ObjectiveTo explore the light sensitivity and kinetic of the new optogenetics tools Channelrhodopsin-XXM2.0 (XXM2.0) and Channelrhodopsin-PsCatCh2.0 (PsCatCh2.0), and analyze whether they could be used to restore the visual function by optogenetics.MethodsMolecular biology techniques were used to link the gene fragments of XXM2.0 and PsCatCh2.0 to the vector pCIG(c)-msFoxn3 containing ampicillin resistant screening gene and reporter gene to form new plasmid pCIG(c)-msFoxn3-XXM2.0 and pCIG(c)-msFoxn3-PsCatCh2.0. The constructed plasmids were transfected into HEK 293T cells, and light responses were recorded in the whole cell mode with the HEKA patch clamp system. The photocurrent was recorded under three light intensity included 2.7×1016, 4.7×1015, and 6.4×1014 photons/(cm2·s). And then, XXM2.0 and PsCatCh2.0 were stimulated with 2.7×1016 photons/(cm2·s) and fully recovered. The opening and closing time constants were analyzed with Clampfit 10.6 software. At the same light intensity, photocurrents of XXM2.0 and PsCatCh2.0 were recorded by the light pulse stimulating of 2-32 Hz. The current attenuation was analyzed at long intervals of 4000 ms and short intervals of 200 ms after repeated stimulation. Comparisons between groups were performed by independent samples t test.ResultsRestriction endonuclease sites of EcoRⅠ and EcoRⅤ were successfully introduced at XXM2.0 and PsCatCh2.0 sequences. When the digestion was completed, they were ligated by T4 DNA ligase to construct new plasmids pCIG(c)-msFoxn3-XXM2.0 and pCIG (c)-msFoxn3-PsCatCh2.0, and then transfected on HEK 293T cells. The light intensity dependence was showed in XXM2.0 and PsCatCh2.0. The greater light intensity was accompanied by the greater photocurrent. Under the light intensity 6.4×1014 photons/(cm2·s) below the retinal safety threshold, large photocurrent was still generated in XXM2.0 and PsCatCh2.0 with 92.8±142.0 and 13.9±5.6 pA (t=1.24, 1.24; P=0.28, 0.29). The opening time constants of XXM2.0 and PsCatCh2.0 were 23.9±6.7 and 2.4±0.8 ms, and the closing time constants were 5803.0±568.2 and 219.9±25.6 ms. Compared with PsCatCh2.0, the opening and closing time constant of XXM2.0 were both larger than PsCatCh2.0. The differences were statistically significant (t=7.10, 31.60; P=0.00, 0.00). In terms of response frequency, XXM2.0 and PsCatCh2.0 could follow to 32 Hz high-frequency pulsed light stimulation, and all could respond to repeated light stimulation at a long (4000 ms) and a short time (200 ms) interval with the small current decay rate.ConclusionXXM2.0 and PsCatCh2.0 could be activated under light intensity with safety for the retina, and could respond to high frequency (at least 32 Hz) pulsed light stimuli with low current attenuation, which could meet the characteristics of opsins required to restore the visual function by optogenetics.
Retinal degeneration is a blind eye disease caused by changes in the function of retinal pigment epithelial cells and photoreceptor cells. Stem cell transplantation, gene therapy, retinal prosthesis implantation and other new biological technologies have made great progress in the restoration of visual function, but they still face many difficulties. Optogenetic is a new interdisciplinary technology that combines optics, physiology and genetics. It can express photosensitive proteins on retinal neurons in retinal degeneration. The light stimulation causing depolarization or hyperpolarization reaction of cells that expressed photosensitive proteins to gain light sensitivity. Compared with the immune rejection of stem cell therapy, the greater individualization of gene therapy and the greater traumatic nature of retinal prosthesis implantation, optogenetic technology has significant advantages, and it is also urgent to solve the problems of low spatial and temporal resolution and light sensitivity. With the gradual development of optogenetics technology, it is bound to form a deeper level of cross and fusion with other fields, so as to contribute to the recovery of visual function of patients with retinal degeneration.
ObjectiveTo explore the light response, retinal inflammation and apoptosis of the retinal ganglion cells (RGCs) 1 year after the new type of channelrhodopsin PsCatCh2.0 was transfected into the retina of rd1 mice. MethodsTwenty-four male rd1 mice were randomly divided into rd1 experimental group and rd1 control group, 12 mice in each group. 1.5 μl of recombinant adeno-associated virus (rAAV)2/2-cytomegalovirus (CMV)-PsCatCh2.0-enhanced green fluorescent protein (EGFP) was injected into the vitreous cavity 1 mm below the corneoscleral limbus of mice in the rd1 experimental group, and the same dose of recombinant virus was injected 2 weeks later at temporal side 1 mm below the corneoscleral limbus. One year after virus injection, the light response of RGCs expressing PsCatCh2.0 was recorded by patch clamp technique; the expression of PsCatCh2.0 in the retina was evaluated by immunofluorescence staining; the transfection efficiency of recombinant virus was evaluated by the transfection efficiency of virus and the number of RGCs. Hematoxylin-eosin staining was performed to measure the inner retinal thickness. Western blotting was used to detect the protein expression of nuclear factor (NF)-κB p65 in retina; real-time quantitative polymerase chain reaction was used to detect the relative expression of tumor necrosis factor (TNF)-α, interleukin (IL)-6 and Bax mRNA. Terminal deoxynucleotidyl transferase kit was used to observe the apoptosis of retinal cells in each group of mice. ResultsOne year after the intravitreal injection of recombinant virus, PsCatCh2.0-expressing RGCs can still generate 30 pA photocurrent. The virus PsCatCh2.0-EGFP was mainly transfected into RGCs, and partly transfected into amacrine cells, almost no transfection was seen in bipolar and horizontal cells. There were no significant differences in the number of RGCs and thickness of the inner retina between the rd1 experimental group and the rd1 control group (F=14.35, 0.05; P＞0.05), while the rd1 experimental group NF-κB p65 protein expression, TNF-α and IL-6 mRNA quantification were significantly lower than those of rd1 control group (F=4.61, 5.91, 5.78; P＜0.05). The number of red fluorescent apoptotic cells in the retina of mice in the rd1 experimental group was less than that in the rd1 control group, and the Bax mRNA expression was lower than that in the rd1 control group, and the difference was statistically significant (F=7.52, P＜0.01). ConclusionOne year after intravitreal injection of recombinant virus, the PsCatCh2.0 expressing RGCs can still generate photocurrent. Long term transfection and expression of PsCatCh2.0 has no obvious cytotoxic effect on RGCs, nor it increases the inflammatory effect of the retina of rd1 mice with retinal degeneration.
Objective To observed and analyze the clinical features of patients with nonarteritic anterior ischemic optic neuropathy (NAION) causes of misdiagnosis. MethodsA retrospective case study. From November 2014 to July 2022, 49 NAION patients with 49 eyes diagnosed in Department of Ophthalmology, The First People’s Hospital of Lanzhou were included in the study. All patients were misdiagnosed with other eye diseases at first diagnosis. All eyes were examined by best corrected visual acuity (BCVA), relative afferent pupil defect (RAPD), orbital magnetic resonance imaging (MRI), visual field, optical coherence tomography (OCT), and graphic visual evoked potential (P-VEP). Fluorescein fundus angiography (FFA) was performed in 32 eyes. Clinical and MRI, visual field, P-VEP、FFA features of the patients were retrospectively analyzed. ResultsThere were 31 males and 18 females among the 49 patients. All cases were monocular. Age was (59.3±7.8) years. All of them complained of painless visual acuity loss or occlusion sensation in one eye. There were 12 (24.5%, 12/49) and 37 (75.6%, 37/49) cases with disease duration ＞2 months and ≤2 months, respectively. In 49 eyes, misdiagnosed as optic neuritis, normal tension glaucoma (NTG) or suspected glaucoma, optic disc vasculitis, cataract, diabetic retinopathy, traumatic optic neuropathy and toxic optic neuropathy were 28 (57.1%, 28/49), 11 (22.4%, 11/49), 5 (10.2%, 5/49), 2 (4.1%, 2/49), 1 (2.0%, 1/49), 1 (2.0%, 1/49), 1 (2.0%, 1/49) eyes. 24 (49.0%, 24/49), 16 (32.7%, 16/49) and 9 (18.4%, 9/49) eyes had BCVA＜0.1, 0.1-0.5 and＞0.5, respectively. RAPD was positive in 45 eyes (91.8%, 45/49). There were 37 (75.6%, 37/49) and 12 (24.5%, 12/49) eyes with and without optic disc edema, respectively. Bleeding was observed on and around the optic disc in 15 eyes (30.6%, 15/49). MRI examination showed no obvious abnormality in the optic nerve segments of all affected eyes. OCT showed an increase in retinal nerve fiber layer thickness (307.1±62.1) μm in 37 patients with optic disc edema. The visual field examination showed that 24 eyes (49.0%, 24/49) had typical lower visual field defect connected with the physiological blind spot and circumvented the central fixation point, 6 eyes (12.2%, 6/49) had limited visual field defect connected with the physiological blind spot, and 19 eyes (38.8%, 19/49) had diffuse visual field defect. By P-VEP examination, the amplitude of P100 wave decreased moderately to severely in all affected eyes. There were 24 eyes (49.0%, 24/49) with mild peak delay and 11 eyes (22.4%, 11/49) with moderate peak delay. In 32 eyes examined by FFA, the arteries had early peridisk limitation or diffuse delayed filling, and mid-course fluorescein leakage in the corresponding area. ConclusionsThe main symptoms of NAION patients are painless visual acuity loss in one eye or occlusion of vision. The main clinical features of NAION patients are visual field defect, retinal nerve fiber layer thickening and visual electrophysiological abnormalities. NAION patients with acute or subacute visual loss accompanied by optic disc edema and/or bleeding are often misdiagnosed as optic neuritis, optic neurovasculitis and other types of optic neuropathy. NAION patients with a disease course of ＞2 months are easily misdiagnosed as NTG.
ObjectiveTo observe the clinical efficacy of oral glucocorticoids in the treatment of acute non-arteritic anterior ischemic optic neuropathy (NAION).MethodsA prospective clinical study. From December 2017 to June 2020, 40 eyes of 40 patients with acute NAION who were diagnosed in Department of Ophthalmology of Tengzhou Central People's Hospital were included in the study. All the affected eyes underwent best corrected visual acuity (BCVA) and optical coherence tomography (OCT) examination of optic disc; 35 eyes (BCVA≥0.1) underwent visual field examination at the same time. The BCVA examination was carried out using the international standard decimal visual acuity chart, which was converted into the logarithm of the minimum angle of resolution (logMAR) visual acuity during statistics. The static visual field inspection was performed with Humphrey automatic perimeter to obtain the average mean deviation (MD) value. The thickness of peripapillary retinal nerve fire layer (pRNFL) around the optic disc of the affected eye was measured with an OCT instrument. According to the wishes of patients, they were divided into hormone treatment group and control group. All were given vitamin B1 and methylcobalamin orally; the hormone treatment group was given oral prednisone acetate treatment, 60 mg/d (regardless of body weight); after 2 weeks, the dose was reduced by 5 mg every 5 days, and the dose was reduced to 40 mg and maintained until optic disc edema subsides; thereafter, the dose was quickly reduced until the drug was stopped. Three and 6 months after treatment, the same equipment and methods were used for related examinations before treatment to observe the thickness changes of BCVA, MD, and pRNFL. The thickness of BCVA, MD, and pRNFL between the two groups was compared by Mann-Whitney U test. The thickness of BCVA, MD, and pRNFL before and after treatment within the group was compared by rank analysis of variance. ResultsAmong 40 eyes of 40 cases, 21 eyes were in the hormone treatment group, and 19 eyes were in the control group. There were differences in age, sex composition, course of disease, associated systemic risk factors, BCVA, MD, and pRNFL thickness between the two groups. There was no statistical significance (P＞0.05). At 3 and 6 months after treatment, the average logMAR BCVA of the eyes of the hormone treatment group and the control group were 0.26±0.32, 0.26±0.34, 0.28±0.30, 0.25±0.32, respectively. The visual field MD were －15.52±6.87, －15.55±6.04 dB and －14.82±7.48, －15.18±6.40 dB; pRNFL thickness was 70.38±10.22, 73.79±11.82 μm and 65.67±10.07, 69.26±10.85 μm. LogMAR BCVA (Z=－0.014, －0.315; P=1.000, 0.768), visual field MD (Z=－0.041, －0.068; P=0.979, 0.957), pRNFL thickness (Z= －0.965, －1.112; P=0.347, 0.270), the difference was not statistically significant. ConclusionCompared with the control group, oral glucocorticoid treatment of acute NAION fail to improve the visual function and morphological prognosis during the 6-month follow-up period.
ObjectiveTo investigate the changes in the nerve fiber layer of the cornea in patients with demyelinating optic neuritis (DON) and its correlation with visual acuity. MethodsA cross-sectional study. From March 2021 to July 2022, 27 cases (39 eyes) of DON patients diagnosed in the Department of Neurology and Ophthalmology of Beijing Tongren Hospital Affiliated to Capital Medical University were enrolled in this study. According to the serological test results, the patients were divided into aquaporin 4 antibody associated optic neuritis (AQP4-ON group) and myelin oligodendrocyte glycoprotein antibody associated optic neuritis (MOG-ON group), with 15 cases (19 eyes) and 12 cases (20 eyes) respectively. According to previous history of glucocorticoid treatment, the patients were divided into glucocorticoid treated group and non-glucocorticoid treated group, with 17 cases (27 eyes) and 10 cases (12 eyes) respectively. Twenty healthy volunteers (20 eyes) with age- and gender-matched were selected as the control group. All eyes underwent best corrected visual acuity (BCVA) and in vivo confocal microscopy (IVCM) examinations. BCVA was performed using Snellen's standard logarithmic visual acuity chart, which was converted into logarithmic minimum angle resolution (logMAR) visual acuity during statistics. The corneal nerve fiber length (CNFL), corneal nerve fiber density (CNFD), corneal nerve fiber branch length (CNBL), corneal nerve fiber branch density (CNBD) and the density of corneal dendritic cells (DC) were detected by IVCM examination. Parameter comparison between groups by t-test and Kruskal-Wallis rank sum test. The correlation between logMAR BCVA and pamameters of corneal nerve fibers were analyzed using Spearman analysis. ResultsThe CNFL, CNFD, and CNBL of the DON group and the control group were (10.67±2.55) mm/mm2, (57.78±12.35) root/mm2, (3.27±1.34) mm/mm2, and (13.74±3.05) mm/mm2, (70.95±13.14) root/mm2, and (4.22±1.03) mm/mm2, respectively; the difference in CNFL, CNFD, and CNBL between the two groups were statistically significant (t=4.089, 3.795, 2.773; P＜0.05). The CNFL, CNBL, and CNBD of the affected eyes in the MOG-ON group and AQP4-ON group were (12.02±2.13) mm/mm2, (3.80±1.19) mm/mm2, (47.97±8.86) fibers/mm2, and (9.25±2.19) mm/mm2, (2.72±1.19) mm/mm2, (39.43±13.86) fibers/mm2, respectively; the differences in CNFL, CNBL, and CNBD between the two groups were statistically significant (t=－4.002, －2.706, －2.306; P＜0.05). The corneal DC density of the patients in the hormone treated group and the non-hormone treated group was (24.43±8.32) and (41.22±9.86) cells/mm2, respectively. The difference in corneal DC density between the two subgroups was statistically significant (P＜0.001). Correlation analysis showed that there was a significant negative correlation between logMAR BCVA and CNBL and CNFL in patients with DON (r=－0.422, －0.456; P＜0.05). ConclusionsThere are different degrees of corneal nerve fiber damage in patients with different types of DON. There was a negative correlation between BCVA and the length of corneal nerve fibers.