The full-field flicker test in glaucomas: influence of intraocular pressure and pattern of visual field losses

Background: The pur pose of this study was to evaluate how temporal contras t sensitivity (TCS) determined with full-field flicker stimuli is influence d by intraocular pressure and whether TCS is reduced in glaucoma patients w ith diffuse perimetric losses as well as in patients with localized visual field deficits. Methods: TCS was determined with sinusoidally flickering li ght (37.1 Hz) in a full-field bowl. Perimetric mean defect (MD) and cumulat ive defect curves (Octopus G1) were used to distinguish between patients wi th localized and diffuse field deficits. Normal subjects (296), low-tension glaucoma patients (98) and open-angle glaucoma patients with previously el evated intraocular pressure (541) were classified into five subgroups takin g into account the depth of their visual field losses. Results: No signific ant correlation between full-field flicker sensitivity and prevailing intra ocular pressure was found in normals (Y=1.36+0.006 X) or in patients (Y=0.9 5-0.0002 X). Analyses of validity at a predefined specificity of 90% reveal a reduction of TCS in patients with early (MD<5 dB) diffuse perimetric los ses (sensitivity 69%) as well as in those showing localized visual field de fects (sensitivity 65%). Sensitivity was 87% in patients with diffuse perim etric defects (MD 5-10 dB), 93% in a group of patients with both types of l osses, and 100% in advanced glaucomas (MD>20 dB). The lack of TCS is simila r in open-angle glaucomas and in field-loss-matched normal-tension glaucoma patients. Conclusions: Significantly reduced TCS in patients with early di ffuse perimetric losses as well as in those showing localized visual field defects indicates that localized damages can be associated with general det erioration of the ability to perceive flickering stimuli. Thus, this flicke r test can be performed in a full-field bowl with no need for fixation. Con sidering its other clinical qualities (photopic conditions, low influence o f prevailing intraocular pressure and media opacity) the test may be a usef ul, convenient supplementary procedure in glaucoma screening.