Frequency doubling perimetry (FDP) may idendtify glaucoma at a relatively early stage even before conventional perimetry does. Scanning laser polarimetry (GDx) has shown to differentiate nerve fiber layer thickness (NFLT) between glaucomatous eyes Frequency doubling perimetry (FDP) may idendtify glaucoma at a relatively early stage even before conventional perimetry does. Scanning laser polarimetry (GDx) has shown to differentiate nerve fiber layer thickness (NFLT) between glaucomatous eyes