The Relationship Between the Photopic Negative Response and Retinal Ganglion Cell Topography

Abstract

PURPOSE. To assess the topographic relationship between the photopic negative response (PhNR) and retinal ganglion cell distribution in healthy individuals. METHOD. Data was recorded from 16 healthy participants. The amplitude of PhNRs obtained in response to focal long duration (250 ms) and brief flash (5 ms), red (660 nm) on blue (469 nm) stimuli of increasing size (58-full field) were measured. The number of retinal ganglion cell receptive fields (RGCf) in each stimulus area was established from the literature and regression analysis used to determine the relationships between: PhNR amplitude and number of RGCfs stimulated, PhNR density and the RGCf density and response per RGCf as a function of eccentricity. RESULTS. The overall amplitude of the PhNR increased with stimulus size and the response density declined from~0.1 lV/deg in the macular region to~0.003 lV/deg approximately 458 from the fovea. Contrary to expectations, the relationship between the PhNR and number of RGCf was nonlinear, the response from more eccentric neurons being about three times greater than those in the macular region. CONCLUSIONS. Although the amplitude of the PhNR broadly maps on to the topographic distribution of RGCf the increase in PhNR amplitude with increasing eccentricity is only partly explained by RGCf numbers. Increases in the PhNR amplitude may be due to topographic variations in the contributions from other non-RGC neurons, as well as eccentricity-related morphologic and physiologic differences in RGCs.

Retinal oxidative stress activates the NRF2/ARE pathway: An early endogenous protective response to ocular hypertension

“…Our data matches studies using different experimental glaucoma models, which have also shown a decrease in PhNR amplitudes in ocular hypertensive monkeys and rabbits [ 17 , 38 ]. In addition, the diagnostic utility of the PhNR for patients who are glaucoma suspects has been demonstrated in multiple studies [ 10 , 38 , 41 , 50 , 51 ]. While the pattern ERG has also been suggested as a preclinical diagnostic for glaucoma and other RGC-related diseases, the PhNR has the advantage of not requiring refractive correction [ 51 ].…”

Examining the concordance of retinal ganglion cell counts generated using measures of structure and function

“…22,23 These models of Drasdo et al 22 and Watson 23 have been used subsequently to determine the number of RGC-RFs underlying stimuli at select retinal locations. 24,25 Whilst average histological models have been widely used to estimate RGC numbers in individual observers, their use is markedly limited by the relative inability to account for interindividual variations in RGC density secondary to physiological and/or pathological processes. Other techniques utilising measures of function or structure attempt to overcome such limitations.…”

“…Curcio and Allen's RGC‐CB data 18 was used in the development of two theoretical equations that model RGC‐RF density in the human visual field 22,23 . These models of Drasdo et al 22 and Watson 23 have been used subsequently to determine the number of RGC‐RFs underlying stimuli at select retinal locations 24,25 …”

“… 22 , 23 These models of Drasdo et al 22 and Watson 23 have been used subsequently to determine the number of RGC‐RFs underlying stimuli at select retinal locations. 24 , 25 …”

Commentary: From diabetic retinopathy toward diabetic retinal disease

“…Photopic negative response (PhNR) in full filed electroretinogram is a marker of retinal ganglion cell activity. [ 5 ] Loss of retinal ganglion cells is an integral aspect of diabetic retinal neuropathy and it was imperative that PhNR would have been studied in detail prior to the present study. However, the present study adds value to the existing body of literature by using both broadband (white on white) and monochromatic (red on blue and blue on yellow) PhNR and correlating them with various stages of diabetic retinopathy.…”