There was a decent discussion about this last week Buying U.S Stocks in £ - Weak Dollar
Might be interesting for you.
Dollar go’s up, pound go’s down yen is strong yen is week it is all within reasonable range from each other. Nevertheless I also was a bit worried since euro/dollar went from 1.07/1.10 tot the current 1.18 basically losing 0.08 per invested dollar since I’m in the euro. But in the financial crisis it has been 1.4 (cheap) and eventually crawled back up to a the 1.07 (expensive)
Fluctuations are to be expected, if you’re going long long-term or really short-term you probably shouldn’t worry. If you buyed beginning of the year and want to sell this year you should just hope the stock’s themselves will cover the exchange losses