Regional Choroidal Blood Flow and Multifocal Electroretinography in Experimental Glaucoma in Rhesus Macaques

Abstract

This is the first demonstration of globally reduced ChBF in chronic experimental glaucoma in the nonhuman primate. Both the alteration of mfERG waveform components associated with outer retinal function and the reduction in ChBF were greatest in the macula, suggesting that there may be a spatial colocalization between ChBF and some outer retinal effects in glaucoma.

Retinal neurodegeneration in experimental glaucoma

“…Our OHT rodent models may resemble an acute angleclosure human glaucoma coursing with elevated IOP peaks , and these increments mimic those reported to be associated with cone loss (Calkins, 2012;Nork, 2000;Nork et al, 2000;Panda and Jonas, 1992). It is likely that the levels of IOP reached in this model may have induced choroidal insufficiency that results in outer retinal pathology (Nork et al, 2014). Nevertheless, our Percentage of surviving RGCs, L-cones, and S-cones after ocular hypertension.…”

“…Scale bar: 1 mm. (Bayer et al, 2001;Calkins, 2012); (ii) in monkey OHT models analyzed with anatomical techniques (Nork, 2000;Nork et al, 2000) or with functional techniques (Liu et al, 2014;Nork et al, 2014); and (iii) in human GONs analyzed with functional (Barboni et al, 2011;Bessler et al, 2010;Drasdo et al, 2001;Holopigian et al, 1990;Kanis et al, 2010;Niwa et al, 2014;Velten et al, 2001;Werner et al, 2011) or anatomical Kanis et al, 2010;Lei et al, 2008Lei et al, , 2011Nork, 2000;Nork et al, 2000;Panda and Jonas, 1992;Werner et al, 2011) techniques. The above reviewed results appear to be in contrast with previous studies that have not found cone photoreceptor loss in OHT monkey (Wygnanski et al, 1995) or human (Kendell et al, 1995) retinas.…”

“…Several groups have documented important molecular, functional, and structural changes in the outer (outer nuclear and outer segment) retinal layers of the retina in clinical human glaucoma studies Drasdo et al, 2001;Holopigian et al, 1990;Kanis et al, 2010;Lei et al, 2008Lei et al, , 2011Nork, 2000;Nork et al, 2000;Panda and Jonas, 1992;Velten et al, 2001;Werner et al, 2011), as well as in nonhuman primate (Nork et al, 2014;Pelzel et al, 2006) and rodent models of glaucoma or OHT (Bayer et al, 2001;Cuenca et al, 2010;Fernández-Sánchez et al, 2014;Georgiou et al, 2014;Holcombe et al, 2008;Kong et al, 2009;Korth et al, 1994;Mittag et al, 2000;Ortín-Martínez et al, 2015;Salinas-Navarro et al, 2009a). These changes range from a diminution in the expression of opsins by photoreceptors to the severe loss of rod and cone photoreceptors with time.…”

Relating glaucomatous visual field loss to retinal oxygen delivery and metabolism

“…However, under conditions of reduced choroidal blood flow which has been shown to occur in experimental glaucoma (Nork et al. ) and human glaucoma (Portmann et al. ; Park et al.…”

Biomechanical, ultrastructural, and electrophysiological characterization of the non-human primate experimental glaucoma model

“…Other functional measures, including scotopic and photopic full-field ERG single-flash a- and b-waves did not demonstrate a corresponding correlation (see supplemental figures). Selective reduction of the ERG waveforms elicited only at high intensity levels argues against optic nerve injury alone being the sole retinal damage caused by glaucoma 30 – 33 . It is of interest that in ExGl eyes, there was a relatively reduced full-field ERG A- and B-wave amplitude at the highest flash intensities.…”