Frequency doubling perimetry uing a liquid crytal diplay

PURPOE: To compare frequency doubling contrat threhold uing a new liquid crytal window diplay with thoe obtained with the commercial video-baed Frequency Doubling Technology perimeter. METHOD: One eye of 49 glaucoma patient and one eye of 49 normal control were teted with the liquid crytal window and Frequency Doubling Technology ytem. Both diplay employed identical timulu condition and tet trategie, although the dynamic range of the liquid crytal window-baed diplay wa approximately 30% maller than that of the Frequency Doubling Technology ytem. Meaurement were repeated uing the video-baed Frequency Doubling Technology perimeter in a ubet of 21 eye. Relationhip between and within diplay were aeed uing a chance-corrected agreement meaure (quadratic weighted kappa) and paired meaurement difference. Variability wa quantified uing tandard deviation from the mean paired meaurement difference. REULT: Over the retricted operating range of the liquid crytal diplay ytem, between-diplay and within-video diplay variability wa 2.3 dB and 3.2 dB, repectively, between-diplay agreement wa 0.66, and within-diplay agreement (tet–retet for Frequency Doubling Technology) wa 0.65. CONCLUION: Level of agreement and variability between the two frequency doubling diplay were of imilar magnitude to repeated (tet–retet) Frequency Doubling Technology meaure, uggeting that contrat threhold meaurement made uing the two diplay may be ued interchangeably. However, the operating range of the current liquid crytal window-baed diplay i maller.