Perimetric profiles and cortical representation

The nature of the interaction between spatial summation and M-scaling was investigated by means of the Octopus automated perimeter. It was found that M-scaling of spatial stimulus parameters, alone, did not result in the expected isosensitivity profile. A clinically flat profile was, however, obtained within the central 30 degrees along the horizontal meridian using a large uniform size target (size 3; projected diameter 0.431 degrees). The eccentricities at which presentation of the standard Goldmann targets would result in an isosensitivity profile across the full extent of the visual field were calculated to further illustrate the over-compensation inherent in the current M-scaling equations.