Electroretinography and optical coherent tomography at early glaucoma stages

Ján Lešták, M.D., Hana Pešková, M.D., Ass. Prof. Šárka Pitrová, M.D. and Eva Obrusníková, M.D.

Ocni oddeleni Poliklinika LIPA, Prague, Czech Republic

Purpose: To ascertain if at early glaucoma stages cellular retinal structure changes precede the nerve fibre layer changes

Methods: The electrical activity of retinal cells was ascertained using ERG and P-ERG (according to ISCEV methods). The nerve fibre layer was measured circularly around the optic nerve head using Optical coherent tomography (OCT). The visual field was examined using special glaucoma threshold program on automated perimetry  Medmont M600.

Findings at 20 glaucoma patients (10 already treated with glaucoma therapy, 10 untreated in the first instance) were compared with 60 unaffected control patients.

Results: The ERG were confirmed at all glaucoma patients (oscillation potencials and P-ERG). Nerve fibre layer thickness was found within normal limits in three of observed untreated glaucoma patients. Automated perimetry demonstrated minute  paracentral scotomas of various depth at arcuate area at 15 of observed glaucoma patients.

Conclusion: Our results contribute that the changes in retinal cells can be at normal nerve fibre layer. This fact deomonstrates at possibility primary damaged retinal cells, that probably precede to the axons damage.