Fractal phototherapy in visual rehabilitation of patients with Stargardt disease

Currently, there are no effective drug therapies for Stargardt disease (SD), although innovative strategies are being sought in several directions. Even minor improvements in individual visual characteristics are of great importance for improving the quality of life (QL) of visually impaired patients. Therefore, non-drug strategies for visual rehabilitation, with special attention paid to technologies that affect the plasticity of the visual system, can play a decisive role in improving QL. Purpose of the study was to evaluate the effectiveness of visual rehabilitation using fractal phototherapy (FP), a neuroplasticity-activating method, in virtual reality in patients with SD based on electroretinography data. Material and methods. Three patients with SD of STGD1 phenotype were observed. Results. In all patients, a decrease in the central retinal activity compared to the age norm was documented before therapy, according to mfERG data, as well as a generalized decrease in functional retinal activity, according to full-field ERG (cone and flicker ERG). After a 2-week course of fractal photostimulation in virtual reality, a tendency towards an increase in the amplitude of the a-wave of the photopic ganzfeld ERG (p = 0.0728) and a decrease in its peak latency (p = 0.0625), as well as an increase in the amplitude of photopic low-frequency RERG at 10 and 12 Hz, in the generation of which cone photoreceptors make a dominant contribution, was observed. This indicates an activating effect of FP on the function of photoreceptors, which is significant for ABCA4 variants leading to disruption of the visual cycle and functioning of visual cells. The most significant and statistically highly significant changes were documented for the mfERG amplitude in the fovea zone (p = 0.0017), which is especially important for the subjective visual sensations of patients and their daily activities. Conclusion. In future studies, it is advisable to confirm the obtained patterns of the effect of FP on ERG in a larger group of patients with SD and clarify the indications for visual training using FP in various phenotypes of the disease.