Abstract
Purpose: :
To develop the measurement of photopic negative response (PhNR) using superior or inferior semicircle photostimulation of focal macular electroretinography (ERG) and to evaluate the association between PhNR and macular retinal thickness of eyes with glaucoma.
Methods: :
PhNR of focal macular ERG was recorded from 13 eyes of 7 patients with glaucoma. The photostimulator device projected a 15-degree visual angle semicircle spotlight onto the superior half or inferior half of the macula. Spectral-domain optical coherence tomography (RTVue-100) was used to measure total retinal thickness and inner retinal layer thickness. We evaluated the relationship between the PhNR amplitude and the average of total retinal thickness or inner retinal layer thickness. Superior or inferior hemifield defects were examined with the Humphrey field analyzer for the diagnosis of glaucoma.
Results: :
On the superior area of macula, the PhNR amplitude, the total retinal thickness, and the inner retinal layer thickness was 1.7 ± 0.7 µV, 208.9 ± 17.9 µm, and 92.1 ± 10.5 µm respectively. Mean deviation (MD) of inferior visual field was -1.7 ± 0.7 dB. On the inferior area of macula, the PhNR amplitude, the total retinal thickness, and the inner retinal layer thickness was 1.3 ± 0.6 µV, 192.1 ± 21.6 µm, and 81.5 ± 13.6 µm respectively. MD of superior visual field was -7.5 ± 9.6 dB. On the inferior area of macula, the significant relationship was found between the PhNR amplitude and the total retinal thickness (r² = 0.56, p<0.005), and also between the PhNR amplitude and the inner retinal layer thickness (r² = 0.67, p<0.001) On the superior area of macula, however, no significant relationship was found between the PhNR amplitude and retinal thickness.
Conclusions: :
A significant correlation was found between the PhNR amplitude and the inner retinal thickness. The result suggested that the PhNR amplitude of focal macular ERG might reflect ganglion cell loss in patients with glaucoma.
Keywords: electroretinography: clinical • macula/fovea • ganglion cells