March 2019, Volume XXXII, No 12
Advances in treating eye disease
A look at new FDA-approved devices
he field of ophthalmology continues to change dramatically, with advancements in technology—tested and approved following clinical trials—drastically improving treatment options for patients facing vision-threatening eye disease. New FDA-approved prostheses and devices, implanted surgically, hold great promise for patients with glaucoma and those with damage or injury to the iris.
In May 2018, the U.S. Food and Drug Administration approved the first prosthetic iris in the U.S. The surgically implanted device treats patients whose iris (the colored part of the eye around the pupil) is missing or damaged. Typical reasons for the iris to be missing are trauma or a congenital condition called aniridia.
Congenital aniridia is a rare genetic disorder in which the iris is completely or partially absent. It affects approximately 1 in 50,000 people in the U.S. With the iris missing, the amount of light entering the eye is extreme, and those with aniridia have sensitivity to light and glare with loss of vision.
The CustomFlex Artificial Iris can also be used to treat iris defects due to trauma, intraoperative damage to the iris during cataract surgery to treat intraoperative floppy iris syndrome due to alpha-one blockers such as tamsulosin, or in patients with small iris melanomas that have been removed surgically.
The iris plays an important part in our vision, adjusting incoming light as we change environments. An absent or partially functioning iris can cause extreme light sensitivity and glare, and even impact the sharpness of vision by allowing abnormal light scatter.
The CustomFlex Artificial Iris is made of thin, foldable medical-grade silicone and is custom-sized and colored for each individual patient. A surgeon makes a small incision, inserts the device under the incision, unfolds it, and smooths out the edges using surgical instruments. The prosthetic iris is held in place by the anatomical structures of the eye or, if needed, by sutures.
Colors are created to replicate those in the iris of the patient’s uninjured or unaffected eye (if one is present). The silicone prosthesis is made in Germany and takes approximately two months to customize for the patient.
The safety and effectiveness of the CustomFlex Artificial Iris was demonstrated primarily in a non-randomized clinical trial of 389 adult and pediatric patients with aniridia or other iris defects. The study measured patients’ self-reported decrease in severe sensitivity to light and glare post-procedure, health-related quality of life, and satisfaction with the cosmetic improvement or appearance of the prosthesis. Following the procedure, more than 70 percent of patients reported significant decreases in light sensitivity and glare, as well as an improvement in health-related quality of life. In addition, 94 percent of patients were satisfied with the artificial iris’ appearance.
The study found low rates of adverse events associated with the device or the surgical procedure. Complications can occur such as dislocation of the iris, especially if the zonules were damaged along with the initial damage to the iris. Increased intraocular pressure (IOP) or glaucoma is more common in patients with damage to the iris because the trabecular meshwork is in close contact with the iris. Inflammation such as uveitis or adhesion of the residual native iris to the cornea or lens (synechiae) can occur. Bleeding is not uncommon during the surgery, and swelling of the retina (cystoid macular edema), corneal edema, or retinal detachment can occur in eyes with difficult underlying issues such as prior trauma.
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The findings were similar to those from a 32-patient retrospective case-series published in the May 2016 issue of Ophthalmology. Both studies reported a low rate of adverse events associated with the device and surgical procedure. Complications included dislocation, strands of device fiber in the eye, increased IOP, and iritis.
Prior to the FDA approval, Minnesota Eye Consultants (MEC) had been involved with Artificial Iris research studies for 18 years, treating 35 eyes within the most recent Artificial Iris research study (2013–2018). Altogether, MEC has performed this procedure over 90 times since 2000, often under the compassionate use process, under which the FDA allows practitioners to use medications or procedures that have not yet been approved when no comparable or satisfactory alternative therapy options are available.
Glaukos iStent inject and Ivantis Hydrus
In 2018 the FDA approved two new minimally invasive glaucoma surgery (MIGS) devices designed to lower intraocular pressure by improving aqueous outflow through the eye’s natural physiological outflow pathway. Both of these implanted stent devices improve aqueous outflow through the trabecular meshwork.
Glaucoma is one of the most common causes of irreversible blindness worldwide. The primary pathophysiology is permanent injury to the optic nerve, a collection of delicate axons that communicate vision-related neurologic impulses between the retina and the occipital cortex of the brain. Glaucomatous damage to this delicate network of neural tissue results from eye pressure, most often due to sluggish drainage of aqueous humor from the eye’s natural outflow pathways.
By enhancing the eyes’ natural physiological outflow pathways, the iStent inject (Glaukos), approved in June, and the Hydrus (Ivantis), approved in August, provide a therapeutic mechanism in stark contrast to more traditional glaucoma surgeries that completely bypass the natural outflow pathways.
While the traditional glaucoma surgeries have greater efficacy than those that enhance physiological outflow, the increased efficacy comes at a steep price, namely significantly more risk. Accordingly, they have been reserved for those with far advanced disease. Newer, safer procedures allow earlier surgical intervention. Surgeons can now individualize surgical risk for patients specific to their disease severity. Those at high risk for glaucoma-related blindness are candidates for the more invasive traditional surgery, while those at lower risk for functional impairment are candidates for the newer, minimally invasive procedures, typically performed simultaneously with cataract surgery.
The opportunity to combine safe glaucoma procedures with cataract surgery has changed the glaucoma management paradigm in recent years. For most patients with glaucoma, medicines and laser treatments are used to manage the condition until a visually significant cataract develops, at which time surgeons can address both of these common conditions. Cataract and glaucoma are among the most common ocular comorbidities. The glaucoma specialists at Minnesota Eye Consultants have been very involved in the development of each device, either as investigators or as medical monitors for the multicenter trials.
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Thomas Samuelson, MD, is a partner and attending surgeon at Minnesota Eye Consultants. He specializes in glaucoma, cataract, and refractive surgery and performs iStent inject procedures at Minnesota Eye Consultants locations in Bloomington and Minnetonka.