Gonioscopy Made Easy

Normally, the iridocorneal angle cannot be seen with a microscope because the cornea-air interface creates “total internal reflection.” 

However, we can use a goniolens, which is a special glass lens with mirrors on its sides, to look directly at the angle. 

When the glass lens is placed directly onto the cornea, the cornea-air interface reflection is broken and light from the angle can escape and be seen through the mirrors.