Most centers offer one type of visual field test, called standard automated perimetry (SAP). While this test is very valuable, many glaucoma specialists believe that by the time that SAP shows visual field damage from glaucoma, 20 or 30% of the optic nerve is already gone.


Moderate visual field loss – left eye


Advanced visual field loss – right eye


At our center, in addition to SAP, we offer blue yellow visual field testing and frequency double testing (FDT). We have found the FDT to be more sensitive in early glaucoma detection, often up to two years before SAP will have uncovered a change.



FDT right eye show visual field loss superior nasal quadrant


FDT left eye shows generalized depression throughout the field