Alexander Gofen

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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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…

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…

We introduced a novel approach to topographic function assessment in visual impairment that requires neither fixation nor reading.

The test measures the time it takes for patients to find and identify 32 targets on a screen. The task discourages steady fixation and the subjects can make eye movements as needed to solve the task. Target size is always double the size threshold, and no manual action is required.

We have used this test on many low vision patients with varying diagnoses. Measurements yielded a wide variety of performance levels, with a factor of 14-16 between best and worst…