Review of a new concept of glaucoma pathogenesis based on the glymphatic theory of cerebrospinal fluid circulation

[Electroretinography in evaluation of neuroprotective effect in an experimental model of glaucoma]

For drugs that have a therapeutic effect on glaucoma through mechanisms not associated with decreasing intraocular pressure (IOP), special attention is paid to the choice of effectiveness criteria. The article examines the possibility of using a- and waves of electroretinography (ERG) in preclinical studies to predict the effectiveness of glaucoma drug candidates.

PURPOSE

To examine the possibility of reliably associating changes in the amplitude of a- and ERG waves with functional changes in the retina of experimental glaucoma rats with morphological evidence of loss of functional integrity of the retina.

MATERIAL AND METHODS

The study was carried out in the laboratory of the Research Institute of Pharmacology of Living Systems of the Belgorod State University. Adult outbred rats were used as a test system. Experimental glaucoma was modelled by multiple injections of hyaluronic acid into the anterior chamber of the eye; they were examined by recording the time history of intraocular pressure changes, and performing ERG, ophthalmoscopy, and histological examination of the retina and subcortical centers of vision. The following groups were formed: intact, pathology control, positive control.

RESULTS

The development of glaucoma in experimental rats was accompanied by neuronal death in the ganglionic layer of the retina; at the same time, characteristic changes were observed in the subcortical visual centers. A change in the ERG was recorded: for thewave, there was a dependence on the degree of changes in the ganglionic layer of the retina, change in the wave can also indicate the involvement of amacrine and horizontal cells in the process; for the a-wave, a correlation with the results of photoreceptor layer histology was noted, which was characterized as a deviation from the norm developing against the background of hydrodynamic load in the eye chambers.

CONCLUSION

ERG is suitable for use in preclinical studies of glaucoma drugs as an indicative in vivo method for diagnosing the state of the retina in animals. The use of this method is especially valuable for conducting preclinical studies of drugs that involve long-term use when ophthalmoscopy and intraocular pressure alone cannot fully characterize the course of glaucoma, and animal euthanasia seems unnecessary and inhumane.