A cataract is a condition characterized by the clouding and loss of transparency of the natural lens of the eye, located behind the pupil, which is essential for vision. This occurs due to the gradual accumulation of proteins in the lens and changes in its structure over time.

The primary factors that cause or increase the risk of cataract formation include:
* Age: The most common cause.
* Genetic Predisposition: A family history of cataracts.
* Systemic Diseases: Conditions such as diabetes and high blood pressure.
* Eye Trauma: Eye injuries or previous eye surgeries.
* Sunlight Exposure: Especially prolonged and intense exposure to UV rays.
* Medication Use: Long-term use of steroid medications (including eye drops) and radiation therapy administered for cancer treatment.
* Lifestyle Factors: Smoking and alcohol consumption.
* Eye Diseases: Conditions such as uveitis (inflammation of the uvea region of the eye).
* Other Conditions: Certain conditions leading to premature aging, such as myopia or Down syndrome, can also contribute to cataract development.
* Environmental Factors: Specific environmental factors may also play a role.

Patients typically present with complaints of "foggy" or "cloudy" vision. This condition significantly impairs visual ability over time. Other symptoms of cataracts include:
* Glare from oncoming lights, particularly at night.
* Difficulty with daily activities such as reading and recognizing faces.
* Difficulty watching television.
* Colors appearing paler, duller, or darker.
* A decreased need for reading glasses (second sight syndrome).
* Straight edges appearing bent or wavy.