DÜSSELDORF, Germany — Andreas Lubitz, who was flying the Germanwings jetliner that slammed into a mountain in the French Alps on Tuesday, sought treatment for vision problems that may have jeopardized his ability to continue working as a pilot, two officials with knowledge of the investigation said Saturday.

The revelation of the possible trouble with his eyes added a new element to the emerging portrait of the 27-year-old German pilot, who the authorities say was also being treated for psychological issues and had hidden aspects of his medical condition from his employer. The police found antidepressants during a search of his apartment here on Thursday, an official said Saturday.

It is not clear how severe his eye problems were or how they might have been related to his psychological condition. One person with knowledge of the investigation said the authorities had not ruled out the possibility that the vision problem could have been psychosomatic.

Mr. Lubitz, the co-pilot, was alone in the cockpit of the Airbus A320 jetliner on the flight from Barcelona to Düsseldorf, ignoring demands from the captain to be let back in, when the plane crashed. The French prosecutor in the case, drawing from cockpit voice recordings and other data about the flight, has said that Mr. Lubitz deliberately guided the plane, with another 149 people on board, into the mountains.

Since then investigators in Germany and France, airline regulators, political leaders and the families of the victims have sought answers about what might have led Mr. Lubitz to do what he did.

The information available so far about a possible motive remains sketchy, and it is not yet clear whether his apparent decision to crash the plane was triggered by a particular development in his life. Investigators and journalists continue to search for clues from every period and corner of his life, including his relationship with a longtime girlfriend and a report in a German newspaper on Saturday that another woman with whom he had a relationship had described him as unstable.