Buckingham Palace is giving little away about how the Queen came to suffer a noticably bloodshot eye.
The red left eye was clearly visible in photographs taken as she watched polo players take to the field at the Cartier Queen's Cup Final in Surrey.
Buckingham Palace is declining to comment on how the Queen suffered the red eye. But it said "nothing untoward" had happened and the monarch was still in "fine fettle".
The Queen was accompanied at Guards Polo Club, in Windsor Great Park by the Duke of Edinburgh, who has returned to royal duties after leaving hospital following treatment for a bladder infection.