A leading Beijing hospital admitted Thursday that a majority of 59 patients who were injected with perfluoropropane gas at its facilities suffered severe damage to their eyesight, following media reports that the gas caused partial blindness in several patients in Beijing and East China's Jiangsu Province.

In an announcement released Thursday, Peking University Third Hospital (PUTH) stated that 45 out of 59 patients suffered retinal damage after receiving an injection of substandard perfluoropropane gas under the hospital's care, The Beijing News reported.

Of the 59 patients at PUTH who received injections of the gas produced by Tianjin Jingming New Technological Development Co in June 2015, 18 patients - the youngest of whom is just 20 years old - went completely blind in one eye, vojs.cn, the website of a Jiangsu-based radio program, reported Thursday.

A product quality engineer surnamed Sun from Tianjin Jingming New Technological Development Co said that the company has not found any toxic substances that could have caused blindness in the gas, adding that the current inspection system may not be able to detect the substance that has caused the side effects.

She also said that the company's complete record of sales of the gas has been taken by authorities for investigation.

According to media reports in early April, five of 26 patients at the Affiliated Hospital of Nantong University (AHNU) in Jiangsu Province who were injected with gas from the same company and same batch also went partially blind.

Sun added that only PUTH and AHNU have reported problems with the gas, while over 600 boxes of the gas were used at hospitals nationwide.

The company claimed it is the only legal producer of perfluoropropane gas in China and that no case of side effects  has been reported since the company was established in 2001.

AHNU issued a notice on its website on April 9, saying that it has used the gas produced by the Tianjin company since 2002 and has not found any other cases of adverse reaction other than those caused by the  gas purchased in June 2015.

Perfluoropropane gas is mainly used for eye surgeries such as vitrectomies and operations to correct retinal detachment. The China Food and Drug Administration (CFDA) issued a notice on July 8 suspending the sale and use of the gas nationwide to avoid the occurrence of more such cases. The notice also declared that the CFDA's inspection showed the batch of gas did not meet relevant quality standards.

The National Health and Family Planning Commission declined to comment on the case on Thursday.

A family member of victim Wu Qijian (pseudonym) said that Wu was hospitalized at PUTH in June 2015 for retinal detachment and lost the ability to sense light in his right eye one week after he was injected with the perfluoropropane gas, while the eyesight in his left eye also deteriorated, vojs.cn reported.

PUTH said that it began providing free rescue treatment to affected patients in February and has provided compensation to some patients. It also said it is suing the company that produced the gas.

AHNU also stated that it has conducted follow-up treatment for affected patients and has filed its own lawsuit against the gas producer.