Cataracts are a common age-related condition where the eye’s natural lens, located behind the iris, becomes clouded. This lens focuses light onto the retina. When proteins in the lens clump together, they form a cataract that interferes with the passage of light, leading to hazy or blurred vision. This article addresses the connection between cataracts and the experience of seeing double.
How Cataracts Cause Double Vision
Cataracts can cause double vision, medically known as diplopia. This happens because the irregular clouding of the lens disrupts the normal path of light entering the eye. Instead of focusing light onto a single point on the retina, the cloudy lens scatters and refracts the light incorrectly.
This light scattering projects multiple, incomplete images onto the retina. The brain interprets these distinct visual signals as two separate, often overlapping, images. This is called monocular diplopia because the double vision persists even when the unaffected eye is covered.
Monocular diplopia distinguishes cataract-related double vision from binocular diplopia, which is caused by issues with eye alignment or coordination. If the affected eye is covered, the double vision disappears. The effect often appears as slight ghosting or shadowing around objects rather than two completely separate images.
Other Visual Changes Associated with Cataracts
Double vision is one of several symptoms that can arise from a cataract. The most common complaint is a progressive blurring or clouding of vision, which reduces clarity and makes fine details difficult to discern, both up close and at a distance.
Other visual changes include:
- Colors appearing faded, dull, or yellowish because the clouded lens absorbs and filters out certain wavelengths of light.
- Increased sensitivity to light and glare, also called photophobia.
- The scattering of light leads to the perception of halos or starbursts around bright light sources, significantly impairing night vision.
- Frequent changes in glasses prescriptions, or a temporary improvement in near vision, sometimes called “second sight,” before overall vision worsens.
Treating Cataract-Related Double Vision
Since the double vision caused by a cataract is a direct result of the physical clouding of the lens, the only permanent solution is surgical removal. Cataract surgery, often using a technique called phacoemulsification, involves breaking up and suctioning out the clouded natural lens.
Once the cataract is removed, a clear, artificial intraocular lens (IOL) is inserted to replace the focusing power of the original lens. This new lens eliminates the irregular light scattering, resolving the monocular diplopia. The procedure restores a clean optical pathway, allowing light to focus correctly onto the retina.
Patients should seek medical advice when cataract symptoms, including double vision, interfere with routine daily tasks like driving or reading. Cataract surgery provides a definitive treatment for the double vision caused by the clouded lens. If a patient also has underlying binocular diplopia, that issue may require separate treatment, such as prism glasses or eye muscle surgery.