The maintenance of a Buy rating suggests a positive outlook on Kala Pharmaceuticals by HC Wainwright & Co., indicating confidence in the company's future performance. However, the reduction in the price target from $22 to $21, although minor, could imply a slight adjustment in expectations regarding the company's short-term growth potential or market conditions. This adjustment is likely based on recent data or market trends analyzed by the analyst. The impact on the stock price in the short term could be neutral as the positive sentiment from maintaining a Buy rating may offset the slight negative sentiment from the lowered price target.