Cataracts
This content is also available in:
Español (Spanish)
Has your vision gradually become hazy or dim, without noticeable eye pain? Do colors appear dull or less vibrant than they used to? It might be cataracts. A cataract is a progressive cloudiness, hardening, and yellowing of the normally transparent lens of the eye.
Introduction to Cataracts
A cataract is when the normally transparent lens inside the eye progressively becomes cloudy, yellow, and hardened. It is the leading cause of vision loss worldwide. The World Health Organization (WHO) has estimated that cataracts cause 51% of blindness worldwide and that more than 20 million people are blind due to cataracts. However, 90% of these cases of blindness from cataracts are found in developing countries.
To understand cataracts, it’s helpful to understand the parts of the eye, including the location and function of the lens, as shown in this diagram of the eye:
Side View Diagram of the eye
The lens comprises transparent, flexible tissue and is located directly behind the iris and the pupil.
Like the lens in a camera, the lens in the eye helps to focus light and images onto the retina, which is the light-sensitive tissue that lines the inside surface of the eye.
Nerve cells in the retina convert incoming light into electrical impulses. The optic nerve (which is like a television cable) carries these electrical impulses to the brain, which finally interprets them as visual images.
At birth, the natural lens is clear and very flexible. The lens becomes more rounded to focus on near objects and thinner (or stretched) to focus on objects that are far away.
Over time, however, a few changes begin to occur in the lens, usually after age 40:
- First, the lens becomes less flexible, begins to harden, and loses its ability to curve as quickly. As a result, it becomes difficult to focus on near images (especially print) without the help of bifocals or reading glasses.
- Second, the lens gradually changes color, becoming yellow-brown and no longer clear or transparent. As a result, vision acquires a “brownish” tint, making it difficult to distinguish between certain colors, such as navy blue, brown, and black, or blue, green, and purple. This color change can also degrade the sharpness of a person’s vision.
Simulation of Vision Loss from Cataracts
Cataracts cause an overall blurring of vision. People, objects, and colors look hazy, cloudy, and “washed out.” This lack of detail makes it difficult to tell time, read, watch television, see food on a plate, and walk safely indoors and outdoors. Surgery can usually be effective in removing cataracts. The National Eye Institute has provided the following photos depicting the sight of one with typical vision compared to the sight of one with cataracts:
What a person with no cataracts sees.
What a person with cataracts sees.
Causes of Cataracts
There are various forms of cataracts; age is the most common cause. Since the ancient Greeks and Romans, scientists have known that the lens matures with time. As we age, the lens changes color, density, and clarity for various reasons, including oxidative damage. In addition to the aging process, cataracts can also be caused by any of the following:
- Medication: Long-term use of corticosteroids such as prednisone has been correlated with cataract development
- Physical injury or trauma: A blow to the eye, a cut or puncture, chemical burns, or electric shock can accelerate the cloudiness of the lens
- Radiation: Long-term exposure to ultraviolet radiation from the sun (both UVA and UVB) can accelerate cataract formation. Radiation used to treat certain types of head and neck cancers can cause cataracts to develop as well
- Poor nutrition: Diets that are deficient in antioxidants, such as beta-carotene (vitamin A), selenium, and vitamins C and E have been shown to increase the progression of cataracts
- Smoking and second-hand smoke: Individuals who smoke 20 or more cigarettes a day have twice the risk of nonsmokers developing cataracts
- Systemic diseases, such as diabetes and diabetic retinopathy
- Eye diseases, such as uveitis, which is an inflammatory process that affects the interior of the eye
- Cataracts can also be inherited or congenital (from birth)
Vision Changes That Affect Daily Functioning
The hardening, yellowing, and cloudiness of the lens caused by a cataract can result in the following vision changes that affect your daily functioning:
Blurred or Hazy Vision
- This lack of detail makes it difficult to tell time, read, watch television, see food on a plate, and walk safely indoors and outdoors since depth perception may also be affected. Some people with cataracts describe the effect as being similar to looking through a window that is hazy and streaked with dirt
- Difficulty reading regular print and need a brighter light to do more focused tasks. However, as this change occurs gradually, most people are unaware that their lighting requirements may have changed over time.
- Frequent changes in prescription eyeglasses or contact lenses.
- Development—or worsening—of nearsightedness
Reduced Ability to Differentiate Colors
Man wearing one brown and one blue sock
- To see an object clearly against a background of the same color, such as a brown chair against a dark rug, becomes more complex and requires increased background contrast to make it stand out.
- This also affects depth perception, such as judging the height of a step or curb or the depth of a bathtub.
- Reduced color perception can make distinguishing between brown and blue socks difficult.
Problems with Glare
- It can be challenging to see when in an environment with especially bright light. Although we need more light as we get older, too much light can also cause problems. Bright outdoor sunlight or reflected light from a hallway with highly polished floors can make it difficult to see clearly because too much light can also produce glare, which can interfere with seeing our surroundings.
- People tend to notice difficulty with night driving due to glare from oncoming headlights.
- Difficulty seeing at night.
- Seeing “halos” around lights, especially at night.
- Double vision (diplopia), or seeing a “ghost” image when using the affected eye. Double vision can also be a sign of a serious neurological condition and needs to be evaluated by a doctor.
By Tina D. Turner, M.D.,
Updated by Sefy Paulose, M.D., March, 2022
How Will My Child Function with Cataracts?
You may learn your child has difficulty recognizing faces and facial expressions, accessing information from a distance, identifying small images or letters on paper, or traveling safely. If this is the case, your child may benefit from travel training from the mobility specialist, increased contrast of the environment, increased contrast of print by using a CCTV or screen-magnification software, and increased room and task lighting. Your child may also benefit from assistive technology to more easily write, read, use the computer, and access information and from techniques and additional accommodations to perform activities with limited vision.
Furthermore, your child may have discomfort and poorer vision in bright light and difficulty seeing in dimly lit environments. For daytime travel, recreation, or work, use sunglasses and hats. An infrared night scope may help with evening travel.
Article updated by Sefy Paulose, M.D., March 2022
Treatment: Surgical Removal
The permanent fix for cataracts is to remove them surgically. No medications or eye drops have been proven to reverse cataract formation. However, your doctor may see if changing your glasses prescription will help you obtain better vision. This is because cataracts can cause nearsightedness. The only treatment for a cataract is the surgical removal of the natural lens.
When to Remove Cataracts?
Most age-related cataracts are a normal part of aging, so simply “having” a cataract should not mean it should be removed. Many people with cataracts do not have any visual symptoms. If you are told you have a cataract, but it does not interfere with your activities of daily life or prevent you from leading an active and productive life, then your doctor may tell you the cataract can be monitored. However, if you are experiencing difficulty reading, disabling glare while driving, or difficulty engaging in your normal life activities, it may be time to consider cataract surgery. In summary, the right time to remove a cataract depends on the patient’s symptoms. However, if an individual has cataracts in both eyes that require surgeries, these surgeries will usually be performed a few weeks apart. Cataract surgery on both eyes simultaneously is not recommended because there is a possibility of complications affecting both eyes; the most worrisome is infection.
Professor John Hull (1935-2015), Author of Touching the Rock: An Experience of Blindness
The late Professor John Hull was the author of Touching the Rock: An Experience of Blindness, his compelling memoir that documents the process of becoming blind. As a young university lecturer in the early ’60s, Hull had adapted to cataracts and the early signs of retinal detachment brought on by numerous surgeries. “For the first few years after I registered as being blind,” he said, “I was not, in effect, a blind person. I was a sighted person who couldn’t see. It’s such a difference. It wasn’t until the light sensation completely vanished and I knew there was no way back that I said, ‘I’ve got to try to understand blindness; otherwise it will destroy my life.’” Learn more about ways to find emotional support for you – and your family members – after a vision loss diagnosis:
How Much Should the Cataract Develop Before Having Surgery?
A cataract does not have to become “ripe” before it can be removed. In the past, the lens could not be extracted safely from the eye unless it was at a relatively advanced stage of development. With modern advances in cataract surgery, the lens can now be removed from the eye at any stage of development.
The Patient’s Decision
It’s important to understand that the patient should—and must—decide to undergo cataract surgery. The doctor is responsible for educating patients and giving them the knowledge they need to make an independent and well-informed decision regarding cataract treatment.
Anesthesia and Medication
Commonly, cataract surgery is performed with topical anesthesia. This is accomplished by instilling a powerful numbing medication into the eye. It is usually accompanied intravenously by medication in the patient’s arm to help them feel relaxed and comfortable. This is the least risky form of anesthesia, and most patients do extremely well with topical anesthesia and some intravenous sedation. Sometimes, medication is injected around the eye socket to numb the eye and paralyze eye and eyelid movement. However, these injections carry their own risk and are used less frequently.
General Anesthesia
Sometimes, general anesthesia may be needed. Since cataract surgery performed with topical anesthesia requires patient awareness and cooperation, general anesthesia is usually required for children, patients with developmental delays, and patients with dementia. During cataract surgery, patients must lay flat and still; therefore, patients with movement disorders, such as Parkinson’s Disease or restless leg syndrome, may also require general anesthesia. Patients who have difficulty breathing while lying flat, or who have back or neck pain/disorders that prevent them from being comfortable when lying flat may also require general anesthesia for cataract surgery.
Discuss Your Options
After deciding to have cataract surgery, the patient and physician should discuss the options for correcting vision post-surgery. Artificial lenses, implanted in the eye during cataract surgery to replace the natural lens being removed, can make the vision clear once again and, in some cases (but not always), reduce the need for corrective eyeglasses after surgery. The surgeon will take special eye measurements before surgery, including the eye’s length and the cornea’s curvature, to determine what power the artificial lens should be. Cataract surgery can decrease an individual’s dependency on eyeglasses and sometimes eliminate the need for eyeglasses after surgery. However, some patients will still need eyeglasses to correct their distance and/or reading vision to 20/20.
Most cataracts are highly treatable. Cataract surgery is one of the most common surgeries performed in the United States, with approximately 98% of patients experiencing improved vision if no other eye conditions are present.
Two very small incisions (one larger, approximately three millimeters, or one-tenth of an inch, and one smaller, approximately one millimeter, or one thirty-second of an inch) are made in the cornea, which is the transparent dome-shaped tissue that covers the front part of the eye. A viscous (thick, sticky, glue-like) material is injected into the front part of the eye to help maintain its shape during surgery. This viscous material is made from substances that occur naturally in the body. Because it is thick, this material will not leak out of the incisions during surgery.
Phacoemulsification was introduced more than 40 years ago and is now the most common surgical method used to remove cataracts. The surgeon creates an opening in the natural “sac” or “bag” that holds the lens in place, called the lens capsule. The lens is separated from the lens capsule by using a balanced salt solution.
Once the capsule is open and the lens can move freely inside it, a special ultrasound device is used to break the lens into small pieces and suck it out of the eye. This technique is called phacoemulsification.
Before the development of phacoemulsification, the lens used to be removed in one solid piece through a very large incision (8-12 millimeters). That surgery entailed considerably more risk and had a significantly longer recovery time.
After the lens is removed, additional viscous material is injected into the capsule to hold it open and make room for the new artificial lens. The folded artificial lens is inserted into the “sac” or capsule, allowing it to unfold. The viscous material that maintained the shape of the eye during surgery is removed. The two incisions usually self-seal and do not require stitches.
Femtosecond Laser for Cataract Surgery or Laser-Assisted Cataract Surgery
Femtosecond lasers have been used in ophthalmic surgery since 2001, and in the late 2000s, work began on their use in cataract surgery. In 2008, the first laser-assisted cataract surgery was performed in Hungary. After gaining FDA approval, the first laser-assisted cataract surgery was performed in the United States in 2010. Since that time, it has been gaining acceptance and popularity.
The laser does not take the place of manual cataract surgery. As stated, the laser “assists” in removing the cataract; phacoemulsification is still used to remove the cataract itself.
- the corneal incisions
- opening of the capsule containing the cataract
- the initial sectioning of the cataract into smaller pieces.
It performs these three steps with incredible precision, and this aspect may prove it to be superior to the current technique in which the surgeon manually performs these steps. The laser can also be used to make incisions in the cornea to treat certain types and amounts of astigmatism.
Further data and well-designed studies are needed to prove that this method is associated with better outcomes and fewer complications than phacoemulsification alone, and much work is being done on this front.
Because insurance does not cover the cost of laser-assisted cataract surgery, patients must contribute a significant out-of-pocket payment. It is important to discuss with your physician what type of procedure would be best for you.
How Long Is the Recovery Time After Cataract Surgery?
Some patients see very well the day after cataract surgery. Other patients see well a few days after surgery; others may need a full month to reach their maximum vision improvement.
The First Week Post Surgery
During the first week after surgery, it is generally recommended that the patient keep his or her eye covered at all times, either with eyeglasses or an eye shield, to protect it from being bumped or rubbed. A small amount of pressure can easily open the incision, and protecting the eye prevents this.
Also, it is recommended that the patient refrain from (a) bending with the head below the waist, (b) lifting more than 10 pounds, and (c) straining (on the toilet, for example) to the point of holding one’s breath. These activities increase the pressure inside the eye and can open the incision.
Antibiotic and anti-inflammatory eye drops are used weeks after cataract surgery to help prevent infection and control inflammation.
A Cataract Cannot Return After Surgery
This is because cataract surgery permanently removes the lens and places an artificial lens in the eye. Unlike natural lenses, these artificial lenses do not harden, yellow, or cloud over time. However, the lens capsule, the small “sac” or membrane that once surrounded the natural lens and held it in place, can change.
Capsular Opacification
The lens capsule is like the shell of a peanut M&M. It can develop a small membrane over time, which can seem like the cloudiness of the artificial lens itself. This is called capsular opacification, which develops in approximately 25% of patients after cataract surgery. If this occurs, the patient may develop symptoms similar to those of a cataract, such as blurry or hazy vision, difficulty reading regular print, and sensitivity to bright lights and glare. Posterior capsular opacification is treated with a laser to create an opening in the center of that membrane to allow light to enter the eye. The procedure is painless, requires less than five minutes, and is usually performed in the doctor’s office.