Alterations in optical coherence tomography angiography findings in patients with high myopia.

PURPOSE: The aim of this study was to determine the macular changes using optical coherence tomography (OCT) and OCT-angiography (OCT-A) in eyes with high myopia. Determining the alterations in vascular structures can provide a clearer understanding of the pathophysiological mechanisms of this disease and help define new treatment options and preventive measures. MATERIALS AND METHODS: Ninety-two patients with high myopia (axial length ≥ 26 mm) and 70 control cases without any known systemic or ocular diseases were enrolled in this prospective study. One eye of each patient was included in the statistical analyses. RESULTS: Retinal nerve fiber layer (RNFL) thickness and Early Treatment Diabetic Retinopathy Study (ETDRS) macula map values were lower in myopia compared with the controls. Both superior and inferior ganglion cell complex (GCC) thicknesses were significantly thinner in the high myopia compared with the controls (p < 0.001). Regarding the OCT-A findings, although superficial or deep foveal avascular zones (FAZ) did not significantly differ between the two groups, the density values of superficial and deep microvessels were significantly lower in the high myopia group compared with the control cases. CONCLUSIONS: In patients with high myopia, with an increase in the axial length and a decrease in RNFL and GCC thicknesses, the vascular densities of the superficial and deep retina were reduced in the macular region.

The effects of thiamine pyrophosphate on ethanol induced optic nerve damage.

BACKGROUND: We aimed to determine the protective effects of thiamine pyrophosphate on ethanol induced optic neuropathy in an experimental model. METHODS: The rats were assigned into 4 groups, with 6 rats in each group as follows: healthy controls (HC group), only ethanol administered group (EtOH group), ethanol + thiamine pyrophosphate (20 mg/kg) administered group (TEt-20 group), and only thiamine pyrophosphate (20 mg/kg) (TPG group) administered group. To the rats in TEt-20 and TPG groups, 20 mg/kg thiamine pyrophosphate was administered via intraperitoneal route. To the rats in HC and EtOH groups, the same volume (0.5 ml) of distilled water as solvent was applied in the same manner. To the rats in TEt-20 and EtOH groups, one hour after application of thiamine pyrophosphate or distilled water, 32% ethanol with a dose of 5 g/kg was administered via oral gavage. This procedure was repeated once a day for 6 weeks. From the blood samples and tissues obtained from the rats, Malondialdehyde (MDA), reduced glutathione (GSH), interleukin 1 beta (IL-1ß) and tumor necrosis factor alpha (TNF-α) levels were studied. Histopathological evaluations were performed to the optic nerve tissue. RESULTS: Serum and tissue IL-1ß, TNF-α and MDA levels were the highest in EtOH group which were significantly lower in thiamine pyrophosphate administered group (TEt-20 group) (p: 0.001). Serum and tissue reduced GSH levels were the lowest in EtOH group which were also significantly higher in TEt-20 group (p:0.001). In histopathological evaluations, in EtOH group there was obvious destruction and edema with hemorrhage and dilated blood vessels which were not present in any other groups. CONCLUSIONS: There was an apparent destruction in ethanol administered group in histopathological analyses with an augmented level of oxidative stress markers and all those alterations were prevented with concomitant thiamine pyrophosphate administration. These protective effects of thiamine pyrophosphate are extremely important in chronic ethanol consumption. Clinical studies are warranted to define the exact role of thiamine pyrophosphate in prevention of ethanol induced optic neuropathy.

The effects of lutein on optic nerve injury induced by ethambutol and isoniazid: an experimental study.

AIM: Ethambutol and isoniazid are two major effective first line agents in tuberculosis treatment having some visual adverse effects. We aimed to determine the protective effects of lutein on oxidative optic neuropathy induced by ethambutol and isoniazid in an experimental model. MATERIAL AND METHOD: Totally 24 albino Wistar male rats were assigned into 4 groups, with 6 rats in each group as follows: healthy controls (HC group), 50 mg/kg ethambutol +50 mg/kg isoniazid administered group (EI), 0.5 mg/kg lutein +50 mg/kg ethambutol +50 mg/kg isoniazid administered group (LEI-05) and only Lutein (0.5 mg/kg) (LUT group) administered group. From the blood samples and tissues obtained from the rats, Malondialdehyde (MDA), total glutathione (GSH), interleukin 1 beta (IL-1ß) and tumor necrosis factor alpha (TNF-α) levels were studied. Histopathological evaluations were performed at the end of the study. RESULTS: Serum and tissue IL-1ß, TNF-α and MDA levels were the highest in EI group which were significantly lower in lutein administered group. On the other hand, serum and tissue total GSH levels were the lowest in EI group which were significantly higher in Lutein administered group. In histopathological evaluations, there were significant differences between EI group and all other three groups with edema and hemorrhage in connective tissue covering optic nerve, dilated and congested capillary, decrease in astrocytes and oligodendrocytes. CONCLUSION: Isoniazid and ethambutol induced toxic optic neuropathy although not common, may have some potential devastating effects on vision. Lutein is determined as an effective agent in prevention of isoniazid and ethambutol induced toxic optic neuropathy.

The Effects of Intravitreal Ranibizumab, Aflibercept or Dexamethasone Implant Injections on Intraocular Pressure Changes.

BACKGROUND The aim of this study was to compare the alterations in intraocular pressure (IOP) values during the early postoperative period after intravitreal ranibizumab, aflibercept, or dexamethasone implant injections. MATERIAL AND METHODS In this retrospective study, a total of 188 patients were grouped into 3 groups: the ranibizumab group, the aflibercept group, and the dexamethasone group. Ocular axial length (AXL) and anterior chamber depth (ACD) were measured in the pre-injection period. IOP was measured just before the injection at 1 minute,10 minutes, 1 hour, 1 day, and 1 month after injection. RESULTS There was a transient peak in the ranibizumab group and the aflibercept group at 1 minute that started to decrease at 10 minutes and IOP values returned to preoperative values at approximately 1 hour. Similar alterations were also determined for the dexamethasone group with a lesser increase noted. In the correlation analysis, only alterations in IOP levels at 1 minute were negatively correlated with preoperative AXL values. There was not any correlation between preoperative AXL or ACD values and IOP alterations at any other time points. CONCLUSIONS There was a sudden, transient increase in IOP values after intravitreal ranibizumab or aflibercept injections; which return to normal values in a short time without requirement of any medical treatments. This transient peak was determined to be negatively correlated with the preoperative AXL.