Abstract
Purpose:
To correlate data from Flicker Defined Form (FDF)-perimetry with standard automated perimetry (SAP) and retinal nerve-fiber-layer (RNFL) thickness in early and moderate open-angle glaucoma (OAG) glaucoma patients.
Methods:
The study included 363 eyes of 221 experienced participants of the Erlangen Glaucoma Registry: 45 ocular hypertensive patients, 32 “preperimetric” OAG, 27 “early” OAG (focal field losses in SAP, mean-defect (MD) < 2.0 dB), and 53 “moderate” OAG (MD: 2.0-9.4 dB). FDF- and conventional perimetry was performed at identical test locations (Octopus, G1 protocol). The age corrected sensitivity values from 64 healthy control subjects were used as a reference to determine the FDF defect values. A Spectralis-OCT was used to measure the RNFL-thickness. Data from subjects younger than 35 years and those revealing non-reliable FDF-measurements (false positive error rate above 4.0) were not analyzed. Statistical analyses used: Spearman correlation, U-test, Fisher-Z analysis to compare correlation coefficients. For an intra-individual analysis we correlated the RNFL-differences between right and left eye with the MD-differences from FDF und SAP. Local correlation between glaucomatous RNFL reduction and visual field losses were calculated for nerve fiber bundle related areas.
Results:
The FDF-MD values of the ‘early’ glaucoma patients (with SAP-MD in the normal range) were significantly (p<0.01) larger than normals. Local RNFL-thickness loss was significantly (p <0.001) correlated with FDF-defects (superior: R=-0.74, inferior: R=-0.52, all values: R=-0.65) and with SAP-defects (superior: R=-0.62, inferior: R=-0.45, all values: R=-0.55). The largest differences between the correlation coefficients of the procedures was found in the superior sector (P < 0.05, not significant after correction for multiple testing). Furthermore, the intraindividual correlations between perimetry and RNFL using differences between right and left eyes revealed significant (p <0.001) correlation coefficients for FDF-stimulation (R=0.72) and SAP (R=0.62).
Conclusions:
In this cohort of trained participants FDF-perimetry was highly correlated with RNFL-thickness. The FDF-stimulus may be a useful method test to study early glaucomatous function loss.
Keywords: 642 perimetry •
610 nerve fiber layer •
758 visual fields