Neuroprotective effect of latanoprost on rat retinal ganglion cells

Background To investigate the neuroprotective effect of intravitreal administration of latanoprost on retinal ganglion cell (RGC) damage induced by N-methyl-D-aspartic acid (NMDA) or optic nerve axotomy.Methods Using Sprague-Dawley rats, retinal ganglion cell damage was induced by either intravitreal administration of NMDA or optic nerve axotomy. Latanoprost at doses of 0.03, 0.3, 3, 30 and 300 pmol was administered intravitreally before NMDA injection or optic nerve axotomy. Retinal damage was evaluated by counting the number of surviving RGCs retrogradely labeled with fluorogold under the microscope.Results Seven days after the NMDA injury, the number of surviving RGCs was significantly increased at doses of more than 30 pmol atanoprost (846±178 cells/mm² P=0.0166) compared with vehicle control (556±122 cells/mm²). Ten days after the optic nerve axotomy, the number of surviving RGC was significantly increased even at a dose of 0.3 pmol (815±239 cells/mm², P=0.0359) compared with control (462±75 cells/mm²).Conclusions Intravitreal administration of latanoprost has a neuroprotective effect on rat RGC damage induced by either NMDA or optic nerve axotomy, while its pharmacological features are different.     

Orbital apex syndrome secondary to myocysticercosis: a rare case report

AIM: To compare surgical outcomes of phacoemulsification combined with glaucoma surgical techniques performed with either Kahook Dual Blade (KDB) or iStent for Japanese patients with either primary open-angle glaucoma or exfoliation glaucoma.METHODS: We retrospectively evaluated the surgical outcomes of 129 eyes of 84 Japanese patients with glaucoma who underwent KDB or 44 eyes of 34 patients who underwent phacoemulsification with iStent procedures combined with cataract surgery. The primary outcome was surgical success or failure [with surgical failure being indicated by <20% reduction from preoperative intraocular pressure (IOP) or IOP >18 mm Hg, criterion A; IOP >14 mm Hg, criterion B; or reoperation requirement]. In addition, we assessed the number of postoperative glaucoma medications and the resulting complications. RESULTS: The probability of success was significantly higher in the KDB group than in the iStent group for criterion A (60.2% vs 46.4%, P=0.019). In the KDB group, the mean preoperative IOP of 19.7±7.2 mm Hg decreased significantly to 13.0±3.1 mm Hg (P<0.01), and the mean number of glaucoma medications at 2.5±1.4 decreased significantly to 1.6±1.6 (P<0.01) 12mo postoperatively. In the iStent group, the mean preoperative IOP of 17.8±2.9 mm Hg significantly decreased to 14.3±2.3 mm Hg (P<0.01), and the mean number of glaucoma medications at 2.2±1.1 decreased significantly to 0.9±1.4 (P<0.01) 12mo postoperatively. The overall IOP reduction percentage was higher in the KDB group (26.2%) than in the iStent group (19.0%) 12mo postoperatively (P=0.03). Hyphema occurred significantly more frequently in the KDB group (16.3%) than in the iStent group (2.3%; P=0.017).CONCLUSION: KDB and iStent procedures combine with cataract surgery both resulted in significant IOP and glaucoma medication reductions after the 12-month follow-up. The patients in the KDB group have a higher success rate for the target IOP of less than 18 mm Hg and a higher complication rate than those in the iStent group.     

玻璃体腔注射大麻素HU-211治疗鼠青光眼视神经损伤的研究

目的：评价玻璃体腔内注射大麻素HU-211对大鼠青光眼模型视神经的保护作用,为青光眼视神经损伤治疗提供实验依据。

方法：采用电凝巩膜表面静脉法制作大鼠青光眼模型18眼,随机分为3组：A组分别隔日一次玻璃体腔注射1mg/0.1mL大麻素HU-211,B组隔日一次玻璃体腔注射0.1mL生理盐水,C组为高眼压组。随机选6只对侧眼为空白对照组,每日观察眼压变化情况,用药4wk后处死大鼠,视网膜冰冻切片,HE染色通过视网膜神经元的密度变化评估大鼠慢性高眼压模型视网膜神经元的损伤程度。

结果： B组的凋亡程度及RGC的损伤程度明显高于A组,差异有统计学意义(P<0.05), B组与C组比较差异无统计学意义(P>0.05)。

结论： 玻璃体腔注射大麻素(HU-211)对大鼠青光眼模型视神经视网膜有明显的保护作用。     

Intravitreal administration of erythropoietin and preservation of retinal ganglion cells in an experimental rat model of glaucoma

PURPOSE: The aim of this pilot study was to evaluate the potential neuroprotective effect of an intravitreal injection of erythropoietin (EPO) on retinal ganglion cell (RGC) preservation in an episcleral vessel cautery-induced rat model of glaucoma. METHODS: The animals were randomly assigned into an unoperated control group (n = 11) and three experimental groups: episcleral vessel cautery only (EVC: n = 4), episcleral vessel cautery with intravitreal normal saline injection (EVC-NS; n = 5), and episcleral vessel cautery with intravitreal EPO treatment (EVC-EPO; n = 9). The intravitreal injections were limited to 5 mul containing either normal saline alone or 200 ng of EPO in normal saline administered immediately after the cautery procedure. RGCs were labeled retrogradely by FluoroGold neuron tracer 5 to 7 days prior to the collection of eyes at day 21 and counted in whole flat-mounted retinas with fluorescence microscopy. RESULTS: Compared to the RGC counts in retinal specimens from unoperated control rats (12,619 +/- 310), the corresponding RGC counts were significantly decreased in both the EVC (9116 +/- 273; p < 0.005) and EVC-NS (9489 +/- 293; p < 0.005) groups but not significantly decreased in the EVC-EPO (11,212 +/- 414; p = 0.051) treated retinas. CONCLUSIONS: A single intravitreal 200 ng dose of EPO appears to have a protective effect on RGC viability in an in vivo rat model of glaucoma. Further experimental studies are needed to confirm these preliminary results and to optimize the appropriate dose and frequency of EPO delivery in animal models of glaucoma.     

不同联合手术治疗伴有和不伴有玻璃体积血的新生血管性青光眼

目的：探讨玻璃体腔注射康柏西普联合青光眼引流器植入及视网膜激光光凝对伴有和不伴有玻璃体积血的新生血管性青光眼(NVG)的疗效。

方法：回顾性分析了2016/01～2017/12在西安市第一医院眼科被确诊的37例39眼伴有和不伴有玻璃体积血的NVG(虹膜房角黏连超过180°)患者的临床资料。根据是否有玻璃体积血分为两组。所有患者均接受0.5mg(0.05mL)玻璃体腔注射康柏西普。没有玻璃体积血的20例21眼(第1组)患者在玻璃体腔注射康柏西普后4d行EX-PRESS(P50)青光眼引流器植入,在青光眼引流器植入后2wk行全视网膜激光光凝。伴有玻璃体积血的17例18眼(第2组)患者在玻璃体腔注射康柏西普后4d行玻璃体切除联合EX-PRESS(P50)青光眼引流器植入及全视网膜激光光凝术,并且根据术中的实际情况选择填充空气或硅油。所有患者术后随访6mo。

结果：第1组患者术前与术后6mo最佳矫正视力(BCVA)无差异(P>0.05); 第2组患者术前与术后6mo BCVA有差异(P<0.05); 第1组患者术后1d,1wk、1、3和6mo眼压分别为20.5±4.3mmHg,19.6±3.8mmHg,20.1±3.7mmHg,19.9±4.2mmHg和19.3±2.9mmHg。第2组患者术后1d,1wk、1、3和6mo眼压分别为22.3±3.7mmHg,20.6±2.8mmHg,20.4±3.8mmHg,18.9±4.1mmHg和19.3±3.4mmHg。第1组和第2组患者术后平均眼压均低于术前眼压(P<0.05),在随访期间3眼出现虹膜新生血管复发,故再行1次玻璃体腔注射康柏西普,治疗1wk后虹膜新生血管消退。

结论：玻璃体腔注射康柏西普联合青光眼引流器植入及视网膜激光光凝能够有效降低伴有和不伴有玻璃体积血的NVG(虹膜房角黏连超过180°)患者的眼内压。     

Diode laser trans-scleral cyclophotocoagulation for glaucoma following silicone oil removal

Purpose : To evaluate the effect of trans‐scleral cyclophotocoagulation (TSCP) on intraocular pressure (IOP) in eyes with medically uncontrolled secondary glaucoma persisting after intravitreal silicone oil removal. Methods : Clinical records of 21 eyes of 21 patients who underwent TSCP for medically uncontrolled glaucoma persisting after the removal of intravitreal silicone oil, injected during vitreoretinal surgery for proliferative vitreoretinopathy (PVR), were reviewed retrospectively. Diode laser contact TSCP was applied at a power setting of 1.5–2.5 W, for a maximum duration of 2 s, and a total of 40 spots (10 spots each quadrant). All the patients were evaluated for visual acuity, IOP and number of medications used. Results : The patients were followed up for a mean ± SD period of 39.9 ± 4.27 weeks (range 36–48 weeks). The IOP was found to have decreased significantly from a pretreatment value of 34.5 ± 5.37 mmHg (range 24–44 mmHg) to 20.47 ± 4.49 mmHg at 6 months of follow up (range 12–30 mmHg, P < 0.01, Student’s paired t‐test). The total number of glaucoma medications being used reduced from 3.38 ± 0.5 to 1.08 ± 0.80 postoperatively (P < 0.01, Wilcoxon’s rank sum test). There was no significant difference in the visual acuity before and after the procedure. Thirteen eyes required a second sitting of TSCP, and five of these required a third sitting. For a successful outcome (IOP < 24 mmHg), a mean of 1.56 sittings (range 1–3 sittings) per eye were needed. Conclusion : Patients with medically uncontrolled glaucoma persisting after intravitreal silicone oil removal can be treated with TSCP; however, the reduction of IOP is variable. The IOP usually falls after a mean of 2–3 sittings of TSCP.     

Intravitreal injection of bevacizumab alone or with triamcinolone acetonide for treatment of macular edema caused by central retinal vein occlusion

AIM: To compare the efficacy and safety of intravitreal bevacizumab alone versus bevacizumab combined with triamcinolone acetonide in eyes with macular edema caused by central retinal vein occlusion (CRVO) in Chinese patients. METHODS: Seventy-five eyes of 75 patients were enrolled in this prospective, randomized, consecutive study. Thirty-six patients in group 1 were treated with an intravitreal injection of bevacizumab (1.25mg/0.05mL), and 39 patients in group 2 were treated with intravitreal bevacizumab (1.25mg/0.05mL) combined with triamcinolone acetonide (2mg/0.05mL). The main outcomes of the mean best corrected visual acuity (BCVA), central retinal thickness (CRT), and intraocular pressure (IOP) were measured. RESULTS: In group 1, the mean BCVA improved from 37.78±6.14 (baseline) to 48.06±3.86, 46.48±4.77 and 44.18±5.78 at four, six and twelve weeks post-injection, respectively (P<0.01, P=0.03, P=0.04). In group 2, the mean BCVA improved from 35.92±6.20 (baseline) to 50.69±4.22, 48.76±5.59 and 45.70±6.56 at the same time points (P<0.01 each). However, there was no significant differences in the mean BCVA (F=0.043, P=0.836) and CRT (F=0.374, P=0.544) between these two groups. During the follow-up, five patients in group 1 and six patients in group 2 with high IOP were controlled with anti-glaucoma drugs. CONCLUSION: Intravitreal injection of bevacizumab alone or combined with triamcinolone acetonide has a short beneficial effect in Chinese patients with macular edema caused by CRVO, but there is no significant difference between the two groups.     

Efficacy and safety of micropulse laser trabeculoplasty for primary open angle glaucoma

AIM: To evaluate the efficiency and safety of micropulse laser trabeculoplasty (MLT) for primary open angle glaucoma (POAG) patients. METHODS: Retrospective study. POAG patients undergoing MLT in Peking University Third Hospital from June 2016 to November 2017. Seventy-two eyes of 72 POAG patients were enrolled. Only one eye of each patient was treated by MLT. The intraocular pressure (IOP) before MLT and at 1d, 1, 4, 12 and 24wk and glaucoma medication before and after treatment were compared. RESULTS: The IOP was 20.6±5.9 mm Hg before MLT and 20.8±6.8 mm Hg at 2h after MTL. The IOP at 1d, 1, 4, 12 and 24wk was 17.9±4.4, 18.0±4.3, 17.5±3.4, 17.0±2.7, and 16.5±2.9 mm Hg, respectively. The IOP before and after MLT demonstrated a statistically significant difference by ANOVA analyses (F=5.797, P<0.001). Least significant difference t-tests showed there was no statistically significant difference between pre-MLT IOP within 2h after MLT (P=0.207). The statistically significant difference was confirmed between the pre-MLT IOP at 1d, 1, 4, 12 and 24wk after MLT (P=0.006, 0.009, 0.001, <0.001, <0.001, respectively). The number of glaucoma medications before MLT was 1.7±1.4 and 1.5±1.4 24wk after MLT with a significantly statistical difference (t=2.219, P=0.031) CONCLUSION: MLT is effective and safe for POAG patients. No patient experienced IOP spikes after MLT. The IOP 6mo after treatment decreased significantly with less glaucoma medication.     

Erythropoietin promotes survival of retinal ganglion cells in DBA/2J glaucoma mice

PURPOSE: Retinal ganglion cell (RGC) loss occurs in response to increased intraocular pressure (IOP) and/or retinal ischemia in glaucoma and leads to impairment of vision. This study was undertaken to test the efficacy of erythropoietin (EPO) in providing neuroprotection to RGCs in vivo. METHODS: The neuroprotective effects of EPO were studied in the DBA/2J mouse model of glaucoma. Mice were intraperitoneally injected with control substances or various doses of EPO, starting at the age of 6 months and continuing for an additional 2, 4, or 6 months. RGCs were labeled retrogradely by a gold tracer. IOP was measured with a microelectric-mechanical system, and EPO receptor (EPOR) expression was detected by immunohistochemistry. Axonal death in the optic nerve was quantified by para-phenylenediamine staining, and a complete blood count system was used to measure the number of erythrocytes. RESULTS: In DBA/2J mice, the average number of viable RGCs significantly decreased from 4 months to 10 months, with an inverse correlation between the number of dead optic nerve axons and viable RGCs. Treatment with EPO at doses of 3000, 6000, and 12,000 U/kg body weight per week all prevented significant RGC loss, compared with untreated DBA/2J control animals. EPO effects were similar to those of memantine, a known neuroprotective agent. IOP, in contrast, was unchanged by both EPO and memantine. Finally, EPOR was expressed in the RGC layer in both DBA/2J and C57BL/6J mice. CONCLUSIONS: EPO promoted RGC survival in DBA/2J glaucomatous mice without affecting IOP. These results suggest that EPO may be a potential therapeutic neuroprotectant in glaucoma.     

Topically administered timolol and dorzolamide reduce intraocular pressure and protect retinal ganglion cells in a rat experimental glaucoma model

AIMS: This study sought to elucidate the effects of timolol and dorzolamide on intraocular pressure (IOP) and retinal ganglion cell (RGC) death in an experimental model of glaucoma in rat. METHODS: Mild elevation of IOP was induced in rats by intracameral injection of India ink and subsequent laser trabecular photocoagulation. IOP was measured before the surgical procedures and weekly thereafter. Timolol (0.5%), timolol XE (0.5%), dorzolamide (1%), and artificial tears (vehicle) were topically applied daily. Retinal sections were prepared for histology to determine RGC number. RESULTS: Timolol, timolol XE, and dorzolamide induced a significant reduction in IOP (p<0.05) and counteracted the reduction in RGC number that occurred in vehicle treated glaucomatous eyes (p<0.05). The coefficient of correlation between RGC number and IOP was significant in the dorzolamide treated group (r = -0.908, p<0.005), but not in other groups (p>0.05). CONCLUSIONS: Both timolol formulation and dorzolamide reduced IOP and protected RGCs in a rat model of experimental glaucoma. It cannot be ruled out that timolol might protect RGCs by additional mechanisms other than simply lowering of IOP.     

A novel neuroprotectant against retinal ganglion cell damage in a glaucoma model and an optic nerve crush model in the rat

PURPOSE: To investigate the effects of repeated treatments with a neuroprotective compound, R(-)-1-(benzo [b] thiophen-5-yl)-2-[2-(N, N-diethylamino) ethoxy] ethanol hydrochloride (T-588), on retinal ganglion cell (RGC) survival in rat eyes with elevated intraocular pressure (IOP) or after optic nerve crush. METHODS: An increase in IOP was induced by a single laser treatment to the trabecular meshwork in one eye of adult Wistar rats. Crush injury was unilaterally produced by clipping the optic nerve 2 mm behind the globe. RGC density was estimated by counting fluorescent dye-labeled cells in the flatmount of the retina. The optic nerve damage in the crush model was also evaluated histologically. RESULTS: In the elevated IOP model, RGC survival decreased to 72.9% +/- 3.8% (mean +/- SEM) of that of the contralateral control eye on the eighth day after laser irradiation. Repeated treatments with T-588 at 30 mg/kg twice daily significantly enhanced RGC survival (86.0% +/- 2.2%, P = 0.0242) without the reduction of IOP. In the optic nerve crush model, RGC survival diminished to 37.2% +/- 8.4% of that of the contralateral control eye after 4 weeks. Repeated applications with T-588 at 10 mg/kg twice daily significantly enhanced RGC survival (77.8% +/- 2.1%, P = 0.0038). Histologically, the rat optic nerve in the group treated with T-588 at 10 mg/kg retained a near-normal morphology. CONCLUSIONS: T-588 has a neuroprotective effect against RGC death caused by elevated IOP and optic nerve crush in the rat.     

Changes in visual fields and lateral geniculate nucleus in monkey laser-induced high intraocular pressure model

Monkey eyes are useful for ophthalmologic research into eye diseases because their histological and functional properties are very similar to those of humans. The monkey laser-induced high intraocular pressure (IOP) model is a common model for ophthalmologic research, especially into glaucoma. Although several studies using this model have focused on changes in visual field, retinal ganglion cells (RGC), and lateral geniculate nucleus (LGN), clear relationships among these changes in one and the same monkey have not been established. We therefore examined visual field changes, RGC and LGN numbers, and glial fibrous acidic protein (GFAP) immunohistochemistry in the LGN in each of two monkeys. Visual field sensitivity, RGC number, and neuronal density of LGN were all decreased by high IOP. The relationship between loss of RGC and decrease in visual field sensitivity depended on the eccentricity from the fovea. Moreover, LGN immunohistochemistry revealed greater increases in GFAP expression in the layers receiving a neuronal input from the high IOP eye than in those receiving a neuronal input from the contralateral untreated eye. From these results, we suggest that glaucoma may lead to changes in glial function not only in the retina, but also in the visual pathway, and that such central nervous system changes may be a hallmark of neuropathy in glaucoma, as in other neurodegenerative diseases.     

Retinal ganglion cell neuroprotection in a rat model of glaucoma following brimonidine, latanoprost or combined treatments

The aim of the present study is to evaluate the neuroprotective effect of two antiglaucomatous substances, regardless of their hypotensive effect in the eye. Brimonidine, which does not reduce IOP when administered intraperitoneally, and latanoprost, which has a renowned hypotensive effect topically. We examined rat retinal ganglion cell (RGC) survival and size distribution in experimental glaucoma in response to different glaucomatous agents. IOP was elevated by episcleral vein cauterization (EVC) prior to the application of different treatments: (I) PBS application (control group), (II) intraperitoneal administration of brimonidine (a general hypotensive agent), (III) topical application of latanoprost (an ocular hypotensive agent), and (IV) latanoprost combined with brimonidine. After 12 weeks, RGCs were retrogradely labeled with fluorogold and RGC density was analyzed. EVC caused a significant increase (42%) in IOP in each group before drug treatment. After 12 weeks of EVC, RGC survival in control vs. EVC rats was 78.9 ± 3.2%. No IOP reduction was observed in brimonidine injected rats, but RGC survival at 12 weeks was total (103.7 ± 2.7%). In latanoprost treated rats, IOP dropped by around 22% and 94.7 ± 3.7% of the RGC population survived. Finally in the latanoprost + brimonidine combined group, IOP was significantly reduced by 25% and 94.4 ± 2.2% of RGCs survived. Surprisingly, whereas EVC led to a 6% increase in RGC soma size, brimonidine treatment was associated with a 9% reduction in the soma size of RGCs at 12 weeks. We conclude that brimonidine exerts a neuroprotective effect via a mechanism which is independent of IOP reduction. These findings indicate that cell survival in glaucoma may be enhanced by neuroprotective strategies which are independent of IOP reduction. No synergistic neuroprotective effect was observed when both treatments were applied simultaneously.     

Effect of diode laser trans-scleral cyclophotocoagulation in the management of glaucoma after intravitreal silicone oil injection for complicated retinal detachments

AIMS: To evaluate the effect of trans scleral cyclophotocoagulation (TSCPC) on intraocular pressure (IOP) in the eyes retaining intravitreal silicone oil with medically uncontrolled secondary glaucoma following intravitreal silicone oil injection. METHODS: Medical records of 11 eyes of 11 patients who underwent TSCPC for medically uncontrolled glaucoma without pupillary block following intravitreal silicone oil injection for complicated retinal detachment were reviewed retrospectively. In all cases, intravitreal silicone oil was not removed for fear of retinal redetachment. Diode laser contact TSCPC was performed at a power of 1.5-2.5 W, for a duration of 2 seconds, and with 20-27 applications. IOP, number of glaucoma medications, and success rate were evaluated. RESULTS: After a mean follow up period of 52.5 (SD 8.2) (range 42-68) weeks, the mean pretreatment level of IOP, 43.0 (14.4) (26-67) mmHg, had fallen to 14.5 (4.3) (7-20) mm Hg (p=0.003). The number of glaucoma medications was reduced from 2.6 (0.8) to 0.6 (1.0) (p= 0.005). Qualified success was achieved in nine eyes (81.8%) and complete success in six (54.5%). After TSCPC, patients' retinal status had not changed. CONCLUSION: Patients with medically uncontrolled glaucoma secondary to intravitreal silicone oil injection can be treated with TSCPC in spite of the retained intravitreal silicone oil.     

Long-Term Outcome of Intravitreal Bevacizumab Followed by Ahmed Valve Implantation in the Management of Neovascular Glaucoma

Background: To report the outcome of intravitreal Bevacizumab followed by Ahmed valve implantation in the management of neovascular glaucoma in a patient group with extended follow-up. Methods: The records of 16 patients (18 eyes) with neovascular glaucoma refractory to medical therapy who presented to a single surgeon between 2006–2008 were reviewed. Patients received pan-retinal photocoagulation and then intravitreal Bevacizumab followed by Ahmed valve implantation. The main outcome measures were: control of IOP (with or without additional medication), visual acuity (VA) and failure (IOP >21 mmHg or <6 mmHg, reoperation for glaucoma, or loss of light perception). Results: Pre-operatively, all patients received pan-retinal photocoagulation followed by IVB at a mean of 15.9 (range 4–60) days prior to AGV. The mean pre-operative IOP was 37.1 mmHg (±13.4) on 3.2 (±0.87) medications. Of the 18 eyes, 14 eyes (78%) were treated with AGV alone and 4 eyes (22%) with AGV combined with cataract extraction. Sixteen eyes (89%) received mitomycin C treatment intraoperatively. Post-operatively, the mean follow-up period was 63 months (24–84). At final follow-up, the success rate was 50% (33.3% complete, 16.7% qualified) with a mean IOP of 18.1 mmHg (±9.5) on a mean number of 1.5 (±1.6) medications. The failure rate was 50%, with five eyes (27.8%) not meeting the IOP criteria for success (of these, three eyes required additional surgery to lower the IOP) and five eyes (22.2%) lost light perception. Conclusion: Intravitreal Bevacizumab followed by AGV offers long-term control of IOP without additional surgical intervention in the majority of cases.     

光相干断层扫描连续监测大鼠慢性高眼压模型视盘神经纤维厚度变化

目的:用光相干断层扫描（OCT）连续观测大鼠慢性高眼压模型视 盘神经纤维层（RNFL）厚度的变化。 方法:选用Wistar大鼠48只，随机分为3组，每组16只鼠32只眼 ，右眼为激光光凝眼，左眼为对照眼。用波长为532 nm氩激光在全麻下光凝右眼小梁网，引 起眼压 慢性、中等程度升高并观测眼压变化。眼压升高后第3、6、9周时用OCT做视盘线性扫描， 计算机自动测量视盘RNFL厚度，然后处死大鼠，将每组8只大鼠右眼做光学切片行组织学 测量RNFL厚度，将另外8只大鼠右眼做全视网膜铺片甲苯胺蓝染色，记数视网膜神经元细胞 密度，将结果进行比较分析。 结果:激光光凝后大鼠眼压缓慢、中等程 度升高，在第3、6、9 周时光凝眼眼压分别比对照眼眼压为显著升高，差异有统计学意义(P＜0.001)。 OCT检查结果显示在3、6、9周时大鼠光凝眼视盘RNFL厚度分别小于对照眼，差 异有统计学意义（P＜0.05）。处死大鼠后组织学测量RNFL厚度，在3、6、9周时，光 凝眼为（64.38±6.54）、（51.47±6.4）、（42.10±6.10）μm，对照眼厚度为（76.23±6.78）、（78.64±6.15）、（77.64±6.63）μm。将两种方法测 得RNF L厚度值进行回归分析，两者变化趋势一致，相关系数(R=0.932，P＜0.001)。全视网 膜铺片甲胺蓝染色结果显示两组视网膜神经元细胞（RGC）密度值差异有统计学意义（P＜0.0 5）。 结论:激光光凝大鼠小梁可以成功建立大鼠慢性高眼压模型；OCT对大鼠慢性高眼压模型视盘RNFL厚度的测量与 在光学显微镜下的测量值变化趋势一致，相关性好；OCT可以连续活体监测大鼠慢性高眼压 模型视盘神经纤维厚度变化，从而了解大鼠青光眼视神经病变的进展。     

米诺环素在L-谷氨酸诱导的视网膜神经节细胞损伤中的保护作用及分子机制

目的 探讨米诺环素在L-谷氨酸诱导的视网膜神经节细胞(RGC)毒性中的保护作用和分子机制.方法 实验研究.原代小鼠RGCs体外培养24 h后,随机分为3组:对照组,L-谷氨酸组(100 μmol/L、500 μmol/L、1 mmol/L和2 mmol/L)及L-谷氨酸+米诺环素组(30 μmol),观察不同浓度L-谷氨酸对RGC的存活率与轴突生长的损伤作用及米诺环素的保护作用.体内实验,将雌性B6小鼠随机分为实验组(30只)和对照组(30只).两组小鼠腹腔内分别注射米诺环素(实验组,60 mg/kg)或生理盐水(对照组),每天1次,连续7 d.第2天时,两组小鼠玻璃体腔内注射2μl L-谷氨酸(2 mmol/L),诱导RGC损伤.免疫组化染色分析β-Ⅲ-tubulin阳性细胞数目变化及视网膜神经胶质酸性蛋白(GFAP)表达情况,Real-time PCR和免疫印迹法分别检测小鼠视网膜组织中干扰素γ(IFN-γ)、白细胞介素(IL-1)、肿瘤坏死因子α(TNF-α)、GFAP与波形蛋白(Vimentin)的mRNA及蛋白表达水平.结果 体外实验显示,与对照组相比,L-谷氨酸降低RGC的存活率,与剂量和干预时间呈负相关.同时L-谷氨酸可明显抑制RGC轴突的生长,RGC轴突长度>2BL、1～2 BL、<1 BL占总细胞数比例分别从50.38%、7.83%和3.72%降至31.43%、5.05%和1.29%.而米诺环素能明显减轻L-谷氨酸对RGC的毒性作用,改善RGC轴突生长,各组细胞比例回升至51.00%、8.10%和2.43%,谷氨酸与对照组相比、米诺环素组与谷氨酸相比,差异有统计学意义(F=18.87,P<0.01).体内实验结果显示,与对照组相比,L-谷氨酸组小鼠RGC数目显著减少(45.00±10.21和68.50±2.86),而米诺环素治疗后可明显改善L-谷氨酸诱导的RGC损伤,RGC数目恢复至62.00±11.65,(F=7.6,P<0.01).谷氨酸处理后视网膜组织中GFAP的表达水平明显增高,而米诺环素明显降低视网膜组织中GFAP的表达.同时,L-谷氨酸显著提高小鼠视网膜组织中炎症相关因子IFN-γ、IL-1、TNF-α及胶质细胞相关蛋白Vimentin和GFAP的基因及蛋白表达水平,而米诺环素可显著抑制这些因子的表达.结论 L-谷氨酸损伤可诱导RGC凋亡、抑制RGC轴突生长,并上调炎症因子及视网膜相关胶质蛋白的基因与蛋白表达水平,米诺环素对L-谷氨酸所导致的视网膜神经节细胞损伤具有明显的保护作用.     

Activation of caspase 9 in a rat model of experimental glaucoma

PURPOSE: We investigated retinal ganglion cell (RGC) death and activation of caspase 9 in rats with experimental glaucoma. METHODS: Elevated intraocular pressure (IOP) was induced in rats using the Morrison model. Surviving backlabeled RGC were counted and TUNEL staining detected apoptosis. Procaspase 9 expression and activated caspase 9 were studied by immunoblot and immunohistochemistry. RESULTS: IOP correlated with surviving RGC. TUNEL-positive RGC were observed in animals with elevated IOP. Procaspase 9 levels increased with IOP intensity. Cleaved caspase 9 was detected by immunoblot only in rats with peak IOP above 35 mm Hg for > or =6 days. Cleaved caspase 9 staining was seen only in the ganglion cell layer of retinas from rats with peak IOP > or =32 mm Hg. CONCLUSIONS: RGC loss is correlated with IOP in experimental glaucoma. These results support activation of caspase 9, the intrinsic caspase cascade, in RGC death in experimental glaucoma.     

α-硫辛酸对青光眼模型大鼠视网膜神经节细胞的保护作用及其机制

目的　探讨α-硫辛酸对青光眼模型大鼠视网膜神经节细胞（RGC）的保护作用及其机制。方法　选取SPF 级雄性SD大鼠 60只,取30只大鼠,选右眼为实验眼,采用烙闭表层巩膜静脉的方法制作大鼠青光眼模型。将造模成功的大鼠随机分为两组:青光眼对照组和青光眼硫辛酸组,每组各15眼。另取30只大鼠,右眼行假手术操作,术后随机分为两组:正常眼压对照组和正常眼压硫辛酸组,每组各15眼。于造模第3周末,正常眼压硫辛酸组和青光眼硫辛酸组大鼠腹腔注射α-硫辛酸150 mg·kg^-1。分别于造模前、造模后第1周末、第2周末、第3周末、第4周末、第5周末、第6周末应用手持式眼压计测量并记录大鼠双眼眼压。分别用相应测试盒检测丙二醛(MDA)和活性氧簇(ROS)含量,超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶（GSH-Px）活性。通过TUNEL法检测RGC凋亡情况,通过免疫组织化学法检测视网膜Caspase-3 蛋白表达情况。应用GraphPadPrism6软件作图,采用SPSS 20.0统计软件分析所有数据。结果　造模后3周末开始腹腔注射α-硫辛酸,青光眼硫辛酸组大鼠右眼眼压在造模后4周、5周、6周与青光眼对照组比较,差异均无统计学意义（均为P＞0.05）。MDA和ROS含量:四组间比较差异均有统计学意义（均为P＜0.05）,均为正常眼压硫辛酸组＜正常眼压对照组＜青光眼硫辛酸组＜青光眼对照组（均为P＜0.05）。GSH-Px及SOD酶活性:四组间比较差异均有统计学意义（均为P＜0.05）,均为正常眼压硫辛酸组＞正常眼压对照组＞青光眼硫辛酸组＞青光眼对照组（均为P＜0.05）。青光眼硫辛酸组和青光眼对照组的凋亡细胞数明显高于正常眼压硫辛酸组和正常眼压对照组。正常眼压硫辛酸组RGC 凋亡指数和正常眼压对照组差异无统计学意义（P>0.05）,但均小于青光眼硫辛酸组和青光眼对照组（均为P＜0.05）;青光眼硫辛酸组RGC 凋亡指数小于青光眼对照组（P＜0.05）。青光眼硫辛酸组和青光眼对照组Caspase-3蛋白表达明显高于正常眼压硫辛酸组和正常眼压对照组。青光眼硫辛酸组Caspase-3蛋白平均光密度值小于青光眼对照组（P＜0.05）。结论　α-硫辛酸通过抗氧化作用降低Caspase-3的表达,抑制RGC凋亡,对青光眼模型大鼠RGC具有一定的保护作用。     

Pattern electroretinography in a rat model of ocular hypertension: functional evidence for early detection of inner retinal damage

With the increasing use of the rat as an animal model for glaucoma and for the evaluation of neuroprotective treatments, there is a need for a sensitive test of retinal ganglion cell (RGC) function in this species. The aims of this study were to detect functional abnormalities of the inner retina in a rat model of high intraocular pressure (IOP) using the pattern electroretinogram (PERG), and to correlate them with morphometric analysis of RGC survival and the functional integrity of the inner retina. Unilateral ocular hypertension was induced in 17 Lewis rats through laser photocoagulation. Pattern ERGs were recorded prior to lasering and 3 weeks later, using a series of shifting patterns of decreasing spatial frequency projected directly onto the animals' fundus. IOP was measured at the same intervals, and the number of surviving RGCs estimated. Low amplitude PERG signals could be recorded in response to a narrow grating of 0.368 cycles per degree (cpd), and increased with stimulus size. Lasering caused mean (+/-s.d.) IOP to increase significantly from 18.3+/-4.5 (baseline) to 29.8+/-8.8 mmHg within 3 weeks (p<0.0001). At this time, PERG amplitudes were significantly reduced (p<0.05), declining an average of 45% compared to the normotensive, control eyes. No outer retinal damage was observed, but the mean number of RGCs decreased significantly (p<0.001), from 2 525.0+/-372.4 to 1 542.8+/-333.8 cells per mm2.This decrease in RGC number was significantly (p=0.03) correlated the decrease in PERG amplitude. The correlation between functional integrity of the inner retina and the rat PERG was further demonstrated by intravitreal tetrodotoxin injections, which temporarily abolished the PERG but did not affect outer retinal activity, reflected in the flash ERG. The evidence for early functional deficits, combined with tonometry and documentation of correlated ganglion cells loss, confirms the sensitivity of this diagnostic tool and the validity and importance of this animal model in glaucoma research.