Bilateral Infectious Keratitis following Photore fractive Keratectomy

PRK is presumed to be safe with a high success rate and few complications.However, since epithelial defects created by surgery disrupt corneal barrier function, infectious keratitis may occur.We experienced a case of bilateral infectious keratitis after PRK in a 32 years old woman who had complained of pain and blurred vision in both eyes.To our knowledge, no bilateral infectious keratitis after PRK has been reported in the literature. In our case, we presumed that infectious keratitis after PRK occurred due to therapeutic soft contact lenses, possibility of intraoperative contamination, physical stress or ultraviolet radiation.Although the causative organism was not identified on culture, clinical pattern of keratitis was similar to bacterial infection.The patient was treated with maximal topical antibiotics on both eyes and with amniotic membrane patching in the left eye.After proper management, the patient'suncorrected visual acuity had returned to 1.0/0.9 in Snellen chart. This case emphasizes the need for an informed consent for postoperative complications, careful preoperative examination, and proper management.

The Relationship between Nitric Oxide and CAtaractohenesis after Eximer Laser Photorefractive Keratectomy

To assess the change of nitric oxide(NO) concentration according to photorefractive keratectomy(PRK) depth and the role of NO in cataractohenesis after excimer laser PRK. The treated 36 rabbits were divided into 12 groups according to PRK depth(-3.0, -7.0, -11.0 diopter [0]), the dates of sampling(the 1st day and the 7th day after PRK), and reatment of NOS inhibitor (NG-nitro-L-arginine methylester, L-NAME). NO concentration and superoxide dismutase(SOD) activity in the aqueous humor and malondialdehyde(MDA) concentration in the lens were measured. Changes of lens epithelium were examined by eletron microscopy on the 3rd day and the 6th day after -11.0D of PRK. The NO and MDA concentration in the group without L-NAME treatment on the 1st day after -11.0D of PRK were significantly higher than those in the L-NAME treated group and control group. The activity of SOD increased in all of the PRK treated group on the 1st day and was even higher on the 7th day. The histopathological changes of lens epithelium on the 3rd day after PRK were compatible with cellular necrosis and those of the 6th day after PRK were compatible with cellular reparing. The results suggested that the toxicity of NO after PRK correcting over -11.0D may a role in cataractogenesis, but the progress could be suppressed by treatment of NOS inhibitor.

The Change of Interleukin-1beta & Nitric Oxide in Tear after Excimer Laser Photorefractive Keratectomy

This study was performed to investigate the amount of IL-1beta & NO in tear film after Excimer laser PRK and to determine whether NO induces cytotoxicity associated with apoptosis of keratocytes. Twelve myopes underwent PRK and were divided into 3 groups according to spherical equivalent. IL-1beta and NO production were measured at preop and postop 1, 4, 7 days, and expression of NOS and apoptosis of keratocytes were evaluated in the corneas of rats at 2 days after PRK. IL-1beta and NO production were significantly increased at postop 1 day(p<0.01) and then gradually decreased to preop levels at postop 7 days. The corneas of rats at 2 days after PTK revealed increased expression of NOS(iNOS, bNOS) and increased apoptosis of keratocytes in stroma of cornea. The degree of corneal opacity and NO production at postop 1 days were increased, positively correlated to ablation depth. It is suggested that NO production induced by IL-1beta may be related with apoptosis of keratocyte, which can influence on the corneal opacity after PRK.