Effect of adenosine triphosphate on amiodarone-induced optic neuropathy in rats: biochemical and histopathological evaluation.

OBJECTIVE: This study aims to investigate possible preventive effect of ATP on optic nerve damage caused by amiodarone in rats. MATERIAL AND METHOD: Thirty albino male Wistar rats weighing between 265 and 278 g were used in the study. Before the experiment, the rats were housed at 22 °C in a 12-h light/dark cycle under appropriate condition. The rats were equally divided into five groups of six animals each: healthy group, 50 mg/kg amiodarone (AMD-50), 100 mg/kg amiodarone (AMD-100), 25 mg/kg ATP + 50 mg/kg amiodarone (ATAD-50), and 25 mg/kg ATP + 100 mg/kg amiodarone (ATAD-100). At the end of 14th day, the animals were sacrificed using cardiac puncture under deep thiopental anaesthesia, and optic nerve tissues were harvested to measure superoxide dismutase (SOD), total glutathione (tGSH), malondialdehyde (MDA), and catalase (CAT) levels. RESULTS: The MDA levels were found to be significantly higher in the AMD-50 and AMD-100 groups compared to the healthy group (p ˂ 0.001). There was also a significant difference between the AMD-50 and ATAD-50 groups, and between the AMD-100 and ATAD-100 groups regarding MDA levels (p ˂ 0.001). tGSH, SOD, and CAT levels were significantly lower in the AMD-50 and AMD-100 groups compared to the healthy group (p ˂ 0.001). ATP was found to partially inhibit amiodarone-induced optic neuropathy. CONCLUSION: The biochemical and histopathological results of this study demonstrated that amiodarone at high doses caused more severe optic neuropathy inducing oxidative damage, but ATP could relatively antagonise these negative effects on the optic nerve. Therefore, we believe that ATP may be beneficial in preventing amiodarone-induced optic neuropathy.

Intrastromal Administration of Vancomycin to Maximize Its Early Effect on Methicillin-resistant Staphylococcus Aureus Keratitis: A Rabbit Study.

PURPOSE: To evaluate the early efficacy of intrastromal injection of vancomycin in the treatment of methicillin-resistant Staphylococcus aureus (MRSA). METHODS: Twenty-four eyes of 24 New-Zealand White rabbits were included in the study. MRSA keratitis was induced in the right eye of each rabbit. On the 24th hour after the inoculation of MRSA, eight rabbits received topical vancomycin therapy, eight rabbits received intrastromal vancomycin therapy, and eight rabbits received balanced salt solution and served as the control group. RESULTS: The pre-post differences in epithelial erosion score and total clinical score were higher in the topical vancomycin group than in the intrastromal vancomycin group (p = .033 and 0.016, respectively). The eyes treated topically had higher bacterial load compared with those treated intrastromally (6.97 ± 0.82 vs. 6.14 ± 0.63 log10 CFU/g, p = .039). CONCLUSION: A single dose of intrastromal vancomycin is more effective than the standard loading dose of topical vancomycin in reducing bacterial load.

Intrastromal versus subconjunctival anti-VEGF agents for treatment of corneal neovascularization: a rabbit study.

OBJECTIVE: To determine whether subconjunctival or intrastromal administration of anti-VEGF agents is more effective on suture-induced corneal neovascularization (CoNV) in rabbits. METHODS: CoNV was induced in 48 eyes of 24 New Zealand white rabbits by using an 8/0 silk suture. On the 7th day after suturing, the rabbits were divided into four treatment groups as follows: six rabbits received subconjunctival bevacizumab (group 1), six rabbits received subconjunctival aflibercept (group 2), six rabbits received intrastromal bevacizumab (group 3) and six rabbits received intrastromal aflibercept (group 4). On the 7th and 14th days after suturing, the CoNV area was calculated by standardised analysis of photographs using the Image-J program. On the 14th day after suturing, all rabbits were sacrificed and then corneal tissue was harvested for the analysis of vascular endothelial growth factor (VEGF)-A, VEGF-B and placental growth factor (PIGF) levels. RESULTS: On the 7th day after suturing, CoNV areas were 17.10 ± 2.98, 18.88 ± 3.78, 17.36 ± 4.52, 18.57 ± 4.16 and 17.31 ± 2.81 mm2 in the groups 1-4 and control group, respectively. On the 7th day after intervention and removal of suture, CoNV areas were 4.85 ± 1.99, 6.66 ± 1.73, 2.83 ± 1.08, 2.63 ± 1.16 and 11.93 ± 2.64 mm2 in the group 1-4 and control group, respectively. CoNV area was reduced by 88.1% and 82.5% in eyes receiving intrastromal aflibercept and bevacizumab, respectively (both p < 0.001), and by 64.5% and 69.9% in eyes receiving subconjunctival aflibercept and bevacizumab, respectively (both p = 0.001). CONCLUSION: Intrastromal anti-VEGF therapy regressed CoNV more effectively than subconjunctival therapy regardless of the type of anti-VEGF agent.