These problems include especially stroke asymetries (breast stroke, butterfly), different types of start, turns and finish. These rules adjustments respect even different level of visual impairement.This creating a spcific rules can by different for each level of clasification.
Different quality of swimming technique of visualy impaired people is proveable as in the period of swimming instruction. So in the terms of recreational swimming and swimming on the highest perfomance level.
This includes more difficult maintainig of a straight swimming direction, often change of swimming pace's length and different execution of specific swimming skills (eg turns). The resources and the time for improvement are the only things that differ from healthy population.
However, the effects of visual impairement on swimming technique persist even on the highest swimming level.