Complex sentence: A number of different dyslexia screeners have been produced by researchers and companies working in the field of learning difficulties and are influenced by different theories of dyslexia's etiology and manifestations.
Split into simpler sentences: A number of different dyslexia screeners have been produced by researchers and companies working in the field of learning difficulties. Each research group or company's screening test is influenced by different theories of dyslexia's etiology and manifestations.