This article is more than 5 years old. Information may no longer be current.
What technologies will lead the way for drug delivery in eye disease?
Click Here to Manage Email Alerts
Nanotechnology key to early intervention in disease process
 Marguerite B. McDonald |
Neural prosthetics: We need smaller electrodes, the size of neurons, for retinal prosthetic devices to give good image resolution.
Hydraulics/biomechanics: Many of our biggest therapeutic challenges in glaucoma and retinal vascular surgery are really hydraulic engineering problems. With nanotechnology, we can bring ophthalmology to the point where we can intervene earlier in the disease process.
Drug delivery: We should update our means of delivering drugs to ophthalmic target tissues. Someday, nanotechnology may allow us to eliminate eye drops and intravitreal injections. Recent studies of retinal rescue indicate that constant drug delivery provides a greater therapeutic effect while using lower drug levels than have been historically employed.
Marguerite B. McDonald, MD, FACS, is a clinical professor of ophthalmology, NYU Langone Medical Center, New York, and an OSN Refractive Surgery Board Member.
Implants are the future
 Baruch Kuppermann |
The field of drug delivery devices is really burgeoning, and a lot of it has to do with the fact that management of many retinal pathologies is increasingly based on pharmacotherapeutics. Studies in the past several years have shown the utility of steroids in conditions such as diabetic macular edema, retinal vein occlusion and even in combination therapy for age-related macular degeneration. Of course, the implication is that if we are going to use these agents — and even anti-VEGF agents in DME, vein occlusion or AMD — we are going to have to inject on a recurrent basis. But the less frequently we can deliver drugs to the eye and still get good effect, the better. And I think really the only answer to that is drug delivery technology.
Another reason we are looking at drug delivery is because we are doing vitrectomies for more disease states in an effort to oxygenate the retina and to minimize the impact of vitreomacular traction at the retinal junction on certain retinal pathologies. However, the dynamics of pharmacokinetics are altered in eyes that have been vitrectomized, and that includes eyes that have had their vitreous altered or removed by pharmacologic vitreolysis. It has been shown that drug delivery devices deliver an equal drug dose to the retina in both vitrectomized and nonvitrectomized eyes.
The dilemma for any drug delivery device is that any drug that is placed inside the eye is considered a new drug, so it has to go through the entire drug approval process as if it were some new, unheard of drug, even though the components that go inside the eye are well-known and nontoxic, and even if the drug is well-known and nontoxic and has a safety profile we understand. It will be interesting to follow this issue to see if it changes over time.
The pharmacodynamics of these new devices raise some challenging questions: For example, will short duration devices that allow a brief drug holiday before reinjection be more or less beneficial than devices that chronically deliver drug over prolonged periods? Will devices deliver a more efficient dose to the eye than intravitreal injections? Currently, we have to deliver super-therapeutic doses via injection to ensure durability after degradation.
It will be interesting to see the data from clinical trials over the next couple of years, especially as currently approved devices are explored in new indications.
Baruch Kuppermann, MD, PhD, is a professor of ophthalmology and chief of the Retina Service at the University of California, Irvine.