Presented by: Artis Montague, MD, PhD
Clinical Associate Professor, Opthalmology
Stanford University Medical Center
May 1, 2014
Cataracts are the most common cause of vision loss in people over age 40. By age 80, more than half of all Americans either have a cataract or have had cataract surgery. Each year, 3 million Americans have their cataracts removed.
A cataract is a clouding of the eye’s natural lens, which lies behind the iris and the pupil. It usually starts out slight, with little effect on your vision at first. Vision may become blurred or hazy, like looking through a cloudy piece of glass. It can make light seem too bright or make night driving difficult because of increased glare from oncoming headlights. Colors may appear subdued, or you may have problems with contrast.
“Cataracts often start out small with overall blurring, but they can progress as the lens becomes more cloudy or yellow,” said Artis Montague, MD, PhD, a clinical associate professor of ophthalmology and director of the Byers Eye Surgery Center, at a presentation sponsored by the Stanford Hospital Health Library. “Cataracts are not a film over the eye nor are they affected by use.”
A Gradual Process
The lens inside the eye works much like a camera lens, focusing light onto the retina for clear vision. It also adjusts the eye to see objects clearly both up close and far away. But as we age the lens may begin to change color or get cloudy, which is referred to as a cataract. Over time, it may grow larger and create more clouding of the lens, making it harder to see.
The condition is caused primarily by aging, although other factors like genetics, trauma, exposure to radiation or UV sunlight, medical problems, and previous retinal surgery may also affect its development. For most people, a cataract will develop slowly over years or even decades, although people with diabetes can often develop cataracts within a few months. Usually one eye starts to cloud up before the other.
When symptoms begin to appear, vision may be augmented by prescription eyeglasses, bifocals, magnifiers, brighter lights, or other visual aids.
“There are no medications or exercises that can prevent or cure the development of cataracts,” said Dr. Montague. “They do not hurt the anatomy of the eye. But they can to be addressed once they start to affect your lifestyle or limit your activities.”
Many people consider poor vision an inevitable fact of aging, but cataract surgery is a simple, relatively painless procedure with excellent outcomes. Nine out of 10 people who have cataract surgery regain vision between 20/20 and 20/40. Like any surgery, it does involve some risk, such as infection or bleeding, which is why only one eye is done at a time. Dr. Montague advised waiting until the benefits outweigh the risk.
Surgery involves making a tiny incision to reach the hardened cloudy lens. The cataract is broken apart with ultrasound (phacoemulsification) so it can be removed, and an artificial replacement lens is folded and inserted into place.
Surgery is done on an outpatient basis and takes about 10 to 15 minutes, Dr. Montague said. There’s no pain, but patients are given a mild sedative and drops to dilate the pupil. After surgery there is usually some redness, scratchiness, and blurring, and drops are prescribed to prevent infection. Within a few days, vision is restored.
Once removed, cataracts do not grow back. About one third of patients can develop a posterior capsular opacity, a normal healing response that causes some blurring, which makes it seem as if the cataract has returned. A YAG laser is used in a quick, safe procedure in the clinic to remove the scar tissue and restore clear vision.
Dr. Montague is an expert in using innovative femtosecond laser technology for cataract surgery. Laser-assisted cataract surgery, based on technology developed in Silicon Valley and coupled with research from Stanford investigators, is opening new and more precise options for patients.
Lasers are incredibly accurate so the incisions used to remove the aging lens and insert the replacement lens are more consistent than incisions made by a surgeon’s hand. The technology, using the Catalys laser at Stanford, makes a three-dimensional scan helps to create a map of each individual’s eye so placement is exact. The laser can break up the cataract into minute pieces, which speeds up the procedure and often requires less ultrasound energy.
“The steps are standardized, more precise, and potentially safer than other techniques,” she said. “The laser cuts a perfect circle that research suggests is 10 times more accurate than traditional methods. Using less ultrasound may result in less damage to nearby tissue and thereby may reduce the risk of infection or inflammation.”
Dr. Montague mentioned some special situations that require different strategies to treat cataracts. Trauma can cause damage to the zonules, spring-like connectors attached to the capsular bag that keep the lens in place. Traditional cataract surgery can be compromised when zonules are loose or missing, so a capsular tension ring can be used to stabilize the capsular bag and the new lens. If the eye is very damaged, the lens can be placed in a different position, such as over the iris.
Men who have taken certain prostate drugs (e.g., Flomax) are at a higher risk of developing a cataract surgery complication called intraoperative floppy iris syndrome (IFIS). These drugs relax the smooth muscle cells of the iris, reducing dilation during the surgery. Patients may require a special visco-elastic substance and/or a stabilizer to retract and hold the iris in place during surgery. Men taking these drugs should be sure to tell their physician before surgery.
People with astigmatism present another challenge since their corneas are shaped differently (more like footballs than basketballs) and therefore have more power in one axis. Dr. Montague is using a device called a Toric lens, an intraocular lens shaped with more power in one axis, that can correct for some corneal astigmatism when aligned appropriately during surgery. Inserting a Toric lens may decrease the need for glasses after cataract surgery.
People who are able to tolerate monovision—with one lens for seeing up close and the other for seeing far away—may be able to do the same with cataract surgery and therefore be less likely to need to wear glasses again. About one-third of patients cannot deal with this approach, Dr. Montague said. Another option is to insert a new lens with concentric circles of near-and-far prescriptions or a different lens that allows the eye muscles to adjust accordingly.
About the Byers Eye Institute
The Byers Eye Institute at Stanford is a comprehensive center that leverages the research and teaching strengths of Stanford’s Department of Ophthalmology by taking an interdisciplinary approach to vision. The Institute comprises six care centers, including a Vitreo-Retina Center and an advanced Diagnostic Imaging Center.
About the Speaker
Artis Montague, MD, PhD, is a clinical associate professor of ophthalmology, director of the Byers Eye Surgery Center at Stanford, and clinic chief of the Department of Ophthalmology. A specialist in laser-assisted cataract surgery, she is conducting ongoing research to compare and refine laser strategies. She received her MD and her PhD in neuroscience from Yale University School of Medicine, did her internship at St. Mary’s Medical Center, and completed her residency at Stanford. Dr. Montague is Board Certified in ophthalmology by the American Board of Ophthalmology. She has been a member of the Stanford faculty since 2001.