Harare - Zimbabwean President Robert Mugabe, 93, is not asleep when he closes his eyes for long periods in public events but is resting his eyes from bright lights, his spokesperson said on Thursday.Mugabe has regularly had his eyes closed at recent appearances, including when he appeared on a discussion panel at last week's World Economic Forum meeting in South Africa."I feel like a failure when there is this reading that the president is sleeping in conferences, no," his spokesperson George Charamba was quoted as saying in the state-run Herald newspaper."At 93, there is something that happens to the eyes and the president cannot suffer bright lights. If you look at his poise, he looks down, avoids direct lighting."Charamba compared Mugabe to Nelson Mandela, whose eyes were sensitive to flash photography after years of working in a limestone quarry when he was imprisoned on Robben Island."You were not allowed to even use flashes whenever he was in the room," he said.Mugabe, who has trouble walking unaided, is in Singapore on one of his regular medical trips.Charamba said the president was receiving specialised treatment for his eyes and that his general health was good.Mugabe's foreign medical trips are often criticised in Zimbabwe, where healthcare has collapsed due to the country's economic troubles.Charamba said that Mugabe's medical care is supervised in Harare by a "very, very, very black" Zimbabwean doctor - and that he only flies abroad for specialist attention.