Advances across the spectrum of modern medicine continue to improve the quality of life while enhancing longevity. Riding the crest of new health care treatments is ophthalmology, the field that utilizes drug therapies and surgical procedures to improve vision.
There can be no question that medical care associated with ophthalmology is vital for the health and well-being of the American population. For perspective, more than 150 million Americans require some type of corrective eyewear or surgery to correct vision caused by nearsightedness (myopia) and farsightedness (hyperopia). Over 10 million people, particularly those over 40 years of age, suffer vision problems associated with glaucoma, macular degeneration, and diabetic retinopathy.
While millions of Americans suffer from some form of vision problem, the good news is that advancements in ophthalmology are correcting eyesight at an unprecedented pace. According to a study conducted by Northwestern University Feinberg School of Medicine in Chicago, older adults today are reporting fewer visual impairment problems than they were a generation ago. The study, published in the journal Ophthalmology, showed that in 1984, 23 percent of elderly adults had difficulty reading or seeing newspaper print because of poor eyesight. By 2010, there was a 58 percent decrease in this kind of visual impairment. The study also showed a substantial decline in eyesight problems that limited elderly Americans from taking part in daily activities, such as bathing, dressing or getting around inside or outside of the home.
Advances in correcting vision impairments can be attributed to a number of factors including new drug therapies and improved surgical procedures for cataracts, glaucoma, macular degeneration, diabetic retinopathy and corneal disease. What follows is an update on the latest treatments being used to correct some of the most prevalent vision problems.
Opthalmology Advancements Restore Vision
By Mike Haskew
Most often the result of aging, cataracts are a clouding of the lens (the part of the eye that focuses light, resulting in sharp and clear visual images). The American Academy of Ophthalmology estimates that nearly 22 million Americans aged 40 or older develop cataracts and approximately half the American population aged 80 or older will experience cataracts in their lifetime.
The most common kind of cataract surgery— called phacoemulsification (phaco)— involves removal of the natural lens and the implantation of an intraocular lens (IOL). The surgeon uses local anesthetic drops, and the patient maintains eye function during the surgery. Through an incision, often as small as three millimeters, a tiny probe is inserted that transmits ultrasound waves to break up the cataract. The emulsified lens is then suctioned out through the probe, and the implant is placed. No stitches are required, and recovery time is minimal.
To the benefit of many people, the past five years have seen new developments in lens options to correct refractive errors, including multifocal lenses, accommodative lenses and monovision lenses. Through different means, all can improve vision at a range of distances, and in many cases, can allow a patient the ability to both read a book or drive a car comfortably without glasses. Through new laser technology to measure the eye, ophthalmologists can predict which lenses are best for each patient.
• Multifocal IOLs provide for simultaneous viewing of both distance vision and near vision. “Really in the last five years, the multifocal implants have come into their own,” says Charles A. Kirby, M.D., an ophthalmologist with Chattanooga Eye Institute. “In the past we had good ones, but the ones we have available now are much better. We are able to provide patients with a much better range of vision.”
• Accommodative IOLs allow for both distance vision and midrange near vision. These IOLs are typically not as strong for closer vision as the multifocal IOLs.
•Monovision IOLs allow for distance vision and near vision by creating a “reading eye” and a “distance vision eye.”
Patients with astigmatism now also have the option of toric lenses. “The eye is not perfectly round,” says Dr. Kirby. “The toric IOL is a lopsided lens to compensate for the lopsided cornea. They have been around for more than 10 years. The new ones—able to correct up to six diopters— have been around for five or six years.”
Also on the cutting edge is the Femtosecond laser (Femtec) machine, which uses a short pulse instead of the surgeon’s hand to make the corneal wound, capsulotomy (incision of the capsule of the lens) and segment the cataract. The new technology also has implications for correcting astigmatism as well as other eye surgeries.
“The femtosecond laser has recently been approved for cataract surgery,” says. Dr. Kirby. “It is being used in limited amounts in the U.S. There may be one or two in the state of Tennessee. It has great potential, but it’s not in widespread use. It’s likely that it’s going to be the new technology.”
Glaucoma is an eye disease involving excessive fluid pressure of the aqueous humor within the eye, damaging the optic nerve in a specific pattern. According to the American Academy of Ophthalmology, 2.3 million Americans over the age of 40 suffer from glaucoma, and another 2 million do not know they have the disease. Treatments may include the use of eye drops, laser procedures, or in more serious cases, operative surgery, including the use of shunts to relieve elevated pressure.
“The majority of people with glaucoma are on drops that can irritate their eyes,” says Dr. Kirby. “There are now new preservative- free drops—like zioptan—and also reformulations of existing medicines without a preservative. This is a big plus for people with sensitive eyes. The preservatives can be toxic to the eye.”
The “gold standard” for surgical treatment for glaucoma is a trabeculectomy, a procedure that removes part of the eye’s tissue located around the base of the cornea, allowing for drainage of aqueous humor. However, the last four years have seen the rise of a revolutionary, minimally invasive procedure called canaloplasty. Canaloplasty involves the introduction of a 250-micron microcatheter to allow freer fluid drainage through an otherwise restricted channel known as Schlemm’s canal. According to Medical News Today, a single micron is the width of up to five human hairs combined, and the procedure is accomplished in approximately 30 minutes.
For many patients who have had previous glaucoma-related surgery, particularly procedures that were unsuccessful due to scarring, tube-shunt surgery may be a viable alternative. During tubeshunt surgery, a plastic tube and silicone pouch are implanted in the eye to facilitate drainage of excess fluid.
The American Academy of Ophthalmology reports that more than 2 million Americans aged 50 and older have advanced age-related macular degeneration, the stage that can lead to severe vision impairment. Macular degeneration is a condition which results in a loss of vision in the center of the visual field (macula) because of damage to the retina. It occurs in both “wet” and “dry” forms. The more severe wet form is caused by abnormal blood vessel growth, while the dry form is the result of accumulated debris between the retina and the choroid, containing the blood supply to the eye.
In recent years, new genetic tests involving scraping of the inner lining of the cheek have been developed to detect a person’s risk of developing macular degeneration. However, perhaps the biggest breakthrough in treatment for wet macular degeneration in the past five years involves the injection of anti- VEGF (Vascular Endothelial Growth Factor) agents to block VEGF molecules, which stimulate the growth of blood vessels. Until recently, the prognosis for wet macular degeneration was unfavorable. However, according to the nationally known Visitech Eye Centers, more than 2,000 patients have received anti- VEGF treatment at their centers with outstanding results.
“This is the best treatment we’ve ever had,” says Dr. Kirby. “Avastin and lucentis work better than anything we have had in the past and have revolutionized the treatment for macular degeneration.”
Troublesome dry eyes affect nearly 5 million men and women in the U.S. over the age of 50. Dry eyes are most common in older adults as both the quality and production of tears diminish with age. The sufferers of chronic dry eyes experience burning, itching, and swelling of eye tissues and are more susceptible to infections.
Mild cases of dry eyes are usually treated with artificial tear solutions. “There is constant research being done for alternative therapy for dry eyes,” says Dr. Kirby. “What tends to be the best is teardrop substitution or improving quality of existing tears. So far, restasis is the best drug for treating dry eyes.”
“Right now, my practice is involved in an FDA phase III study of rebamipide, an investigational drug that increases the mucin in the tears. It has great promise. We are currently enrolling patients in a 6-week study.”
For more severe cases of dry eyes, the Mayo Clinic advocates the LipiFlow thermal pulsation system, recently approved by the Food and Drug Administration. LipiFlow addresses the basic cause of dry eyes—obstructed meibomian glands (the glands that produce oils necessary for the lubrication of the eye). During clinical studies, 79 percent of patients treated with LipiFlow reported diminished symptoms. The procedure exerts gentle pressure and applies heat to the inner eyelids, releasing lipids from the meibomian glands and allowing them to function with greater efficiency. LipiFlow is completed in 12 minutes and usually done in the doctor’s office.
Patients with severe dry eye or other ocular disorders may eventually require replacement of the cornea, the clear structure at the front of the eye that covers the iris and pupil. In the past, such surgery has involved the transplant of a healthy cornea from a human donor, often with a significant risk for rejection.
However, according to the Wilmer Eye Institute at Johns Hopkins University, two types of artificial corneas are now approved by the Food and Drug Administration, offering hope to those who have undergone multiple failed cornea transplants. The Dohlman cornea combines artificial materials with the human cornea of the donor to assist in acceptance by the recipient’s eye. The AlphaCor device is implanted and temporarily covered with the patient’s own tissue to promote healing and acceptance. Both have shown great promise.
Research at the Stanford University School of Medicine may soon yield a new synthetic cornea that replicates the actual function of the human cornea. In a cooperative effort with the Stanford University Department of Chemical Engineering, the work centers around wear-resistant blended polymers that readily adhere to human corneal tissue.
People who are not a candidate for a corneal transplant may consider a stem cell transplant to improve the surface of the eye tissue.
Another relatively new procedure to treat corneal disease is DSAEK (Descemet’s Stripping Automated Endothelial Keratoplasty), now frequently used in place of a conventional full-thickness corneal transplant. In DSAEK, the inside lining of the cornea is stripped and replaced with healthy lining held in place by an air bubble. The bubble is usually absorbed in two days by the eye, allowing the patient to resume normal activity with improved vision.
Nearsightedness (Myopia) and Farsightedness (Hyperopia)
The American Academy of Ophthalmology reports that more than 36 million people in the United States wear contact lenses. Millions more wear eyeglasses. During the last 25 years, refractive procedures to correct visual impairment have emerged and been continually refined.
Today, the preferred surgical procedures are Photorefractive Keratectomy (PRK), which uses a laser to remove tissue from the surface of the eye, reshaping the cornea, and LASIK, which includes the making of a a thin flap in the eye surface so that laser reshaping of the cornea may take place. Both procedures take just a few minutes and involve little to no pain. PRK is sometimes preferred due to the absence of risk involving the flap, although the recovery time and reduced patient discomfort associated with forms of LASIK are superior to PRK.
For people with myopia, Dr. Kirby says another option may be a phakic intraocular lens (PIOL). The PIOL is a special kind of intraocular lens that is implanted surgically in to the eye to correct nearsightedness. They are called “phakic” because the eye’s natural lens is left untouched.
People with severe hyperopia (farsightedness) and/or presbyopia (far-sightedness caused by loss of lens elasticity) may choose to undergo a refractive lens exchange (RLE). An RLE is essentially cataract surgery but exclusively for refractive purposes.
In recent years, new frontiers have opened in the treatment of conditions affecting vision and ocular health. Needless to say, the restoration or correction of vision has been and will continue to be invaluable to millions of people.
Mike Haskew is a graduate of the University of Tennessee at Chattanooga and holds a degree in history. He is a native Chattanoogan and is currently an executive with Community Trust & Banking Company.