Therapeutic lenses offer treatment options for common disorders

A new generation of contact lenses has become a mainstay in the management of common ocular disorders.

Bandage contact lenses can be used as adjunctive therapy for a wide range of surface and refractive disorders, providing surgeons with treatment options that promote healing and improve vision, according to several clinicians.

Because of their high oxygen permeability and low rate of complications, high Dk silicone hydrogel lenses are now advocated by many eye care professionals as safe and effective for a new generation of lens wearers.

Donald J. Doughman, MD, said high Dk lenses have become a present-day answer to secondary infections, deposits and even drug delivery needs, primarily because of their success in meeting or exceeding oxygen requirements for most patients’ corneas.

Donald J. Doughman

“They give the practitioner a valuable therapeutic tool for ocular surface disease and refractive surgery,” Dr. Doughman said, who spoke on the subject at the American Society of Cataract and Refractive Surgery meeting and in a subsequent interview with Ocular Surgery News.

According to William H. Ehlers, MD, many studies have found that silicone hydrogel lenses, which are becoming the lens of choice for many patients and clinicians, have helped reduce problems such as redness, dryness and neovascularization.

“Studies by Dwight Cavanagh and others found that bacteria binding to corneal epithelium was inversely related to the oxygen permeability of the contact lens, and it was believed that microbial keratitis would be virtually eliminated by the use of high Dk silicone lenses,” Dr. Ehlers said. “Initial pre-approval studies seemed to support this. But overnight wear remains a significant risk factor for infectious keratitis, and this ought to be discussed with every patient who wants to wear a lens on an extended basis.”

History of therapeutic contact lenses

Contact lenses have come a long way since the first century when physician Aulus Cornelius Celsus applied honey-soaked linen dressing to the inferior fornix in an effort to prevent symblepharon, according to Dr. Doughman.

In modern times, doctors created the first lenses in the 1950s using hard PMMA scleral shells molded from cornea. However, complications with these ranged from exposure to keratoconjunctivitis to keratitis.

First approved for use in the United States in the 1970s, bandage contact lenses were known primarily for their thick design and low water content. Although lenses of that day were effective at controlling pain from keratopathy and surface defects, they were often associated with secondary infection, corneal vascularization, giant papillary conjunctivitis (GPC) and deposits, Dr. Doughman said.

Second-generation lenses contained a higher water content of 55%, and their thinner design provided relief against most conditions.

Companies such as Ciba Vision, Vistakon and Bausch & Lomb were among the pioneers that later introduced lenses with an ultrathin design and high oxygen permeability, he said. Although those lenses controlled surface irregularity, many patients found them uncomfortable and endured deposits and tight lens syndrome due to tear film evaporation.

Some years later, manufacturers created lenses with a silicone elastomer material that were produced without water content but offered high oxygen permeability.

Lens reshapes cornea

Problems associated with lens wear have been well-documented, so manufacturers have been working to create breakthroughs in patient care management.

Peter C. Donshik

Orthokeratology involves a special “reverse geometry” rigid gas permeable lens that is an alternative to refractive surgery for patients with low amounts of myopia. The lens flattens the cornea, allowing light to focus properly on the retina and enabling clear vision in nearsighted people without the risks and complications of surgery.

“It works by reshaping the cornea as long as you wear the lens,” Peter C. Donshik, MD, OSN Optics, Refraction and Contact Lenses Section Member said. “You wear it at night, take it off in the morning and have good vision during the day. But you have to keep wearing them at night. … If you don’t continually wear them at night, the cornea will revert back to the original shape.”

Drs. Doughman and Donshik said orthokeratology treats the eye by making it flatter. “It redistributes the surface of the cornea, creating a different surface. And by flattening, you can treat low degrees of nearsightedness,” Dr. Doughman said.

Management strategies

Several strategies are available to help with pain relief, healing and stabilizing corneal wounds. Many also help improve vision, minimize frictional lid forces and are useful in treating severe dry eye.

Dr. Ehlers said lenses with high water content or certain surface characteristics are more likely to attract deposits, but that surface modification of some hydrogel lenses make them more resistant to deposits. Although he generally discourages overnight wear, he recommends high DK lenses as long as the patient understands the risk and the need to contact a doctor at the earliest sign of problems.

He also discusses with patients alternative refractive options such as refractive surgery and suggests his extended-wear patients see him twice a year to monitor the health of their eyes.

“I also inform them that they should not swim or get in hot tubs with their lenses in, and they should avoid getting water in their eyes in the shower,” Dr. Ehlers said.

Another procedure, called contact lens assisted pharmacologically induced kerato steepening (CLAPIKS), corrects residual hyperopia, myopia and astigmatism after conventional or custom LASIK, LASEK, PRK and other laser-assisted refractive surgery procedures.

Treatment involves fitting an extended-wear contact lens somewhat tightly and prescribing a nonsteroidal anti-inflammatory drop, typically four times a day.

“Some surgeons have reported successful treatment with 0.5 D to 3 D of myopic overcorrection or residual hyperopia,” Dr. Ehlers said. “It is important to note that this is not an approved indication for this drug, and the appropriate use of this technique is still being developed.”

Dr. Doughman said CLAPIKS affects only a small number of patients. “It is labor-intensive and takes a long time for the lenses to mold to the cornea. The patient must wear them week after week, and most do not want to do that. It is just too much work. It takes a lot on the patient’s part, and we’re not sure about compliance.”

GPC, an inflammation of the tarsal conjunctiva, is a less common condition associated with contact lens wear. Caused primarily by a coating on the surface of the lens, its main symptoms are irritation, mucous production and contact lens intolerance.

“GPC is manageable,” Dr. Doughman said. “Mucous and epithelial cells that shed from the eye become like a reactor that creates an allergic reaction and bumps on the upper lid.”

Dr. Donshik suggested that surgeons instruct their patients to decrease the length of time spent wearing lenses, refit them with daily disposable lenses and prescribe inflammatory medicines such as mast cell stabilizers and antihistamines. “You just have to remove the contact lenses, but most people who develop it want to stay in them,” he said.

Treating dry eye

Dr. Ehlers recommended that patients with severe dry eye avoid contact lens use because they may increase evaporation of the tear film. However, he said therapies are available that may maximize the patient’s ability to wear lenses, including using supplemental tears on a regular basis, punctal occlusion and Restasis (cyclosporine ophthalmic emulsion, Allergan).

“When supplemental tears are used, I strongly prefer the nonpreserved tears, as preservatives may build up in the matrix of the lens,” Dr. Ehlers said. “The selection of an appropriate lens is also important and higher water content lenses should be avoided because of their tendency to dry out on the eye. RGP lenses are another option.”

According to Dr. Doughman, surgeons have had more success treating dry eye with therapeutic contact lenses that have low water content.

“You don’t want a high water contact lens because it becomes like a taco in your eye,” he said. “One of the goals is therapy, so you want to stabilize the surface defect. Using a high Dk lens avoids vascularization. And with post-surgery refractive LASIK, PRK or keratoplasty, high Dk lenses will allow the eye to heal.”

For older patients who have undergone LASIK, Dr. Doughman uses a high Dk lens for 2 to 5 days and follows up with antibiotics. “I like silicone hydrogel lens and give them the usual drops afterward, especially antibiotics, when a patient is wearing the lens.”

Future trends

Dr. Ehlers said he expects there will be development of new materials for contact lenses and lens cases that can inhibit microorganism growth. He also sees potential growth for lenses that can be used for drug delivery, especially for chronic eye conditions such as glaucoma.

“Careful attention is needed to the potential for epithelial toxicity, of course,” he said. “There are also contact lenses under development that may help patients with diabetes monitor their control of it, as glucose is not only present in the blood but also in tears.”

For more information:

• Peter C. Donshik, MD, can be reached at 47 Jolley Drive, Bloomfield, CT 06002; 860-286-5448; fax: 860-286-5449; e-mail: pdonshik@snet.net. Dr. Donshik has no direct financial interest in the products mentioned in this article nor is he a paid consultant for any companies mentioned.
• Donald J. Doughman, MD, can be reached at Minnesota Lion’s Eye Bank, 516 Delaware St., Minneapolis, MN 55455; 612-625-4400; fax: 612-626-3119; e-mail: dough001@umn.edu. Dr. Doughman has no direct financial interest in the products mentioned in this article nor is he a paid consultant for any companies mentioned.
• William H. Ehlers, MD, can be reached at University of Connecticut Health Center, 263 Farmington Ave., Farmington, CT 06030; 860-679-3540; fax: 860-679-1390; e-mail: ehlers@adp.uchc.edu. Dr. Ehlers has no direct financial interest in the products mentioned in this article nor is he a paid consultant for any companies mentioned.

• John Misiano is an OSN Staff Writer who covers all aspects of ophthalmology.