To study the association between FDF and RNFL in patients with early defects, patient eyes with mean defects exceeding 5 dB in SAP were excluded. Visual acuity was 20/40 or better, pupil widths were between 2.1 and 5.2 mm, and myopic refractive error was between −8.5 and 5.3 diopters (D). The purpose of the present investigation is to study the structure–function relationship between FDF perimetry and RNFL thickness in patients with early signs of glaucomatous nerve atrophy, and to compare these data with the relationship between Octopus SAP and RNFL thickness.Īll individuals that participated in the study ( Table 1) were familiar with psychophysical and perimetric tests. 18 Currently, a comparison of the FDF (using the Heidelberg Edge Perimeter, Heidelberg Engineering, Heidelberg, Germany) with Octopus G1 perimetry is lacking. Recently, the flicker-defined form (FDF) stimulus 17 was proposed to be a useful technique for perimetric measurements in glaucoma. In these studies, it has been stated that perimetry, such as the frequency-doubling technology (FDT), 10– 13 flicker tests, 7, 14, 15 or pulsar perimetry 16 may be helpful in glaucoma diagnosis. As flickering targets proved to be particularly suitable for the early detection of glaucomatous damages, 7– 9 new devices for sensory tests using temporally modulating targets have been developed. Assuming that such a reduction in number of nerve fibers is accompanied by some sort of functional change, it is expected that more sensitive functional methods to detect glaucoma can be developed. According to the linear model of Hood and Kardon, 6 at the upper limit of the normal range (2 dB) of conventional perimetric defects, 37% of the total available nerve fibers may already have been lost. 1– 5 It was shown that minor visual field defects (expressed in decibels) are accompanied by a substantial retinal nerve fiber layer (RNFL) thickness decrease. There is a strong relationship between glaucomatous reduction of the nerve fiber layer thickness and defects in routinely performed standard perimetry (SAP). The FDF perimetry may be an efficient functional test to detect early glaucomatous nerve atrophy. The FDF perimetry is able to uncover functional changes concurrent with the changes in RNFL thickness. The FDF MD was significantly ( R = −0.61, P < 0.001) correlated with RNFL thickness with a (nonsignificantly) larger correlation coefficient than conventional SAP MD ( R = −0.48, P < 0.001). However, FDF MD was abnormal in 28 of 55 OAG patients with normal SAP MD. Of a total of 42 OAG patients with abnormal SAP MD, 38 also displayed abnormal FDF MD. The FDF perimetry and SAP showed high concordance in this cohort of experienced patients (MD values, R = −0.69, P < 0.001). The age-corrected sensitivity values and the local results from the controls were used to determine FDF mean defect (FDF MD). The correlations between the perimetric data on one hand and RNFL thicknesses on the other hand were analyzed statistically. Exclusion criteria were subjects younger than 34 years, SAP mean defect (SAP MD) > 5 dB, eye diseases other than glaucoma, or nonreliable FDF measurements. The FDF perimetry and SAP were performed at identical test locations (G1 protocol). All subjects underwent FDF perimetry, SAP, and peripapillary measurements of the RNFL thickness. Definition of glaucoma was based exclusively on glaucomatous optic disc appearance. We compared the results of flicker-defined form (FDF) perimetry with standard automated perimetry (SAP) and retinal nerve fiber layer (RNFL) thickness measurements using spectral domain optical coherence tomography (OCT).Ī total of 64 healthy subjects, 45 ocular hypertensive patients, and 97 “early” open-angle glaucoma (OAG) patients participated in this study.