A new diffuse loss index for estimating general glaucomatous visual field depression

Abstract

Experience with a number of visual fields has shown that the algorithm used earlier for estimating general depression in glaucomatous visual fields was too conservative. A new, more sophisticated algorithm for calculating diffuse loss has been devised and the results obtained in the evaluation of 20 glaucomatous visual fields were compared with those obtained manually. The new algorithm is less restrictive, yet produces values for diffuse loss which agree well with the empirical estimates (R = 0.97, N = 14). The new diffuse loss index is also compared with the mean defect index (R = 0.77, N = 159), the 18th Bebie curve ranked value (R = 0.87, N = 159), and the previous diffuse loss index (R = 0.98, N = 105). A general discussion of various aspects of diffuse loss is included.

Analytical and Statistical urvey of Early Stages of Open-Angle Glaucoma With Low Luminance Visual Field

“…Short-and long-term fluctuations [4] were not considered in this survey. We thought it necessary to gather the early-sign measurements of the perimetric defects in be ginning glaucoma.…”

A novel strategy for the estimation of the general height of the visual field in patients with glaucoma

“…There have been other strategies to select the TD values to be used for the estimation of the height of the hill of vision. For instance, Funkhouser [15] proposed to look at the “plateau” in the TD-rank curve and used these TD values for the calculation of the general height. But this method does not take into account that, as more locations become damaged and their TD values decrease, positions in the TD-rank curves change [20].…”

“…For its display, the TD values in (a) and (b) were ranked and plotted against their rank position; this is the TD-rank curve —also known as the Bebie cumulative defect curve [22]. The TD-rank curve for the artificial visual field in (c) is not shown to preserve clarity. The TD-rank curves have been used to derive algorithms for the estimation of the height of the hill of vision [15, 16, 18], some defined from direct visual inspection [15]. From a visual inspection of the TD-rank curve for the glaucomatous visual field in Fig A1b, we see that part of the curve is roughly parallel with the mean normal TD-rank curve (black solid curve).…”

“…The TD-rank curves have been used to derive algorithms for the estimation of the height of the hill of vision [15, 16, 18], some defined from direct visual inspection [15]. From a visual inspection of the TD-rank curve for the glaucomatous visual field in Fig A1b, we see that part of the curve is roughly parallel with the mean normal TD-rank curve (black solid curve).…”

The visualFields package: A tool for analysis and visualization of visual fields

“…The spatial profile and extent of damage can be shown with a gray scale, on which darker grays represent lower sensitivities, or with probability maps (Heijl, Lindgren, & Olsson, 1987a;Heijl, Lindgren, Olsson, &Åsman, 1989). TD rank curves (also known as Bebie cumulative defect curves) may be used as an alternative analysis to estimate the global loss (Bebie, Flammer, & Bebie, 1989;Funkhouser, 1991). Global summary indices of the visual field such as mean deviation (Heijl et al, 1987b), pattern standard deviation (Heijl et al, 1987b), mean defect (Flammer, 1986), loss variance (Flammer, 1986), and the visual field index (Bengtsson & Heijl, 2008) are used to summarize the depth of defect and its change over time.…”