Relationship of chromatic visual-evoked potentials and the changes of foveal photoreceptor layer in central serous chorioretinopathy patients

Chromatic visual evoked potentials: A review of physiology, methods and clinical applications

Objective assessment of the visual system can be performed electrophysiologically using the visual evoked potential (VEP). In many clinical circumstances, this is performed using high contrast achromatic patterns or diffuse flash stimuli. These methods are clinically valuable but they may only assess a subset of possible physiological circuitries within the visual system, particularly those involved in achromatic (luminance) processing. The use of chromatic VEPs (cVEPs) in addition to standard VEPs can inform us of the function or dysfunction of chromatic pathways. The chromatic VEP has been well studied in human health and disease. Yet, to date our knowledge of their underlying mechanisms and applications remains limited. This likely reflects a heterogeneity in the methodology, analysis and conclusions of different works, which leads to ambiguity in their clinical use. This review sought to identify the primary methodologies employed for recording cVEPs. Furthermore cVEP maturation and application in understanding the function of the chromatic system under healthy and diseased conditions are reviewed. We first briefly describe the physiology of normal colour vision, before describing the methodologies and historical developments which have led to our understanding of cVEPs. We thereafter describe the expected maturation of the cVEP, followed by reviewing their application in several disorders: congenital colour vision deficiencies, retinal disease, glaucoma, optic nerve and neurological disorders, diabetes, amblyopia and dyslexia. We finalise the review with recommendations for testing and future directions.

Chromatic visual evoked potentials identify optic nerve dysfunction in patients with Graves' orbitopathy

PURPOSE

To explore visual dysfunction in Graves' orbitopathy (GO) objectively by analyzing chromatic visual evoked potentials (cVEP) and evaluate its diagnostic efficiency for dysthyroid optic neuropathy (DON).

METHODS

In this cross-sectional study, we analyzed pattern-reversal VEP (pVEP), red-green (R-G) and blue-yellow (B-Y) cVEP in 93 subjects (21 with DON, Group A, 30 with GO, Group B, and 42 healthy controls, Group C) at Wuhan Union Hospital, China.

RESULTS

Compared with Group C, the amplitudes of B-Y cVEP were significantly lower in Group B, whereas all amplitudes of cVEP, latencies and amplitudes of pVEP in Group A were significantly impaired. In addition, the pVEP latency at 60 arcmin (60'), pVEP amplitudes and R-G cVEP amplitudes were significantly different between Group A and B. Moreover, 60'cVEP R-G negative-positive (N-P) amplitude was correlated with crowding index (P = 0.001), the average thickness of ganglion cell layer and inner plexiform layer (P = 0.004). Furthermore, combination of 60'cVEP R-G amplitude and 60'pVEP P100 latency had better diagnostic efficiency than each single parameter, with optimal cut-off values of 14.20 μV and 110.65 ms, respectively.

CONCLUSION

GO may induce electrophysiological changes. The presence of B-Y cVEP anomalies in moderate to severe GO patients may be an early sign of preclinical DON. A decline in 60'cVEP R-G amplitude is associated with apical crowding and thinner inner intra-retinal layers. The combination of 60'cVEP R-G N-P amplitude and 60'pVEP latency can be a useful diagnostic index for DON.