Casein kinase-2 inhibition promotes retinal ganglion cell survival after acute intraocular pressure elevation

Intraocular pressure elevation can induce retinal ganglion cell death and is a clinically reversible risk factor for glaucoma,the leading cause of irreversible blindness.We previously demonstrated that casein kinase-2 inhibition can promote retinal ganglion cell survival and axonal regeneration in rats after optic nerve injury.To investigate the underlying mechanism,in the current study we increased the intraocular pressure of adult rats to 75 mmHg for 2 hours and then administered a casein kinase-2 inhibitor(4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole)by intravitreal injection.We found that intravitreal injection of 4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole promoted retinal ganglion cell survival and reduced the number of infiltrating macrophages.Transcriptomic analysis showed that the mitogen activated protein kinase signaling pathway was involved in the response to intraocular pressure elevation but was not modulated by the casein kinase-2 inhibitors.Furthermore,casein kinase-2 inhibition downregulated the expression of genes(Cck,Htrsa,Nef1,Htrlb,Prph,Chat,Slc18a3,Slc5a7,Scn1b,Crybb2,Tsga10ip,and Vstm21)involved in intraocular pressure elevation.Our data indicate that inhibition of casein kinase-2 can enhance retinal ganglion cell survival in rats after acute intraocular pressure elevation via macrophage inactivation.

Single-cell RNA sequencing analysis of the retina under acute high intraocular pressure

High intraocular pressure causes retinal ganglion cell injury in primary and secondary glaucoma diseases,yet the molecular landscape characteristics of retinal cells under high intraocular pressure remain unknown.Rat models of acute hypertension ocular pressure were established by injection of cross-linked hyaluronic acid hydrogel(Healaflow■).Single-cell RNA sequencing was then used to describe the cellular composition and molecular profile of the retina following high intraocular pressure.Our results identified a total of 12 cell types,namely retinal pigment epithelial cells,rod-photoreceptor cells,bipolar cells,Müller cells,microglia,cone-photoreceptor cells,retinal ganglion cells,endothelial cells,retinal progenitor cells,oligodendrocytes,pericytes,and fibroblasts.The single-cell RNA sequencing analysis of the retina under acute high intraocular pressure revealed obvious changes in the proportions of various retinal cells,with ganglion cells decreased by 23%.Hematoxylin and eosin staining and TUNEL staining confirmed the damage to retinal ganglion cells under high intraocular pressure.We extracted data from retinal ganglion cells and analyzed the retinal ganglion cell cluster with the most distinct expression.We found upregulation of the B3gat2 gene,which is associated with neuronal migration and adhesion,and downregulation of the Tsc22d gene,which participates in inhibition of inflammation.This study is the first to reveal molecular changes and intercellular interactions in the retina under high intraocular pressure.These data contribute to understanding of the molecular mechanism of retinal injury induced by high intraocular pressure and will benefit the development of novel therapies.

Protective effects of nerve regeneration factor and brain-derived neurotrophic factor on retinal ganglion cells in a rabbit model of acute hyper-intraocular pressure

BACKGROUND： Previous studies have shown that nerve regeneration factor （NRF） provides neuroprotective effects. However, the neuroprotective effects on retinal ganglion cells in an animal model of glaucoma remain uncertain. OBJECTIVE： To determine the neuroprotective effects of NRF on retinal ganglion cells in a rabbit model of acute hyper-intraocular pressure and to compare the effects on brain-derived neurotrophic factor （BDNF）. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at Jiangsu Provincial Key Laboratory of Neural Regeneration from September 2006 to August 2007. MATERIALS： Sterone, a major component of NRF, was provided by the Key Laboratory of Neural Regeneration, Nantong University in China; BDNF was provided by BioDesign Inc., USA. METHODS： A total of 24 healthy rabbits were randomly assigned to NRF, BDNF, and phosphate buffered saline groups, with 8 rabbits per group. The left eyes were considered normal controls, and acute hyper-intraocular pressure was induced in the right eyes via anterior chamber perfusion. The right camera vitrea bulbi was injected with 4.5 μg NRF, 3.75 μg BDNF, or 5 μL 0.1 mol/L phosphate buffered saline, respectively. MAIN OUTCOME MEASURES： Retinal ganglion cells were reverse-labeled using horseradish peroxidase to quantify cell density at 2, 4, and 6 mm from the optic disc edge. RESULTS： NRF increased the number of surviving retinal ganglion cells at the optic disc edge （P 〈 0.01 or P 〈 0.05）. The density of surviving retinal ganglion cells decreased with increasing distance from the optic disc. The number of retinal ganglion cells in the BDNF group was similar to the NRF group （P 〉 0.05）. At 2, 4, and 6 mm away from the optic disc edge, there was no significant difference in retinal ganglion cell density between NRF and BDNF groups （P〉 0.05）. CONCLUSION： NRF provided protection to retinal ganglion cells in a rabbit model of acute hyper-intraocular pressure, Le., NRF enhanced the survival rate of retinal ganglion cells. The neuroprotective effect was similar to BDNF.

Time Course of Age-dependent Changes in Intraocular Pressure and Retinal Ganglion Cell Death in DBA/2J Mouse

Purpose:To characterizes the progression of glaucoma in DBA/2J mice by measuring intraocular pressure(IOP) and retinal ganglion cells(RGCs) numbers in mice of various ages. Methods:A quantitative assessment of the pathophysiology of the DBA/2J mice was performed and the C57/BL6 mice was used as control. The IOP was measured by the servo-null micropipette system; the regional patterns of the loss of RGCs were determined by cell count of retrogradely-labeled RGCs. Results:The baseline IOP for DBA/2J mice at 7 weeks was (16.6 ± 1.2)mm Hg.Then IOP increased extend to 12 months, with the peak of (25.2 ± 1.2)mm Hg at 6 months of age. Retinal ganglion cell numbers did not decrease relative to control until 12 months of age(P=0.006), when the loss was proportionally higher in peripheral regions(P<0.05). Conclusion:The elevation in IOP precedes the loss of RGCs by several months. RGCs cell loss occurs particularly in peripheral regions of the retina. These findings expand our understanding of the changes in DBA/2J mice and provide information for experiments design when they are used as a glaucoma model for future studies of RGCs degeneration in glaucoma.

Retinal vessel diameter changes induced by transient high perfusion pressure

·AIM: To investigate the effects of transient high perfusion pressure on the retinal vessel diameter and retinal ganglion cells.·METHODS: The animals were divided into four groups according to different infusion pressure and infusion time(60 mm Hg-3min, 60 mm Hg-5min, 100 mm Hg-3min, 100 mm Hg-5min). Each group consisted of six rabbits. The left eye was used as the experimental eye and the right as a control. Retinal vascular diameters were evaluated before, during infusion, immediately after infusion, 5min, 10 min and 30 min after infusion based on the fundus photographs. Blood pressure was monitored during infusion. The eyes were removed after 24 h.Damage to retinal ganglion cell(RGC) was analyzed by histology.·RESULTS: Retina became whiten and papilla optic was pale during perfusion. Measurements showed significant decrease in retinal artery and vein diameter during perfusion in all of the four groups at the proximal of the edge of the optic disc. The changes were significant in the 100 mm Hg-3min group and 100 mm Hg-5min group compared with 60 mm Hg-3min group(P 1=0.025, P 2=0.000).The diameters in all the groups recovered completely after 30 min of reperfusion. The number of RGC)showed no significant changes at the IOP in 100 mm Hg with5 min compared with contralateral untreated eye(P 】0.05).·CONCLUSION: Transient fluctuations during infusion lead to temporal changes of retinal vessels, which could affect the retinal blood circulation. The RGCs were not affected by this transient fluctuation. Further studies are necessary to evaluate the effect of pressure during realtime phacoemusification on retinal blood circulation.

Sensitized heat shock protein 27 induces retinal ganglion cells apoptosis in rat glaucoma model

AIM: To investigate the relationships between the changes of heat shock protein 27 antibody(anti-HSP27) in serum/cerebrospinal fluid(CSF), intraocular pressure(IOP), retinal ganglion cell(RGC) apoptosis in a rat glaucoma model and disclose the underlying pathogenesis of glaucoma.METHODS: A total of 115 Wistar rats were randomly divided into 4 groups. Group 1 was the ocular hypertension group by condensing 3 episcleral & limbal veins or episcleral area of right eye(HP group, n=25) and sham operation group with conjunctiva incision without coagulation(n=25). Group 2: HSP27 or dose-matched PBS was injected into the vitreous(V-HSP27 group, n=15;V-PBS group, n=15). Group 3: HSP27 and complete Freund's adjuvant or dosematched PBS was injected subcutaneously into the hind limb accompanied intraperitoneal injection of pertussis toxin [sensitized group(I-HSP27 group), n=15;I-PBS group, n=15)]. Group 4 was normal group without any treatment(n=5). IOPs of the rats were measured before, day 3, weeks 1, 2, 4, 6, and 8 after treatment. Paraffin-embedded sections were prepared for HE staining and RGCs apoptosis were detected by TUNEL. Anti-HSP27 level in serum and CSF were examined by ELISA. RESULTS: IOPs were elevated significantly in HP and V-HSP27, V-PBS groups(P<0.01) and positively related to anti-HSP27 levels in serum and CSFs. Anti-HSP27 levels in serum and CSF were elevated significantly in I-HSP27group compared to other groups(P<0.05). However, the IOPs did not show any relationship with the high-level antiHSP27 in serum and CSFs. RGC apoptosis were all elevated significantly in the HP, V-HSP27, V-PBS and I-HSP27 groups and also positively relative with anti-HSP27 level in serum and CSFs except that high-level of anti-HSP27 in the serum of I-HSP group.CONCLUSION: The increases of anti-HSP27 levels in serum and CSFs both promote IOP escalation and the increase of RGC apoptosis in retina when anti-HSP27 is at low level. The case of high-level anti-HSP27 is opposite and shows protective function in preventing IOP increase and RGC apoptosis.

c-Jun N-terminal kinase 3 expression in the retina of ocular hypertension mice:a possible target to reduce ganglion cell apoptosis

Glaucoma, a type of optic neuropathy, is characterized by the loss of retinal ganglion cells. It remains controversial whether c-Jun N-terminal kinase （JNK） participates in the apoptosis of retinal ganglion cells in glaucoma. This study sought to explore a possible mechanism of action of JNK signaling pathway in glaucoma-induced retinal optic nerve damage. We established a mouse model of chronic ocular hypertension by reducing the aqueous humor followed by pho- tocoagulation using the laser ignition method. Results showed significant pathological changes in the ocular tissues after the injury. Apoptosis of retinal ganglion cells increased with increased intraocular pressure, as did JNK3 mRNA expression in the retina. These data indicated that the increased expression of JNK3 mRNA was strongly associated with the increase in intraocular pressure in the retina, and correlated positively with the apoptosis of retinal ganglion cells.

Visual functional changes during acute elevation of intraocular pressure

Glaucoma is closely related to elevation of intraocular pressure （IOP）. Many studies have done on the effect of chronic elevation of lOP on the retina and optic nerve, but less attention was paid to the effect of acute elevated lOP. Here we briefly review experimental studies on functional changes of the visual system from the retina to the visual cortex under acute elevated lOP condition, which is similar to that of acute primary angle-closure glaucoma.

Effects of chronic elevated intraocular pressure on parameters of optical coherence tomography in rhesus monkeys

AIM: To determine the progression of parameters from optical coherence tomography(OCT) in chronic elevated intraocular pressure(IOP) monkeys.METHODS: A chronic elevated IOP model of rhesus monkeys was induced by laser photocoagulation. Representative OCT parameters, including the average and four-quadrant retinal nerve fiber layer(RNFL) thickness, and parameters from optic nerve head(ONH) analysis were collected before and after laser treatments biweekly for up to 28 wk. The performance of each parameter for early progression detection was analyzed. The progressive trends toward elevated IOP were analyzed using a linear mixed-effects model.RESULTS: There were 10 successfully maintained high IOP eyes in 7 monkeys. The follow-up time was 24±5.37 wk. With cumulative IOP elevation, the cup area, rim area and C/D area ratio were statistically significantly changed as early as 2 wk after elevated IOP induction(P<0.05). The quadrant RNFL thickness changed at 6wk after high IOP induction, and the superior and inferior RNFL thicknesses exhibited more obvious reductions than other quadrants. The average RNFL thickness was the last one to show a significant decrease at 8wk.CONCLUSION: The parameters of ONH are most sensitive to elevated IOP in a primate glaucomatous model. These findings suggest that we should focus on those parameters instead of RNFL thickness in patients with elevated IOP, as they might present with earlier glaucomatous changes.

Quantitative analysis by reversed-phase high-performance liquid chromatography and retinal neuroprotection after topical administration of moxonidine

AIM:To determine moxonidine in aqueous humor and iris-ciliary body by reversed-phase high performance liquid chromatography(RP-HPLC),and to evaluate the retinal neuroprotective effect after topical administration with moxonidine in a high intraocular pressure(IOP)model.METHODS:The eyes of albino rabbits were administered topically and ipsilaterally with 0.2%moxonidine.A RPHPLC method was employed for the identification and quantification of moxonidine between 2 and 480 min,which presented in the aqueous humor and iris-ciliary body.Flash electroretinography(F-ERG)amplitude and superoxide dismutase(SOD)level were measured between day 1 and day 15 after topical administration with moxonidine in a rabbit model of high IOP.Histological and ultrastructural observation underwent to analyze the changes of retinal morphology,the inner retinal layers(IRL)thickness,and retinal ganglion cell(RGC)counting.RESULTS:Moxonidine was detectable between 2 and 480 min after administration,and the peak concentration developed both in the two tissues at 30 min,0.51μg/m Lin aqueous humor and 1.03μg/g in iris-ciliary body.In comparison to control,F-ERG b-wave amplitude in moxonidine eyes were significantly differences between day 3 and day 15(P<0.01)in the high IOP model;SOD levels were significantly higher at all time-points(P<0.01)with a maximum level of 20.29 U/mgprot at day 15;and RGCs were significantly higher(P<0.05).CONCLUSION:Moxonidine is a viable neuroprotective agent with application to high IOP model.All layers of retina,including RGC layer,retinal nerve fiber layer and INL,are more preserved after moxonidine administration.SOD plays a neuroprotective role in ocular hypertension-mediated RGC death.

Inhibition on Apoptosis Induced by Elevated Hydrostatic Pressure in Retinal Ganglion Cell-5 via Laminin Upregulating β1-integrin/Focal Adhesion Kinase/Protein Kinase B Signaling Pathway

Background：Glaucoma is a progressive optic neuropathy characterized by degeneration of neurons due to loss of retinal ganglion cells （RGCs）.High intraocular pressure （HIOP）,the main risk factor,causes the optic nerve damage.However,the precise mechanism of HIOP-induced RGC death is not yet completely understood.This study was conducted to determine apoptosis of RGC-5 cells induced by elevated hydrostatic pressures,explore whether laminin is associated with apoptosis under pressure,whether laminin can protect RGCs from apoptosis and affirm the mechanism that regulates the process of RGCs survival.Methods：RGC-5 cells were exposed to 0,20,40,and 60 mmHg in a pressurized incubator for 6,12,and 24 h,respectively.The effect of elevated hydrostatic pressure on RGC-5 cells was measured by Annexin V-fluorescein isothiocyanate/propidium iodide staining,3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide assay,and Western blotting of cleaved caspase-3 protein.Location and expression oflaminin were detected by immunofluorescence.The expression of β 1-integrin,phosphorylation of focal adhesion kinase （FAK） and protein kinase B （PKB,or AKT） were investigated with real-time polymerase chain reaction and Western blotting analysis.Results：Elevated hydrostatic pressure induced apoptosis in cultured RGC-5 cells.Pressure with 40 mmHg for 24 h induced a maximum apoptosis.Laminin was declined in RGC-5 cells after exposing to 40 mmHg for 24 h.After pretreating with laminin,RGC-5 cells survived from elevated pressure.Furthermore,β1-integrin and phosphorylation of FAK and AKT were increased compared to 40 mmHg group.Conclusions：The data show apoptosis tendency of RGC-5 cells with elevated hydrostatic pressure.Laminin can protect RGC-5 cells against high pressure via β 1-integrin/FAK/AKT signaling pathway.These results suggest that the decreased laminin of RGC-5 cells might be responsible for apoptosis induced by elevated hydrostatic pressure,and laminin or activating β1-integrin/FAK/AKT pathway might be potential treatments to prevent RGC loss in glaucomatous optic neuropathy.

High glucose levels impact visual response properties of retinal ganglion cells in C57 mice—An in vitro physiological study

This study investigated visual response properties of retinal ganglion cells(RGCs) under high glucose levels. Extracellular single-unit responses of RGCs from mouse retinas were recorded. And the eyecup was prepared as a flat mount in a recording chamber and superfused with Ames medium. The averaged RF size of the ON RGCs(34.1±2.9, n=14) was significantly smaller than the OFF RGCs under the HG(49.3±0.3, n=12)(P<0.0001) conditions. The same reduction pattern was also observed in the osmotic control group(HM) between ON and OFF RGCs(P<0.0001). The averaged luminance threshold(LT) of ON RGCs increased significantly under HG or HM(HG: P<0.0001; HM: P<0.0002). OFF RGCs exhibited a similar response pattern under the same conditions(HG: P<0.01; HM: P<0.0002). The averaged contrast gain of ON cells was significantly lower than that of OFF cells with the HM treatment(P<0.015, unpaired Student's t test). The averaged contrast gain of ON cells was significantly higher than OFF cells with the HG treatment(P<0.0001). The present results suggest that HG reduced receptive field center size, suppressed luminance threshold, and attenuated contrast gain of RGCs. The impact of HG on ON and OFF RGCs may be mediated via different mechanisms.

Interleukin-4 promotes microglial polarization toward a neuroprotective phenotype after retinal ischemia/reperfusion injury

Glaucoma results from irreversible loss of retinal ganglion cells(RGCs)through an unclear mechanism.Microglial polarization and neuroinflammation play an important role in retinal degeneration.Our study aimed to explore the function of microglial polarization during glaucoma progression and identify a strategy to alleviate retinal neuroinflammation.Retinal ischemia/reperfusion injury was induced in C57BL/6 mice.In a separate cohort of animals,interleukin(IL)-4(50 ng/mL,2μL per injection)or vehicle was intravitreally injected after retinal ischemia/reperfusion injury.RGC loss was assessed by counting cells that were positive for the RGC marker RNA binding protein,mRNA processing factor in retinal flat mounts.The expression of classically activated(M1)and alternatively activated(M2)microglial markers were assessed by quantitative reverse transcription-polymerase chain reaction,immunofluorescence,and western blotting.The results showed that progressive RGC loss was accompanied by a continuous decrease in M2 microglia during the late phase of the 28-day period after retinal ischemia/reperfusion injury.IL-4 was undetectable in the retina at all time points,and intravitreal IL-4 administration markedly improved M2 microglial marker expression and ameliorated RGC loss in the late phase post-retinal ischemia/reperfusion injury.In summary,we observed that IL-4 treatment maintained a high number of M2 microglia after RIR and promoted RGC survival.

Siponimod exerts neuroprotective effects on the retina and higher visual pathway through neuronal S1PR1 in experimental glaucoma

Sphingosine-1-phosphate receptor(S1PR)signaling regulates diverse pathophysiological processes in the central nervous system.The role of S1PR signaling in neurodegenerative conditions is still largely unidentified.Siponimod is a specific modulator of S1P1 and S1P5 receptors,an immunosuppressant drug for managing secondary progressive multiple sclerosis.We investigated its neuroprotective properties in vivo on the retina and the brain in an optic nerve injury model induced by a chronic increase in intraocular pressure or acute N-methyl-D-aspartate excitotoxicity.Neuronal-specific deletion of sphingosine-1-phosphate receptor(S1PR1)was carried out by expressing AAV-PHP.eB-Cre recombinase under Syn1 promoter in S1PR1mice to define the role of S1PR1 in neurons.Inner retinal electrophysiological responses,along with histological and immunofluorescence analysis of the retina and optic nerve tissues,indicated significant neuroprotective effects of siponimod when administered orally via diet in chronic and acute optic nerve injury models.Further,siponimod treatment showed significant protection against trans-neuronal degenerative changes in the higher visual center of the brain induced by optic nerve injury.Siponimod treatment also reduced microglial activation and reactive gliosis along the visual pathway.Our results showed that siponimod markedly upregulated neuroprotective Akt and Erk1/2 activation in the retina and the brain.Neuronal-specific deletion of S1PR1 enhanced retinal and dorsolateral geniculate nucleus degenerative changes in a chronic optic nerve injury condition and attenuated protective effects of siponimod.In summary,our data demonstrated that S1PR1signaling plays a vital role in the retinal ganglion cell and dorsolateral geniculate nucleus neuronal survival in experimental glaucoma,and siponimod exerts direct neuroprotective effects through S1PR1 in neurons in the central nervous system independent of its peripheral immuno-modulatory effects.Our findings suggest that neuronal S1PR1 is a neuroprotective therapeutic target and its modulation by siponimod has positive implications in glaucoma conditions.

Loss of melanopsin-containing retinal ganglion cells in a rat glaucoma model

Background Glaucoma can cause progressive damage to retinal ganglion cells. These cells can be classified as cells projecting to the superior colliculus and melanopsin-containing retinal ganglion cells, which project to the suprachiasmatic nucleus. This study was to investigate the effects of chronic intraocular pressure elevation on melanopsin-containing retinal ganglion cells in rats. Methods Chronic intraocular pressure elevation was induced in one eye of adult Wistar rats by cauterization of three episcleral veins. Intraocular pressure was measured at different intervals with a rebound tonometer. Superior collicular retinal ganglion cells were retrogradely labeled from the superior colliculus with Fluorogold. Melanopsin-containing retinal ganglion cells were visualized by free-floating immunohistochemistry on whole-mount retinas. The number of labeled superior collicular and melanopsin-containing retinal ganglion cells were counted in the sample areas on flat-mounted retinas. Results Compared with contralateral control eyes, the numbers of both superior collicular and melanopsin-containing retinal ganglion cells were significantly reduced after 12 weeks of experimental intraocular pressure elevation （（2317.41±29.96）/mm^2 vs （1815.82±24.25）/mm^2; （26.20±2.10）/mm^2 vs （20.62±1.52）/mm^2, respectively）. The extent of cell loss of the two types of retinal ganglion cells was similar. However, no morphologic changes were found in melanopsin-containing retinal ganglion cells. Conclusion Both melanopsin-containing and superior collicular retinal ganglion cells were damaged by chronic ocular hypertension, indicating that glaucomatous neural degeneration involves the non-image-forming visual pathway.

A modified chronic ocular hypertension rat model for retinal ganglion cell neuroprotection

This study aimed to modify a chronic ocular hypertension(OHT)rat model to screen for potential compounds to protect retinal ganglion cells(RGCs)from responding to increased intraocular pressure(IOP).A total of 266 rats were prepared and randomly grouped according to different time-points,namely,weeks 3,8,16,and 24.Rats were sedated and eye examination was performed to score as the corneal damage on a scale of 1 to 4.The OHT rat model was created via the injection of a hypertonic saline solution into the episcleral veins once weekly for two weeks.OHT was identified when the IOP at week 0 was≥6 mmHg than that at week-2 for the same eye.Viable RGCs were labeled by injecting 4%FluoroGold.Rats were sacrificed,and the eyes were enucleated and fixed.The fixed retinas were dissected to prepare flat whole-mounts.The viable RGCs were visualized and imaged.The IOP(meanβ±βSD)was calculated,and data were analyzed by the paired t-test and one-way ANOVA.The OHT model was created in 234 of 266 rats(87.97%),whereas 32 rats(12.03%)were removed from the study because of the absence of IOP elevation(11.28%)and/or corneal damage scores over 4(0.75%).IOP was elevated by as much as 81.35%for 24 weeks.The average IOP was(16.68β±β0.98)βmmHg in non-OHT eyes(n=234),but was(27.95±0.97)βmmHg in OHT eyes(n=234).Viable RGCs in the OHT eyes were significantly decreased in a time-dependent manner by 29.41%,38.24%,55.32%,and 59.30%at weeks 3,8,16,and 24,respectively,as compared to viable RGCs in the non-OHT eyes(P<β0.05).The OHT model was successfully created in 88%of the rats.The IOP in the OHT eyes was elevated by approximately 81%for 24 weeks.The number of viable RGCs was decreased by 59%of the rats in a time-dependent manner.The modified OHT model may provide an effective and reliable method for screening drugs to protect RGCs from glaucoma.

Characteristics of Optic Nerve Damage Induced by Chronic Intraocular Hypertension in Rat

Purpose:To set up the Sharma’s chronic intraocular hypertension model and investigate the intraocular pressure (IOP) as well as the optic nerve damage of this model in rat. Methods:The operations of the chronic intraocular hypertension model were performed as described by Sharma in 60 male Lewis albino rats. IOP was measured using the Tono-Pen XL immediately after surgery and then at 5 day, 2 week or 4 week intervals. Cresyl violet staining of whole-mounted retinas was used to label retinal ganglion cells (RGCs), then RGCs were counted. Paraphenylenediamine (PPD) staining was performed in the semi-thin cross sections of optic nerve of rat, in order to know whether the axons of optic nerve were degenerated or not. Results:There were 47 rats with higher IOP after the episcleral veins cauterized in 60 rats. The ratio of elevated IOP was 78.3%. The IOPs were stable in 4 weeks. After cresyl violet staining, the RGCs loss was 11.0% and 11.3% was found in the central and peripheral retina respectively after 2 weeks of increased IOP. After 4 weeks of increased IOP, the loss of RGCs was 17% for the central retina and 24.6% for the peripheral retina. In the retinas without higher IOP, there was no loss of RGCs. PPD staining showed that optic nerve of rat with about 5.3% damage of axons located at the superior temporal region. Region of affected optic nerve 1 mm posterior to the globe by light microscope showed evidence of damaged axons with axonal swelling and myelin debris. Conclusion:Sharma’s chronic intraocular hypertension model is a reproducible and effective glaucoma model, which mimics human glaucoma with chronically elevation IOP and induced RGCs loss and damage of optic nerve. Eye Science 2004;20:25-29.

Value of optical coherence tomography measurement of macular thickness and optic disc parameters for glaucoma screening in patients with high myopia

BACKGROUND The basic method of glaucoma diagnosis is visual field examination,however,in patients with high myopia,the diagnosis of glaucoma is difficult.AIM To explore the value of optical coherence tomography(OCT)for measuring optic disc parameters and macular thickness as a screening tool for glaucoma in patients with high myopia.METHODS Visual values(contrast sensitivity,color vision,and best-corrected visual acuity)in three groups,patients with high myopia in Group A,patients with high myopia and glaucoma in Group B,and patients with high myopia suspicious for glaucoma in Group C,were compared.Optic disc parameters,retinal nerve fiber layer(RNFL)thickness,and ganglion cell layer(GCC)thickness were measured using OCT technology and used to compare the peri-optic disc vascular density of the patients and generate receiver operator characteristic(ROC)test performance curves of the RNFL and GCC for high myopia and glaucoma.RESULTS Of a total of 98 patients admitted to our hospital from May 2018 to March 2022,totaling 196 eyes in the study,30 patients with 60 eyes were included in Group A,33 patients with 66 eyes were included in Group B,and 35 patients with 70 eyes were included in Group C.Data were processed for Groups A and B to analyze the efficacy of RNFL and GCC measures in distinguishing high myopia from high myopia with glaucoma.The area under the ROC curve was greater than 0.7,indicating an acceptable diagnostic value.CONCLUSION The value of OCT measurement of RNFL and GCC thickness in diagnosing glaucoma in patients with high myopia and suspected glaucoma is worthy of development for clinical use.

高度近视与原发性开角型青光眼临床特征的研究进展

随着人们生活方式的显著改变,全球近视患病率日益上升,引发了临床医生的密切关注。近视易合并其他严重的眼科疾病,尤其是高度近视(HM)患者,常合并原发性开角型青光眼(POAG),其发病率远远高于屈光状态正常的人群。当高度近视与原发性开角型青光眼并存时,病情变得尤其复杂。近年我们在临床工作中集中关注患者的眼底改变特征。从高度近视人群中早期发现原发性开角型青光眼患者,这是对两种疾病深入了解并进行有效防治的关键。文章通过回顾分析近年文献,从流行病学、发病机制及临床特征方面对高度近视与原发性开角型青光眼的关系及研究进展进行综述,以期为疾病早期发现、早期诊断、早期治疗提供帮助。

急性高眼压模型大鼠视网膜病理变化及视网膜中胶质原纤维酸性蛋白表达变化动态观察

目的动态观察急性高眼压模型大鼠视网膜病理变化及视网膜中胶质原纤维酸性蛋白(GFAP)表达变化,探讨急性高眼压大鼠视网膜的损伤情况。方法将24只SD大鼠随机分为正常对照组6只和急性高眼压模型组18只,正常对照组不做任何处理。急性高眼压模型组采用沿角巩膜缘结膜下环扎缝合法制备急性高眼压模型。急性高眼压模型组大鼠造模前、缝合即刻、缝合后1 h、缝合后1 d、缝合后2 d、缝合后3 d、缝合后4 d、缝合后5 d、缝合后7 d时,分别使用Tonolab眼压计监测眼压,正常对照组于同一时间点测量眼压。取急性高眼压模型组大鼠,于缝合后1 d、缝合后3 d、缝合后7 d时分别处死后,采用HE染色法观察视网膜组织形态变化,采用Thy-1免疫组化染色法测算视网膜神经节细胞数量,采用免疫组织化学染色法检测视网膜中GFAP蛋白。结果急性高眼压模型组大鼠缝合即刻、缝合后1 h、缝合后1 d、缝合后2 d眼压均高于正常对照组(P均<0.05),且急性高眼压模型组大鼠缝合即刻、缝合后1 h、缝合后1 d、缝合后2 d眼压均高于其他时间点眼压,呈下降趋势(P均<0.05)。正常对照组视网膜各层结构未发生明显改变,急性高眼压模型组大鼠缝合后1 d时视网膜神经纤维层出现水肿,大鼠缝合后3 d时视网膜水肿开始减轻,大鼠缝合后7 d时视网膜厚度及神经纤维层厚度均变薄。急性高眼压模型组大鼠缝合后3 d、7 d时视网膜神经节细胞数量均低于正常对照组和急性高眼压模型组大鼠缝合后1 d时(P均<0.05),且急性高眼压模型组大鼠缝合后7 d时视网膜神经节细胞数量低于缝合后3 d时(P均<0.05)。正常对照组、急性高眼压模型组大鼠缝合后1 d、3 d、7 d时大鼠视网膜中GFAP蛋白表达水平分别为65.762±16.246、115.777±18.780、145.056±9.777、169.751±10.378,两两相比,P均<0.05。结论急性高眼压模型大鼠视网膜发生病理变化,出现神经节细胞丢失,视网膜中GFAP蛋白表达升高。