Causes

The cause of most cataracts is unknown, but at least two factors associated with aging contribute to cataract development. One, clumping (aggregation) of lens proteins leads to scattering of light and a decrease in the transparency of the lens. Two, the breakdown of lens proteins leads to the accumulation of a yellow-brown pigment that clouds the lens.

Choose another disease or condition... Allergic Rhinitis Allergies, Food Allergy & Asthma Center Alzheimer's Disease Anxiety Aortic Aneurysms Arrhythmia Arthritis, Osteo- (OA) Arthritis, Rheumatoid (RA) Asthma Atopic Dermatitis Attention Deficit Hyperactivity Disorder (ADHD) Back Pain Brain Tumor Bones, Joints & Muscles Center Breast Cancer Brain & Behavior Center Brain Tumor Cancer Center    Brain Tumor    Breast Cancer    Cancer Prevention    Clinical Trials    Colorectal Cancer    Endometrial Cancer    Living With and Beyond Cancer    Lung Cancer    Prostate Cancer    Skin Cancer Cardiomyopathy Cataracts Cholesterol Control Clinical Trials Chronic Obstructive Pulmonary Disease (COPD) Colorectal Cancer Congenital Heart Disease Congestive Heart Failure (CHF) Coronary Artery Disease (CAD) Crohn's Disease Depression Diabetes Center Diabetes, Type 1 Diabetes, Type 2 Digestive Disorders Center Eczema Endometrial Cancer Erectile Dysfunction (ED) Eye & Vision Center Fibromyalgia Food Allergies Gallstone Disease Gastroesophageal Reflux Disease (GERD) GERD Glaucoma Hay Fever Headache Heart Center Hepatitis A Hepatitis B Hepatitis C High Blood Pressure Hypertension Hypertrophic Cardiomyopathy (HCM) Impotence Insomnia Irritable Bowel Syndrome (IBS) Living With and Beyond Cancer Losing Weight Lung Cancer Macular Degeneration Memory Loss Osteoarthritis (OA) Osteoporosis Parkinson's Disease Peptic Ulcer Prediabetes Prostate Cancer Respiratory Disorders Center Restless Legs Syndrome (RLS) Rheumatoid Arthritis (RA) Sexual & Reproductive Health Center Sinusitis Skin Cancer Sleep Apnea Sleep Center Stroke Type 1 Diabetes Type 2 Diabetes Ulcerative Colitis (UC) Weight Control Get more information online about cataracts See our in-depth guide on glaucoma More on eyes in our Eye and Vision Center Cataracts-Related Clinical Trials Information Email this page Print this section

Certain chemical changes have been noted in the eyes of people with cataracts. These changes include a reduced uptake of oxygen by the lens and a rise in the water content of the lens, which is later followed by dehydration. Amounts of calcium and sodium in the lens increase, while levels of potassium, vitamin C, and protein decrease during cataract formation. In addition, glutathione (an antioxidant) appears to be deficient in lenses with cataracts. Studies on the use of medications or vitamins to alter the levels of these substances in the lens have not produced promising results, however.

The extent of vision damage and how quickly vision becomes impaired depend not only on the size and density of the cataract but also its location in the lens. For example, a cataract on the outside edge of the cortex has little effect on vision because it does not interfere with the passage of light through the center of the lens, while a dense nuclear cataract causes severe blurring of vision.