If you feel your vision is blurry at night but normally when adequate amounts of light are present. You may be suffering from a condition known as night blindness. The condition is not the nighttime equivalent of true blindness-nonetheless, those who have it know how limiting its effects can be. One of the most common causes of night blindness is deterioration due to age. In the natural aging process, the eye lens becomes less clear and grows cloudy over time, making it difficult to see in dim light. Another general cause is uncorrected myopia, or nearsightedness. Even with vision correction, nearsighted people may find their nearsightedness is exacerbated when their pupils dilate at night. In some cases, night blindness is a symptom of a serious underlying condition, such as retinitis pigmentosa, which is inherited. This degenerative retinal disorder causes the retina's rod cells-which, as we mentioned above, distinguish light from dark-to deteriorate and eventually stop functioning. Night blindness is often the first symptom of a cataract, as well. Early cataract development increases glare and decreases the amount of light reaching the back of the eye.