The interface of Flash Focus was compared much to Brain Age in the sense that it retains the same calendar interface, requires the player to sign his or her name in a box, and allows the player to design the calendar stamps. It also has a "check" program and a list of exercises, and players gradually unlock further exercises as they accumulate stamps, like Brain Age. Unlike Brain Age, the player holds the game horizontally instead of rotating it 90 degrees. Unlike the Brain Age series, where the face of creator Ryuta Kawashima prominently appears in the game, Ishigaki's face does not appear in Flash Focus.
The first part of the program is the "Eye Age Check," where players do several training exercises. The game then displays a number that tells the player how old his or her eyes are.
The training exercises are split into two groups: the "Core Training" and the "Sports Training." The Core Training games were described as the type of tests seen at an optometrist's office. The "Sports Training" involved strengthening vision through sports games such as table tennis, basketball, and baseball. For instance, in baseball, players tap the screen when the baseball enters the strike zone. Reviewers found the Sports Training games to be more visually impressive than the Core Training games.