Anatomic and functional correlation of frequency-doubling technology perimetry (FDTP) in multiple sclerosis

To study the correlation between the results of frequency-doubling technology perimetry (FDTP), visual function (visual acuity, contrast vision, standard automated perimetry (SAP)) and the thickness of the retinal nerve fiber layer (RNFL) throughout the course of multiple sclerosis (MS). Sixty-six eyes of thirty-three patients suffering from MS were chosen. Thirty-five eyes had a previous history of optic neuritis (ON group) and thirty-one eyes had no previous history of optic neuritis (non-ON group). The FDTP was performed with the N-30 screening program. Visual acuity was determined with the Snellen scale and the ETDRS (Early Treatment Diabetic Retinopathy Study) scale, the contrast vision with the Pelli-Robson and Sloan tests and the SAP with the Humphrey 750 perimeter. The thickness of the RNFL was measured using the STRATUS OCT™ optical coherence tomography (OCT). The visual field FDTP was divided into three sectors corresponding to the three SAP sectors and to the three RNFL quadrants of the OCT. The FDTP was significantly correlated (P < 0.0001) to the contrast vision and to the SAP results (mean deviation (MD) and the different sectors among themselves). In the ON group, the MD FDTP was significantly correlated to the average RNFL thickness (r = 0.44, P = 0.0091). A decrease of 5 decibels (dB) of the MD FDTP corresponded to a decrease of 11.7 μm of the average RNFL thickness (Y = 2.34 × X + 87.5). The strong correlation with SAP and RNFL confirms the value of FDTP in assessing optic nerve damage throughout the course of MS.