[Synopsis of various electrophysiological tests in early glaucoma diagnosis--temporal and spatiotemporal contrast sensitivity, light- and color-contrast pattern-reversal electroretinogram, blue-yellow VEP].
BACKGROUND
Of the three glaucoma-defining criteria intraocular pressure, optic-nerve damage, and visual field damage, the latter is a late symptom. Therefore, in order to improve an early sensory diagnosis, new tests are necessary. It is the aim of the present paper to test new sensory methods, to rank them in an order of sensitivity, and to base them on possible pathophysiological mechanisms.


METHODS
The tests were carried out in subjects of the Erlangen Glaucoma registry: Normals, patients with ocular hypertension, and patients with open-angle glaucoma without or with field defects. The tests are designed to preferentially probe the function of different groups of ganglion cells. Psychophysical methods: Temporal contrast sensitivity in a ganzfeld as "Erlangen flicker test" and spatio-temporal contrast sensitivity to test Magno-cell function. Electrophysiological methods: Pattern-reversal electroretinogram with a luminance-contrast pattern to test Magno-cell function, color-contrast pattern electroretinogram for Parvo-cell function, and blue-on-yellow visual evoked potential to test the "blue-sensitive" pathway.


RESULTS
The most sensitive test is the temp.CS, it is significantly reduced in OHT (p < 0.01). The spatio-temp.CS is reduced in perimetric stages (p < 0.01). The BY-VEP is altered in the preperimetric stage (p < 0.01), the PR-ERG in perimetric stages (p < 0.01). The CC-ERG is reduced in even later stages. These results are in agreement with the hypothesis that tests selective for non-redundant neurons are of early diagnostic value. Multivariate analyses increase the early diagnostic value when different functions are tested in combination.


CONCLUSIONS
When a particular test is taylored to the the special needs of certain groups of ganglion cells sensory defects can be observed before the occurrence of optic-nerve damage (OHT). The most sensitive psychophysical test is the "Erlangen flicker test" which is a screening test selective for M cells. The most sensitive electrophysiological test is the BY-VEP testing the blue-sensitive ganglion cells.
Korth
M J
MJ
Augenklinik mit Poliklinik, Univ. Erlangen-Nürnberg.
Jünemann
A M
AM
Horn
F K
FK
Bergua
A
A
Cursiefen
C
C
Velten
I
I
Budde
W M
WM
Wisse
M
M
Martus
P
P
D003118:Color Perception; D015350:Contrast Sensitivity; D003937:Diagnosis, Differential; D004056:Differential Threshold; D004596:Electroretinography / Q000379:methods*; D005074:Evoked Potentials, Visual; D005425:Flicker Fusion; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D015999:Multivariate Analysis; D009798:Ocular Hypertension / Q000175:diagnosis* / Q000503:physiopathology*; D009900:Optic Nerve / Q000503:physiopathology*; D011601:Psychophysics; D012042:Registries / Q000706:statistics & numerical data; D058609:Visual Field Tests / Q000379:methods*