Sudden glare in vision describes an unexpected increase in brightness perception or light sensitivity, making clear vision difficult. This common visual disturbance involves uncomfortable, bright light that disrupts vision. Understanding its causes helps maintain visual comfort and health.
How Glare Affects Vision
Vision relies on light entering the eye and focusing precisely onto the retina. Glare occurs when light scatters abnormally within the eye, rather than focusing sharply. This scattering reduces the contrast of the retinal image, creating a “veil of light” that impairs vision.
This scattering effect leads to two main types of glare: discomfort glare and disability glare. Discomfort glare is a psychological sensation from high brightness that may cause annoyance, fatigue, or headaches without necessarily impairing vision. Disability glare actively impairs vision by reducing contrast, making details harder to distinguish. Both types arise from light scattering within the eye’s optical components, such as the cornea or lens.
Temporary Factors Causing Glare
Exposure to very bright light sources, such as direct sunlight, reflections off surfaces like water or snow, or oncoming car headlights at night, can cause temporary glare. This happens because the eye’s system can be overwhelmed by excessive light, temporarily reducing visual clarity.
Temporary dry eyes can also cause glare, particularly at night, as insufficient tear film scatters incoming light. Eye strain from prolonged visual tasks may contribute to light sensitivity and perceived glare. Post-dilation from an eye exam can result in increased light sensitivity and glare due to the enlarged pupil. Some individuals also experience glare as part of a migraine aura, where visual disturbances precede a headache.
Medical Conditions Causing Glare
Cataracts, the clouding of the eye’s natural lens, are a common cause of glare. As the lens clouds, it scatters light instead of focusing it precisely, leading to increased glare, halos around lights, and blurred vision.
Corneal issues, such as abrasions, infections like keratitis, or conditions like keratoconus and Fuchs’ dystrophy, can also cause glare. The cornea, the eye’s clear outer layer, plays a crucial role in focusing light. When its surface is irregular or damaged, light scatters, resulting in glare, blurred vision, and light sensitivity. Keratoconus, where the cornea thins and bulges into a cone shape, distorts vision and causes significant glare.
Glaucoma, a group of diseases damaging the optic nerve, can also lead to light sensitivity and glare. Elevated intraocular pressure, common in glaucoma, contributes. Acute angle-closure glaucoma, a medical emergency, can cause sudden and intense symptoms, including halos around lights.
Retinal problems, such as early macular degeneration or retinitis pigmentosa, can manifest with glare sensitivity. The retina converts light into signals sent to the brain; any disruption impairs vision, including increased sensitivity to bright lights. Optic nerve conditions, like optic neuritis, involve inflammation of the nerve connecting the eye to the brain, causing blurred vision and light sensitivity.
When to Consult an Eye Doctor
Consult an eye doctor if sudden glare is persistent, worsening, or significantly interferes with daily activities. Symptoms warranting prompt professional evaluation include glare alongside eye pain, sudden vision loss, or a noticeable decrease in visual acuity.
The presence of halos around lights, flashes of light, or an increase in new floaters also signals a need for immediate attention. Double vision, severe headaches, or any sudden changes in vision should also prompt a visit. Early diagnosis and treatment can prevent potential long-term vision problems.