Novel Role of Molecular Hydrogen: The End of Ophthalmic Diseases?

Molecular hydrogen (H2) is a colorless, odorless, and tasteless gas which displays non-toxic features at high concentrations. H2 can alleviate oxidative damage, reduce inflammatory reactions and inhibit apoptosis cascades, thereby inducing protective and repairing effects on cells. H2 can be transported into the body in the form of H2 gas, hydrogen-rich water (HRW), hydrogen-rich saline (HRS) or H2 produced by intestinal bacteria. Accumulating evidence suggest that H2 is protective against multiple ophthalmic diseases, including cataracts, dry eye disease, diabetic retinopathy (DR) and other fields. In particular, H2 has been tested in the treatment of dry eye disease and corneal endothelial injury in clinical practice. This medical gas has brought hope to patients suffering from blindness. Although H2 has demonstrated promising therapeutic potentials and broad application prospects, further large-scale studies involving more patients are still needed to determine its optimal application mode and dosage. In this paper, we have reviewed the basic characteristics of H2, and its therapeutic effects in ophthalmic diseases. We also focus on the latest progress in the administration approaches and mechanisms underlying these benefits.

Crosstalk Between Microglia and Müller Glia in the Age-Related Macular Degeneration: Role and Therapeutic Value of Neuroinflammation.

Age-related macular degeneration (AMD) is a progressive neurodegeneration disease that causes photoreceptor demise and vision impairments. In AMD pathogenesis, the primary death of retinal neurons always leads to the activation of resident microglia. The migration of activated microglia to the ongoing retinal lesion and their morphological transformation from branching to ameboid-like are recognized as hallmarks of AMD pathogenesis. Activated microglia send signals to Müller cells and promote them to react correspondingly to damaging stimulus. Müller cells are a type of neuroglia cells that maintain the normal function of retinal neurons, modulating innate inflammatory responses, and stabilize retinal structure. Activated Müller cells can accelerate the progression of AMD by damaging neurons and blood vessels. Therefore, the crosstalk between microglia and Müller cells plays a homeostatic role in maintaining the retinal environment, and this interaction is complicatedly modulated. In particular, the mechanism of mutual regulation between the two glia populations is complex under pathological conditions. This paper reviews recent findings on the crosstalk between microglia and Müller glia during AMD pathology process, with special emphasis on its therapeutic potentials.

Application of Hydrogels in the Device of Ophthalmic Iontophoresis: Theory, Developments and Perspectives.

The human eye is a consolidated organ with delicate structures and unique immune privileges. Ocular diseases are intractable due to the intrinsic biological barriers within the eyeball. Hydrogels are excellent drug-carrying substances with soft material and excellent properties. They have been extensively used to deliver drugs into ocular tissue via iontophoresis devices. Ophthalmic iontophoresis is an electrochemical technique using tiny electrical currents to deliver drugs into the eye non-invasively. The early infantile iontophoresis technique often required long applying time to achieve therapeutic dose in the posterior ocular segment. The potential limitations in the initial drug concentration and the maximum safe currents would also impede the efficiency and safety of iontophoresis. Moreover, the poor patient compliance always leads to mechanical damage to the cornea and sclera during application. Advantageously, the flexible drug-carrying hydrogel can be in direct contact with the eye during iontophoresis, thereby reducing mechanical damage to the ocular surface. Moreover, the water absorption and adjustable permeability of hydrogels can reduce the electrochemical (EC) reactions and enhance the efficiency of iontophoresis. In this review, we focus on recent developments of hydrogels iontophoresis in ophthalmologic practice. Refinements of the knowledge would provide an outlook for future application of hydrogels in treating ocular disease.

The novel chalcone analog L2H17 protects retinal ganglion cells from oxidative stress-induced apoptosis.

Chalcone is a plant metabolite widely found in fruits, vegetables, spices and tea, and has anti-tumor, anti-inflammation, immunomodulation, antibacterial and anti-oxidation activities, as well as many other pharmacological and biological effects. Our team has shown that its analogs have antioxidant activity, and oxidative stress is a pathological hallmark of retinal ischemia/reperfusion injury that can lead to retinal damage and visual loss. This investigation aims to identify a chalcone that protects retinal ganglion cells in vitro from the effects of oxidative stress and examine its mechanism. Rat retinal ganglion cell-5 cells were pretreated with chalcones and then exposed to tert-butyl hydroperoxide that causes oxidative damage. Controls received dimethyl sulfoxide only or tert-butyl hydroperoxide in dimethyl sulfoxide. Only (E)-3,4-dihydroxy-2'-methylether ketone (L2H17), of the five chalcone analogs, markedly increased the survival rate of oxidatively injured RGC-5 cells. Thus, subsequent experiments only analyzed the results of the L2H17 intervention. Cell viability and apoptosis were measured. Intracellular superoxide dismutase and reactive oxygen species levels were used to assess induced oxidative stress. The mechanism of action by L2H17 was explored by measuring the ER stress/UPR pathway and the expression and localization of Nrf2. All results demonstrated that L2H17 could reduce the apoptosis of oxidatively injured cells, inhibit caspase-3 activity, increase Bcl-2 expression, decrease Bad expression, increase the activity of superoxide dismutase, inhibit the production of reactive oxygen species, increase Nrf2 immunoreactivity, and reduce the activating transcription factor 4, phospho-eukaryotic initiation factor 2 and CHOP expression. L2H17 protects retinal ganglion cells induced by oxidative stress by regulating Nrf2, which indicates that it has the potential to become a drug for retinal ischemia/reperfusion.

A modified approach to actively remove high viscosity silicone oil through 23-gauge cannula.

AIM: To report a simple approach to actively remove high viscosity silicone oil through a 23-gauge cannula via pars plana. METHODS: Forty-eight eyes of 48 patients underwent silicone oil (5700 centistokes) removal (SOR) were enrolled. A section of blood transfusion set was prepared to connect a standard 23-gauge cannula and vitrectomy machine. Silicone oil was removed with suction of 500-mm Hg vacuum through the cannula. Main outcome measures were SOR duration, number of sutured sites, intraocular pressure (IOP), best-corrected visual acuity (BCVA), and complications. RESULTS: Silicone oil was successfully removed in all cases. The mean SOR time was 5.70±0.85min. Nine eyes (18.75%) needed suture partial sclerotomies. No intraoperative complications were noted. Transient hypotony (≤8 mm Hg) was seen in 3 eyes (6.25%) on postoperative day 1, but all resolved within 1wk. Retinal reattachment was achieved in all cases and no other postoperative complications were noted during 3-month following-up. BCVA at the final visit improved or stabilized in all patients comparing to the preoperative level. CONCLUSION: Active removal of high viscosity silicone oil through a 23-gauge instrument cannula jointed with blood transfusion set is a practical and reliable technique when considering two sides of efficacy and safety.

Passive Removal of Silicone Oil with Temporal Head Position through Two 23-Gauge Cannulas.

Purpose. To report a new approach for removal of silicone oil. Methods. All surgeries were performed using 23-gauge vitrectomy system with two transconjunctival sutureless cannulas. At the beginning, most of the silicone oil was removed by traditional microinvasive vitrectomy system through inferior-temporal cannula. Then, the blood transfusion tube is removed from the inferior-temporal cannula, and the fluid-air exchange is performed. A passive fluid-air exchange was performed to aspirate the residual silicone oil after gradually turning the patient's head temporally by approximately 90° gradually. Results. After the surgery, all patients had a clear anterior chamber and vitreous cavity on slit lamp and B scan examination, respectively. The mean time taken for silicone oil removal and total surgery was 8.0 ± 1.4 minutes and 12.4 ± 2.5 minutes, respectively. The mean intraocular pressure 1 day, 3 days, 1 week, 1 month, and 3 months after surgery was 9.0 ± 5.8 mmHg, 11.3 ± 7.6 mmHg, 16.1 ± 6.9 mmHg, 17.7 ± 4.8 mmHg, and 17.1 ± 3.5 mmHg, respectively. Conclusion. This new approach may provide a safe and fast method to remove the silicone oil.

Application of 5-Fluorouracil-Polycaprolactone Sustained-Release Film in Ahmed Glaucoma Valve Implantation Inhibits Postoperative Bleb Scarring in Rabbit Eyes.

This study was designed to investigate whether 5-fluorouracil (5-Fu)-polycaprolactone sustained-release film in Ahmed glaucoma valve implantation inhibits postoperative bleb scarring in rabbit eyes. Eighteen New Zealand white rabbits were randomly divided into three groups (A, B and C; n = 6 per group). Group A received combined 5-Fu-polycaprolactone sustained-release film application and Ahmed glaucoma valve implantation, group B received local infiltration of 5-Fu and Ahmed glaucoma valve implantation, and group C received Ahmed glaucoma valve implantation. Postoperative observations were made of the anterior segment, intraocular pressure, central anterior chamber depth, blebs, drainage tube, and accompanying ciliary body detachment. The pathology of the blebs and surrounding tissues were observed at month 3 postoperatively. We revealed that the 5-Fu-polycaprolactone sustained-release film maintained a release concentration range of 13.7 ± 0.12 to 37.41 ± 0.47 µg/ml over three months in vitro. Postoperatively, diffuse blebs with ridges were found in all eyes in group A, two blebs were observed in group B, and no bleb formation was present in group C. The postoperative central anterior chamber depth in group A was significantly less than that of the other two groups. The postoperative intraocular pressure of group A stabilized at 6.33-8.67 mmHg, whereas that of group C gradually remained at 7.55-10.02 mmHg. The histopathology showed that the fibrous tissue thickness of the blebs in group A was significantly thinner than that of the other groups. We conclude that the 5-Fu-polycaprolactone sustained-release film had a sustained drug release effect, which promoted the inhibition of bleb scarring after Ahmed glaucoma valve implantation.

PI3K-mediated glioprotective effect of epidermal growth factor under oxidative stress conditions.

AIM: To determine the effects of epidermal growth factor (EGF) on the proliferation and migration of Müller cell line Moorfields/Institute of Ophthalmology-Müller 1 (MIO-M1), and its related molecular mechanisms under normal and oxidative stress conditions. METHODS: Müller cells were cultured with different concentrations of EGF in the presence or absence of varied amounts of H2O2 and glucose oxidase (GO) which induced oxidative stress. The proliferation and migration of Müller cells were examined by 5-Bromo-2-deoxyUridine (BrdU), MTT assay, Transwell assay and scratch wound healing assays. The cell viability was determined with the MTT assay. The secretion of EGF by Müller cells was evaluated by ELISA. Western blot was performed to detect the activation of extracellular regulated protein kinases (ERK)1/2 and Akt signal pathways. RESULTS: EGF stimulated the proliferation and migration of Müller cells in a concentration-dependent manner in vitro. Under oxidative damage condition, 2h of pretreatment with 10-100 ng/mL EGF can mostly inhibit 50% lethal dose of 0.08 mmol/L H2O2-induced cell damage. The Western blot results showed that after Müller cells were exposed to varying EGF for 24h, Akt and ERK1/2 were phosphorylated in a dose-dependent manner. In the presence of the LY294002, the potent PI3K inhibitor, the p-Akt was significantly attenuated. CONCLUSION: EGF may induce the proliferation and migration of human Müller cells through the Akt and the ERK1/2 signal pathways, and induce PI3K-mediated glioprotective effect under oxidative stress.

[Vitrectomy without internal limiting membrane peeling associated with gas tamponade for treatment of foveoschisis in pathologic myopia].

OBJECTIVE: To evaluate the efficacy of vitrectomy without internal limiting membrane (ILM) peeling associated with gas tamponade in eyes with myopic foveoschisis. METHODS: A prospective study was conducted, in which 49 pathological myopia patients (52 eyes) with myopic foveoschisis were enrolled and divided into three groups according to the different therapeutic procedures: 22 patients (24 eyes) underwent vitrectomy without internal limiting membrane (non-gas tamponade group), 15 patients (16 eyes) received vitrectomy without internal limiting membrane peeling but combined with gas tamponade (gas tamponade group) and 12 patients (12 eyes) did not receive surgical treatments (control group). SAS 9.13 was used for the statistic analysis. Best-corrected visual acuity (BCVA) and optical coherence tomographic (OCT) findings of the foveal thickness before and after the operation (the 3rd, 6th, and 9th month postoperatively) were obtained and compared by the Wilcoxon Rank-Sum test. Non-parameters Wilcoxon symbols test was used to compare the BCVA, the central foveal thickness (CFT) and maximum foveal thickness (MxFT) of each group before and after the surgery. RESULTS: Postoperative visual acuity was significantly increased in the two operation groups (t = 2.57, P < 0.05; t = 3.58, P < 0.05) but not increased in the control group (t = 1.84; P > 0.05). The difference of BCVA between these three groups was not significant (χ(2) = 0.24, P > 0.05). OCT showed the mean foveal thickness was significantly decreased postoperatively. Vitrectomy without peeling of the ILM significantly promoted the retinal reattachment in eyes with myopic foveoschisis. No retinal reattachment was found in the control group while 16 and 13 retinal reattachment were found in the non-gas tamponade (66.7%) and gas tamponade group (81.3%), the difference between these two operation groups and the control was statistically significant (χ(2) = 20.50, P < 0.05). During the follow-up, two eyes in the control group developed a macular hole and both developed retinal detachment (RD) in the 6 and 8 month, respectively. The remaining 10 eyes did not develop any complications, although the thickness of the macula increased significantly. A transient increase of intraocular pressure occurred in three eyes and had been cured by medications within 2 weeks after gas tamponade. A macular hole was recognized in one eye 2 months after surgery and the retina was reattached at the fovea 1 month after reoperation. CONCLUSIONS: Vitrectomy without ILM peeling could be a safe and effective surgical approach for the treatment of foveoschisis in pathologic myopia. In addition, gas tamponade can improve the success rate of the operation.

Elevated erythropoietin in vitreous of patients with rhegmatogenous retinal detachment and proliferative vitreoretinopathy.

AIM: Our purpose was to determine the vitreous erythropoietin (EPO) level in patients with rhegmatogenous retinal detachment (RRD) and proliferative vitreoretinopathy (PVR). METHODS: The levels of EPO in vitreous were measured using a sandwich enzyme-linked immunosorbent assay kit from 64 patients, of whom 40 had RRD, 13 had PVR and 11 had idiopathic macular hole as control. RESULTS: The mean levels of EPO in the RRD group (54.6 +/- 7.3 mU/ml) and PVR group (104.1 +/- 20.8 mU/ml) were significantly higher than that in the idiopathic macular hole control group (14.4 +/- 3.6 mU/ml; p < 0.001, p = 0.003, respectively). The mean EPO level in PVR was higher than that in RRD, but the difference was not significant (p = 0.112). CONCLUSION: The vitreous EPO level was upregulated in eyes with RRD and PVR.

Erythropoietin as a novel therapeutic agent for atrophic age-related macular degeneration.

The purpose of this article is to propose a novel therapeutic approach to the treatment of age-related macular degeneration (ARMD), the leading cause of blindness in the elderly population (over 60 years of age) in developed countries. Although recent advances have been made in the treatment of the neovascular form of ARMD, there is still no effective treatment for the most prevalent atrophic form of ARMD. Although the exact etiology and molecular pathogenesis of the atrophic ARMD are not fully understood, it is believed that oxidative stress and local inflammation play a major role in the pathologic processes and that the disease is triggered by dysfunction in the retinal pigment epithelia, leading to the degeneration of macular photoreceptor cells, followed by irreversible loss of vision. Considering that erythropoietin (EPO) has antioxidant, anti-inflammatory, and neuroprotective properties, we hypothesize that it can be developed as a novel therapeutic agent for the treatment of the atrophic form of ARMD. Future studies are needed to confirm or rule out this hypothesis. If successful, such studies may also help shield the lights on molecular mechanisms of atrophic ARMD.

Clinical characteristics of acute zonal occult outer retinopathy in Chinese patients.

PURPOSE: To review the clinical features of acute zonal occult outer retinopathy (AZOOR) in Chinese patients. METHODS: All patients with AZOOR during 2002-2004 in our hospitals were reviewed retrospectively. RESULTS: Seven consecutive Chinese patients with AZOOR were recruited and followed up for 4-18 months. Their age ranged from 26 to 47 years and all were affected bilaterally. They were from the cities near the Pacific Ocean and were used to eating seafood. The common complaints were slightly reduced visual acuity and photopsia. At least one eye of each patient had a visual field defect or decreased local area sensitivity and one patient had bilateral blind spot enlargement. Ten in 14 eyes showed increased numbers of vitreous cells and 4 eyes had anterior chamber inflammatory cells and a keratic precipitate. In their initial examination, minimal or no fundus changes were found, only yellow-white dots or gray dots presented on the deep retina or outer retinal layer. Fundus fluorescent angiography showed large-area depigmentation and hyperfluorescein spots corresponding to fundus findings. Electroretinogram (ERG) or multifocal ERG was abnormal in all eyes with no changes in their follow-up examination. Not all of the initial diagnoses of these patients were consistent with the final ones. CONCLUSIONS: AZOOR is not a common disease in China, but easy to misdiagnose. Female predilection, photopsia, visual field defect, ERG abnormality and minimal ophthalmoscopic changes are the common characteristics of AZOOR in Chinese patients. Living habits may play a role in the development of AZOOR.

[Prognosis of traumatic eyes with no light perception undergone vitrectomy and analysis of risk factors].

OBJECTIVE: To evaluate the prognosis of traumatic eyes with no light perception post vitrectomy, and to analyze the risk factors influencing the final results. METHODS: Five hundred and ninety nine mechanically injured eyes in 577 patients undergone vitrectomy were registered from 1999 - 2004. Thirty-eight eyes in this group showed no light perception in initial visual examination. Thirty-two eyes (84.2%) had open-globe injury, the other 6 eyes (15.8%) had closed-globe injury. Excluded the enucleated eyes, the others were followed up for at least 6 months, averaged 7.2 months. All registered data were filled in predesigned forms. Each parameter was evaluated strictly according to the standards of the protocol. The risk factors of poor prognosis and traumatic no light perception were analyzed by logistic regression. RESULTS: Fourteen eyes (36.8%) achieved anatomic and functional success. Three eyes (7.9%) attained anatomic success. Nine eyes (23.7%) were enucleated. Hypotony occurred in 4 eyes. Seven eyes were maintained by silicone oil. Atrophy of eyeball occurred in 1 eye. Twenty-one eyes (55.3%) achieved a final visual acuity of light perception or better, including: 0.2 in 3 eyes, 0.02 in 2 eyes, count finger in 3 eyes, hand move in 3 eyes, light perception in 10 eyes. Eight eyes (21.1%) remained no light perception. The logistic regression analysis identified the significant risk factors predictive of poor prognosis, including traumatic no light perception, presence of a relative afferent pupillary defect (RAPD), massive suprachoroid hemorrhage (MSCH), panretinal detachment with closed-funnel, ciliary body injury, preoperative atrophy of eyeball, prolapse of iris and aniridia, extrusion of crystalline lens, length of scleral wound greater than 10 mm and ruptured injury. These factors were also the risk factors of traumatic no light perception, excluded traumatic no light perception, prolapse of iris and aniridia. More than one risk factor usually co-exists in each eye. CONCLUSIONS: The eyes with traumatic no light perception have poor prognosis. However, 45% of them can achieve functional and anatomic success undergone vitrectomy. Eyes with no light perception are related to the combination of various risk factors. MSCH, severe retinal injury and extensive ciliary body injury are the main risk factors for poor prognosis.

Binocular membranous cataract associated with binocular retinal detachment.

A 36-year-old man with a history of consanguineous marriage between his parents presented with bilateral membranous cataract that was complicated by bilateral rhegmatogenous retinal detachment (RRD). Biomicroscopy revealed an absence of the crystalline lens bilaterally, a single piece of integrated fibrotic membrane in the right eye, and a membrane with a central cleft at the level of the ciliary process in the left eye. A small amount of residual cortex was revealed in the peripheral part of the membranes bilaterally when the pupils were dilated. Funduscopic examination showed that the vitreous liquefied and retina detached bilaterally. The successful retinal reattachment by vitrectomy and the finding of a retinal tear proved that the RD was rhegmatogenous. This case investigates bilateral membranous cataract with bilateral RRD as a new syndrome, or whether RRD may be a new complication of membrane cataract.

Proposed classification of lens capsule defects.

BACKGROUND: Capsule defects are common during or after intraocular surgery of various kinds. The purpose of this work is to establish a classification system of lens capsule defects to provide uniform description of these defects for ophthalmic research and IOL implantation. METHODS: A retrospective study of 128 patients (156 eyes) with lens capsule injury after ocular trauma and intraocular surgery was performed. The patients were divided into two groups. Capsule defects were defined and classified according to the location, size, shape and tension of the capsule and its effect on posterior chamber IOL implantation. RESULTS: Lens capsule defects were classified into four types: Type I - complete capsule; Type II - incomplete capsule, but has enough area and tension to support two IOL haptics; Type III - incomplete capsule, is able to support only one IOL haptic and the other haptic needs a suture; Type IV - no capsule, both IOL haptics need suture fixation. Type I and Type II were each divided into three subtypes. Type III was divided into two subtypes. The shape of the capsule defects included fissure-like, triangle, round, irregular and fan-like. All eyes with capsule defects can be sorted into one of these types, and it is easy to guide IOL implantation according to the classification. Type II was the most common among the two groups in this study. CONCLUSION: The classification of lens capsule defects is feasible and favorable for uniform clinical description, clinical research and IOL implantation.

[Diagnosis and differential diagnosis of acute zonal occult outer retinopathy].

OBJECTIVE: To study the clinical manifestations of acute zonal occult outer retinopathy (AZOOR) and to differentiate it from other retinal diseases. METHODS: Six patients diagnosed AZOOR had complete eye examinations including fundus photography, fundus fluorescein angiography (FFA), electroretinography (ERG), visual evoked potentials and visual field examination. Medical consultation and neurological consultation were performed in those patients. All patients were followed up and the data were collected for analysis, discussion, diagnosis and differential diagnosis. RESULTS: Six patients (five female and one male) aged 26 - 42 years (mean 35 years) with AZOOR were followed up for 4 - 18 months [mean (7.5 +/- 3.2) months]. All of them were affected bilaterally and their visual acuity were slightly reduced except one eye was CF/40 cm. Half of them had photopsia. At least one eye of each patient had visual field defect or decreased sensitivity in local area or blind-spot enlargement. Biomicroscopic examination revealed vitreous cells in 10/12 eyes and anterior chamber inflammatory cells and keratic precipitate in 4/12 eyes. Minimal (10/12 eyes) or no (2/12 eyes) fundus changes were found in their initial examination. Funduscopic examination revealed yellow-white dots (4/12 eyes) and gray dots (6/12 eyes) at the posterior pole of deep retina or retinal pigment epithelium-Bruch membrane-choroid capillary complex layer. FFA showed depigmentation (2/12 eyes) or hyperfluorescein spots (10/12 eyes) that identical to the retinal lesions. In the follow-up examination, the visual acuity was reduced in one eye and visual field defect enlarged in both eyes of one patient; the number of retinal dots increased in one eye, decreased in one eye and extinguished in one eye. ERG or mERG revealed abnormal in all of their eyes with no changes in their follow-up examination. All of the initial diagnoses of six patients were not consistent with final diagnosis. CONCLUSIONS: AZOOR is a rare eye disease, usually occurs in young females, with the characteristics of photopsia, visual field defects, abnormal ERG and slight changes in the fundus. The differential diagnosis of this disease is relatively complicate and is easily to be misdiagnosed.