The experience of seeing lights scatter, blur, or produce streaks after dark is a common visual complaint, frequently noticed when looking at car headlights or streetlights. This phenomenon, which often makes night driving difficult, is a symptom of light being improperly focused or scattered within the eye’s optical system. The underlying issue is a disruption in how light travels through the cornea, lens, or tear film before reaching the retina. Understanding the precise visual sensation and its root cause is the first step toward effective correction.
Identifying Specific Visual Disturbances
The general complaint of blurry lights at night can be broken down into three distinct visual disturbances, based on how light is scattered. Halos appear as bright, concentric rings or circles of light that surround a light source, like a streetlamp. They are caused by the diffraction of light as it passes through a medium, such as moisture, clouding, or microscopic irregularities within the eye.
Glare is an intense and uncomfortable brightness that significantly impairs vision by washing out surrounding details and reducing contrast. This happens when a bright light source overwhelms the eye’s ability to process the image, making it difficult to discern objects near the light. Glare can be disabling, particularly because the eye’s pupil dilates in low light, allowing more scattered light to enter.
Starbursts, sometimes called streaks, are characterized by fine lines or spikes of light that radiate outward from a central light source, creating a star-like pattern. This distortion is frequently a result of uncorrected refractive errors or minute irregularities on the eye’s surface. Recognizing which visual effect you are experiencing is helpful in identifying the underlying cause.
Primary Ocular Causes of Nighttime Blurring
The scattering of light that produces these night vision issues is often traced to physical changes in the eye’s transparent structures. Astigmatism, a common refractive error, is a frequent cause of starbursts because the cornea or lens has an irregular, football-like curvature instead of a spherical one. This uneven shape causes incoming light to focus at multiple points instead of a single one, stretching point sources of light into streaks.
The development of cataracts is a major factor, particularly as the lens inside the eye begins to cloud with age. This clouding scatters light in multiple directions instead of transmitting it clearly, leading to glare and the appearance of halos. The effect is often worse at night because the pupil widens, exposing the eye’s periphery where the lens clouding may be more pronounced.
Dry Eye Syndrome, characterized by an unstable tear film, can create an irregular surface on the cornea that temporarily scatters light. When the tear film breaks up between blinks, the smooth optical surface is compromised, resulting in transient glare and blurring until the next blink restores the surface. This effect is often exacerbated during prolonged night driving.
Night vision problems may also arise following refractive surgeries such as LASIK. While modern procedures have reduced the incidence, corneal reshaping can sometimes induce subtle irregularities known as higher-order aberrations. These microscopic changes in the corneal surface profile can cause light to scatter, leading to persistent halos or starbursts, especially when the pupil dilates beyond the treated area.
Diagnostic Procedures for Night Vision Issues
Pinpointing the cause of night vision disturbances requires a thorough examination by an eye care professional. A comprehensive eye exam begins with a standard visual acuity test and a refraction test to determine if an updated prescription for myopia or astigmatism is needed. This step rules out simple uncorrected refractive errors.
The doctor will then use a slit lamp examination to inspect the anterior segment of the eye at high magnification. This allows for detailed visualization of the cornea and the lens, helping to detect subtle irregularities in the tear film, corneal surface damage, or the early formation of cataracts. The slit lamp is crucial for confirming physical clouding or surface issues.
For more complex cases, specialized imaging tests are employed to map the eye’s curvature and optical path. Corneal topography generates a detailed contour map of the corneal surface, which identifies the precise location and severity of astigmatism or other corneal irregularities. Wavefront analysis measures how light travels through the entire optical system, identifying higher-order aberrations that standard refraction cannot detect.
Treatment and Management Options
Treatment for blurry night lights is dependent on the diagnosis. For issues related to refractive error, updated refractive correction is often the simplest solution. This may involve prescribing specialized toric lenses for astigmatism or eyeglasses featuring an anti-reflective coating, which reduces internal reflections that contribute to glare.
When the problem is linked to an underlying condition, medical management is necessary. Patients with dry eye syndrome benefit from lubricating eye drops to maintain a stable, smooth tear film surface. If night vision issues persist after refractive surgery, medicated eye drops may be temporarily used to limit pupil dilation, preventing light from entering the eye through the peripheral, untreated cornea.
For visual impairment caused by cataracts, surgical intervention is the definitive treatment. Cataract surgery involves removing the clouded natural lens and replacing it with a clear artificial intraocular lens (IOL). This typically resolves the light scattering and associated halos and glare.
Simple environmental adjustments can also help manage symptoms. These include ensuring eyeglasses are clean and scratch-free, and adjusting the brightness of the car’s dashboard lights to prevent excessive pupil dilation.