A comparison of visual fields by frequency doubling perimetry and white on white perimetry in glaucoma patients
G. Schwartze, C. Erb, A. Rust, F. Sistani
Introduction: Frequency doubling perimetry (FDP) is considered to be an innovative and rapid visual field test for an earlier detection of glaucoma-tous nerve fiber damage. The theoretical background of this method is based upon the detection of early glaucoma induced damage of the magnocellular system, whose function should be assessed by a new test stimulus. The purpose of this work was to examine the sensitivity and the comparability of visual fields by this new method with those of w/w-perimetry.
Methods: FDT (Humphrey Instruments) N-30 threshold program and Octopus 1 2 3 (Interzeag) G1 threshold program were used to evaluate and compare the results of visual field examination of 205 eyes (109 glaucoma patients).
Results: Comparable results concerning the extent of glaucoma induced defects could be observed in merely 48.8% (100 eyes). In cases of non correspondence, we could observe a lesser extent of visual field defects compared to G1 in 25.8% (53 eyes) and more severe defects in 25.4% (52 eyes). Especially in early glaucoma stages assessed with G1, there were less defects, i.e. false positive results, in 50.8% of cases after FDP. There were 13 inconspicuous cases of glaucomatous damage after G1 compared to 73 inconspicuous cases after FDT.
Discussion: Our results suggest that FDT perimetry appears to be unsuitable for an earlier glaucoma diagnosis at present and therefore for glaucoma screening.
Department of Ophthalmology, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany