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Dissociated optic nerve fiber layer (DONFL) appearance is characterized by dimpling of the fundus when observed after vitrectomy with the internal limiting membrane (ILM) peeling in macular diseases. However, the cause of DONFL remains largely unknown. Optical coherence tomography (OCT) findings have indicated that the nerve fiber layer (NFL) and ganglion cells are likely to have been damaged in patients with DONFL appearance. Since DONFL appearance occurs at a certain postoperative period, it is unlikely to be retinal damage directly caused by ILM peeling because apoptosis occurs at a certain period after tissue damage and/or injury. However, it may be due to ILM peeling-induced apoptosis in the retinal tissue. Anoikis is a type of apoptosis that occurs in anchorage-dependent cells upon detachment of those cells from the surrounding extracellular matrix (i.e., the loss of cell anchorage). The anoikis-related proteins βA3/A1 crystallin and E-cadherin are reportedly expressed in retinal ganglion cells. Thus, we theorize that one possible cause of DONFL appearance is ILM peeling-induced anoikis in retinal ganglion cells.

Purpose: To determine whether P7C3-A20 can inhibit the phosphorylation of the mammalian target of rapamycin (mTOR), depress neuroinflammation, and protect retinal ganglion cells (RGCs) of rats from optic nerve crush (ONC)., Methods: The left optic nerve was crushed, and 5.0 mg/kg/d of P7C3-A20, 1.0 mg/kg/d of rapamycin, or their vehicle was injected intraperitoneally for 3 consecutive days beginning 1 day before the ONC. The protective effects on the RGCs were determined by immunohistochemical staining for Tuj-1. The level of phosphorylated mTOR was determined by immunoblotting. The neuroinflammation in the optic nerve was determined by changes in the expression of CD68, TNF-α, MCP-1, and iNOS., Results: The density of Tuj-1-stained cells in the control was 2010 ± 81.5/mm2 and 1842 ± 80.4/mm2 on days 7 and 14 after the sham operation. These levels were lower at 995 ± 122/mm2 and 450 ± 52.4/mm2 on days 7 and 14 after the ONC, respectively. Rapamycin and P7C3-A20 preserved the density at significantly higher levels on both days (P < 0.05, Scheffe test). The level of phosphorylated mTOR increased by 1.56-fold above the control level on day 7. Rapamycin and P7C3 significantly lowered the level of phosphorylated mTOR to 0.89-fold and 0.67-fold of the control, respectively. There was an accumulation of CD68+ cells that were immunoreactive to TNF-α at the crush site. The expression of MCP-1 and iNOS was increased chiefly in the astrocytes around the lesion. These inflammatory events were suppressed by both rapamycin and P7C3., Conclusions: P7C3-A20 can inhibit mTOR phosphorylation in the crushed optic nerve, which may suppress neuroinflammation and preserve the RGCs.

The purpose of this study was to determine whether inhibition of aquaporin 4 (AQP4) is neuroprotective or neurodestructive after crushing the optic nerve of rats. The left optic nerves of rats were crushed, and TGN-020 (5.0 mg/kg, crush TGN-020) or its vehicle (DMSO, crush placebo) was injected intraperitoneally just after the crushing. As controls, the left optic nerves were exposed but not touched in other rats (sham controls). The retinal damages were determined by the density of retinal ganglion cells (RGCs) and the ratio of BAX/Bcl-2 on day 7. The glutamate level in the optic nerve on day 1 after the crushing was determined. The expressions of glutamine synthetase, glutamate-aspartate transporter (GLAST), and AQP4 were determined on day 3 by immunoblotting. The effects of AQP4 inhibition on the glutamate-induced changes of AQP4 expression and on the glutamate uptake were determined for optic nerve astrocytes in culture. The results showed that the density of RGCs was 2040 ± 91.3 cells/mm(2) (n = 6) in the sham control, and it was significantly decreased to 1072 ± 134.3 cells/mm(2) after crushing the optic nerve (P < 0.0001, crush placebo, n = 7; Fisher). An intraperitoneal injection of TGN-020 led to a further significant (P = 0.02, Fisher) decrease of the density of RGCs to 743 ± 371 cells/mm(2) (crush TGN-020, n = 7). The mRNA level of BAX/Bcl-2 ratio was 0.37 ± 0.05 in the sham control (n = 6) which was significantly increased to 0.88 ± 0.10 after crushing the optic nerve (placebo crush, n = 7; P = 0.0001, Scheffe). TGN-020 also significantly increased the BAX/Bcl-2 ratio to 1.29 ± 0.4 (n = 6) from the crush placebo group (P = 0.04, Scheffe). Immunoblotting showed similar changes in the protein levels. The glutamate level in the optic nerve was significantly increased to 53.7 ± 6.0 μM/mg/protein on day 1 (n = 4) from the sham control level of 45.9 ± 3.1 μM/mg/protein (n = 4; P = 0.04, t test). TGN-020 significantly (P < 0.05, Scheffe) depressed the expression of glutamate metabolism-related proteins on day 3. Exposure of cultured optic nerve astrocytes to glutamate (1.0 mM, n = 4) significantly increased the expression of AQP4 (P < 0.001, Scheffe) that was depressed by TGN-020 (100 nM, n = 4). In addition, glutamate uptake was inhibited by TGN-020 at 10 nM or higher. These results indicate that an inhibition of AQP4 enhances the loss of RGCs and retinal damages after crushing the optic nerve. Inhibition of AQP4 impairs glutamate metabolism which may account in part for these neurodestructive events., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Aims: Nitric oxide (NO) is associated with neuroinflammation in the central nervous system. We determined whether NO increases the expression of aquaporin-4 (AQP4) in optic nerve astrocytes of rats., Methods: Isolated astrocytes were incubated under normoxic or hypoxic conditions with or without glucose (5.5 mM). The astrocytes were also exposed to different concentrations of S-nitroso-N-acetyl-DL-penicillamine (SNAP, 1.0-100 μM), an NO donor. The expression of AQP4 was determined by Western blot analyses, and NO formation was measured by the Griess reaction. The changes in astrocytic cellular volumes were determined by flow cytometry., Results: Hypoxia and glucose deprivation increased AQP4 expression and NO formation. Inhibition of NO synthetase (NOS) significantly suppressed these changes. SNAP caused a significant increase in AQP4 expression, and the increase was significantly suppressed by carboxy-PTIO, a scavenger of NO. Incubation with 8-Br-cyclic guanosine monophosphate (cGMP) mimicked the effects of SNAP, while the addition of either 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ; inhibitor of soluble guanylate cyclase) or KT5823 (protein kinase G inhibitor) suppressed the SNAP-induced increase in AQP4 significantly. SNAP also caused a significant increase in astrocytic cellular volume through the AQP4 channels., Conclusions: NO increased the AQP4 expression of optic nerve astrocytes through the cGMP/protein kinase G pathway and enlarged their volume., (© 2015 S. Karger AG, Basel.)

The purpose of this study was to determine the temporal and spatial changes in the expression of AQP4 and AQP9 in the optic nerve after it is crushed. The left optic nerves of rats were either crushed (crushed group) or sham operated (sham group), and they were excised before, and at 1, 2, 4, 7, and 14 days later. Four optic nerves were pooled for each time point in both groups. The expression of AQP4 and AQP9 was determined by western blot analyses. Immunohistochemistry was used to determine the spatial expression of AQP4, AQP9, and GFAP in the optic nerve. Optic nerve edema was determined by measuring the water content in the optic nerve. The barrier function of the optic nerve vessels was determined by the extravasated Evans blue dye on days 7 and 14. The results showed that the expression of AQP4 was increased on day 1 but the level was significantly lower than that in the sham group on days 4 and 7 (P<0.05). In contrast, the expression of AQP9 gradually increased, and the level was significantly higher than that in the sham group on days 7 and 14 (P<0.05, Tukey-Kramer). The down-regulation of AQP4 was associated with crush-induced optic nerve edema, and the water content of the nerve was significantly increased by 4.3% in the crushed optic nerve from that of the untouched fellow nerve on day 7. The expression of AQP4 and GFAP was reduced at the crushed site where AQP4-negative and AQP9-positive astrocytes were present. The barrier function was impaired at the crushed site on days 7 and 14, restrictedly where AQP4-negative and AQP9-positive astrocytes were present. The presence of AQP9-positive astrocytes at the crushed site may counteract the metabolic damage but this change did not fully compensate for the barrier function defect.

Purpose: The photopic negative response (PhNR) is a negative wave following the b-wave of the photopic electroretinogram (ERG). The PhNR originates from the retinal ganglion cells (RGCs), and it can be used to assess the function of RGCs noninvasively and objectively. The purpose of this study was to determine whether the relative amplitudes (affected/normal eye) of the PhNR are significantly correlated with the degree of the relative afferent pupillary defect (RAPD) in eyes with unilateral or asymmetrical damage of the optic nerve. Methods: The PhNRs of the full-field photopic ERGs were measured. In addition, videopupillography and automated perimetry were performed on 27 cases with asymmetrical optic nerve disorders including glaucoma. The differences of these assessments were expressed by the relative amplitudes of the PhNRs of the two eyes, the neutral density (ND) filter required to equate the amplitudes of the pupillary light reflexes between the two eyes, and differences of the mean defects (ΔMDs) of the sensitivities of the Humphrey visual fields. The correlations between these values were determined by linear regression analyses. Results: The relative PhNR amplitudes were significantly and negatively correlated with the ΔMDs (R2 = 0.58, P = 0.0001). In addition, the relative PhNR amplitudes were moderately but significantly and positively correlated with the RAPDs (R2 = 0.36, P = 0.002). Conclusion: The relative amplitudes of the PhNR of the affected eyes to the contralateral eyes indicate an asymmetric alteration of the RGCs, and they can be used to monitor the physiology of the RGCs objectively. [ABSTRACT FROM AUTHOR]

Purpose: To retrospectively review and analyze the clinical and imaging data of patients with vitreomacular traction syndrome (VMTS) with strong peripheral vitreoretinal adhesion. Subjects and Methods: This retrospective case-series study involved 4 eyes of 4 VMTS patients with vitreoretinal adhesion in both the macular region and the periphery who underwent vitreous surgery. In all 4 cases, preoperative refraction, fundoscopic findings, optical coherence tomography (OCT) findings, and intraoperative findings were evaluated. Results: The preoperative fundoscopy and OCT findings revealed fibrous membranes around the optic nerve head in 3 eyes. Thickened posterior vitreous membranes extending from the posterior pole to the periphery were observed in all eyes. Apparent VMTS or epimacular membrane was also found in the fellow eyes of 2 patients. The preoperative refractive errors ranged from +0.5 diopters (D) to +2.75 D (mean, +1.13 D). Intraoperatively, a thickened posterior vitreous membrane was found strongly adhered to the retina in the macula regions, optic nerve head, and periphery. In 2 eyes, when artificial posterior vitreous detachment (PVD) was created, an iatrogenic tear developed in the periphery. Conclusion: The features of VMTS that cause strong peripheral vitreoretinal adhesion include the preoperative presence of a thickened posterior vitreous membrane over a wide area, hypermetropia, and a short axial length. [ABSTRACT FROM AUTHOR]

Background: We encountered a rare patient with lens luxation in which the lens had become stuck on the optic disc. Findings obtained during vitreous surgery suggested that the luxated lens had become stuck on the optic disc via residual vitreous gel.Case Presentation: An 88-year-old Japanese man experienced lens luxation into the inferior vitreous cavity while undergoing treatment for glaucoma in his left eye. Because no inflammation was present upon examination, we observed the patient without prescribing any additional medications except for the eye drop treatment for glaucoma. Two years later, the patient revisited our clinic after suddenly noticing a visual disturbance in his left eye. A fundus examination revealed that the luxated lens had become stuck on the optic disc and displayed no changes in relation to the patient's head position or eye movement. Subsequently, vitreous surgery was performed to remove the luxated lens. During the surgery, we observed an aggregation of vitreous gel between the luxated lens and the optic disc. The luxated lens was successfully mobilized by pushing with a vitreous cutter and then extracted through a corneoscleral incision using perfluorocarbon liquid. At 4 months after surgery, the patient's visual acuity had improved to 20/25.Conclusions: The findings of this study suggest that the luxated lens had become stuck on the optic disc via residual vitreous gel on the optic disc. The surgical procedure of extracting the luxated lens through a corneoscleral incision using perfluorocarbon liquid was found to be both safe and effective. [ABSTRACT FROM AUTHOR]

The original publication of this paper contains mistakes. [ABSTRACT FROM AUTHOR]

Purpose. To assess the influence of the blood glucose level on ocular capillary circulation, we induced clinically significant hyperglycemia (200-300mg/dl) in rabbits and investigated the changes in the optic nerve head (ONH) circulation. Methods. Hyperglycemia was induced by injection of glucose (5.6mmol/kg) into an auricular vein of healthy albino rabbits and changes in the ONH circulation were measured by the laser speckle method. In order to examine the role of nitric oxide (NO), glucose was administered after intravenous injection of an NO synthetase inhibitor (N[sup G]nitro-L-arginine methyl ester, L-NAME, l mg/kg), then changes in the ONH circulation were measured. Results. The blood glucose level reached a peak at 30 min after glucose loading and returned to its initial level by 2 hours. ONH circulation showed a 60% increase compared with its initial level at 15 min after glucose loading and subsequently remained almost unchanged throughout the 2-hour observation period. There were no significant changes of the blood pressure, heart rate, or intraocular pressure. The glucose-induced increase of ONH circulation was completely inhibited by pretreatment with L-NAME. Conclusions. ONH circulation was increased by administration of glucose to healthy rabbits. A high blood glucose level seems to promote ocular capillary circulation and NO as well as insulin appear to have a role in this process. [ABSTRACT FROM AUTHOR]

Tauopathies are neurodegenerative diseases characterized by abnormal metabolism of misfolded tau proteins and are progressive. Pathological phosphorylation of tau occurs in the retinal ganglion cells (RGCs) after optic nerve injuries. Cyclin-dependent kinase-5 (Cdk5) causes hyperphosphorylation of tau. To determine the roles played by Cdk5 in retinal degeneration, roscovitine, a Cdk5 inhibitor, was injected intravitreally after optic nerve crush (ONC). The neuroprotective effect of roscovitine was determined by the number of Tuj-1-stained RGCs on day 7. The change in the levels of phosphorylated tau, calpain-1, and cleaved α-fodrin was determined by immunoblots on day 3. The expression of P35/P25, a Cdk5 activator, in the RGCs was determined by immunohistochemistry. The results showed that roscovitine reduced the level of phosphorylated tau by 3.5- to 1.6-fold. Calpain-1 (2.1-fold) and cleaved α-fodrin (1.5-fold) were increased on day 3, suggesting that the calpain signaling pathway was activated. P35/P25 was accumulated in the RGCs that were poorly stained by Tuj-1. Calpain inhibition also reduced the increase in phosphorylated tau. The number of RGCs decreased from 2191 ± 178 (sham) to 1216 ± 122 cells/mm2 on day 7, and roscovitine preserved the level at 1622 ± 130 cells/mm2. We conclude that the calpain-mediated activation of Cdk5 is associated with the pathologic phosphorylation of tau. [ABSTRACT FROM AUTHOR]

Background: Valsalva retinopathy is known to occur as a sudden preretinal or sub-internal limiting membrane hemorrhage induced by a rapid rise in venous pressure following increased intrathoracic or intraabdominal pressure. Here we report a case of Valsalva retinopathy that was probably induced by straining that occurred due to following a handstand.Case Presentation: A 15-year-old boy became aware of decreased visual acuity in his left eye immediately after doing a handstand for approximately 10 s during physical education class, and subsequently visited a local clinic on the same day. Upon examination, a vitreous hemorrhage (VH) in the posterior pole of the fundus was found in his left eye, and he was subsequently referred to our department 7 days later. Upon examination, the VH around the optic nerve head of the left eye appeared to be resolved, and an oval-shaped sub-internal limiting membrane (sub-ILM) hemorrhage was found in the superonasal side of the optic nerve head. No abnormalities were observed in the macular area. Four months later, the sub-ILM hemorrhage was found to have spontaneously resolved. Subsequent fluorescein angiography examinations revealed no abnormal findings at the lesion site.Conclusions: In this patient, we hypothesize that the Valsalva retinopathy was induced by straining that occurred due to a handstand, and that the resultant sub-ILM hemorrhage progressed to VH. [ABSTRACT FROM AUTHOR]