Clinical applications of high-throughput genetic diagnosis in inherited retinal dystrophies: Present challenges and future directions

The advent of next generation sequencing(NGS) tech-niques has greatly simplified the molecular diagnosis and gene identification in very rare and highly heterogeneous Mendelian disorders. Over the last two years, these approaches, especially whole exome sequencing(WES), alone or combined with homozygosity mapping and linkage analysis, have proved to be successful in the identification of more than 25 new causative retinal dystrophy genes. NGS-approaches have also identified a wealth of new mutations in previously reported genes and have provided more comprehensive information concerning the landscape of genotype-phenotype correlations and the genetic complexity/diversity of human control populations. Although whole genome sequencing is far more informative than WES, the functional meaning of the genetic variants identified by the latter can be more easily interpreted, and final diagnosis of inherited retinal dystrophies is extremely successful, reaching 80%, particularly for recessive cases. Even considering the present limitations of WES, the reductions in costs and time, the continual technical improvements, the implementation of refined bioinformatic tools and the unbiased comprehensive genetic information it provides, make WES a very promising diagnostic tool for routine clinical and genetic diagnosis in the future.

Delivery strategies for CRISPR/Cas genome editing tool for retinal dystrophies:challenges and opportunities

CRISPR/Cas,an adaptive immune system in bacteria,has been adopted as an efficient and precise tool for site-specific gene editing with potential therapeutic opportunities.It has been explored for a variety of applications,including gene modulation,epigenome editing,diagnosis,mRNA editing,etc.It has found applications in retinal dystrophic conditions including progressive cone and cone-rod dystrophies,congenital stationary night blindness,X-linked juvenile retinoschisis,retinitis pigmentosa,age-related macular degeneration,leber’s congenital amaurosis,etc.Most of the therapies for retinal dystrophic conditions work by regressing symptoms instead of reversing the genemutations.CRISPR/Cas9 through indel could impart beneficial effects in the reversal of gene mutations in dystrophic conditions.Recent research has also consolidated on the approaches of using CRISPR systems for retinal dystrophies but their delivery to the posterior part of the eye is a major concern due to high molecular weight,negative charge,and in vivo stability of CRISPR components.Recently,non-viral vectors have gained interest due to their potential in tissue-specific nucleic acid(miRNA/siRNA/CRISPR)delivery.This review highlights the opportunities of retinal dystrophies management using CRISPR/Cas nanomedicine.

Simultaneous expression of two pathogenic genes in four Chinese patients affected with inherited retinal dystrophy

●AIM:To describe the complex,overlapping phenotype of four Chinese patients with inherited retinal dystrophies(IRDs)who harbored two pathogenic genes simultaneously.●METHODS:This retrospective study included 4 patients affected with IRDs.Medical and ophthalmic histories were obtained,and clinical examinations were performed.A specific Hereditary Eye Disease Enrichment Panel(HEDEP)based on exome capture technology was used for genetic screening.●RESULTS:Four patients were identified to harbor disease-causing variants in two different genes.Patient retinitis pigmentosa(RP)01-II:1 exhibited both classical ABCA4-induced Stargardt disease(STGD)1 and USH2 Aassociated RP,patient RP02-III:2 exhibited both classical ABCA4-induced STGD1 and CDH23-associated RP,patient RP03-II:1 exhibited both USH2 A-induced autosomal recessive retinitis pigmentosa(arRP)syndrome and SNRNP200-induced autosomal dominant retinitis pigmentosa(adRP),and patient RP04-II:2 exhibited USH2 Ainduced arRP syndrome and EYS-induced arRP at the same time.●CONCLUSION:Our study demonstrates that genotype–phenotype correlations and comprehensive genetic screening is crucial for diagnosing IRDs and helping family planning for patients suffering from the disease.

Automated Classification of Inherited Retinal Diseases in Optical Coherence Tomography Images Using Few-shot Learning

Objective To develop a few-shot learning(FSL) approach for classifying optical coherence tomography(OCT) images in patients with inherited retinal disorders(IRDs).Methods In this study, an FSL model based on a student–teacher learning framework was designed to classify images. 2,317 images from 189 participants were included. Of these, 1,126 images revealed IRDs, 533 were normal samples, and 658 were control samples.Results The FSL model achieved a total accuracy of 0.974–0.983, total sensitivity of 0.934–0.957, total specificity of 0.984–0.990, and total F1 score of 0.935–0.957, which were superior to the total accuracy of the baseline model of 0.943–0.954, total sensitivity of 0.866–0.886, total specificity of 0.962–0.971,and total F1 score of 0.859–0.885. The performance of most subclassifications also exhibited advantages. Moreover, the FSL model had a higher area under curves(AUC) of the receiver operating characteristic(ROC) curves in most subclassifications.Conclusion This study demonstrates the effective use of the FSL model for the classification of OCT images from patients with IRDs, normal, and control participants with a smaller volume of data. The general principle and similar network architectures can also be applied to other retinal diseases with a low prevalence.

Retinal imaging in inherited retinal diseases

Inherited retinal diseases(IRD)are a leading cause of blindness in the working age population.The advances in ocular genetics,retinal imaging and molecular biology,have conspired to create the ideal environment for establishing treatments for IRD,with the first approved gene therapy and the commencement of multiple therapy trials.The scope of this review is to familiarize clinicians and scientists with the current landscape of retinal imaging in IRD.Herein we present in a comprehensive and concise manner the imaging findings of:(I)macular dystrophies(MD)[Stargardt disease(ABCA4),X-linked retinoschisis(RS1),Best disease(BEST1),pattern dystrophy(PRPH2),Sorsby fundus dystrophy(TIMP3),and autosomal dominant drusen(EFEMP1)],(II)cone and cone-rod dystrophies(GUCA1A,PRPH2,ABCA4 and RPGR),(III)cone dysfunction syndromes[achromatopsia(CNGA3,CNGB3,PDE6C,PDE6H,GNAT2,ATF6],blue-cone monochromatism(OPN1LW/OPN1MW array),oligocone trichromacy,bradyopsia(RGS9/R9AP)and Bornholm eye disease(OPN1LW/OPN1MW),(IV)Leber congenital amaurosis(GUCY2D,CEP290,CRB1,RDH12,RPE65,TULP1,AIPL1 and NMNAT1),(V)rod-cone dystrophies[retinitis pigmentosa,enhanced S-Cone syndrome(NR2E3),Bietti crystalline corneoretinal dystrophy(CYP4V2)],(VI)rod dysfunction syndromes(congenital stationary night blindness,fundus albipunctatus(RDH5),Oguchi disease(SAG,GRK1),and(VII)chorioretinal dystrophies[choroideremia(CHM),gyrate atrophy(OAT)].

RDH12-associated retinal degeneration caused by a homozygous pathogenic variant of 146C>T and literature review

AIM:To describe the clinical,electrophysiological,and genetic features of an unusual case with an RDH12 homozygous pathogenic variant and reviewed the characteristics of the patients reported with the same variant.METHODS:The patient underwent a complete ophthalmologic examination including best-corrected visual acuity,anterior segment and dilated fundus,visual field,spectral-domain optical coherence tomography(OCT)and electroretinogram(ERG).The retinal disease panel genes were sequenced through chip capture high-throughput sequencing and Sanger sequencing was used to confirm the result.Then we reviewed the characteristics of the patients reported with the same variant.RESULTS:A 30-year male presented with severe early retinal degeneration who complained night blindness,decreased visual acuity,vitreous floaters and amaurosis fugax.The best corrected vision was 0.04 OD and 0.12 OS,respectively.The fundus photo and OCT showed bilateral macular atrophy but larger areas of macular atrophy in the left eye.Autofluorescence shows bilateral symmetrical hypo-autofluorescence.ERG revealed that the amplitudes of a-and b-wave were severely decreased.Multifocal ERG showed decreased amplitudes in the local macular area.A homozygous missense variant c.146C>T(chr14:68191267)was found.The clinical characteristics of a total of 13 patients reported with the same pathologic variant varied.CONCLUSION:An unusual patient with a homozygous pathogenic variant in the c.146C>T of RDH12 which causes late-onset and asymmetric retinal degeneration are reported.The clinical manifestations of the patient with multimodal retinal imaging and functional examinations have enriched our understanding of this disease.

Cerium oxide nanoparticles as promising ophthalmic therapeutics for the treatment of retinal diseases

Nanotechnology offers exciting new approaches for biology and medicine. In recent years, nanoparticles,particularly those of the rare metal cerium, are showing potential for a wide range of applications in medicine.Cerium oxide nanoparticles or nanoceria are antioxidants and possess catalytic activities that mimic those of super oxide dismutase and catalase, thereby protecting cellsfrom oxidative stress. The retina is highly susceptible to oxidative stress because of its high oxygen consumption and high metabolic activity associated with exposure to light. Many retinal diseases progress through oxidative stress as a result of a chronic or acute rise in reactive oxygen species. Diseases of the retina are the leading causes of blindness throughout the world. Although some treatments may delay or slow the development of retinal diseases, there are no cures for most forms of blinding diseases. In this review is summarized evidence that cerium oxide nanoparticles can function as catalytic antioxidants in vivo in rodent models of age-related macular degeneration and inherited retinal degeneration and may represent a novel therapeutic strategy for the treatment of human eye diseases. This may shift current research and clinical practice towards the use of nanoceria, alone or in combination with other therapeutics.

Clinical Characterization and Frequency of Observation of Hereditary Retinal Diseases： Multicentric Study in Panama in 2012-2013

Retinal dystrophies are genetically determined diseases, implying the loss of function of the retina with a wide phenotypic and genotypic variability. There are very few phenotypic, genotypic and epidemiological data on retinal dystrophies in Latin America. The Objective of this study is to describe the epidemioiogical and clinical characteristics of hereditary retinal and choroidal diseases, in retina practices in Panama. A descriptive study, from 2012 to 2013, was performed in the main retina practices in Panama. All detected patients were given a free appointment to gather their phenotypic characteristics and pedigrees. An incidence of five new cases per year, and an accumulated incidence of 5.35 patients per I0,000 was calculated for the public hospitals. A frequency of 2.7 cases per 1,000 patients was observed in the main retina practices, where 69% had rod-cone dystrophies, 14.3% cone-rod dystrophies, 7.1% Stargardt disease, 4.8% Stargardt-like macular dystrophy and two patients presented other dystrophies. Blindness was the main family antecedent （45.2%）. Retinal pigment was present in 59% and strabismus in 21.4% of the patients. Rod-cone and cone-rod dystrophies had similar geographic distribution and the autosomal recessive inheritance pattern was the most frequently observed. This study gives the first phenotypic data of retinal dystrophies in Panama to orient clinicians for a better diagnosis and phenotyping-genotyping correlation for retinal dystrophies in Central America.

Stem cell therapy in retinal diseases

Alteration of the outer retina leads to various diseases such as age-related macular degeneration or retinitis pigmentosa characterized by decreased visual acuity and ultimately blindness.Despite intensive research in the field of retinal disorders,there is currently no curative treatment.Several therapeutic approaches such as cell-based replacement and gene therapies are currently in development.In the context of cell-based therapies,different cell sources such as embryonic stem cells,induced pluripotent stem cells,or multipotent stem cells can be used for transplantation.In the vast majority of human clinical trials,retinal pigment epithelial cells and photoreceptors are the cell types considered for replacement cell therapies.In this review,we summarize the progress made in stem cell therapies ranging from the pre-clinical studies to clinical trials for retinal disease.

AB046.The Endocytic Adaptor Protein Numb Functions in Müller Glia to Maintain Retinal Polarity and Photoreceptor Survival through the Polarity Determinant Crumbs

Background:The loss of cell polarity plays a key part in retinal dystrophies such as retinitis pigmentosa(RP)and Leber congenital amaurosis(LCA),resulting in photoreceptor(PR)degeneration and vision loss.Despite not knowing the direct genotype-to-phenotype correlation,many disease-causing mutations in the polarity determinant Crumbs(Crb1),have been identified.Indeed,the loss of Crb1 in mice was shown to cause PR death,due to the loss of adhesions between PR and Müller cells at the apical surface of the retina.Unfortunately,although the role of Crb1 in neuron polarity and survival is well established,little is known about how its intracellular trafficking is regulated.With future treatments for retinal degenerative diseases in mind,the goal of this project is to understand the mechanism by which Crb1 is regulated and how it maintains retinal integrity.Previous work in our laboratory showed that Numb,an endocytic adaptor protein,is an important regulator of protein trafficking in retinal cells.We therefore hypothesized that Numb might function as regulator of Crb1 in Müller glia.Methods:To study Numb function in Müller cells,we generated a conditional knockout(cKO)mouse line to inactivate Numb specifically in Müller cells by crossing a Glast-CreERT2 mouse line with a Numb-floxed line.At 30 days,mice were administered tamoxifen to trigger inactivation of Numb and retinas were then collected at time points varying from 2 weeks to 17 months for analysis.Firstly,we studied the retinal morphology and outer limiting membrane integrity by histology and immunohistochemistry.Using electron microscopy(EM),adhesions between Müller glia and photoreceptors were analysed and retinal function was assayed in live mice by electroretinography(ERG).To detect protein expression levels,protein extracts were prepared from cKO and control retinas for immunoblotting.To test for the presence of a biochemical interaction,Hek-293 cells were transfected with Numb and Crb1 vectors,and protein extracts were processed for co-immunoprecipitation.Results:When Numb was deleted in Müller cells,we observed a similar retinal phenotype than what was reported in the Crb1 KO.In 3-month-old animals,we found a disruption of the outer limiting membrane and an ingression of photoreceptor cells in the inner layers of the retina.In older animals(17 months),we observed a clear thinning of the photoreceptor layer and reduced ERG responses.Immunoblotting of retinal lysates revealed that Numb cKO retinas had significantly lower expression of Crb1,suggesting that Numb function in Müller cells is critical to maintain Crb1 levels and thereby outer limiting membrane integrity.Interestingly,we found that Numb can interact with Crb1 both in vitro and in vivo,suggesting that Numb might function as an adaptor protein regulating Crb1 trafficking.Conclusions:Based on these results,we suggest that,in the absence of Numb,Crb1 cannot be trafficked to the apical membrane of Müller cells,and is instead degraded.This ruptures the adhesion between Müller and photoreceptor cells,leading to photoreceptor degeneration.We anticipate that understanding the mechanisms by which Crb1 maintains the structural integrity of the retina will lead to new possibilities for target-based therapies against retinal dystrophies.

Lycium barbarum glycopeptide(wolfberry extract)slows N-methyl-N-nitrosourea-induced degradation of photoreceptors

Photoreceptor cell degeneration leads to blindness, for which there is currently no effective treatment. Our previous studies have shown that Lycium barbarum(L. barbarum) polysaccharide(LBP) protects degenerated photoreceptors in rd1, a transgenic mouse model of retinitis pigmentosa. L. barbarum glycopeptide(Lb GP) is an immunoreactive glycoprotein extracted from LBP. In this study, we investigated the potential protective effect of Lb GP on a chemically induced photoreceptor-degenerative mouse model. Wild-type mice received the following: oral administration of Lb GP as a protective pre-treatment on days 1–7;intraperitoneal administration of 40 mg/kg N-methylN-nitrosourea to induce photoreceptor injury on day 7;and continuation of orally administered Lb GP on days 8–14. Treatment with Lb GP increased photoreceptor survival and improved the structure of photoreceptors, retinal photoresponse, and visual behaviors of mice with photoreceptor degeneration. Lb GP was also found to partially inhibit the activation of microglia in N-methyl-N-nitrosourea-injured retinas and significantly decreased the expression of two pro-inflammatory cytokines. In conclusion, Lb GP effectively slowed the rate of photoreceptor degeneration in N-methyl-N-nitrosourea-injured mice, possibly through an anti-inflammatory mechanism, and has potential as a candidate drug for the clinical treatment of photoreceptor degeneration.

基因治疗递送系统的研究新进展:遗传性视网膜疾病治疗的曙光

遗传性视网膜疾病是多种先天性视网膜神经退行性疾病的总称,临床上以夜盲、进行性视野缩小、视力下降甚至失明为特点,具有多种遗传形式。由于其病变的根源在于基因突变,通过基因治疗,即利用外源性核苷酸替换或沉默基因缺陷细胞内的致病基因,使细胞表达正确的蛋白质,恢复细胞的功能,就有可能治愈疾病。同时,眼睛具有免疫“豁免”特性,是实现基因治疗的理想器官。为了完成遗传物质的修正,治疗性核苷酸需要进入细胞内发挥作用,携带健康基因的载体递送系统是实现这一过程的有利工具。该文重点总结了包括病毒载体和非病毒载体在内的遗传性视网膜疾病基因治疗递送系统的研究进展及面临的问题。

卵黄样黄斑营养不良的多模式影像特征观察

目的:观察卵黄样黄斑营养不良(BVMD,别称Best病)的多模式影像特征。方法:收集2016-06/2022-10于南京医科大学眼科医院确诊为Best病Ⅰ-Ⅳ期的患者30例60眼的临床资料进行回顾性分析,均双眼发病。所有患者均行最佳矫正视力(BCVA)、裂隙灯显微镜、间接眼底镜、眼压、眼底彩色照相、频域光学相干断层扫描(SD-OCT)、眼底自发荧光(FAF)、荧光素眼底血管造影(FFA)、眼电图(EOG)及光学相干断层扫描血管成像(OCTA)。结果:共纳入患者30例60眼,其中Ⅰ期8眼,Ⅱ期24眼,Ⅲ期22眼,Ⅳ期6眼,眼底彩色照相、FAF、FFA、SD-OCT的影像特征与既往文献报道基本一致,EOG显示Arden比均<1.55,OCTA能够发现早期病灶,观察到卵黄样物质、光感受器外节、液体的位置分布及有无CNV形成。结论:多模式影像有助于Best病的诊断,减少临床上漏诊、误诊,其中OCTA较其他检查有明显优势,快捷无创是其最大优势。

中国肢带型肌营养不良携带者筛查专家共识

肢带型肌营养不良(LGMD)是一组以近端肌(骨盆带肌和肩胛带肌)肌无力为主要表现的遗传性肌病,有常染色体显性、常染色体隐性和X连锁3种遗传方式。LGMD具有高度遗传和临床异质性,极易漏诊误诊。LGMD至今仍缺乏特效的治疗药物,其预后较差,给家庭及社会均带来巨大负担。为指导LGMD携带者高风险人群的筛查,并提供生育相关遗传咨询,在综合考虑国内外相关研究和指南基础上,特制定适合我国现状的LGMD携带者筛查的中国专家共识,以期进一步促进LGMD的规范化防控。

多能干细胞治疗视网膜退行性疾病:从实验室到临床转化的现状与挑战

视网膜色素上皮细胞(Retinal pigment epithelial cells,RPE)是位于视网膜底部致密的细胞层,其损伤导致年龄相关性黄斑变性(Age-related macular degeneration,AMD)、Stargardt病(Stargardt macular dystrophy,STGD)和色素性视网膜炎(Retinitis pigmentosa,RP)等视网膜疾病,RPE移植已成为治疗RPE损伤性疾病的有效方案。来源于人多能干细胞(Human pluripotent stem cells,hPSC)的视网膜色素上皮细胞,具有与人原代RPE相似的功能和容易制备等优点,已成为RPE移植的最主要细胞来源之一。文章对hPSC-RPE治疗视网膜退行性疾病的临床试验进展进行了总结和归纳,并阐述了目前面临的挑战与风险。

The m^(6)A reader YTHDC2 maintains visual function and retinal photoreceptor survival through modulating translation of PPEF2 and PDE6B

Inherited retinal dystrophies (IRDs) are major causes of visual impairment and irreversible blindness worldwide, while the precise molecular and genetic mechanisms are still elusive. N6-methyladenosine (m^(6)A) modification is the most prevalent internal modification in eukaryotic mRNA. YTH domain containing 2 (YTHDC2), an m^(6)A reader protein, has recently been identified as a key player in germline development and human cancer. However, its contribution to retinal function remains unknown. Here, we explore the role of YTHDC2 in the visual function of retinal rod photoreceptors by generating rod-specific Ythdc2 knockout mice. Results show that Ythdc2 deficiency in rods causes diminished scotopic ERG responses and progressive retinal degeneration. Multi-omics analysis further identifies Ppef2 and Pde6b as the potential targets of YTHDC2 in the retina. Specifically, via its YTH domain, YTHDC2 recognizes and binds m^(6)A-modified Ppef2 mRNA at the coding sequence and Pde6b mRNA at the 5′-UTR, resulting in enhanced translation efficiency without affecting mRNA levels. Compromised translation efficiency of Ppef2 and Pde6b after YTHDC2 depletion ultimately leads to decreased protein levels in the retina, impaired retinal function, and progressive rod death. Collectively, our finding highlights the importance of YTHDC2 in visual function and photoreceptor survival, which provides an unreported elucidation of IRD pathogenesis via epitranscriptomics.

视网膜色素变性和视锥-视杆细胞营养不良患者基因突变频谱分析

目的:分析中国宁夏地区常染色体隐性遗传视网膜色素变性(ARRP)及视锥-视杆细胞营养不良(CORD)的基因突变频谱。方法:纳入2016-09/2020-02在宁夏人民医院眼科医院就诊的35例ARRP患者和18例常染色体隐性CORD患者,行详细的眼科检查。抽取外周静脉血,对先证者应用包含232个致病基因的遗传性视网膜疾病捕获芯片进行靶向捕获富集高通量测序。利用在线分析软件对可疑基因变异致病性进行预测,利用Sanger测序对家系成员进行共分离分析。结果:ARRP患者35例中,检测到致病基因16个,以RP1基因突变率最高,占14%(5/35),其次为ABCA4、CRB1和EYS基因,均占11%(4/35);18例常染色体隐性CORD患者中,检测到致病基因10个,以ABCA4基因突变率最高,占28%(5/18),其次为ALMS1、PROM1、RPE65、USH2A基因,均占11%(2/18);ARRP和CORD患者中,共同致病基因有ABCA4、CLN3、CRB1、PROM1、NRL共5个,占42%(22/53)。结论:ARRP及CORD两种疾病在表型之间具有一定程度的相似性和交叉性,致病基因突变谱上存在一定重叠性。宁夏地区最常见的重叠基因为ABCA4。

遗传性视网膜变性rd小鼠及其感光细胞凋亡研究

目的 研究遗传性视网膜变性rd小鼠感光细胞层的发育变化及细胞凋亡。方法 对出生后 5d到4 0d的rd小鼠及对照小鼠视网膜感光细胞层进行光镜及超微结构观察、TUNEL法检测及形态计量学分析。结果 与同龄对照鼠相比 ,rd小鼠出生后第 10d视网膜开始变性 ,尔后 1周内感光细胞迅速减少 ,第 18d时只残留一层视椎细胞。rd小鼠出生后第 10d感光细胞层开始出现TUNEL染色阳性细胞 ,第 14d及 16d达到高峰。电镜下变性高峰期rd小鼠视网膜感光细胞层可见大量浓缩核、染色质边聚及凋亡小体。结论 rd小鼠视网膜感光细胞在发育过程中变性 ,并通过凋亡的方式死亡。

结晶样视网膜色素变性患者血脂浓度的变化

背景 结晶样视网膜色素变性（BCD）为一种先天性遗传性眼病,已有研究认为其与血清中脂肪酸代谢异常有关,但目前鲜见关于BCD与血清中脂质水平变化关系的报道. 目的 分析BCD患者血清脂质浓度的变化情况.方法 采用前瞻性研究设计,本研究经过北京同仁医院伦理委员会批准,受检者受检前均签署知情同意书.纳入2011年11月至2013年3月于北京同仁医院眼科就诊的双眼BCD患者50例及同期进行健康体检、年龄和性别匹配的健康体检者50人,采集受检者外周静脉血3 ml,由检验科专业人员检测受检者血清三酰甘油（TG）、总胆固醇（TC）、低密度脂蛋白胆固醇（LDL-C）、高密度脂蛋白胆固醇（HDL-C）浓度,结果的判定参照《中国成人血脂异常防治指南》（2007版）中成年人的正常值标准,并将BCD患者组检测结果与正常对照组进行比较.结果 50例BCD患者中血脂水平异常者占58.00％（29/50）,其中高TG血症者占34.48％ （10/29）;高TC血症者占34.48％ （10/29）;混合型高脂血症者占27.59％（8/29）.BCD患者血清TG、TC、LDL-C浓度分别为（1.63±1.19）、（5.10±1.05）、（3.27±0.97） mmol/L,明显高于正常对照组的（0.93±0.33）、（4.33±0.56）、（2.63±0.51） mmol/L,差异均有统计学意义（t=4.036、4.496、4.095,均P=0.000）. 结论 血脂异常可能与BCD发病有关.

RCS大鼠视网膜感光细胞的凋亡

为研究遗传性视网膜变性中感光细胞组织结构的时程变化及凋亡，对ＲＣＳ（ＲｏｙａｌＣｏｌｅｇｅｏｆＳｕｒｇｅｏｎｓ）大鼠及ＳＤ大鼠视网膜进行光镜观察和凋亡细胞ＴＵＮＥＬ（ＴｄＴ－ｍｅｄｉａｔｅｄｂｉｏｔｉｎ－ｄＵＴＰｎｉｃｋ－ｅｎｄｌａｂｅｌｉｎｇ）检测。结果表明，与同龄ＳＤ大鼠相比，ＲＣＳ大鼠视网膜感光细胞从出生后１５ｄ开始，出现外节膜盘堆积；２０ｄ时，内节排列紊乱、消失；３０ｄ时，细胞核固缩，细胞消失；到出生后６０ｄ，仅少许感光细胞保留；１００ｄ时，几乎所有感光细胞消失。ＴＵＮＥＬ检测，从出生后２５ｄ开始，ＲＣＳ大鼠视网膜有ＴＵＮＥＬ呈阳性的感光细胞出现，３５ｄ时达高峰。结果提示：ＲＣＳ大鼠视网膜变性过程中，感光细胞逐渐出现结构异常，并以凋亡的形式死亡。