Fundus photography,fluorescein angiography,optical coherence tomography and electroretinography of preclinical animal models of ocular diseases

The eye is an immune-privileged and sensory organ in humans and animals.Anatomical,physiological,and pathobiological features share significant similarities across divergent species(1).Each compartment of the eye has a unique structure and function.The anterior and posterior compartments of the eye contain endothelium(cornea),epithelium(cornea,ciliary body,iris),muscle(ciliary body),vitreous and neuronal(retina)tissues,which make the eye suitable to evaluate efficacy and safety of tissue specific drugs(2).

A New Classification for Retinitis Pigmentosa Including Multifocal Electroretinography to Evaluate the Disease Severity

Aim: To establish a useful and objective classification for retinitis pigmentosa (RP) to evaluate the disease severity. Methods: This is a retrospective cross-sectional study. Visual acuity (VA), visual field (VF) width, ellipsoid zone width on optic cohorence tomography (OCT) and multifocal electroretinography (mf ERG) values were obtained from medical records of patients with RP. A scoring criterion was developed wherein each variable was assigned a score from 0 to 5 depending on its distribution. The cumulative score (from 0 to 20) was used to classify disease severity from grade 0 to 5. The scores were correlated with each other and the final grade. Results: Data of 152 eyes of 92 patients who had the results of all tests were reviewed. The mean age was 41.2 years. The mean VA of the patients was 0.13 ± 0.16 Snellen lines. The majority of patients had a VA less than 20/40 (88.6%), a visual field smaller than 20˚ (78%), and an ellipsoid zone width smaller than 7˚ (84.4%). The majority of the patients (85.4%) were in advanced stage of the disease (Grade 4 and 5). Conclusions: We present a simple, objective and easy to use disease severity classification for RP which can be used to categorize patients and to evaluate and compare treatment results.

Comparison of ring 1 parameters in 37-segment multifocal electroretinography between onset and offset conditions of ring 2 to 4 in normal subjects

AIM: To investigate whether the response of a central hexagonal element corresponding to the macular area in conventional multifocal electroretinography(mfERG) tests was the same as that of experimental mfERG using single central hexagonal element stimulation. METHODS: Prospective, observational study. Thirty healthy subjects were included in this study. mfERG recordings were performed according to two protocols: stimulus with 37 hexagonal elements(protocol 1), and stimulus with a single central element created by deactivating the other 36 hexagonal elements(protocol 2). We compared differences between ring 1 parameters in each protocol. RESULTS: In protocol 1, the first positive component(P1) implicit time and P1 amplitude were 37.8±1.8 ms and 6.3±2.7 μV. After single element stimulation(protocol 2), double positive waves appeared. The implicit time and amplitude of P1 were 40.7±2.4 ms(P<0.001) and 9.1±3.3 μV(P=0.001), respectively. The implicit time and amplitude of the second positive component(P2) were 68.0±4.5 ms(P<0.001, compared with P1 in protocol 1) and 12.3±4.7 μV(P<0.001, compared with P1 in protocol 1), respectively. The amplitude of P2 in protocol 2 was about two times higher than that of P1 in protocol 1. CONCLUSION: mfERG responses of a central hexagonal element in a single element stimulation protocol are different from those of multiple element stimulation. The positive wave is more enhanced compared to that of the conventional protocol and it elongated into two wavelets.

Demonstration of reversible retinal ganglion cell dysfunction in inflammatory optic neuropathies utilizing pattern electroretinography

Dear Editor,I am Dr.Austin Bach from Larkin Community Hospital in South Miami,Florida,USA.I am writing to you to present three cases of inflammatory optic neuritis that was followed to resolution using pattern electroretinography（PERG）.

Prophylactic Pattern Scanning Laser Retinal Photocoagulation for Diabetic Retinopathy in Spontaneously Diabetic Torii Fatty Rats: Preliminary Experimental Results

Research Background and Purpose: The number of diabetic patients is rapidly increasing, making it crucial to find methods to prevent diabetic retinopathy (DR), a leading cause of blindness. We investigated the effects of prophylactic pattern scanning laser retinal photocoagulation on DR development in Spontaneously Diabetic Torii (SDT) fatty rats as a new prevention approach. Methods: Photocoagulation was applied to the right eyes of 8-week-old Spontaneously Diabetic Torii (SDT) fatty rats, with the left eyes serving as untreated controls. Electroretinography at 9 and 39 weeks of age and pathological examinations, including immunohistochemistry for vascular endothelial growth factor and glial fibrillary acidic protein at 24 and 40 weeks of age, were performed on both eyes. Results: There were no significant differences in amplitude and prolongation of the OP waves between the right and left eyes in SDT fatty rats at 39 weeks of age. Similarly, no significant differences in pathology and immunohistochemistry were observed between the right and left eyes in SDT fatty rats at 24 and 40 weeks of age. Conclusion: Prophylactic pattern scanning retinal laser photocoagulation did not affect the development of diabetic retinopathy in SDT fatty rats.

Adipose mesenchymal stem cell-derived extracellular vesicles reduce glutamate-induced excitotoxicity in the retina

Adipose mesenchymal stem cells(ADSCs)have protective effects against glutamate-induced excitotoxicity,but ADSCs are limited in use for treatment of optic nerve injury.Studies have shown that the extracellular vesicles(EVs)secreted by ADSCs(ADSC-EVs)not only have the function of ADSCs,but also have unique advantages including non-immunogenicity,low probability of abnormal growth,and easy access to target cells.In the present study,we showed that intravitreal injection of ADSC-EVs substantially reduced glutamate-induced damage to retinal morphology and electroretinography.In addition,R28 cell pretreatment with ADSC-EVs before injury inhibited glutamate-induced overload of intracellular calcium,downregulation ofα-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid receptor(AMPAR)subunit GluA2,and phosphorylation of GluA2 and protein kinase C alpha in vitro.A protein kinase C alpha agonist,12-O-tetradecanoylphorbol 13-acetate,inhibited the neuroprotective effects of ADSC-EVs on glutamate-induced R28 cells.These findings suggest that ADSCEVs ameliorate glutamate-induced excitotoxicity in the retina through inhibiting protein kinase C alpha activation.

Neural and Müller glial adaptation of the retina to photoreceptor degeneration

The majority of inherited retinal degenerative diseases and dry age-related macular degeneration are characterized by decay of the outer retina and photoreceptors,which leads to progressive loss of vision.The inner retina,including second-and third-order retinal neurons,also shows aberrant structural changes at all stages of degeneration.Müller glia,the major glial cells maintain retinal homeostasis,activating and rearranging immediately in response to photoreceptor stress.These phenomena are collectively known as retinal remodeling and are anatomically well described,but their impact on visual function is less well characterized.Retinal remodeling has traditionally been considered a detrimental chain of events that decreases visual function.However,emerging evidence from functional assays suggests that remodeling could also be a part of a survival mechanism wherein the inner retina responds plastically to outer retinal degeneration.The visual system’s first synapses between the photoreceptors and bipolar cells undergo rewiring and functionally compensate to maintain normal signal output to the brain.Distinct classes of retinal ganglion cells remain even after the massive loss of photoreceptors.Müller glia possess the regenerative potential for retinal recovery and possibly exert adaptive transcriptional changes in response to neuronal loss.These types of homeostatic changes could potentially explain the well-maintained visual function observed in patients with inherited retinal degenerative diseases who display prominent anatomic retinal pathology.This review will focus on our current understanding of retinal neuronal and Müller glial adaptation for the potential preservation of retinal activity during photoreceptor degeneration.Targeting retinal self-compensatory responses could help generate universal strategies to delay sensory disease progression.

Magnesium acetyltaurate prevents retinal damage and visual impairment in rats through suppression of NMDA-induced upregulation of NF-κB,p53 and AP-1(c-Jun/c-Fos)

Magnesium acetyltaurate(MgAT)has been shown to have a protective effect against N-methyl-D-aspartate(NMDA)-induced retinal cell apoptosis.The current study investigated the involvement of nuclear factor kappa-B(NF-κB),p53 and AP-1 family members(c-Jun/c-Fos)in neuroprotection by MgAT against NMDA-induced retinal damage.In this study,Sprague-Dawley rats were randomized to undergo intravitreal injection of vehicle,NMDA or MgAT as pre-treatment to NMDA.Seven days after injections,retinal ganglion cells survival was detected using retrograde labelling with fluorogold and BRN3A immunostaining.Functional outcome of retinal damage was assessed using electroretinography,and the mechanisms underlying antiapoptotic effect of MgAT were investigated through assessment of retinal gene expression of NF-κB,p53 and AP-1 family members(c-Jun/c-Fos)using reverse transcription-polymerase chain reaction.Retinal phospho-NF-κB,phospho-p53 and AP-1 levels were evaluated using western blot assay.Rat visual functions were evaluated using visual object recognition tests.Both retrograde labelling and BRN3A immunostaining revealed a significant increase in the number of retinal ganglion cells in rats receiving intravitreal injection of MgAT compared with the rats receiving intravitreal injection of NMDA.Electroretinography indicated that pre-treatment with MgAT partially preserved the functional activity of NMDA-exposed retinas.MgAT abolished NMDA-induced increase of retinal phospho-NF-κB,phospho-p53 and AP-1 expression and suppressed NMDA-induced transcriptional activity of NF-κB,p53 and AP-1 family members(c-Jun/c-Fos).Visual object recognition tests showed that MgAT reduced difficulties in recognizing the visual cues(i.e.objects with different shapes)after NMDA exposure,suggesting that visual functions of rats were relatively preserved by pre-treatment with MgAT.In conclusion,pre-treatment with MgAT prevents NMDA induced retinal injury by inhibiting NMDA-induced neuronal apoptosis via downregulation of transcriptional activity of NF-κB,p53 and AP-1-mediated c-Jun/c-Fos.The experiments were approved by the Animal Ethics Committee of Universiti Teknologi MARA(UiTM),Malaysia,UiTM CARE No 118/2015 on December 4,2015 and UiTM CARE No 220/7/2017 on December 8,2017 and Ethics Committee of Belgorod State National Research University,Russia,No 02/20 on January 10,2020.

Correlation between optical coherence tomography, multifocal electroretinogram findings and visual acuity in diabetic macular edema

AIM:To analyze the correlation between macular morphology and function in eyes with diabetic macular edema(DME).METHODS:Fifty-five eyes with different visual acuity(VA)of 32 patients who suffered from DME were analyzed using multifocal electroretinography(mfERG)and optical coherence tomography(OCT).The parameters of mfERG including implicit times and response amplitude were compared to those of 50 normal eyes of 36 age-matched subjects.Correlation analysis was performed between VA,the parameters of mfERG including implicit times and response amplitude,and the central macular thickness(CMT).RESULTS:The amplitude of N1 and P1 were significantly decreased and their latency were significantly increased in five ring regions of the retina in patients with DME.There was statistically significant correlation between logMAR BCVA and P1 amplitude densities in rings 1-4(r=-0.306,-0.536,-0.470,-0.362;P=0.023,<0.01,<0.01,0.007 respectively),N1 amplitude in ring 2 and ring 3(r=-0.035,-0.286;P=0.019,0.034 respectively).There was poor correlation between the CMT and best-corrected visual acuity(BCVA;r=0.288,P=0.033),but there was no significant correlation between CMT and amplitude or implicit time of N1 and P1(P>0.05)in the central macular ring.Multiple stepwise regression analysis showed that P1 amplitude density in ring 2 was the only contributor to the VA.CONCLUSION:It seems to be more appropriate of combining use of mfERG with OCT for the evaluation of macular function in eyes with DME.

Suprachoroidal injection of ketorolac tromethamine does not cause retinal damage

Rabbit right eyes were injected with 3 or 6 mg ketorolac tromethamine into the suprachoroidal space. Electroretinography results demonstrated no abnormal changes in rod cell response, maximum rod cell or cone cell mixing reaction, oscillation potential, cone cell response, waveform, amplitude, and potential of 30 Hz scintillation response in right eyes before injection, and at 1,2, and 4 weeks after injection. There was no difference between left （control） and right eyes. Under light microscopy, the histomorphology of cells in each retinal layer was normal at 4 weeks following 6 mg ketorolac tromethamine administration. These results indicate that a single suprachoroidal injection of 3 or 6 mg ketorolac tromethamine into rabbits was safe. Suprachoroidal space injection appears to be safe.

Incomplete fluid-air exchange technique for idiopathic macular hole surgery

AIM: To explore an improved procedure involving incomplete fluid-air exchange for idiopathic macular hole(IMH), and the closure rate, visual function, and the visual field of macular holes(MHs) were evaluated.METHODS: This prospective randomized controlled study, included 40 eyes of 40 patients with IMH who were treated with pars plana vitrectomy and peeling of the internal limiting membrane. They were grouped by random digital table. Twenty-one eyes underwent incomplete fluidair exchange(IFA) and 19 eyes underwent traditional complete fluid-air exchange(CFA) as the control group. Outcomes included best-corrected visual acuity(BCVA), intraocular pressure, and optical coherence tomography, light adaptive electroretinography, and visual field evaluations.RESULTS: All MHs <400 μm were successfully closed. BCVAs before and 6 mo after surgery were 0.82±0.41 logMAR and 0.28±0.17 logMAR in IFA group and 0.86±0.34 logMAR and 0.34±0.23 logMAR in CFA group, respectively. The electroretinogram analysis of patients in IFA group revealed increases in b-wave amplitudes at 1, 3, and 6 mo after surgery. Additionally, patients in IFA group showed an amplitude increase of 28.6% from baseline at 6 mo(P<0.05), while no obvious improvements were noted in CFA group. Although there were no statistically significant improvements in either group, the IFA group showed a slight increase in mean sensitivity(P>0.05).CONCLUSION: IFA is a reliable method that offers comparable closure rate to CFA and facilitates improvements in visual function.

Negative effects of enlarging internal limiting membrane peeling for idiopathic macular hole surgery

AIM: To observe the effects of the different extents of internal limiting membrane(ILM) peeling on the surgical success and anatomical and functional outcomes of idiopathic macular hole(IMH).METHODS: In this retrospective cohort study, 36 patients were reviewed and divided into two groups according to the extent of ILM peeling: group A(18 patients), with the peeling area within one-half of the optic disc macular distance as the radius;group B(18 patients), with the peeling area larger than that of group A but did not exceed the optic disc macular distance as the radius. The main outcomes included the best corrected visual acuity(BCVA), light-adaptive electroretinography, macular hole(MH) closure rate, central macular thickness(CMT), retinal nerve fiber layer(RNFL) and ganglion cell complex(GCC) thickness [nine regions based on the Early Treatment of Diabetic Retinopathy Study(ETDRS) ring] before and 1, 3, and 6mo after surgery.RESULTS: The closure rate was 94.4%(17/18) both in groups A and B. The BCVA in both groups improved significantly compared with the preoperative values, but there was no difference between the two groups. The b-wave amplitude of the electroretinogram analysis was significantly improved in both groups compared to that of the preoperative period, with a greater increase in group A than in group B at 6mo(P=0.017). The CMT in both groups gradually decreased after surgery, and there was no difference between the two groups. The RNFL thickness of the temporal outer ring region in group B was significantly lower than that in group A at 3 and 6mo after surgery(P=0.010, 0.032). The GCC thickness of the temporal outer ring region in group B was significantly lower than that in group A at 6mo after surgery(P=0.038).CONCLUSION: Enlarging the extent of ILM peeling doesn’t affect the IMH closure rate and visual acuity recovery, but the greater the extent of peeling, the greater the damage to the inner retinal structures.

Safety threshold of intravitreal clonidine in rabbit's eyes

AIM： To determine the safe dose of intravitreal clonidine（IVC）, a potential drug for neuroprotection and angiogenesis inhibition in rabbits. METHODS： A total of 28 rabbits were divided into four groups. Three groups received IVC with concentrations of 15（Group A）, 25（Group B）, and 50（Group C） g/0.1 m L and the control group（Group D） received 0.1 m L balanced salt solution（BSS）. To investigate IVC safety, electroretinography（ERG） was performed at baseline, then at 1, 4 and 8 wk after injection. After last ERG, all rabbits were euthanized, their eyes were enucleated and subjected to routine histopathological evaluation, immunohistochemistry for glial fibrillary acidic protein（GFAP） and terminal deoxynucleotidyl transferase d UTP nick end labeling（TUNEL） test.RESULTS： Based on ERG, histopathology, GFAP and TUNEL assay findings, 15 g IVC was determined as the safe dose in rabbit eyes. While, the results of routine histopathology and TUNEL assay were unremarkable in all groups, toxic effects attributed to 25 and 50 g IVC were demonstrated by ERG and GFAP tests. CONCLUSION： Totally 15 g clonidine is determined as the safe dose for intravitreal injection in rabbits. Contribution of IVC in neuroprotection and inhibition of angiogenesis deserve more studies.

Relationship between Copper-Induced Lipid Peroxidation and Retinal Damage in Intraocular Copper Foreign Bodies

At different,time after copper wire induced into the vitreous of the rabbits,malondialdehydes(MDA)in the retinas and trace element coppar in the aqueous humor and Pa-thology were observed.One day after the induction of copper,the level of MDA increasedabout three times in the retinas of experimental eyes as compared with the control eyes(p【0.01)and the amplitude of electroretinography(ERG)dropped rapidily following increase ofcopper ions in the vitreous.The tncrease of concentration of copper ions in the vitreous wasclosely correlated with that of MDA in the retinas (p【0.01).Early EM examination of ex-perimental eyes reveaisd damage of retinal membranous structure rich in oxygen andpolyunsaturated acid(PUFA),including the ovaer and inner segments of the photoreceptors.These results indicate thu copper-induced isptd peroxidation is an important cause of retinaldumage.

The ocular toxicity and pharmacokinetics of simvastatin following intravitreal injection in mice

AIM：To investigate the retinal toxicity and pharmacokinetics of simvastatin intravitreally injected into mice.METHODS：Forty-eight 6-8-week-old C57BL/6J mice were used in this study.Simvastatin was intravitreally injected into the right eye of each mouse;the left eye was injected with vehicle and was used as a control.Bilateral dark-adapted electroretinography（ERG）was performed 1 and 7d following injection.Histology was examined using a combination of light,fluorescence and electron microscopy.Highperformance liquid chromatography（HPLC）was used to determine the decay in the retinal simvastatin concentration.RESULTS：ERG revealed no significant changes in the simvastatin-injected eyes compared to control.Histologic studies showed normal retinal morphology in eyes injected with simvastatin up to a final vitreal concentration of 200μmol/L.No significant changes in the number of photoreceptors,bipolar cells or ganglion cells were found.The retinal simvastatin concentration decayed exponentially,with a half-life of 1.92-2.41h.CONCLUSION：Intravitreal injection of up to 200μmol/L simvastatin produced no signs of adverse effects in the mouse retina.Simvastatin reaches the retina shortly after intravitreal injectionand has a short half-life.

Hyperbaric oxygen treatment for experimental intraocular hypertension in rats: An electroretinogram detection

BACKGROUND： Hyperbaric oxygen （HBO） is used for treating glaucoma, and affirmative curative effect has been obtained. HBO can sensitively reflect the obviously heightened b wave of electroretinogram （ERG） of injured tissue. OBJECTIVE： To observe the effect of HBO treatment on retinal function of rats with acute experimental intraocular hypertension with ERG. DESIGN： Randomized controlled experiment. SETTING： Department of Ophthalmology, Third Xiangya Hospital, Central South University; Department of Hyperbaric Oxygen, Xiangya Hospital, Central South University; Department of Anatomy, Xiangya Hospital, Central South University. MATERIALS： Eighteen adult healthy Wistar rats, of either gender, weighing from 150 to 250 g, were provided by the Animal Room of Central South University. Type YLCO. 5/I A baby hyperbaric oxygen chamber, type LMS-2A two-channel physiological recorder, type BG-1 retina exposure system, Jiangwan type Ⅰ stereotaxis instrument. METHODS： This experiment was carried out in the Central South University between March and September 2006. Eighteen healthy Wistar rats were made into models of acute experimental intraocular hypertension. Then, they were divided into two groups： model group and HBO treatment group, with 9 in each group. Following 7 days of HBO treatment, the rats in HBO treatment group were placed in Type YLCO. 5/I A baby hyperbaric oxygen chamber, which was pressurized with pure oxygen（ volume fraction 0.825 ± 0.025）.The treatment pressure was 0.2 MPa. The rats in HBO treatment group daily inhaled HBO for 80 minutes within 7 days; Rats in the model group were untouched. The performance of eyes was observed under the status of intraocular hypertension. ERG was recorded before, during and 7 days after modeling, meanwhile, the recovery rate of b wave from ERG was calculated. Recovery rate of b wave from ERG=（amplitude orb wave 7 days after modeling/amplitude orb wave before modeling）× 100%. MAIN OUTCOME MEASURES： ①Performance of eyes under the status of intraocular hypertension. ②Recovery rate orb wave of ERG. RESULTS： All the 18 rats were involved in the final analysis. ①Performance of eyes under the status of intmocular hypertension.： When intraocular pressure increased until b wave of ERG disappeared, two eyes of rats with corneal opacity, dilated pupils, pale iris and stiffened eyeballs were found. ②Recovery rate of b wave of ERG in the HBO treatment group was significantly higher than that in the model group [（60.04±19.33）% vs. （41.85 ± 13.20）%, t =3.298, P 〈 0,01]. CONCLUSION： HBO treatment can obviously promote the recovery of retinal function following acute intraocular hypertension.

Neuroretinal dysfunction in patients affected by neurofibromatosis type 1

AIM:To examine neuroretinal function by using the multifocal electroretinography(mf ERG)test in patients with neurofibromatosis type 1(NF1)without optic pathway gliomas(OPGs).METHODS:This study was conducted on 35 patients(35 eyes)with NF1 and 30 healthy subjects(30 eyes)for the control group.Each subject underwent a complete ophthalmological examination including spectral domainoptical coherence tomography(SD-OCT)and mf ERG.The 1.5-Tesla magnetic resonance imaging(MRI)scan of the brain was performed in NF1 patients to assess the presence of OPGs.All participants were recruited having a best corrected visual acuity(BCVA)of no less than 20/20 in each eye.The amplitude and implicit time of the P1 wave(first-order Kernel component)were evaluated on mf ERG.Data analysis was carried out in the two central degrees and in the four quadrants from two to 25 degrees of visual field.RESULTS:Statistically significant results were obtained for the P1 wave amplitudes in the 4 quadrants in NF1 patients compared to healthy controls,while the reduction was not significant in the 2 central degrees between the groups.A statistically significant difference was observed among the P1 wave amplitudes as recorded in the 4 quadrants within the NF1 group,with lower amplitudes detected in the nasal quadrants.No differences in the implicit times were recorded in the 2 central degrees and in the 4 quadrants as compared between NF1 patients and controls.CONCLUSION:Impaired neuroretinal function in NF1 patients is expressed in a decreased amplitude of the P1-wave between 2 and 25 central retinal degrees on mf ERG.Altered intracellular signal transduction due to abnormal neurofibromin-mediated cyclic adenosine monophosphate(c AMP)generation,can be involved.The possible use of mf ERG as subclinical retinal damage indicator has a potential utility in clinical practice for the follow-up of NF1 patients.

What is new in central serous chorioretinopathy?

Central serous chorioretinopathy(CSCR) is considered a benign, self-limiting disease. However, as many as third of the patients have recurrent episodes or chronic disease that may cause significant functional impairment. New diagnostic tools and new treatment modalities are emerging in order to improve the functional outcomes of these patients. Spectral domain optical coherence tomography(SD-OCT) has the ability to image individual layers of the retina and choroid. SD-OCT images in CSCR patients have demonstrated increased subfoveal thickness measurements, high reflective deposits in areas of subretinal precipitates and changes in the Retinal pigment epithelium layers of the asymptomatic eyes of patients with supposedly unilateral CSCR. A positive correlation was found between the level of distribution to the layer of inner segment/outer segment junction of the photoreceptors and the visual impairment. Fundus autoflouresence images show a wide variety during different stages of the disease in CSCR patients. Minimal abnormalities during the early stages are followed by hyperautofluoresence in the detached area in later stages, often in a manner of inferior gravitation and at the borders of the detachments. The chronic phase is characterized by varying degrees of atrophy and areas of decreased autofluorescence surrounding areas ofchronic leaks. These changes help differentiate an active disease from an inactive state. Multifocal electroretinography(mf ERG) has the ability to demonstrate a persistent depression despite the resolution of subretinal detachments. It is therefore being investigated as a follow up tool for patients with chronic CSCR. An excellent correlation was found between changes in mf ERG and visual function. Macular microperimetry, measuring retinal sensitivity within the central visual field, is intended to compensate for the underestimation of visual impairment in patients with macular diseases. Reduced retinal sensitivity was found in areas of previous subretinal fluids in CSCR patients. The device can also serve as a follow up tool in these patients. Regarding treatment in CSCR patients, focal argon laser photocoagulation treatment may be applied to small extrafoveal leaks. However, the main purpose of this treatment is to shorten disease duration, with no advantage over observation regarding final visual outcome, rate of progression to chronic CSCR or number of recurrences. Photodynamic therapy(PDT) with verteporfin has been shown to completely resolve serous detachment in 60%-80% of patients and to have a partial affect in the remaining patients. Reduced-fluence treatment is replacing fullfluence therapy in order to minimize side effects with no accompanying reduced effectiveness. Visual acuity is also improved following reduced-fluence PDT compared to placebo. It has also been found that patients with intense hyperfluorescence are more likely to show resolution of accumulating fluid compared to patients with mild or no leakage observed on indocyanine-green angiography prior to treatment. Regarding newer treatment modalities, intravitreal injections of anti-vascular endothelial growth factor agents have a limited effect in patients with CSCR. Recent reports have not demonstrated an advantage for this treatment in regards to anatomic and functional outcome. Micropulse diode laser was not proven to be safer or more effective than argon laser or PDT. Corticosteroid antagonists, not tested in controlled trials, may have a beneficial effect in patients with CSCR. Aspirin may also play a role in treating these patients, with rapid recovery of visual acuity and reduced number of recurrences observed. In conclusion, imaging is evolving rapidly while the clinical implications of these new imaging modalities are less clear. Large randomized trials investigating different treatment modalities are still lacking.

AB043.The glial protein Nogo-A is necessary to maintain retinal structure and function in physiological conditions

Background:Our previous studies revealed that Nogo-A gene ablation improved visual function recovery after retinal injury.Moreover,Nogo-A expression is highly expressed in the healthy retina.Its physiological role in retinal function is not known.The purpose of this current study was to determine the effects of acute Nogo-A silencing on retinal neuron structure and function in physiological conditions.Methods:Nogo-A silencing was done by intravitreal injection of adeno-associated virus serotype 2.2 containing a short hairpin RNA sequence(AAV2.2 shRNA-Nogo-A)and a GFP reporter gene in adult C57BL/6J mice.As control,an empty AAV2.2 vector was used.Infection of retinal cells was followed by fluorescent fundoscopy.Changes in Nogo-A expression were analysed by Western blotting in whole retinal lysates.Electroretinography was used to monitor retinal activity.The assessment of optokinetic reflex(OKR)allowed to follow visual acuity in unrestrained mice.Immunofluorescence on histological sections using the following cell markers,i.e.,RNA-binding protein with multiple splicing(RBPMS)and sex-determining region Y-box 2(Sox-2)allowed to visualize retinal ganglion cells(RGCs)and Müller glia respectively.Results:GFP fluorescence revealed efficient AAV2.2 transfection in the ganglion cell layer and the inner nuclear layer 30 days after viral injection.By Western blotting,Nogo-A expression was decreased by~75%in AAV2.2-shRNA-Nogo-A-treated retinae(n=3)as compared to the control mice(n=3).Strikingly,AAV2.2-shRNA-Nogo-A-injected animals(n=10)had a visual acuity reduction of 43.7%as compared to control(n=7),60 days after transfection.Electroretinography(ERG)b-wave and a-wave amplitudes were also decreased by~35%and 24.4%respectively relative to controls.After two months of transfection,RBPMS-positive RGCs were reduced by~30%in AAV2.2-shRNA-Nogo-A(n=4)compared to non-injected contralateral eyes(n=4).The number of Sox2-expressing Müller cells was not affected after Nogo-A knockdown.Conclusions:Nogo-A gene silencing in the retina has deleterious effects on the mouse retinal structure and function,suggesting an important role for Nogo-A in retinal physiology.

Multifocal electroretinograms in the early stages of diabetic retinopathy

OBJECTIVE: To investigate the characteristics of multifocal electroretinograms (mf-ERG) of different phases in diabetic retinopathy (DR) and its clinical significance. METHODS: Multifocal electroretinograms in patients with DR (I - II stage) were tested with VERIS IV system. RESULTS: In I - II stage, the absolute values of N1, P1 and N2 response densities, and the N1-P1 and P1-N2 response densities were attenuated is a field of about 45 degrees in diameter. CONCLUSION: As a new objective and quantitative examination for spatial visual function, multifocal electroretinograms may be valuable in the diagnosis of diabetic retinopathy.