Abstract
Abstract: :
Purpose: Visual training with Visual evoked assisted biofeedback was previously used to improve performances in high speed drivers or precision shooting. Our goal was to assess if this way could be useful to improve and consequently partially restore visual capability in RP patients. Methods: We treated 15 patients affected by R.P. (age range 8-55) with Visual Pathfinder (LACE inc.), (pattern VEP flicker and sound stimulation). Before and after treatment, a complete ophthalmologic examination, BCVA measurement and VEP were carried out according ISCEV standard with 4C/° checkerboard pattern. All patients underwent in a weekly session of 30 minutes each for six 10 sessions after that, all examinations were repeated. Results: BCVA at the end of the study improved significantly starting from 0.67±0.14 to 0.84±0.11(p=0.035), while VEP amplitude of P100 wave increased from 2.14±0.88µV to 4.86±1.12µV (p=0.012). Conclusion: Visual training improves significantly visual acuity and pattern VEP resulting in better performances and higher quality of vision, this effect could be due either to neural plasticity of the retina or to facilitating effect caused by the repeated high frequency stimulations. In fact in tapetoretinal degenerations even the outer retina is partially destroyed inner associative system are usually well conserved. In this view training via alternative pathways (i.e. horizontal cells or amacrine cells) could be possible to obtain a considerable increase of visual performances for higher amount of not regularly involved but yet stimulated pathways. Thus may cause visual recovery that may allow improvement of quality of vision and re-introduction in acceptable life of the patient. These effects could be explained by neural plasticity of visual system that has also been demonstrated either in adaptation-dependent conditions or after experimental photoreceptor damage, as demonstrated either in chimaeric rd mice and wild-type genotypic combination or in heterozygotic (RDS/+)mice. In these studies in surviving rod inner segment was recorded an increase in number of synaptic ribbons and presence of increased number in profiles of second order neurons processes.
Keywords: 562 retinal degenerations: hereditary • 485 neuro-ophthalmology: cortical function/rehabilitation • 393 electrophysiology: clinical