Findings in low luminance kinetic and static perimetry

Purpose To transfer the neutral density filter test to perimetry; i.e. to show that the diagnostic battery can be supplemented by low luminance visual fields, if the standard procedures yield unsatisfactory information. Methods The Goldmann perimeter uses one single incandescent light source for both stimulus and background illumination (BI). By dimming the luminance was reduced by 0.6 log units. The accompanying change in colour temperature was ignored. The i) Twinfield and ii) Tübingen automatic perimeters were modified to low luminance conditions using neutral grey filters i) in front of the eye, or ii) in the stimulus and the BI light paths. Special attention was paid to perform glaucoma fields at normal IOP level as proven by GAT and/or by Corvis tonometry (the latter to avoid affection of the tear film by anesthetics). Results Low luminance perimetry produces more pronounced scotomas in kinetic, and more distinct loss of sensitivity in static perimetry than otherwise identical perimetric procedures in standard luminance. Cases concern inflammatory, ischemic and compressive optic nerve diseases, glaucoma, and ischemic and diabetic retinopathies. Results in hereditary, dystrophic and toxic retinal conditions vary depending on whether the rods and the scotopic system are mainly affected, or the cones and the photopic system. Cone diseases lack visual field deterioration in low luminance and instead may show improvement. Conclusion Low luminance perimetry is a supplementary diagnostic tool which may add helpful diagnostic information, particularly if standard results are insignificant.Commercial interest