Abstract
Purpose: :
To evaluate a new non-conventional perimetric test, the Flicker-Defined Form perimetry (FDF), provided by the Heidelberg Edge Perimeter, and to analyse its capacity to detect visual field defect, comparatively to Matrix using doubling-frequency technology (FDT), in normal subjects and in patients treated for primary angle glaucoma (POAG).
Methods: :
Comparative trial including 65 eyes of 35 subjects who performed: full clinical examination, measurement of the retinal nerve fiber layer thickness (RNFL) by scanning laser polarimetry GDx PRO, standard automated perimetry (SAP) using Humphrey SITA 24.2 test, FDT-Matrix 24.2 test and FDF test. Perimetric tests (SAP, FDT-Matrix and FDF) were performed two times, and only the second test was used in the study. Were excluded: visual acuity (VA) < 8/10, refraction error > 3 dioptries, and associated ocular disease. Subjects were divided in 2 groups: a control group composed of 35 eyes of 19 normal subjects, mean age of 40,5 years, without any abnormality in GDx or SAP, and a POAG group consisted of 30 eyes of 16 patients, mean age 69,1 years, treated for POAG, presenting glaucomatous alterations of RNFL in GDx and visual defect in SAP: 23 early, 4 moderate and 3 advanced POAG.
Results: :
Control group: 37% (13/35 eyes) present visual field defect in FDF, and 6% (2/35) in FDT-Matrix. Defects detected by FDF are significantly more frequent than those detected by FDT-Matrix (Pearson Chi-2 test: p < 0,01). Among the 13 cases of FDF defects, the visual field loss was extended more than 1 quadrant in 8 eyes.POAG group: 87% (26/30 eyes) present defect in FDF, and 90% (27/30) in FDT-Matrix. No significant difference was found between the 2 tests (Pearson Chi-2 test: p > 0,9). All moderate and advanced POAG eyes present defects in both tests. Eyes with normal FDF or FDT-Matrix presented mild SAP defects.In POAG group, FDF test and FDT-Matrix show high sensibilities: 87% and 90%. Inversely, FDF specificity is found very low, 63%, comparatively to FDT-Matrix, 94%, probably because of a learning effect with FDF perimetry. These results must be confirmed by further studies.
Conclusions: :
The new non-conventional perimetric test, the FDF perimetry, seems to be useful to detect visual field defect in POAG, but with a low specificity.
Keywords: perimetry • visual fields • optic nerve