"The greatest athletes in the world, they see things faster, quicker, and make decisions better than others," said Da Silva, who leads IMG's vision training program. "We're talking about split-second differences that can be obtained."
The drills, including some adapted from training for fighter pilots, often leave prospects rubbing their eyes from the exertion of a visual workout.
"We are helping the eye muscles be more efficient," and helping the brain's visual cortex respond faster, Da Silva said.
IMG is one of only a handful of sites that teach such techniques, he said. Players such as Boston College linebacker Luke Kuechly, Texas A&M quarterback Ryan Tannehill, and Rutgers wide receiver Mohamed Sanu have been training there in anticipation of the draft.
One training technique originated after World War II, when the military showed pilots brief images of aircraft silhouettes, Da Silva said. The airmen had to quickly determine from the shape whether the plane was an enemy or friendly.
It's only relatively recently, Da Silva said, that such methods have migrated to sports. At IMG, players look through a tachistoscope, a device that quickly flashes a series of images, each containing a number.
The backgrounds and colors change - maybe in one flash the numbers are on a ball, in another the digits are on an image of a football player - and players have to write down the numbers they see. The 10 flashes show up for as little as .13 seconds each, and appear on a 35- to 40-inch television screen, forcing the players' eyes to cover a wide area.
The challenge is to find, identify, and process the information.
Next come Saccades, what Da Silva describes as visual push-ups. A pair of vertical columns and a pair of horizontal columns, each with a series of letters, are mounted on a wall. The players have to read off the letters by darting their eyes back and forth between the columns. On the vertical set up, they read from the first row on the left, then the first row on the right, move to the second row on the left, then second on the right and so on.
The challenge is trying to relocate where they left off as their eyes move, and processing what they see. It's similar to the challenge of a running back finding a hole and reacting, or spotting an oncoming pass rusher, Da Silva said.
A Dynavision board set up with lights requires players to slap the lights as they flash. A computer times the athletes' reactions, and analyzes whether they were faster to their right or left side, looking up or looking down.
Outside, the players don glasses with LCD lenses that flash, occasionally obscuring their vision. They have to perform agility drills and make decisions - such as where to throw - while seeing less than usual.
When they take the glasses off, it's like a sprinter taking off a parachute and running at full speed, unencumbered and, they hope, with one more edge heading into the NFL.
Contact staff writer Jonathan Tamari at 215-854-5214, firstname.lastname@example.org,
or @JonathanTamari on Twitter.