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[Frequency-doubling perimetry in retrochiasmatic disorders]
C D Cerio-Ramsden1, F J Muñoz Negrete, J G M Moro
1Servicio de Oftalmología, Unidad de Glaucoma, Hospital Ramón y Cajal, Madrid, España.
Objective:
To determine the ability of frequency doubling technology (FDT) to evaluate retrochiasmatic lesions.
Methods:
21 patients with characteristic retrochiasmatic visual field defects in automated perimetry (Humphrey field analyzer, 24-2 SITA) underwent FDT using C-20 screening and threshold tests. Two independent observers described the visual field defects, the degree of congruence and macular sparing of the three explorations.
Results:
The visual field defect found in the 24-2 test was inferred in 63.2% and 70% of the eyes from the C-20 screening and C-20 threshold test respectively. The retrochiasmatic lesions were congruent in 45% of the cases in automated perimetry, 5.6% in C-20 screening and 15% in C-20 threshold test. Macular sparing was present in 45% of cases with automated perimetry, 89% with C-20 screening and 82% with C-20 threshold test.
Conclusions:
The FDT allows us to suspect retrochiasmatic lesions in more than one-half of patients, but it tends to underestimate the defects. It is not useful for detecting macular sparing or the evaluation of visual field congruence. Both FDT strategies offer similar results, so the C-20 screening test could be more advisable because of its speed (mean: 70 seconds). However, in retrochiasmatic lesions the FDT accuracy is considerably lower than the 24-2 SITA strategy.