Corrections Department director-general Kobkiat Kasivivat has played down a complaint by an ex-senator that jailed former yellow-shirt People's Alliance for Democracy leader Sondhi Limthongkul is suffering severely in prison from the loss of vision in one eye.
Mr Kobkiat insisted Tuesday that Sondhi's eyesight problems predated his imprisonment.
He added that Sondhi, 71, now serving his jail term at Klongprem prison after being found guilty in a case involving a breach of the Securities and Exchange Act, lost the vision in his left eye after being shot in an assassination attempt in 2009.
Mr Kobkiat said Sondhi has not completely lost his sight.
If Sondhi's condition worsens, Mr Kobkiat said the prison must transfer him to the Police General Hospital for treatment from physicians specialising in his condition, adding Sondhi should have informed prison officials if his condition had deteriorated.
Former senator and prominent anti-Thaksin Shinawatra campaigner Paisal Puechmongkol wrote on his Facebook page saying Sondhi was suffering from his eyesight woes and often had headaches though he continued to work as a lecturer to educate other inmates.
Mr Paisal said he wanted to be a voice for justice to Sondhi as many corruption case inmates claimed health problems and enjoyed better conditions staying in hospital.
Mr Kobkiat said prison authorities did not force Sondhi to do teaching work.
Sondhi behaved himself like other inmates. He mostly spent his time reading, meditating and other activities. Also, he has never asked for any privileges, the director-general said.
He insisted the department had its rules and regulations for treating elderly and sick inmates.
In September last year the Supreme Court handed down a 20-year-jail sentence to Sondhi in a case involving a breach of the Securities and Exchange Act.
Meanwhile, Jittanart Limthongkul, Sondhi's son, said his father gradually lost his left eyesight because of cataracts before being imprisoned.
However, his condition has worsened while in prison, Mr Jittanart said. On top of that, he also had headaches caused by shrapnel embedded in his skull from the assassination attempt.
The only way to cure him is for him to undergo an operation to remove the shrapnel, he said.
"The treatment process must be conducted in accordance with the Corrections Department's regulations. I confirm Sondhi is still in good spirits and works as a lecturer to pass on his knowledge and experience to other inmates," he said.