Four changes have been made to the qualifying criteria, with the most significant involving the Scottish Open and French Open leading up to the Open and the European International qualifier at Sunningdale.
"Last year at Lytham we were given something of a fright because the way the exemptions fell at one point we had 161 competitors, but because of scratching and injuries we got back down to our usual field of 156," R&A chief executive Peter Dawson said today.
"That has caused us to look at our exemptions and cut them back this year because we wanted to maintain the number of qualifying places through international qualifying and local qualifying that we had committed to.
"In recent years we've given a spot in the French Open and Scottish Open to a player finishing in the top five who wasn't otherwise exempt. This year that has been cut back to the winner of the Scottish Open only.
"Mirroring that in the United States, the same exemption applied to the Greenbrier Classic and the John Deere Classic. That has been cut back to the winner of the John Deere Classic only.
"In Japan, we had an exemption for the top two (money) winners who were not otherwise exempt, but that has been cut back to the top two only. The last change we've made is to take the number of qualifiers from the European International qualifier at Sunningdale down from 10 to nine.
"It's always impossible to estimate with accuracy how many exempt players you will end up with as it depends on how many joint exemptions a player receives, but we feel a little safer with that number.
"We could see it coming some weeks out and we would just have had to play with a bigger field. It would have been difficult but fortunately we got away with it."
Any vacant places will be filled from the world ranking and Dawson was confident the changes would not affect the strength of field at the Scottish Open, which takes place from July 11-14 at Castle Stuart in Inverness.
The following week the 142nd Open will take place at Muirfield, with the course's popularity amongst players set to be tested by an extra 158 yards and "plenty of rough."
New tees have been added on seven of the holes, taking the overall distance from 7,034 yards when Ernie Els won in 2002 to 7,192 yards (par 71) this summer.
The biggest difference is on the ninth, where a land swap with neighbours the Renaissance Club has enabled the tee to be moved back almost 50 yards, extending the par-five to 554 yards with a new bunker added on the right of the fairway and other bunkers moved closer to the green.
"We are absolutely delighted to be back at Muirfield for the 16th time," Dawson added. "It's immensely popular with the players....but we will be setting the golf course up to challenge these golfers.
"The rough has been cut down over the winter but will regenerate over the coming weeks. The amount of rough is weather-dependent, but we will get plenty."
Other new features this year will include a "wi-fi mesh" around the course, primarily available in the grandstands and tented villages, a free "Open in the Square" event in Edinburgh the weekend before the championship and LED scoreboards on the seventh, 11th, 16th and 17th in addition to the famous yellow scoreboard on the 18th.
Mobile phones will be allowed again after a largely successful re-introduction last year, although executive director of championships Johnnie Cole-Hamilton admitted: "It did not go completely without incident. We have learnt lessons from last year and we did not get any complaints from the players, which was important. I think it will improve year on year."
Jim McArthur, chair of the championship committee, added: "We took a big risk but we had some belief in the spectators' respect for the game. It (allowing phones) brings so many benefits that we think we need to continue with this unless we have any major problems.
"We will also have complete control over the content displayed on the LED scoreboards - which have video capability to show live footage - to ensure that we don't disrupt the players. We will err on the side of caution."
Dawson also re-iterated the R&A's stance on taking the Open to clubs like Muirfield, Sandwich and Royal Troon which are male-only, after saying last week courses would not be bullied into changing their policies by the threat of losing the Open.
"We come for the golf course," he said. "To think we would not come to a course as wonderful as this is something we could not countenance. It's like taking the Boat Race to the Humber if you did not like (mayor of London) Boris (Johnson's) policies."