When a bright light source, such as a streetlamp or an oncoming car’s headlight, appears distorted, blurred, or surrounded by visual artifacts, this is a symptom of light scattering within the eye. This experience is not a single diagnosis but rather a common visual complaint that points toward a number of underlying conditions affecting the eye’s ability to focus light precisely. The visual effect of blurred lights, especially noticeable in low-light environments, signals an issue with how light travels through the cornea, the lens, or the tear film before reaching the retina.
Understanding Glare Halos and Starbursts
The phenomena associated with blurred lights are specifically categorized into three terms: glare, halos, and starbursts. These effects occur because light is scattered before it can focus cleanly onto the retina. This scattering prevents a crisp, singular image from forming, leading to the perception of light distortion.
Glare describes an uncomfortable brightness that reduces overall visual clarity. Halos appear as distinct, luminous rings surrounding a light source. Starbursts, also called streaks or rays, manifest as fine lines of light radiating outward from a central light source, creating a star-like pattern. All three symptoms are typically more pronounced at night when the pupil dilates to let in more light.
Causes Stemming from Refractive Errors
One of the most frequent reasons for perceiving blurry lights involves refractive errors, which are problems with the shape of the eye that cause light to focus incorrectly. These conditions include myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. For people with myopia, light focuses in front of the retina instead of directly on it, which can cause excessive glare and halos around distant lights.
Astigmatism is a condition where the cornea or the lens has an uneven curvature instead of a spherical one. This irregularity causes incoming light rays to split and focus on multiple points instead of a single point, which produces starbursts and streaks. The visual distortions are amplified in low light because the dilated pupil exposes more of the irregularly shaped corneal or lens surface. Hyperopia, where light focuses behind the retina, can also contribute to visual distortion.
Causes Stemming from Eye Health Conditions
Blurry lights can also signal structural changes or diseases within the eye. Cataracts, which involve the clouding of the eye’s lens, are a primary cause of glare and halos. The cloudy lens scatters light as it passes through, preventing a clear image from forming and producing the characteristic rings and streaks.
Dry eye syndrome can also cause significant visual disturbances. When the tear film that covers the cornea is unstable or deficient, the corneal surface becomes irregular and roughened. This instability causes light to scatter, leading to fluctuating vision, glare, and blurred sight that often temporarily improves with blinking.
Keratoconus is a progressive condition where the cornea thins and bulges outward into a cone shape, creating a highly irregular surface. This significant distortion drastically affects how light is refracted, resulting in severe starbursts, halos, and blurred vision. Individuals who have undergone refractive surgery, such as LASIK, may experience temporary or long-term halos and starbursts due to the altered corneal shape, which typically fades as the eye heals.
Management and When to Consult a Professional
Occasional halos or mild glare around bright lights are not always a cause for alarm, but persistent, worsening, or suddenly appearing symptoms warrant a consultation with an eye care professional. It is particularly urgent to seek immediate care if the onset of halos is sudden and accompanied by severe eye pain, headache, nausea, or vomiting, as this may indicate a medical emergency like angle-closure glaucoma. Difficulty driving safely at night because of light distortion is also a strong signal that an eye examination is necessary.
Management strategies are tailored to the underlying cause identified during a comprehensive eye exam:
- For refractive errors like astigmatism or myopia, the solution is often updating a prescription for glasses or contact lenses.
- Dry eye syndrome is typically managed with lubricating eye drops, which help restore a smooth, stable tear film on the corneal surface.
- More structural issues, such as advanced cataracts, may require surgical intervention, like cataract removal and lens replacement.
- Severe keratoconus may require specialized treatments like corneal cross-linking.