Abstract
Purpose :
To assess retinal function in NMOSD patients using ERG with an extended photopic protocol and to investigate correlations of functional changes with retinal measures observed in OCT.
Methods :
Forty patients were included, 25 with AQP4+ (50 eyes) and 15 with MOG+ (30 eyes). Only 7 patients (5 from the AQP4+ group and 2 from the MOG+ group) did not present optic neuritis, while the others had between 1 and 13 episodes. A group of healthy individuals with a similar age range was evaluated for result comparison. Ophthalmological assessment was performed, including OCT and ERG with an extended photopic protocol, consisting of a series of stimuli with increasing light intensity to investigate the relationship between the b-wave amplitude and luminance. This was described by a Gaussian function (photopic hill) deriving three parameters: h (maximum amplitude), x0 (luminance to reach the maximum), and w (Gaussian width). In addition to the photopic hill, all stimuli recommended in the ISCEV standard and to elicited the photopic negative response (PhNR) were also applied.
Results :
There was no difference between the groups for the parameters calculated in the photopic hill. However, there was a difference in the PhNR, which presented a bigger amplitude in eyes with AQP4+: -22.2 ± 3.0 µV, compared to MOG+: -36.0 µV ± 3.8 µV (p=0.0179). A decrease in RNFL thickness was observed in eyes with optic neuritis from AQP4+ group in the superior (p=0.0030) and inferior (p=0.0236) optic nerve sectors. In the macula, thinning was observed in the ganglion cell layer (GCL) and inner plexiform layer of eyes with optic neuritis from AQP4+ group. Furthermore, a significant correlation was found between thinning of the outer nuclear layer and GCL and the amplitude of PhNR. There was also a correlation between the thickness of the outer retinal complex (photoreceptors and retinal pigment epithelium) and the x0 parameter in eyes with optic neuritis from the AQP4+ group.
Conclusions :
The parameters of the photopic hill were not altered in eyes with optic neuritis compared to controls, indicating that these parameters do not express activities of the retinal cells affected in optic neuritis. On the other hand, the PhNR showed a difference between the groups, highlighting that functional retinal changes caused by optic neuritis can be detected with this protocol.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.