Purpose: The authors prospectively compare perimetric results obtained by conventional differential light sensitivity (DLS) perimetry and frequency-doubling perimetry (FDP) in normal-tension glaucoma (NTG) with a hemifield visual field defect, assuming that some of these eyes already have early glaucomatous changes in the "intact" hemifield.
Methods: Eleven eyes of 11 patients with NTG who met the enrollment criteria were studied. Seven eyes had an upper hemifield defect and four had a lower defect, determined by DLS with a Humphrey Field Analyzer (Zeiss-Humphrey, Inc., San Leandro, CA, U.S.A.). Frequency-doubling perimetry and DLS perimetry were conducted less than 7 days apart. To quantitatively detect nerve fiber layer defect (NFLD), scanning laser ophthalmoscopy was also performed.
Results: Of the 11 intact hemifields, seven showed NFLD. Of the seven, six also showed visual field defects by FDP. Of the four eyes without NFLD, two showed no defects in the intact hemifield by FDP. The threshold values of FDP and DLS perimetry did not significantly correlate in either the intact or the defective hemifields, or in the total field. The average test time of FDP was approximately 6 minutes.
Conclusions: Frequency-doubling perimetry may detect early glaucomatous visual field defects.