Scanning laser polarimetry (SLP) is a technology used to measure the thickness of the human retinal nerve fiber layer (NFL) in vivo. SLP has been demonstrated to well differentiate between glaucomatous, ocular hypertensive, and normal eyes, despite overlapping data. Recently increased interest is seen in the polarizing properties of the cornea and crystalline lens that may lead to spurious measurements. Although the instruments that use SLP compensate for these anterior segment polarizing properties, recent interest has focused on the extent and effects of incomplete compensation. If well compensated in all, SLP may better separate diseased from normal eyes. Its promising role in the follow-up of glaucoma is still under investigation.