A cataract is a progressive clouding of the normally clear lens of the eye. This clouding can weaken vision. The amount and pattern of cloudiness in the lens, as well as the rate at which it develops, can vary.
The eye functions much like a camera. Light rays enter through the front of the eye, passing through the cornea, the pupil and the aqueous humor (transparent fluid in the front of the eye) onto the lens. The lens then bends light rays to focus objects onto the retina in the back of the eye. From there, the retina, the optic nerve, and the brain process the images and form vision.
Chemical and structural changes occur within the lens over time. These changes make the lens cloudy and prevents light from passing through, which causes some loss of vision. This is a normal part of the aging process.
Cataracts can also progress more rapidly due to:
Other factors that increase the risk of developing cataracts include cigarette smoke, air pollution and heavy alcohol use.
Cataracts are a normal aging change of the eye. Cataracts often form slowly and cause few symptoms. When symptoms are present, they can include:
A thorough eye examination by your eye doctor (ophthalmologist) can identify a cataract, as well as any other conditions that may be causing blurred vision.
The eye exam will tell your doctor how much vision you have lost. If there is not a great deal of vision loss, your doctor may prescribe eyeglasses (including bifocals), magnification devices, contact lenses or other visual aids.
In the early stages of cataract development, vision may be improved simply by a change in glasses prescription. Over time, the cataract increases and symptoms are no longer relieved by glasses. The patient will need surgery to restore useful vision once the cataract worsens.
Cataract surgery should be considered when the cataract causes enough loss of vision to interfere with daily activities that are important to the patient, such as reading, driving, or recreational activities such as golf or tennis.
Occasionally, cataract surgery will be necessary to evaluate and treat other eye conditions, such as diabetic or age-related changes in the retina. Your ophthalmologist can help you with the decision about surgery under these circumstances.
Cataract surgery is performed on an outpatient basis with local anesthesia (the patient is awake but does not feel the procedure). Frequently, medication is given to help you feel relaxed, as well. You will not see the actions of the surgeon nor anything sharp near your eye. During the surgery, the clouded lens of the eye is broken up with high-frequency sound waves (ultrasound) or laser, and then suctioned from the eye by a process called phacoemulsification. The clouded lens is then replaced with a clear, plastic intraocular lens implant in order to restore vision. The prescription of the artificial lens is selected to fit your eye and to help restore normal vision.
When patients have cataracts in both eyes, the surgeries are usually done separately.
A laser, known as the femtosecond laser, can be used to assist in the cataract surgery. This may allow for treatment of astigmatism or other conditions.
After surgery, it is normal to feel itching and some mild discomfort. Your doctor may recommend that you take a pain reliever for a short time. You may also have increased tearing from the eye and may be sensitive to light for a short time after the procedure.
For a few weeks after surgery, you may need to use eye drops to aid healing, prevent infection, and control the pressure inside your eye. Strenuous activity, such as heavy lifting or activities that might lead to risk of a blow to the eye, should be avoided for several weeks. Normal non-strenuous activities, including bending, lifting, reading, and driving, can be resumed the day after surgery.
Most patients will have good vision in the operated eye about a week after surgery. You may still need to wear glasses after cataract surgery.
Nearly 98% of all cataract surgeries are performed each year without serious complications. Though this type of surgery is very safe, you should discuss the risks with your ophthalmologist. Cataract surgery with lens implantation is the most frequently performed surgery in the United States, with more than 1.5 million surgeries each year.
Because the exact cause of cataracts is uncertain, there is no proven method to prevent them from forming. Lifestyle changes, including smoking cessation, UV light protection, and healthy diet and exercise may be beneficial.
Lens implants are permanent and ordinarily do not need to be replaced. They are good for the life of the patient.
In a minority of patients, a clouding occurs on the lens capsule months or years after surgery. In this case, an office procedure using a laser can restore normal vision.
Cataract surgery is typically covered by Medicare, insurance and HMOs.
© Copyright 1995-2019 The Cleveland Clinic Foundation. All rights reserved.
This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 07/03/2018