying medical conditions. A prevalent cause is cataracts, where the eye’s natural lens becomes cloudy, scattering light and causing halos and blurred vision. This condition is common in older adults and progresses slowly, and can significantly impair vision over time.
Acute angle-closure glaucoma is an urgent scenario where rapidly increased pressure inside the eye causes the cornea to swell. This corneal edema alters how light enters the eye, leading to sudden halos, often accompanied by severe eye pain, headache, nausea, or vomiting.
Other corneal conditions, such as Fuchs’ dystrophy, involve fluid buildup in the cornea, which can also cause swelling and light scattering, leading to halos. Migraines with aura can also manifest as visual disturbances, including halos or other light patterns, typically preceding the headache phase. Certain medications can also have visual side effects, including the perception of halos.
When to Consult an Eye Doctor
Recognizing when halos signal a need for professional medical attention is important. Seek immediate evaluation if halos appear suddenly or worsen rapidly, especially if accompanied by other symptoms.
Red flags include eye pain, redness, significant vision changes, or blurred vision alongside halos. Halos accompanied by nausea, vomiting, or severe headaches suggest a serious condition like acute angle-closure glaucoma, requiring urgent care.
If halos interfere with daily activities, such as driving at night, or if their color or intensity changes, seek an eye examination. Individuals with a history of eye conditions like glaucoma or cataracts should report any new or changing halo perceptions to their eye care provider.
Understanding Diagnosis and Treatment Options
When consulting an eye doctor for halos, a comprehensive eye examination is performed to determine the underlying cause. This may include dilating pupils to view the eye’s internal structures and a slit-lamp examination to inspect the front of the eye.
Tonometry, a test to measure intraocular pressure, is often conducted, especially if glaucoma is suspected. Further specialized tests, such as corneal topography to assess the cornea’s shape, might be necessary.
Treatment approaches for halos depend entirely on the diagnosis. For instance, lubricating eye drops may be prescribed for halos caused by dry eyes. If refractive errors are the cause, an updated prescription for glasses or contact lenses might resolve the issue.
Medical conditions like glaucoma may require specific medications to manage eye pressure, while cataracts often necessitate surgical intervention to replace the cloudy lens. Corneal issues might be managed with medications or, in some cases, surgical procedures.