Seeing radiating lines or rings around light sources, particularly in dim environments, is a common visual experience. This phenomenon can be a normal part of how the eye processes light, especially at night. However, these visual effects can also prompt consideration of underlying vision factors.
Understanding Light Streaks and Halos
Seeing lines or rings around lights are visual phenomena commonly known as light streaks, starbursts, or halos. Halos are bright, circular rings surrounding a light source, often colorful. Starbursts are light rays extending outwards from a central source, resembling a star. Light streaks are elongated lines of light. These terms describe visual aberrations where light scatters or appears distorted rather than being sharply focused. While often a normal optical occurrence, these visual effects can sometimes signal an underlying eye condition.
How Light Streaks and Halos Form
Light streaks and halos arise from how light interacts with the eye’s structures before reaching the retina. One mechanism involves light diffraction, where light bends as it passes the edges of the pupil or other ocular structures. Light scattering also plays a role, occurring when light rays are dispersed by imperfections or particles within the eye’s media, such as the tear film or the lens.
The tear film, a thin liquid layer covering the eye’s surface, is important; irregularities or instability can cause light to scatter, impacting visual clarity. Pupil size also influences these phenomena. In low-light conditions, the pupil naturally dilates, allowing more light to enter, including light from the periphery of the lens. This wider aperture can make optical imperfections more noticeable, increasing perception of halos or starbursts. Consequently, even in healthy eyes, these effects can be experienced, particularly when pupils are dilated at night.
Eye Conditions Causing Light Streaks
Several eye conditions can cause or worsen light streaks and halos by altering how light enters and focuses within the eye. Astigmatism, a refractive error from an irregularly shaped cornea or lens, causes light to focus unevenly on the retina, often leading to starbursts or streaks. Cataracts, clouding of the eye’s natural lens, scatter incoming light as it passes through opaque areas, producing halos and glare. This scattering impairs vision, especially in low light.
Dry eye syndrome, characterized by an insufficient or unstable tear film, can also lead to these disturbances. An uneven tear film creates an irregular surface on the eye, causing light to distort and scatter rather than refracting smoothly. Changes in corneal shape following refractive surgeries like LASIK can result in temporary or persistent halos and light streaks due to alterations in how light is processed. While often part of the healing process, these can occasionally be long-term side effects.
Acute angle-closure glaucoma, a serious condition involving a rapid increase in eye pressure, can cause sudden halos, often with rainbow colors, along with other symptoms. This condition is a medical emergency. Corneal edema, swelling of the cornea, can scatter light and contribute to halos and blurred vision.
When to Seek Professional Eye Care
While seeing light streaks or halos can sometimes be a normal experience, certain signs suggest professional eye care is needed. Consult an eye care professional if these visual disturbances appear suddenly or worsen. This is especially true if accompanied by other symptoms, such as eye pain, redness, or a significant decrease in vision.
Other warning signs warranting prompt medical attention include the sudden appearance of new floaters, flashes of light, or a curtain-like shadow across your field of vision. If light streaks or halos interfere with daily activities, such as driving at night, seeking an evaluation is important. Regular comprehensive eye exams are recommended for early detection and management of underlying eye conditions, even without noticeable symptoms.