This article is more than 5 years old. Information may no longer be current.
BLOG: The optic nerve, the final frontier
Click Here to Manage Email Alerts
Nothing is more humbling than the vastness of space, and nothing challenges our science more than traveling beyond our planet. The focus of our cover story in this issue of OSN is “spaceflight-associated neuro-ocular syndrome,” or SANS. This condition, which involves swelling of the optic nerve following months of travel in zero gravity, may pose a threat to the vision of astronauts traveling on a 3-year mission to Mars. We still don’t completely understand its origins or treatment, but headward shifts in body fluids due to low gravity is the leading suspected culprit.
It’s daunting for scientists to face a new syndrome in which we have so little understanding. Even more humbling is that our understanding of chronic open-angle glaucoma is similarly primitive. With glaucoma, we clearly see a correlation between IOP and disease progression, but it’s just not that simple. Individual variations in nerve susceptibility appear to explain the spectrum from low-tension glaucoma to primary open-angle glaucoma to ocular hypertension without nerve damage. What is exciting in glaucoma are three significant efforts underway to improve treatment based on IOP.
First, drug delivery is helping us realize that eye drops, where only one-third of patients take their medication as prescribed and 80% overreport their compliance, need to become a relic of the past. Implants in the anterior chamber, attached to an intraocular lens implant or placed in tear punctum, are a far more reliable way passively to deliver steady-state doses of medication without ocular surface toxicity. With all the great treatments coming, I predict that in 5 years alternate forms of drug delivery will overtake half of the current market for eye drops.
Second, minimally invasive glaucoma surgery (MIGS) is about to explode. We will soon see the approval of the iStent inject (Glaukos) and the Ivantis Hydrus trabecular bypass devices. Both of these can easily be performed during cataract surgery, and both show impressive long-term results for pressure reduction. Other approaches like the Kahook Dual Blade (New World Medical), the Sight Sciences Omni device, the Trabectome (NeoMedix) and others can be use in stand-alone procedures and also have a track record of impressive pressure lowering. Last year, only 40% of U.S. cataract surgeons responding to the ASCRS Clinical Survey reported that they were performing MIGS. I predict this number will increase to 80% within the next 2 years.
The third hope is managing glaucoma by modulating pressure around the outside of the eye. The Equinox pressure goggles are showing in clinical trials that intraocular pressure can be managed without medications or surgery. Comfortable goggles worn on the face can regulate IOP across wide ranges, regardless of the starting pressure. While still investigational, this device is likely to earn a respected place among other treatment modalities, especially for hard-to-control glaucoma. These same devices are being tested in the space program as a possible preventive treatment for SANS.
Truly, the optic nerve is the final frontier. Like the mysteries of the brain and the complexities of space flight, it challenges our best scientists. But the biggest challenges bring the best advances, and our hope for the future is becoming brighter each year as advances in treatments of optic nerve disease become available.
Disclosure: Hovanesian reports he is a consultant or investor to Alcon, Allergan, Bausch + Lomb, Glaukos, Ivantis, Sight Sciences and Equinox.