Gradient?s parameters:

Create Futuristic EyeBall in Photoshop CS

Select now the shown instrument and choose the appropriate clich? from the next table, that one accentuated with red color:

Create Futuristic EyeBall in Photoshop CS

Create Futuristic EyeBall in Photoshop CS

Blending
Options-Outer Glow

Create Futuristic EyeBall in Photoshop CS

Blending Options-Gradient Overlay

Create Futuristic EyeBall in Photoshop CS

Gradient?s parameters:

Create Futuristic EyeBall in Photoshop CS