Glaucoma refers to a group of eye conditions that damage the optic nerve, the pathway connecting the eye to the brain. This damage often happens when fluid builds up in the front part of the eye, increasing pressure inside the eye. While glaucoma can sometimes progress without noticeable symptoms in its early stages, visual disturbances like “halos” around lights can be a warning sign for certain types or stages of the condition. Recognizing these visual changes can be important for early detection and management.
Describing Glaucoma Halos
Glaucoma halos typically appear as bright circles or rings of light surrounding illuminated objects, such as streetlights, car headlights, or household bulbs. People often describe these halos as iridescent, rainbow-colored, or hazy. They are most commonly noticed at night or in dimly lit environments, where bright light sources stand out. This visual phenomenon is not a normal part of vision and can be particularly disruptive, especially when driving in the dark.
Unlike occasional glare or starbursts that can be normal responses to bright lights, persistent halos suggest an underlying issue. The presence of these halos indicates a distortion in how light is processed by the eye, hinting at changes within its structures.
Why Halos Appear in Glaucoma
Halos occur in glaucoma due to increased intraocular pressure (IOP). When this pressure rises significantly, it can lead to swelling of the cornea, the clear front surface of the eye. This swelling is medically known as corneal edema. Normally, the cornea functions to focus light clearly onto the retina.
However, when the cornea swells, its normally clear and uniform structure becomes irregular. This irregularity causes light entering the eye to scatter abnormally instead of being focused precisely. The scattered light then creates the perception of halos or colored rings around light sources. This effect is common in types of glaucoma where eye pressure rises rapidly, such as acute angle-closure glaucoma.
When to Seek Medical Attention
If you suddenly begin seeing halos around lights, especially if accompanied by other symptoms, consult an eye care professional immediately. These other symptoms might include severe eye pain, headaches, blurred vision, nausea, or vomiting. The sudden onset of these combined symptoms can signal acute angle-closure glaucoma, a medical emergency requiring prompt treatment to prevent permanent vision loss.
Even if halos appear without severe accompanying symptoms, persistent or recurring halos should prompt an eye examination. Early detection and treatment are important for managing glaucoma and preserving vision. Regular eye check-ups are also recommended, especially for individuals over 40 or those with risk factors for glaucoma.