Abstract:
To compare the ability of visual field tests among the frequency doubling illusion perimetry (FDT screener (FDT), Humphrey Matrix (Ma)) and Humphrey field analyzer (HFA) to detect the early stage of normal tension glaucoma (NTG).
We included 40 patients 79eyes with normal tension glaucoma (NTG), (M:F=17:23, mean age: 54.8±15.5 y.o., refraction: –0.56D±3.60). NTG subjects with –6dB or above of mean deviation (MD) in HFA–SITA standard were selected. These underwent FDT N30–2 threshold and Ma 30–2 threshold within six months periods. The item examined in three visual field tests were i) the correlation of MD and PSD, ii) the retinal sensitivity in the four quadrants, iii) the retinal sensitivity in 19 blocks (Fig. 1), iv) the comparison by scoring probability symbols of pattern deviation (scoring according to P>5%=0, <5%=1, <2%=2, <1%=3, <0.5%=4).
The correlation of MD was highest for HFA and Ma (r=0.748) and lowest for HFA and FDT (r=0.503). For the retinal sensitivity, the correlation between HFA and Ma were high in all blocks (r=0.710) and quadrants (upper nasal r=0.829, lower nasal r=0.810, upper temporal r=0.603, lower temporal r=0.705). The correlation were also highest in the upper and lower nasal quadrant for all measurement methods. The score of probability symbols across all subjects for FDT>Ma>HFA.
HFA and Ma exhibited the highest correlation in the retinal sensitivity in stead of lowest for FDT and HFA. Although the FDT probability symbol score was highest, the correlation with HFA was low, suggesting effect due to factor unrelated to glaucoma. It appeared that Ma 30–20 threshold was the most sensitive for early detection of NTG in the three visual field tests.
Keywords: visual fields • perimetry • contrast sensitivity