The 33 trapped miners buried 700 meters below ground in Chile have been informed that it will take months to rescue them, dpa reported.
Till then, they will be recorded via tiny high-tech cameras so that doctors can assess their health, in particular the state of their eyes, Chilean officials said Thursday.
The miners have been trapped since August 5, after the shaft they were working in collapsed. On Sunday - 17 days after their shaft collapsed - they were confirmed to be alive, although getting them up to the surface was likely to take three to four months.
The workers, who have for three weeks been living in constant darkness, high humidity and 35-degree-Celsius temperatures, have complained of itchy eyes.
Chilean authorities have requested help from US space agency NASA in order to keep the miners alive through this ordeal. Plans include sending them food, water and oxygen through ducts measuring only 10 centimetres in diameter.
The group - initially feared dead - were told that drilling a fresh shaft will not be completed until before Christmas, Chilean Health Minister Jaime Manalich told local media late Wednesday.
Digging on the relief tunnel is to begin Saturday.