Projects

The Macular Mapping Test (MMT) is a tool for the assessment of the topography of vision. It is a quick and low-cost alternative to conventional perimetry in practical low vision care.

While standard perimetry uses a detection task, the MMT measures the recognition of single letters in the center and near periphery (+/- 10 deg) of the visual field. Their sizes increase according to eccentricity and can be shown at different contrast levels. Each letter is displayed only for a brief moment (250 ms). One test run of 36 trials takes only about 3 minutes.

We have tested patients with early age…

Patients with spots of diminished or no vision (scotomas) often do not realize the nature of their deficit. This technique can help patients to heighten their awareness of scotomas.

In the process of learning eccentric viewing, several stages have to be passed:

1. Patients use their own hand movements to find the location of best vision in the visual field of one eye, while the other eye is closed and gaze is fixed.

2. Patients use eye movements to adjust gaze so that a target in a stable location looks best.

3. Coordinate eye and hand movements, so that a magnifier can be moved where it is…

Diminished motion perception was used as indicator of early effects of eye diseases in the periphery of the visual field. We investigated whether subtle defects in patients with age-related maculopathy (ARM) can be found in regions of the retina that lie outside the macula, i.e. 10 deg eccentricity. The results showed that such defect can indeed be found. Bottom line: Early ARM already affects areas of the retina that do not belong to the macula.

Purpose -To study the dynamic visual field characteristics in age-related maculopathy (ARMD) we measured motion sensitivity, double-pulse resolution…

We developed software to make the retinal placement of stimuli during micro-perimetry by a scanning laser ophthalmoscope (SLO) independent of involuntary fixational eye movements. This greatly increases the accuracy of the measurement and enhances the ability to reliably repeat a measurement on the same patient, as well as making comparisons between patients.

Reference

MacKeben M & Gofen A. (2007) Gaze-contingent display for retinal function testing by scanning laser ophthalmoscope. J Opt Soc America A, vol. 24/5, May, pp. 1402-1410 (feature issue on “Retinal Imaging”)

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We investigated whether relative motion can serve as a cue for sustained attention. We found that relative motion perception has a long latency and that it can indeed attract attention to improve discrimination performance.

Reference

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Poggel DA, Strasburger H, MacKeben M. (2007) Cueing attention by relative motion in the periphery of the visual field. Perception 36(7) 955 - 970. (pubmed)

We studied letter recognition in 8 deg eccentricity from the fovea after attracting sustained focal attention to the stimulated location by a cue. Young and elderly healthy subjects, as well as patients with central vision loss participated. We found that the ability to utilize focal attention has an irregular topographic component in some subjects. The experiments in patients indicated that locations with high attentional potential are more likely to be used as preferred retinal loci after central vision loss.

References

MacKeben, M. (1999) Sustained Focal Attention and Peripheral Letter…

Typographical features of letters were manipulated in such a way that frequently occurring letter confusions in eccentric viewing happened less frequently. This demonstrated that a combination of psychophysics and goal-directed modification of typographic features is a viable experimental strategy.

Reference

MacKeben M. (2000) Enhancement of peripheral letter recognition by typographical features. Visual Impairment Research 2, (2) 95 -103. (link to VIR)

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We studied the ability of dyslexic young teenagers to fluently name pictograms (shapes of objects). We found that some dyslexics are very good at this task, some were even better than the control subjects.

We also investigated whether dyslexics make instantaneous automatic adjustments of reading saccades depending on word length. We found evidence that dyslexics have the mechanisms to make such adjustments, but that they are quantitatively impaired.

References

Trauzettel-Klosinski S, MacKeben M, Reinhard J, Feucht A, Dürrwächter U & Klosinski G (2002) Pictogram naming in dyslexics and normal…