How Cataract Affects Vision
A cataract is a clouding of the natural lens inside the eye. As the lens gradually becomes less transparent, light passing through it is scattered rather than focused precisely on the retina. This results in vision that becomes progressively blurred, hazy, or less clear.
The way cataract affects vision can vary depending on the location of the opacity within the lens — nuclear cataracts (at the centre of the lens), cortical cataracts (in the outer layers), and posterior subcapsular cataracts (at the back of the lens) each have slightly different effects on vision.
Early Signs of Cataract
1. Gradual Blurring of Vision
One of the earliest and most common signs is a gradual, progressive blurring of vision. Unlike sudden vision changes, cataract-related blur tends to develop slowly over months or years. Objects may appear slightly hazy or out of focus even with spectacles.
2. Increased Sensitivity to Light and Glare
People with cataract often report that bright lights seem more dazzling or uncomfortable than before. This can be particularly noticeable when driving at night — oncoming headlights may produce significant glare or halos, making night driving more difficult.
3. Halos Around Lights
The scattering of light through a cloudy lens can produce halos or starbursts around light sources, particularly at night. This is commonly reported by people with early cataract.
4. Faded or Yellowed Colours
The lens in a cataract often takes on a yellowish or brownish tint. This can cause colours to appear less vivid, faded, or with a yellow tint. The change is usually gradual and may not be noticed until it is more pronounced.
5. Frequent Changes in Spectacle Prescription
Some people with early nuclear cataract experience frequent changes in their spectacle or contact lens prescription. In some cases, there may be temporary improvement in near vision (a phenomenon sometimes called 'second sight') as the changing lens power allows clearer near vision without reading glasses. This temporary change does not persist.
6. Double Vision in One Eye
A cataract can sometimes cause double vision (diplopia) in one eye. This is different from the more common double vision caused by eye alignment problems (which occurs when both eyes are open). If you notice double vision in one eye when covering the other, seek an eye examination.
7. Needing More Light for Reading or Close Tasks
Requiring significantly brighter light to read comfortably or carry out close work can be an early sign of cataract, particularly posterior subcapsular cataract, which disproportionately affects vision in bright light and at near distances.
What to Do If You Notice These Signs
If you notice one or more of these signs, the appropriate step is to schedule a comprehensive eye examination with an ophthalmologist. An eye examination will determine whether a cataract is present, how it may be affecting your vision, and whether any management is currently indicated.
In the early stages, cataract may simply be monitored with regular examinations. When cataract progresses to the point where it significantly affects daily activities, further management — which may include surgery — can be discussed with your ophthalmologist.