Donald Trump doesn’t tweet in front of other people because he dislikes wearing the reading glasses he needs to see his iPhone screen, The New York Times reported Saturday, citing people close to him.

Instead, when Trump arrives in the West Wing each morning he prefers to verbally dictate his tweets to Dan Scavino, the White House social media director.

The Times reported that Scavino sits in a closet-sized room next to the Oval Office until Trump yells “Scavino!” at which point Scavino will tweet the president’s messages from the @realDonaldTrump account.

Scavino even suggests tweets of his own, printing them off in extra-large fonts and presenting them to Trump, The Times reported.

The news came as part of a Times analysis of the more than 11,000 tweets Trump has sent during his 33 months as president, many of which included insults, threats, policy announcements, and boasts.

Trump has only rarely been spotted wearing glasses in the past, though media outlets have speculated about his eyesight and his frequent squinting.

Trump was photographed in glasses through his limousine window in October 2017, as he was leaving his golf club.

His eyewear habits also made headlines in August 2017 when he gazed directly into a solar eclipse without protective glasses, though he put them on shortly afterward.

However, Trump’s apparent lack of reading glasses has also seemed to cause problems at times.

During a legal deposition a few years ago, Trump said he could not read from a document because he did not have his glasses, adding “this is such small writing,” according to CBS News. Some photos also show Trump reading without glasses using notes typed in a large font and in all caps.

Although the details of Trump’s case aren’t known, almost everyone experiences changes in vision as they get older.

These changes are due to a condition that comes with aging called presbyopia. People with presbyopia have trouble focusing on nearby objects, like book pages. Normally, when people look at something close up, the lenses in their eyes change shape with the help of an eye muscle, according to the Mayo Clinic. But as people age, the eyes’ lenses become more rigid and less able to change shape, making it harder to focus on things that are nearby.