So, the large insect might actually see a little better and would certainly have no trouble resolving two points which the smaller insect could resolve. Thus, our giant insect could still see but, like its smaller cousin, would not have anywhere near the fine resolving power of the lens-based eye of molluscs and vertebrates. There are many other scaling effects which could be considered. One is hearing. All types of hearing systems resonate, responding optimally to certain frequencies.
Small structures resonate with higher frequencies.
So, if we scaled our grasshopper up to human size or larger, we would expect that the sounds it could hear and the sounds it could make would be extremely low frequency. This and other scaling problems indicate that physics puts very severe constraints on the types of structures that can be utilized at each level of scale and size. Small, less complex invertebrates use quite a different design plan in many ways that more complex vertebrates. Recently, a news article pointed out problems of scaling ever so strikingly. Some engineers are trying to make micro-miniaturized aircraft, some no larger than an insect.