Abstract
Purpose: :
Aim of this study was to evaluate the use of fundus–controlled function tests to discover psychic visual discturbance as well as simulation or malignering.
Methods: :
11 females and 1 male (age: 12 to 58 years), who presented with unclear visual deterioration, metamorphopsia or visual field defects were examined with the scanning laser ophthalmoscope as well as they underwent a routine ophthalmologic examination and electrophysiology. Static as well as kinetic perimetry, reading tests and mfERG simulation (RETIscan) were performed with the SLO.
Results: :
In all patients stable central fixation was observed. In cases with concentric visual field constriction in conventional Goldmann perimetry, even further reduced visual fields were detected in kinetic fundus perimetry as well as areas of fixation located to various grades inside the scotomatous area. Reading proved to be possible only for large optotypes while for smaller letters, fixation shifted clearly towards the beginning of the text. In two cases a pathologic mfERG (SLO) could be explained by a grossly instable fixation during recording.
Conclusions: :
Besides the discordance between stable foveal fixation and the subjective reduction of visual acuity, the VCR–based observation of fixation movements during perimetry or specific reading tasks proved to be very helpful in the diagnosis of simulation or malingering. The different size of the residual visual field in dependence to the examined retinal area appears striking. The option to assess the location and stability of fixation as well as the possibility to compare the results with fundus perimetry makes fundus perimetry and mfERG with the SLO precise and objective diagnostic techniques.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • visual acuity • low vision