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The uniform field and pattern ERG in macaques with experimental glaucoma: removal of spiking activity.
Invest Ophthalmol Vis Sci. 2000 Aug; 41(9):2797-810.IO

Abstract

PURPOSE

To determine whether the uniform field and pattern ERGs that are reduced in macaque eyes with experimental glaucoma have the same inner-retinal origins.

METHODS

ERGs were recorded from 14 anesthetized adult macaques using DTL electrodes. Six monkeys had laser-induced experimental glaucoma, and two others received intravitreal injections of tetrodotoxin (TTX, 6 microM) to block spiking activity of inner-retinal neurons. The remaining 6 animals were normal. Uniform fields and grating patterns (0.1-3 cpd) were square-wave modulated at 1.7 Hz (transient) and 8 Hz (steady state). The test field (42 degrees x 32 degrees) had a mean luminance of 44 cd/m2 and a contrast of 10% to 82%.

RESULTS

In normal eyes transient ERGs to uniform fields contained photopic negative responses (PhNR) after the b-wave and after the d-wave. Transient pattern electroretinograms (PERGs) at each contrast reversal showed positive (P50) potentials followed by negative (N95) potentials of time course similar to that of the PhNR. The PhNR and N95 were greatly reduced or eliminated by experimental glaucoma and by TTX. Summing responses to luminance increments and decrements of the uniform field could simulate the PERG to low spatial frequency stimuli. Further, the PERG responses to high spatial frequencies were similar to the simulation in shape but slightly delayed in time. Experimental glaucoma and TTX had similar effects on the N95 of the simulated PERG as to those on the actual PERG. However, P50 was more reduced by experimental glaucoma than by TTX, indicating a nonspiking contribution to P50. For the steady state condition, the uniform field ERG, the simulated PERG, and the actual PERG all were affected by experimental glaucoma and TTX, indicating that they contained contributions from the spiking activity of ganglion cells.

CONCLUSIONS

The changes in the uniform field and PERG responses produced by experimental glaucoma are related and are largely a consequence of reduced spiking activity of ganglion cells and their axons. These findings raise the possibility that the uniform field ERG could serve as a useful alternative to the PERG in the assessment of clinical glaucomatous neuropathy.

Authors+Show Affiliations

College of Optometry, University of Houston, Texas 77204-6052, USA.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

10937600

Citation

Viswanathan, S, et al. "The Uniform Field and Pattern ERG in Macaques With Experimental Glaucoma: Removal of Spiking Activity." Investigative Ophthalmology & Visual Science, vol. 41, no. 9, 2000, pp. 2797-810.
Viswanathan S, Frishman LJ, Robson JG. The uniform field and pattern ERG in macaques with experimental glaucoma: removal of spiking activity. Invest Ophthalmol Vis Sci. 2000;41(9):2797-810.
Viswanathan, S., Frishman, L. J., & Robson, J. G. (2000). The uniform field and pattern ERG in macaques with experimental glaucoma: removal of spiking activity. Investigative Ophthalmology & Visual Science, 41(9), 2797-810.
Viswanathan S, Frishman LJ, Robson JG. The Uniform Field and Pattern ERG in Macaques With Experimental Glaucoma: Removal of Spiking Activity. Invest Ophthalmol Vis Sci. 2000;41(9):2797-810. PubMed PMID: 10937600.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The uniform field and pattern ERG in macaques with experimental glaucoma: removal of spiking activity. AU - Viswanathan,S, AU - Frishman,L J, AU - Robson,J G, PY - 2000/8/11/pubmed PY - 2000/8/19/medline PY - 2000/8/11/entrez SP - 2797 EP - 810 JF - Investigative ophthalmology & visual science JO - Invest Ophthalmol Vis Sci VL - 41 IS - 9 N2 - PURPOSE: To determine whether the uniform field and pattern ERGs that are reduced in macaque eyes with experimental glaucoma have the same inner-retinal origins. METHODS: ERGs were recorded from 14 anesthetized adult macaques using DTL electrodes. Six monkeys had laser-induced experimental glaucoma, and two others received intravitreal injections of tetrodotoxin (TTX, 6 microM) to block spiking activity of inner-retinal neurons. The remaining 6 animals were normal. Uniform fields and grating patterns (0.1-3 cpd) were square-wave modulated at 1.7 Hz (transient) and 8 Hz (steady state). The test field (42 degrees x 32 degrees) had a mean luminance of 44 cd/m2 and a contrast of 10% to 82%. RESULTS: In normal eyes transient ERGs to uniform fields contained photopic negative responses (PhNR) after the b-wave and after the d-wave. Transient pattern electroretinograms (PERGs) at each contrast reversal showed positive (P50) potentials followed by negative (N95) potentials of time course similar to that of the PhNR. The PhNR and N95 were greatly reduced or eliminated by experimental glaucoma and by TTX. Summing responses to luminance increments and decrements of the uniform field could simulate the PERG to low spatial frequency stimuli. Further, the PERG responses to high spatial frequencies were similar to the simulation in shape but slightly delayed in time. Experimental glaucoma and TTX had similar effects on the N95 of the simulated PERG as to those on the actual PERG. However, P50 was more reduced by experimental glaucoma than by TTX, indicating a nonspiking contribution to P50. For the steady state condition, the uniform field ERG, the simulated PERG, and the actual PERG all were affected by experimental glaucoma and TTX, indicating that they contained contributions from the spiking activity of ganglion cells. CONCLUSIONS: The changes in the uniform field and PERG responses produced by experimental glaucoma are related and are largely a consequence of reduced spiking activity of ganglion cells and their axons. These findings raise the possibility that the uniform field ERG could serve as a useful alternative to the PERG in the assessment of clinical glaucomatous neuropathy. SN - 0146-0404 UR - https://www.unboundmedicine.com/medline/citation/10937600/The_uniform_field_and_pattern_ERG_in_macaques_with_experimental_glaucoma:_removal_of_spiking_activity_ L2 - https://iovs.arvojournals.org/article.aspx?volume=41&issue=9&page=2797 DB - PRIME DP - Unbound Medicine ER -