CLINICAL APPLICATIONS & DISEASE - Glaucoma

Clinical Applications & Disease > Glaucoma 1 | 2 |

Summary from: "Functional Assessment of Glaucoma Using Visual Fields, Contrast Sensitivity and Night Driving Simulation." (In references, see: Ginsburg AP, et al. Functional assessment of glaucoma using visual fields, contrast sensitivity and night driving simulation.)

Patients with glaucomatous visual field loss and no other ocular media or retinal abnormalities may have normal Snellen acuity (1,2). Sine-wave contrast sensitivity offers another method of testing functional central vision (1-6). Previous studies have examined the correlation between loss in contrast sensitivity and glaucomatous field loss (2,4,7). There can be significant differences in the results of those two tests in glaucoma suspects (2,4,7). Loss in contrast sensitivity may precede visual field loss due to glaucoma (1).

The goal of glaucoma management is to reduce the rate of progressive optic nerve damage and subsequent vision loss. The effect of loss in contrast sensitivity and visual field abnormalities on the functional aspects of daily living in glaucoma patients is not known. The purpose of this study is to evaluate the relationship between loss in contrast sensitivity, visual field depression and the functional ability of glaucoma patients to drive safely at night.

Nine study patients with open angle glaucoma underwent sine-wave contrast sensitivity testing and target detection and identification in a night driving simulator. All subjects viewed the FACT sine-wave grating contrast sensitivity test chart shown in Figure 1. Contrast sensitivity testing was performed at three visibility conditions: day, night and night with fog. All subjects were tested monocularly in the Night Driving Simulator (NDS) shown in Figure 2 for detection and identification distances to road message, warning and pedestrian hazard targets in rural and city night driving scenes under clear and fog visibility conditions.

Figure 1 - FACT Sine-wave Grating Test Chart

Figure 2 - Night Driving Simulator (NDS)

For more information on the NDS, see Night Driving Simulator.

The severity of glaucoma as measured by visual field loss did not correlate well with the loss of functional vision as measured by contrast sensitivity nor with the night driving simulator data. This general lack of correlation is surprising since visual field loss would seem to be a hallmark of decreased retinal function. The FACT contrast sensitivity chart measures a 1.8 degree central visual field and thus it is a relatively better predictor of driving performance than is overall visual field depression with central sparing.

These data reinforce the importance of testing a full range of spatial frequencies with the highest sensitivity and specificity uniquely provided by sine-wave gratings in order to understand the effects of glaucoma on functional vision.

In references, see:

(1) Atkin A, et al. Interocular comparison of contrast sensitivities in Glaucoma patients and suspects.

(2) Motolko MA, et al. Contrast sensitivity in asymmetric glaucoma.

(3) Zulauf M, et al. Correlation of spatial contrast sensitivity and visual fields in glaucoma.

(4) Ross JE, et al. Detection of optic nerve damage in ocular hypertension.

(5) Sample PA, et al. Isolating the effects of primary open-angle glaucoma on the contrast sensitivity function.

(6) Ginsburg AP. Clinical findings from a new contrast sensitivity chart.

(7) Sponsel WE, et al. Association of Vistech contrast sensitivity and visual field findings in glaucoma.)

Clinical Applications & Disease > Glaucoma 1 | 2 |

 

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