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R. Arogyasami, D. C. Hood, V. C. Greenstein, A. J. Llinas, B. S. Fuchs, J. G. Odel, R. Ritch; Using Microperimetry to Analyze Visual Field Defect Uniformity in Patients With Glaucoma. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1613. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate glaucomatous visual field defects with a microperimetric technique to ascertain whether the defects reflect either local or regional loss of underlying retinal ganglion cells.
Six patients (12 eyes) with a diagnosis of open-angle glaucoma were selected for the study. Inclusion criteria were as follows: glaucomatous optic neuropathy with a cup-disc ratio >0.6 and reliable repeatable visual field defects on standard automated perimetry (SAP). In addition, the patients had to have an abnormal multifocal visual evoked potential (mfVEP) with measurable, but reduced, amplitudes in a local region of the field, a region with a corresponding loss in sensitivity on 24-2 SAP. Following pupil dilation microperimetry was performed on each eye with the Nidek MP-1. The display was an 8 by 8 degree grid consisting of 64 test stimuli 0.11 degree in diameter, 200 msec in duration, placed at 1 degree intervals. The grid was centered on the region of the field with abnormal, but measurable, mfVEPs. Visual sensitivity to the test stimuli was measured using a 4-2-1 test strategy. The test was repeated three times: a total of 4 tests on each eye per patient. Results were compared to those of age-similar controls.
The MP-1 showed decreased sensitivity in areas corresponding to those found on SAP and mfVEP. In comparison to the MP-1 results obtained from age-similar controls the patients had repeatable test points with marked decreases in sensitivity (0dB), which were adjacent to test points with sensitivity values resembling those of age-similar controls (12 dB). These test points occurred within regions that corresponded to an area on SAP that had slight to moderate decreases in sensitivity.
The results suggest that glaucomatous visual field defects are not homogeneous but rather reflect areas of local retinal ganglion cell loss.
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