12 Vision Changes That Warrant an Eye Exam

10. Halos Around Lights - Optical Phenomena and Underlying Pathology

The appearance of halos or rings of light around bright objects, particularly at night, can indicate various eye conditions ranging from minor refractive issues to serious diseases requiring immediate treatment. While small halos around lights may be normal, especially in low-light conditions or when pupils are dilated, prominent or persistent halos often signal underlying problems. Acute angle-closure glaucoma classically presents with rainbow-colored halos around lights, accompanied by severe eye pain, nausea, and rapid vision loss. This represents a true medical emergency requiring immediate intervention to prevent permanent blindness. Cataracts commonly cause halos around lights as the clouded lens scatters incoming light, creating a ring-like appearance around bright objects. This symptom often worsens at night when pupils dilate, allowing more scattered light to enter the eye. Corneal edema, or swelling of the cornea, can cause halos by disrupting the cornea's normally smooth surface and creating optical irregularities. This condition can result from various causes, including eye trauma, infections, or complications from eye surgery. Fuchs' dystrophy, a progressive condition affecting the cornea's inner layer, often begins with morning halos that improve throughout the day as corneal swelling decreases. Certain types of contact lenses or refractive surgery complications can also cause halos around lights. Additionally, some medications that affect pupil size or corneal hydration may contribute to halo formation. When halos around lights develop suddenly, are accompanied by pain or vision loss, or significantly interfere with night driving or daily activities, prompt ophthalmologic evaluation is essential to determine the cause and initiate appropriate treatment.