The role of multifocal electroretinography in the preclinical diagnosis of tumor-associated distant maculopathy in small melanoma of the choroid of extramacular localization

To assess the role of multifocal electroretinography (mf-ERG) in preclinical diagnosis of tumor-associated distant maculopathy in small choroidal melanoma (CM) of extramacular localization. Material and methods . 35 patients (35 affected and 35 fellow eyes) with small CM of extramacular localization and 23 healthy volunteers (46 eyes) aged 59.67 ± 14.2 years were given general ophthalmological examinations and mf-ERG. Density (nV/deg2), culmination time of the P1 component and amplitude (μV) of the N1 component were measured for 5 response rings (R1–R5) at different distances from the fixation point: central hexagon R1: 2.3° (fovea zone); R2: 2.3–6.9° (parafovea); R3: 6.9–14.3° (perifovea); R4: 14.3–20.8° and R5: 20.8–29.9° (middle periphery areas of the retina). Results . Eyes affected by CM showed a decrease in the density of the P1 component in the R1 hexagon by 25.7% of the normal values (p = 0.03). The fellow eyes showed an increase in the density of the P1 component in the R2 ring (p < 0.05). The peak latency of the P1 component in the R1–R5 rings in the affected and fellow eye was found to elongate by 30–45% (p < 0.05). The amplitude of the N1 component in the central hexagon of CM-affected eyes increased by 12.96%, whilst in the R4–R5 rings it decreased by 36–45% as compared with healthy individuals (p < 0.05). The fellow eye showed supernormal values of the N1 amplitude in R1 and its suppression in R4 and R5 rings (p < 0.05). Conclusion . The mf-ERG method is useful for preclinical diagnosis of tumor-associated distant maculopathy in small CM of extramacular localization. Changes in mf-ERG of the fellow eye in patients with small CM have been documented.