In a remote mountain wilderness in the Mosquitia region of eastern Honduras lay a territory shrouded by dense layers of jungle foliage. For centuries, the contents of the region remained a mystery. As legend had it, it was home to a lost city, long referenced in the tales of indigenous tribes who spoke of their ancestors fleeing there to escape the Spanish conquistadores. The area became known as the White City or the City of the Monkey God, based on one (bunk) account of it being a walled settlement decorated with ornate monkey carvings.
Expeditions to find the White City began in the 1920s, but all efforts proved unsuccessful until a pair of documentary filmmakers, Steve Elkins and Bill Benenson, launched their own search. Elkins and Benenson identified a crater-shaped valley encircled by steep mountains as a possible location. To survey the area, in 2012 they enlisted the help of the Center for Airborne Laser Mapping at the University of Houston. A Cessna Skymaster carrying a million-dollar lidar scanner flew over the valley, probing the jungle canopy with laser light. Lidar—short for light detection and ranging—works by bouncing thousands of pulses of infrared laser beams off the terrain below and recording the point location of each reflection. The pulses that hit trees and undergrowth can be removed, leaving a map of only the pulses that reach the underlying terrain.
When Elkins and Benenson’s lidar images were processed, they revealed unnatural features stretching for more than a mile through the valley. Evidence of architecture and possible irrigation canals and reservoirs led to the conclusion that the settlement was, indeed, a lost city. But an archaeological discovery can’t be confirmed until it has been ground-truthed. When Elkins and Benenson’s team ground-truthed what the lidar images had identified, they found more than they had anticipated: not just a lost city, but a lost civilization.
In remote sensing, ground truthing refers to the process of collecting information on location, and it is essential for interpreting unknown materials. This emphasis on direct observation is one we value in our scientific field as well, particularly when it comes to glaucoma. Historically, IOP has been the focus of our interventions, as a tangible and modifiable disease parameter. Von Graefes’ surgical iridectomy was devised solely to relieve IOP. Fortunately, advances in OCT—our own lidar technology—have enabled us to see beyond IOP and to view the optic nerve as the true point of disease.
Despite the insights OCT imaging has given us into the optic nerve, however, there remains a wealth of clinically meaningful information to be discovered on a deeper, more cellular level. In this issue of Glaucoma Today, contributors look beyond IOP to discuss the true foundations of glaucoma. Such ground truthing is vital to understand what is buried beneath layers of disease complexities and to ultimately develop a curative or preventive response to what we find. And, as you’ll read, we may be much closer to this discovery than we think.
Arsham Sheybani, MD
Associate Medical Editor
