Drivers often experience visual phenomena like beams of light, glare, or starbursts when driving at night. These are real occurrences stemming from identifiable causes, ranging from eye conditions to external environmental factors. Understanding these phenomena can help in addressing them effectively.
Understanding Common Light Visualizations
Glare occurs when light sources appear excessively bright, reducing clarity and making it difficult to discern objects. Starbursts manifest as light radiating outwards from a central point, resembling spokes on a wheel, often seen around headlights or streetlights.
Halos appear as rings of light encircling illuminated sources, such as streetlights or oncoming vehicle headlights. Streaks or beams are elongated lines of light extending from a source. These light anomalies can significantly impact night driving visibility.
Underlying Factors Contributing to Light Phenomena
Ocular/Eye-Related Causes
Astigmatism is a common condition where the cornea or lens has an irregular curvature, causing light to focus on multiple points instead of a single clear point. This often makes lights appear as starbursts or streaks, particularly noticeable when driving at night. Uncorrected astigmatism can make bright lights seem hazy, stretched, or doubled, impairing the ability to discern details.
Cataracts involve the clouding of the eye’s natural lens, scattering light instead of focusing it clearly onto the retina. This leads to increased glare sensitivity, halos, and starbursts around lights, making night driving challenging. As cataracts progress, they can cause blurred vision and difficulty seeing in low-light conditions.
Dry eyes can also contribute to visual disturbances at night. When the tear film on the eye’s surface is compromised, light can scatter abnormally instead of being focused for clear vision. This decreased lubrication creates glare from streetlights and headlights, an effect often more pronounced at night because pupils dilate in low light, allowing more scattered light to enter the eye.
Following LASIK or other refractive surgeries, some individuals may experience temporary or persistent glare, halos, and starbursts. This can occur as the cornea reshapes and heals, leading to changes in light sensitivity and how light enters the eye. Swelling in the cornea after surgery is a common reason for these visual disturbances, which usually diminish over several weeks or months.
The natural aging process also influences night vision. As people age, the pupil’s ability to dilate in dim light decreases, reducing the amount of light reaching the retina. The cornea and lens can also become less clear, causing light to scatter and increasing sensitivity to glare from headlights and reflective surfaces. This can make it harder to distinguish objects and navigate safely in low-light environments.
Corneal edema, or swelling of the cornea, results from fluid buildup in this clear outer layer of the eye. This swelling can distort vision, causing blurred vision, light sensitivity, and the appearance of halos around lights. Various factors, including injury, infection, inflammation, or certain eye diseases, can lead to edema.
External/Environmental Factors
Modern headlight technologies, such as LED and HID lights from oncoming vehicles, produce intense and focused beams. Their brightness can significantly contribute to glare for other motorists, temporarily overwhelming the eyes and making it challenging to see the road clearly.
A dirty or scratched windshield can severely impair night vision by scattering light. Dirt, smudges, or scratches on the glass can cause incoming light from headlights or streetlights to refract unpredictably, creating glare, blurriness, or exacerbating starburst and halo effects. This scattering reduces clarity and forces the eyes to work harder to interpret visual information.
Similarly, dirty or scratched eyeglasses and contact lenses can scatter light and increase glare. Smudges, dust, or fingerprints on corrective lenses can diffuse light, leading to distorted vision and making it harder to see clearly, especially at night. Maintaining clean lenses is important for optimal visual acuity and to minimize light disturbances.
Poorly adjusted headlights on one’s own car can contribute to reduced visibility and increased glare. Headlights aimed too high can blind oncoming drivers, while those aimed too low may not adequately illuminate the road ahead. Proper alignment ensures light is directed where needed, optimizing visibility without creating excessive glare for others.
Recognizing When Professional Help is Needed
Persistent or worsening visual symptoms when driving at night warrant evaluation by an eye care professional. If beams of light, glare, or halos suddenly appear, intensify, or significantly interfere with daily activities, seek medical attention. Any new visual disturbances, particularly if accompanied by eye pain or significant changes in vision, should prompt a visit to an optometrist or ophthalmologist.
A comprehensive eye examination can help identify underlying eye conditions such as cataracts, astigmatism, or corneal issues that might be contributing to these phenomena. Early detection of certain conditions can lead to timely and effective management, potentially preventing further vision impairment. Regular check-ups are important, especially as vision can change with age.
Enhancing Visibility for Night Driving
Regularly cleaning both the inside and outside of your car’s windshield removes dirt, smudges, and streaks that can scatter light and intensify glare. Ensuring your headlights are clean and free from oxidation also helps them project light effectively and reduces light diffusion.
For those who wear corrective lenses, it is important to keep eyeglasses and contact lenses meticulously clean. Smudges and dirt on lenses can significantly worsen glare and blurriness, impacting visual clarity. Ensuring your prescription is current can also address any refractive errors that contribute to light distortions.
Adjusting your vehicle’s mirrors can help mitigate glare from headlights behind you. Angling the rearview mirror to its “night mode” setting or slightly adjusting side mirrors can reduce the intensity of reflected light. Avoiding direct eye contact with oncoming headlights by shifting your gaze slightly to the right side of the road can also minimize temporary blinding effects.
Anti-glare or anti-reflective coatings on eyeglasses can significantly reduce reflections from headlights and streetlights. These coatings allow more light to transmit through the lenses, enhancing clarity and reducing eye strain. Taking breaks during long night drives can help alleviate eye fatigue, which can worsen visual disturbances.