Serial multifocal electroretinograms during long-term elevation and reduction of intraocular pressure in non-human primates

Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave F4/336, Madison, WI 53792-3220, USA.
Documenta Ophthalmologica (Impact Factor: 1.63). 06/2010; 120(3):273-89. DOI: 10.1007/s10633-010-9231-4
Source: PubMed


The purpose of this study was to evaluate the relationship between elevations of intraocular pressure (IOP) and the multifocal electroretinogram (mfERG) in non-human primates. Experimental glaucoma was induced in 4 rhesus and 4 cynomolgus monkeys by laser trabecular meshwork destruction (LTD) in one eye. To evaluate the contribution of ganglion cells to mfERG changes, one monkey of each species had previously underwent unilateral optic nerve transection (ONT). After >or=44 weeks of elevation, the IOP was reduced by trabeculectomy in 2 non-transected animals. In the intact (non-transected) animals, there was an increase in the amplitude of the early mfERG waveforms (N1 and P1) of the first-order kernel (K1) throughout the period of IOP elevation in all of the rhesus, but not all of the cynomolgus monkeys. A species difference was also present as a decrease of the second-order kernel, first slice (K2.1) in all of the cynomolgus monkeys but only in 1 of the rhesus monkeys (the 1 with the ONT). Similar IOP effects on the mfERG were seen in the ONT animals. Surgical lowering of IOP resulted in a return of the elevated K1 amplitudes to baseline levels. However, the depressed K2.1 RMS in the cynomolgus monkeys did not recover. These results demonstrate species-specific changes in cone-driven retinal function during periods of elevated IOP. These IOP-related effects can occur in the absence of retinal ganglion cells and may be reversible.

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Available from: James Ver Hoeve, Aug 25, 2014
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    • "Currently, there is no universal protocol for the timing of retreatment if laser treatment does not elevate the IOP. Due to inflammation of the anterior segment persisting for two weeks, most researchers have chosen a three-week interval (Nork et al., 2010; Albrecht May et al., 2006). However, when considering post-treatment trabecular meshwork scar healing, scar proliferation is most active within the two weeks following treatment (Baldassare et al., 1996), but the recovery time can extend to one month or longer (Yan et al., 2011). "
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