PURPOSE:Investigating on histopathologic changes of the photoreceptors in retinitis pigmentosa. METHODS:Observation of the photoreceptors of retinitis pigmentosa in 11 eyes among 9 cases using light and electron microscope. RESULTS: The pathologic changes of the photoreceptors were found to be mostly marded at the equatorial area and less at the periphery,posterior pole and macular region of the retina. In relatively early cases,degeneration and shortening of outer segments,reduction or loss of connecting cilia,stubby inner segments and swollen mitochondria Were the predominant findings. In advanced cases,the inner and outer segments and connecting cilia were diminished with reduction of nuclei in number and disarangement,cellular degeneration and disorganization. The outer limiting membrane adhered to RPE or Bruch membrane. The spaces left over by the above pathologic changes were replaced by the displaced Muuml;ller cells and their hypertrophic processes. Also there were degeneration of the RPE cells,and some of them might migrate into the retina. CONCLUSION:Obvious invasions of pathologic processes in photoreceptors of the retina did present in patients with retinitis pigmentosa. （Chin J Ocul Fundus Dis,1996,12:160-162）
Objective To study on the ultrastructural characteristic of segments of photoreceptors from neonatal retinas for supporting donor retina choice of retinal transplantation． Methods Photoreceptors from neonatal calf and adult calf were analysed by scanning electron microscopy and transmission electron microscopy． Results Segments of photoreceptors from neonatal calf appeared the mushroom pattern, in which, distal end of outer segment which was ball-shaped formed the head with mushrooms appearance, and the inner segments along with some of outer segments formed the body with mushrooms appearance． Within the outer segment, plasma membranes of adjacent evaginations form a disk subsequently． The a rray of most disks were vertical to the entire length of segments, but some were parallel and slope to．Owing to the incomplete formation, some rim of disk near distal end of outer segment revealed step-shaped appearance． The distal end of outer segment displays some processes consisted of membranous discs, much vesicular material and mitochondria, much rough endoplasmic reticulum (RER) and numerous polyso mes．Segments of photoreceptor connected with outer nuclear layer via the external limiting membrane． Conclusion The typical morphol ogical structures of outer segments suggest the immature and b gowth ability of photoreceptors of the retina of neonatal calf, and therefore the competence for donor material of retinal transplantation． (Chin J Ocul Fundus Dis, 2001,227-229)
Aminoadipic acid(AAA) is known to damage retinal glia cells primarily when it is given to animals intravitreally. The present study is to demonstrate marked increase of retinal susceptibility to photic damage following administration of sub-thres-hold doses of this agent to albino rats. Right eyes were intravitreally injected with 10 ?l of 10 mM AAA, a dose which caused transient swelling of Muller cell nucleiimmediately after treatment, and total recovery by 24 hours. These rats were exposed to fluorescent light at 150 f.c. for one hour three days after injection. The left eyes were injected with the same amount of physiologic saline solution and exposed to light with an identical time schedule. The animals were killed at the 24th hour,third and seventh day, following light exposure. Cytologic changes in the retinae of both eyes were compared light microscopically. The light exposed left eyes showed mild disorganization of photoreceptor outer segements. Usually this change disappeared by the seventh day. AAA-injected right eyes showed marked destruction in the photoreceptor cell layer. The change in the photoreceptor cells was progressive and disappearance of outer segments and degeneration of numerous nuclei occurred during the following period. （Chin J Ocul Fundus Dis,1992,8:17-19）
ObjectiveTo observe the morphological characteristics of photoreceptor necroptosis in experimental retinal detachment, and explore the mechanism. MethodsA total of 60 Sprague-Dawley male rats were included in this study. Retinal detachment were induced in the right eyes with 1% sodium hyaluronate (50 μl) injection (experimental group), while the left eyes received no treatment (control group). At 3 days after modeling, the morphological characteristics of photoreceptor cell were observed by electron microscopy. Cleaved Caspase 8 and phosphorylation receptor-interacting protein 1 (p-RIP1) were measured by Western blot and immunoprecipitation. ResultsAt 3 days after modeling, photoreceptor necroptosis showed the following morphological features: chromatin condensation, severe vacuolation, early loss of plasma membrane integrity, and many autophagosomes. Western blot showed that the protein expression of cleaved Caspase 8 were 0.78±0.03, 0.06±0.01 in experimental group and control group respectively, which was significantly different (F=4 023.21, P < 0.05). Immunoprecipitation showed that the protein expression of p-RIP1 were 0.23±0.03, 0.14±0.02 in experimental group and control group respectively, which was significantly different (F=56.44, P < 0.05). ConclusionsPhotoreceptor necroptosis showed chromatin condensation, severe vacuolation, early loss of plasma membrane integrity, and many autophagosomes. Necroptosis activation was associated with the increase of RIP1 phosphorylation.
Objective To demonstrate if apoptosis is one of the mechanisms of siderotic retinopathy. Methods Autoclaved iron particles were implanted in the vitreous cavities of 32 eyes of SD rats.Glass chips were implanted in 10 control eyes.The experimental eyes were enucleated at various time intervals from days 1 to 15.Retinal degeneration was examined using the TdT-mediated,dUTP-biotin nickend labeling(TUNEL)method.Electrophoresis on agarose gel was used to detect internucleosomal DNA fragmentation.Results TUNEL-positive nuclei were observed only in the outer nuclear layer beginning on day 2.The nuclei spread throughout the outer nuclear layer by the end of day 3.No TUNEL-positive nuclei were observed in other layers throughout the experimental perios.Analysis of DNA,extracted from the retinas by electrophoresis on agarose gel,revealed a typical ladder pattern of internucleosoma DNA cleavage in the experimental eyes.ConclusionApoptosis of photoreceptors occurs at the early phase of iron-induced retinopathy in the rats.
Objective To observe the effects of local macular foveal photoreceptor defects on visual acuity.Methods Thirty-one patients (31 eyes) with photoreceptor defect in macular fovea (case group) diagnosed by spectral domain optical coherence tomography (SD-OCT) and 30 patients (30 eyes) age- and diopter- matched normal subjects (control group) were enrolled in this study. There were 22 eyes with full photoreceptor defects and 9 eyes with outer segment defects in case group. All subjects were examined for best corrected visual acuity (BCVA), slit-lamp microscopy, direct ophthalmoscope and SD-OCT. Independent sample t-test was used to compare central foveal thickness (CFT) between case group and control group. Difference of logMAR BCVA, CFT, maximum width and height of photoreceptor defects, defected area and residual retinal thickness in macular between patients with full photoreceptor defects and outer segment defects were also compared.Results The CFT of case group and control group were (225.32plusmn;19.70),(240.02plusmn;10.70) mu;m, the difference was not statistically significant (t=-1.96, P＞0.05). In full photoreceptor defects and outer segment defects patients, the mean logMAR BCVA were 0.22plusmn;0.31, 0.32plusmn;0.43; the mean CFT were (224.09plusmn;20.57), (228.33plusmn;18.17) mu;m; the maximum width of photoreceptor defects were (131.32plusmn;108.18), (143.22plusmn;66.93) mu;m; the mean defected area were (0.022plusmn;0.054), (0.019plusmn;0.019) mm2; the mean maximum height of photoreceptor defects were (77.41plusmn;6.62), (44.89plusmn;4.26) mu;m; the mean residual retinal thickness were (87.00plusmn;20.31), (128.33plusmn;23.54) mu;m respectively. There was no statistical significance between full photoreceptor defects and outer segment defects patients in the mean logMAR BCVA, CFT, maximum width of photoreceptor defects and defected area (t=-0.76, -0.538, -0.305, 0.166; P＞0.05), but there were significant difference in mean maximum width of photoreceptor defects and residual retinal thickness (t=12.72, -4.91;P＜0.05). Conclusions The local photoreceptor defects in macular fovea can lead to decrease of visual acuity. The wider the photoreceptor defects, the worse the visual acuity.
Objective To observe the relationship between the size of idiopathic macular hole (IMH) and the healing types of postoperative photoreceptor layer after vitrectomy. Methods This prospective uncontrolled study included 33 eyes of 31 consecutive patients who underwent vitrectomy for IMH. There were 9 males (9 eyes) and 22 females (22 eyes), with the mean age of (58.16±9.10) years. The mean duration of symptoms was (4.97±5.97) months. The best corrected visual acuity (BCVA) and optical coherence tomography (OCT) were measured for all patients. BCVA was measured with international standard visual acuity chart and then converted to logarithm of the minimum angle of resolution (logMAR). The mean logMAR BCVA was 1.07± 0.38. The mean intraocular pressure was (14.05±0.54) mmHg (1 mmHg=0.133 kPa). The minimum size of the macular hole (MIN), the base diameter of the macular hole (BASE), the average width of the macular hole (AWMH) and the average height of the macular hole (AHMH) were (465.19±232.84), (943.63±389.26), (704.72±292.64), (443.84±72.47) μm, respectively. According to the MIN value, the hole size were divided into small, medium and large group which had 9 eyes, 15 eyes, 9 eyes, respectively. According to the postoperative OCT characteristics, the healing types of the photoreceptor layer were divided into 0 - Ⅳ types. All patients underwent pars plana vitrectomy (25G or 27G standard three-incision) with internal limiting membrane peeling with tamponade agents. The mean follow-up was (326.42±157.17) days. The first postoperative OCT characteristics were defined as the early period. The therapy results were evaluated according to the last follow-up time point. BCVA and intraocular pressure before and after operation were compared by paired t test. The postoperative BCVA were compared with preoperative BCVA, MIN, AWMH, AHMH and follow-up using Pearson correlation analysis. Results At the last follow-up, the LogMAR BCVA was 1.52 - 1.40 in 3 eyes, 1.30 - 0.52 in 22 eyes and 0.40 - −0.07 in 8 eyes. Compared with preoperative that, the difference was statistically significant (t=−6.023, P＜0.001). The photoreceptor healing was type 0 in 10 eyes (30.3%), type Ⅰ in 4 eyes (12.1%), typeⅡ in 10 eyes (30.3%), type Ⅲ in 9 eyes (27.3%) at the early postoperative period. The photoreceptor healing was type 0 in 5 eyes (15.2%), type Ⅰ in 5 eyes (15.2%), type Ⅲ in 12 eyes (36.4 %), type Ⅳ in 11 eyes (33.3%) at the last follow-up. The preoperative size of IMH was negatively correlated to the photoreceptor healing types at early postoperative period (r=−0.590, P＜0.01) and the last follow-up (r=−0.768, P＜0.01), respectively. The correlation analysis showed that the postoperative BCVA associated with the preoperative BCVA, the stage of the macular hole, the size of the macular hole, MIN, BASE, AWMH, AHMH, the healing types of photoreceptor layer of the early and the last follow-up after surgery (r=0.500, 0.370, 0.470, 0.435, 0.533、0.505, 0.462, −0.442, −0.656, P＜0.05). There was no correlation between age, visual decreasing times and follow-up times (r=0.285, 0.234, −0.310, P＞0.05). Conclusion The preoperative sizes of IMH were associated with the postoperative healing types of photoreceptor layer.
Objective To analyze the thickness of peripapillary retinal nerve fiber layer (pRNFL) and photoreceptor (PR) sublayer in Leber hereditary optic neuropathy (LHON) and G11778A mutation carriers. MethodsA cross sectional study. From September 2020 to October 2021, 68 LHON patients (136 eyes) (patient group) and 40 G11778A mutation carriers (80 eyes) of LHON patients' families (carrier group) were included in the study. All patients were found to have G11778A mutation by Genetic testing. Forty healthy volunteers with 80 eyes matched to the age and gender of the patient group were recruited as a normal control group. All eyes were examined by optical coherence tomography (OCT). The pRNFL thickness was automatically measured by the built-in software of the OCT device. The total retinal thickness (MT) and the thickness of the outer bundle layer (OPL), outer nuclear layer (ONL), external limiting membrane to retinal pigment epithelium (ELM-RPE) in macular OCT images were measured by Image J software. Linear mixed model was used to analyze and compare the thickness of pRNFL, macular fovea and four layers above the nasal and temporal paracentral retina in patients, carriers and normal controls. The correlation between pRNFL and macular retinal sublayer thickness and the course of disease was also analyzed. ResultsThe thickness of the upper and lower pRNFL, temporal pRNFL and average pRNFL of the patients were smaller than those of the carriers and the normal control group (P＜0.01), and the nasal pRNFL thickness of the patients was smaller than that of the carriers (P＜0.01). Fovea: compared with the normal control group, the thickness of MT and ONT in the patient group was decreased, ONL thickness decreased in carrier group, with the significant different (P＜0.05). Parafovea: compared with normal control group, the thickness of MT and temporal ONL decreased and temporal OPL increased in the patients group, with the significant different (P＜0.05). In the carrier group, the thickness of MT and temporal, nasal ONL decreased, and the thickness of nasal OPL increased, with the significant different (P＜0.05). Compared with the carrier group, the MT thickness of the patient group was decreased, and the nasal ONL and nasal ELM-RPE thickness were increased, with the significant different (P＜0.05). Correlation analysis results showed that the thinning of pRNFL in the superior, nasal, temporal and average (r=－0.22, －0.21, －0.25, －0.22), and the thickening of ELM-RPE in foveo-temporal (r=0.19) were correlated with the course of disease (P＜0.05). ConclusionsThe pRNFL of LHON patients with G11778A mutation becomes thinner and is related to the course of the disease. There were significant differences in the thickness of MT and PR sublayers between patients and carriers compared to the normal control group.
ObjectiveTo observe the effect of metformin on the polarization state and photoreceptor cell activity of microglia (BV2 cells) in a high glucose environment. MethodsAn experimental study. BV2 cells were divided into a control group, a high glucose group, and a metformin+high glucose group. The cells in the high glucose group were cultured with 75 mmol/L glucose in the medium; the cells in the metformin+high glucose group were pretreated with 2 mmol/L metformin for 12 h and then placed in 75 mmo/L glucose concentration medium. The relative expression of M1 marker inducible nitric oxide synthase (iNOS), CD86 and M2 markers arginase 1 (Arg-1), and CD206 protein were detected by Western blot. Interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-4 were detected by enzyme-linked immunosorbent assay (ELISA). BV2 cells were co-cultured with mouse retinal photoreceptor cells (661W cells) for 24 h. The proliferation rate of 661W cells in each group was measured by methyl thiazolyl tetrazolium (MTT) colorimetric assay; the apoptosis rate of 661W cells in each group was measured by flow cytometry and terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL). An independent sample t-test was used for comparison between groups. ResultsWestern blot assay showed that the relative expression of iNOS and CD86 protein was increased and the relative expression of Arg-1 and CD206 protein was decreased in BV2 cells in the high glucose group compared with the control group, and the differences were all statistically significant (t=－16.783, －11.605, 4.325, 4.649; P＜0.05); compared with the high glucose group, the relative expression of iNOS and CD86 protein was decreased and the relative expression of Arg-1 and CD206 protein was increased in BV2 cells in the metformin + high glucose group compared with the high glucose group, and the differences were all statistically significant (t=7.231, 5.560, －8.035, －8.824; P＜0.01). ELISA results showed that compared with the control group, the BV2 cells in the high glucose group had increased IL-6, TNF-α content and IL-4 content was decreased in BV2 cells in the high glucose group compared with the control group, and the differences were all statistically significant (t=－64.312, －127.147, 71.547; P＜0.001); compared with the high glucose group, IL-6 and TNF-α content was significantly decreased and IL-4 content was significantly increased in BV2 cells in the metformin+high glucose group, and the differences were all statistically significant (t=44.426, 83.232, －143.115; P＜0.001). After co-culture of BV2 cells with 661W cells for 24 h, the results of MTT colorimetric assay showed that compared with the control group, the activity of 661W cells in the high glucose group was significantly reduced, and the difference was statistically significant (t=7.456, P＜0.01); compared with the high glucose group, the activity of 661W cells in the metformin+high glucose group was increased (t=－3.076, P＜0.05). TUNEL method and flow cytometry showed that the apoptosis rate of 661W cells in the high glucose group was significantly higher compared with the control group, and the differences were both statistically significant (t=－22.248, －22.628; P＜0.001); compared with the high glucose group, the apoptosis rate of 661W cells in the metformin+high glucose group was significantly decreased, and the difference was statistically significant (t=11.767, 6.906; P＜0.001, 0.01). ConclusionIn the high glucose environment, metformin inhibited the inflammatory response and attenuated the apoptosis of photoreceptor cells by regulating the polarization of microglia toward the M2 type.
Objective To investigate the mechanism of the toxic effect of N methyl N-nitrosourea (MNU) on photoreceptor cell apoptosis of rat’s retina. Methods Thirty 50-day-old female Sprague-Dawley ( SD ) rats were intraperitoneally injected with MNU (60 mg/kg) and were put to death by dislocation of cervical vertebra 12, 24, 48, and 72 hours and 7 days after the injection, respectively. The photoreceptor cell apoptosis was detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and transmission electron microscope. The expression of proliferating cell nuclear antigen (PCNA), vimentin and glial fibrillary acidic protein (GFAP) was detected at different time after injection by immunohistochemical methods. Results The apoptotic index of the retina in the posterior pole was (33. 6±2. 3), (46. 5±5. 7), (20. 1±5. 3), (8. 2±3. 6) and (2. 5±1. 3~//oo at the 12th,24th, 48 th, and 72nd hour and on the 7th day, respectively, after injection. Karyopyknosis was found in most photoreeeptor cells 24 hours after injection. The expression of PCNA was found in internal granularlayer and between internal granular layer and choroid 24 hours after injection, reached the peak after 72 hours, and reduced obviously after 7 days. The positive expression of GFAP and vimentin was found in internal and external granular layer 24 hours after injection, reached the peak after 72 hours, and reducedobviously after 7 days.Conclusion MNU may selectively lead the photoreceptor cell apoptosis and proliferation of Mvller cells. (Chin J Ocul Fundus Dis，2004，20：33-36)