eye disorders
Cataract
Symptoms of Cataract
Cataracts usually develop slowly over years. Because all light entering the eye passes through the lens, the cataract (clouding of the lens) can block and scatter light, which causes poor vision. Early symptoms may include Seeing halos and starbursts around lights (glare) Difficulty reading because of a worsening ability to distinguish the contrast between the light and dark of printed letters on a page Needing more light to see well Problems distinguishing dark blue from black Blurred vision Colors seeming more yellow and less vibrant Less commonly, mild double vision (also called ghost images) Although cataracts almost never cause pain, very rarely they swell and increase the pressure in the eye ( Glaucoma ), which can be painful. On the left, a normal lens receives light and focuses it on the retina. On the right, a cataract blocks some light from reaching the lens and distorts the light being focused on the retina. How much vision is changed by a cataract depends on the intensity of light entering the eye and on the location of the cataract. With a cataract in the center (inside) of the lens (nuclear cataract), the following symptoms are most common: Worsened distance vision Initially, improved near vision because the cataract acts as a stronger lens, thus refocusing light People who have needed reading glasses since their mid-40s may discover that they can see up close again without their glasses, a phenomenon called "second sight." This effect is temporary and goes away as the cataract becomes more opaque. With a cataract near the back of the lens (posterior subcapsular cataract), the following symptoms are most common: Blurred vision (less visual acuity) when the pupil constricts (for example, in bright light or during reading) Loss of contrast Halos and starbursts (glare) from bright lights or car headlights while driving at night People who take medications that constrict their pupils (for example, certain glaucoma eye drops) may also have greater vision loss. Sometimes a cataract in a certain part of the lens can cause near vision to improve for a while, and a person can read again without needing reading glasses. 