Exome sequencing analysis identifies novel homozygous mutation in ABCA4 in a Chinese family with Stargardt disease

AIM: To identify the disease-associated mutations in a Chinese Stargardt disease(STGD) family, extend the existing spectrum of disease-causing mutations and further define the genotype-phenotype correlations.METHODS: A Chinese STGD family and 200 normal controls were collected. Whole exome sequencing(WES) and bioinformatics analysis were performed to find the pathogenic gene mutation. Physico-chemical parameters of mutant and wildtype proteins were computed by Prot Param tool. Domains analysis was performed by SMART online software. HOPE online software was used to analyze the structural effects of mutation. Immunofluorescence, quantitative real-time polymerase chain reaction and Western blotting were used for expression analysis.RESULTS: Using WES, a novel homozygous mutation(NM_000350: c.G3190 C, p.G1064 R) in ABCA4 gene was identified. This mutation showed co-segregation with phenotype in this family. It was not found in the 200 unrelated health controls and absent from any databases. It was considered "Deleterious" as predicted by five function prediction softwares, and was highly conserved during evolution. ABCA4 was expressed highly in the human eye and mouse retina. The p.G1064 R was located in AAA domain, may force the local backbone into an incorrect conformation, disturb the local structure, and reduce the activity of ATPase resulting in the disease pathology. CONCLUSION: We define a novel pathogenic mutation(c.G3190 C of ABCA4) of STGD. This extends the existing spectrum of disease-causing mutations and further defines the genotype-phenotype correlations.     

Comparing refractive outcomes of a standard industry toric IOL calculator using anterior corneal astigmatism and total corneal refractive power

Graefe's Archive for Clinical and Experimental Ophthalmology - To evaluate refractive outcomes for a standard industry calculator using anterior corneal astigmatism or total corneal refractive...     

Characterization of antibody against the N-terminus of RDS/peripherin

Mutations in the gene encoding RDS/peripherin cause a variety of retinal disorders. Attempts to model such disorders in vitro and in vivo have been hampered by the paucity of available immunological reagents. Moreover, available antibodies have been generated from undefined or C-terminal epitopes and therefore may not suitable for detecting all known RDS/peripherin mutants. We consequently generated affinity-purified rabbit antibody against a 14 amino acid peptide corresponding to the highly conserved N-terminus of human RDS/peripherin. This new antibody, N-RDS, recognizes RDS/peripherin in the retina of man, macaque, and rat. N-RDS may prove useful in studying RDS/peripherin mutants, particularly those with abnormal C-terminal domains.     

Visual and refractive outcomes of posterior chamber phakic IOL in stable keratoconus

We evaluated the visual and refractive outcomes after phakic visian toric implantable collamer lens (ICL) insertion in stable keratoconus (KC). This retrospective study investigated toric ICL implantation in 14 eyes of 8 patients with stable KC. After 6mo, the mean uncorrected distance visual acuity improved significantly from 0.77 to 0.15 logMAR. The mean best corrected distance visual acuity (BCDVA) improved from 0.18±0.1 to 0.15±0.1 logMAR. Fifty percent of eyes maintained their preoperative BCDVA; 42.8% gained one line. There was no statistical difference in high order or coma aberration. The mean refractive manifest spherical equivalent (MSE), mean refractive manifest spherical error, mean manifest astigmatism decreased significantly postoperatively. At 6mo postoperatively, our achieved mean spherical equivalent was approximately 74%. No intraoperative or postoperative complications occurred. Toric ICL implantation was effective, predictable and safe to correct refractive error and improve visual acuity in patients with stable KC.     

Structure and function of ABCA4 and its role in the visual cycle and Stargardt macular degeneration

ABCA4 is a member of the superfamily of ATP-binding cassette (ABC) transporters that is preferentially localized along the rim region of rod and cone photoreceptor outer segment disc membranes. It uses the energy from ATP binding and hydrolysis to transport N-retinylidene-phosphatidylethanolamine (N-Ret-PE), the Schiff base adduct of retinal and phosphatidylethanolamine, from the lumen to the cytoplasmic leaflet of disc membranes. This ensures that all-trans-retinal and excess 11-cis-retinal are efficiently cleared from photoreceptor cells thereby preventing the accumulation of toxic retinoid compounds. Loss-of-function mutations in the gene encoding ABCA4 cause autosomal recessive Stargardt macular degeneration, also known as Stargardt disease (STGD1), and related autosomal recessive retinopathies characterized by impaired central vision and an accumulation of lipofuscin and bis-retinoid compounds. High resolution structures of ABCA4 in its substrate and nucleotide free state and containing bound N-Ret-PE or ATP have been determined by cryo-electron microscopy providing insight into the molecular architecture of ABCA4 and mechanisms underlying substrate recognition and conformational changes induced by ATP binding. The expression and functional characterization of a large number of disease-causing missense ABCA4 variants have been determined. These studies have shed light into the molecular mechanisms underlying Stargardt disease and a classification that reliably predicts the effect of a specific missense mutation on the severity of the disease. They also provide a framework for developing rational therapeutic treatments for ABCA4-associated diseases.     

Verion导航系统和传统标记器法行Toric IOL轴向标记的精确性比较

目的：比较采用Verion导航系统和传统标记器法行Toric IOL轴向标记的精确性。

方法：前瞻性随机对照研究。选取2016-06/2019-12在我院行白内障超声乳化联合Toric IOL植入术的年龄相关性白内障患者47例56眼随机分为两组：导航组术前Verion导航系统采集眼前节图像,设定Toric目标轴向27眼,标记器组术前使用Toric标记器标记水平0°、180°,术中根据标记环标记Toric目标轴向29眼。术后1h,1wk,1、3mo患者散瞳后眼前节照相,Photoshop软件分析两组患者实际轴向和目标轴向的偏差值,并记录患者裸眼视力(UCDVA)、最佳矫正视力(BCDVA)以及残余散光度。

结果：术后1h,3mo导航组患者IOL实际轴向和目标轴向的偏差值小于标记器组(1.5°±1.8° vs 3.1°±2.1°; 1.9°±1.6° vs 3.3°±2.4°,均P<0.05)。术后3mo,导航组和标记器组平均UCDVA(LogMAR)比较无差异(0.04±0.08 vs 0.06±0.07,P=0.338); 残余散光度比较无差异(-0.39±0.32 vs -0.45±0.31D,P=0.491)。

结论：Verion导航和手动标记方法标记Toric IOL轴向都有较高的准确性,尽管导航组并未显示出UCDVA和残余散光度方面的优势,但是IOL轴向偏差导航组显著小于标记器组,导航标记下植入Toric IOL轴向更精准。     

Comparison of preoperative simulated and postoperative real safety distances using anterior segment OCT in patients with phakic IOL according to iris configuration

AIM: To compare the simulated safe distance (SSD) preoperatively versus real safe distance (RSD) postoperatively in patients with iris-claw phakic intraocular lens (pIOL) implantation according to iris configuration. METHODS: Totally 60 eyes of 60 patients underwent pIOL implantation for surgical correction of myopia. Anterior chamber depth (ACD) was measured with the IOLMaster 700, and nasal and temporal safety distances (SD) were measured pre- and postoperatively using Anterior Segment Visante-OCT. SD was defined as a line measured between the edge of the optic or its simulated image to the endothelium. Eyes were divided into 3 groups: convex, concave, and plane according to preoperatory iris configuration. Statistical analysis was performed using the R program, for the comparison of independent groups and multiple comparisons, the Kruskal-Wallis test and the Dunn test were used respectively. RESULTS: Mean difference between nasal preoperative SSD and postoperative RSD was -0.36±0.38, -0.29±0.48, and -0.18±0.30 mm in the concave, convex, and plane group, respectively. Mean difference between temporal SSD and RSD was -0.36±0.37, -0.14±0.38, and -0.24±0.33 mm in the concave, convex, and plane group, respectively. There were statistically significant differences between SSD and RSS for both nasal and temporal sides in the concave and plane group (P<0.002). CONCLUSION: Preoperative SSD and postoperative RSD for iris-claw pIOL shows significant differences in patients with concave and plane iris.     

不同测量仪器和不同IOL屈光度计算公式对硅油填充合并白内障眼IOL屈光度测算的比较

背景 玻璃体切割联合硅油填充眼易诱发和加速白内障的形成,白内障联合硅油取出术前人工晶状体(IOL)屈光度的准确测算是术眼获得术后良好视觉质量的关键. 目的 研究不同仪器和不同IOL计算公式在硅油填充合并白内障眼行白内障摘出联合IOL植入术前IOL屈光度测算的差异,并测算术前预测IOL屈光度与术后术眼屈光度的误差,为临床相关工作提供参考依据. 方法 采用前瞻性非随机对照的研究方法,于2011年8月至2013年10月在苏州大学附属第二医院连续纳入玻璃体切 割术后硅油填充合并白内障者36例36眼,患眼均于硅油乳化后4个月～2年拟行白内障超声乳化+IOL植入+硅油取出术,术前分别用IOLMaster及A型超声联合手动角膜曲率计(MK)测量术眼眼轴长度(AL)、角膜曲率(CC)和前房深度(ACD)等生物学参数,分别采用SRK-Ⅱ、SRK/T、Hoffer Q、Holladay 1和Haigis计算公式和预留的屈光度计算拟植入的IOL屈光度,分析和比较IOLMaster及A型超声联合MK用上述计算公式测算的IOL理论屈光度值与术后术眼实际屈光度值的平均预测误差(MPE)和平均绝对屈光误差(MAE). 结果 A型超声+MK和IOLMaster测得的AL分别为(25.21±1.02) mm和(25.43±0.90) mm,ACD分别为(3.07±0.62) mm和(3.22±0.38)mm,A型超声+MK测量的AL和ACD值明显小于IOLMaster测量结果,差异均有统计学意义(均P=0.000).IOLMaster与A型超声+MK测得的CC分别为(44.58±1.57)D和(44.56±1.62)D,差异无统计学意义(P=0.568).用IOLMaster测量时,SRK/T公式的MAE明显小于SRK-Ⅱ、Hoffer Q、Holladay 1和Haigis公式的MAE,差异均有统计学差异(P=0.017、0.009、0.012、0.001);Haigis公式的MAE明显大于SRK-Ⅱ、HofferQ和Holladay 1公式的MAE,差异均有统计学意义(P=0.026、0.035、0.021).用A型超声+MK测量时,Haigis公式的MAE明显大于与SRK-Ⅱ、SRK/T、Hoffer Q和Holladay 1公式的MAE,差异均有统计学意义(P=0.007、0.004、0.018、0.006).用SRK-Ⅱ、SRK/T、Hoffer Q和Holladay 1公式计算时,IOLMaster与A型超声+MK间测量的MAE≤1.0D眼数比较差异均无统计学意义(x2=0.107、2.250、0.845、0.084,均P＞0.05);用Haigis公式计算时,IOLMaster测量的MAE≤1.0D眼数明显多于A型超声+MK测量结果,差异有统计学意义(x2=4.431,P=0.035). 结论 使用IOLMaster时SRK/T公式测算的IOL屈光度准确性最高,用A型超声+MK测量时推荐使用SRK-Ⅱ、SRK/T、Hoffer Q和Holladay 1测算公式.     

VERION数字导航系统行散光矫正型人工晶状体（Toric IOL）轴位标记与传统裂隙灯标记方法的对比研究

目的　评价VERION数字导航系统行散光矫正型人工晶状体（Toric intraocular lens,Toric IOL）轴位标记的准确性和有效性。方法　回顾性分析2016年6月至2017年5月行白内障超声乳化摘出联合Toric IOL植入术的患者75例（75眼）,所有患者术前应用VERION数字导航系统采集眼前节图像并设定IOL预设植入轴位（目标轴位）,并于裂隙灯下采用1 mL注射器针头标记水平轴位。术中随机参考VERION导航下的IOL目标轴位或裂隙灯下标记的目标轴位植入IOL,记为VERION组（42眼）和裂隙灯组（33眼）,术后1 d、1周、1个月、3个月记录患者最佳矫正视力,散瞳后进行眼前节照相,应用Photoshop软件进行图像分析,比较两组患者术后不同时间点的最佳矫正视力以及IOL实际轴位与目标轴位的偏差值。结果　VERION组术后1 d、1周、1个月、3个月最佳矫正视力≥0.8的眼数所占比例分别为61.9%、78.6%、71.4%、76.2%,裂隙灯组分别为69.7%、78.8%、81.8%、75.8%,各时间点两组相比差异均无统计学意义（均为P>0.05）。VERION系统标记的IOL目标轴位与裂隙灯下针头标记的IOL目标轴位的差值为（3.04±1.99）°。两组患者术后不同时间点IOL实际轴位与目标轴位的偏差值均无统计学意义（均为P>0.05）。结论　应用VERION数字导航系统行Toric IOL轴位标记,术后效果准确稳定。     

FFA及OCT对STZ诱导的早期糖尿病大鼠视网膜的活体观察

背景 链脲佐菌素（STZ）诱导的糖尿病SD大鼠是进行糖尿病视网膜病变（DR）发病机制研究常用的动物模型,以往主要用离体眼球进行观察,荧光素眼底血管造影（FFA）和光学相干断层扫描（OCT）技术可活体观察眼底,但目前FFA和OCT联合用于DR模型的观察尚未报道. 目的 将FFA和OCT联合用于STZ诱导的糖尿病SD大鼠的眼底检查,动态观察糖尿病模型早期阶段视网膜血管的渗漏及视网膜厚度的变化情况.方法 将60只清洁级SD大鼠按随机数字表法随机分为2个组,糖尿病组大鼠一次性腹腔内注射溶于柠檬酸钠溶液的STZ诱导糖尿病大鼠模型,对照组大鼠以同样的方式注射柠檬酸钠溶液.分别于造模前及造模成功后第4、8、12周在大鼠全身麻醉状态下采用FFA联合Spectralis HRA＋OCT（SD-OCT）动态观察和比较各组大鼠左眼视网膜血管的渗漏情况及视网膜厚度的变化情况.FFA检查时大鼠腹腔内注射质量分数20％荧光素钠（0.012 ml/g）并快速观察视盘及上方、下方、鼻侧、颞侧、鼻上、鼻下、颞上、颞下视网膜共9个方位的视网膜血管情况,OCT检查时测量距视盘上方、下方、鼻侧、颞侧2个视盘直径（DD）处的视网膜厚度.采用组织病理学检查测量视网膜厚度并与OCT测量结果进行比较.结果 FFA检查结果显示,大鼠的视盘位于视网膜中央,血管走行呈放射状.荧光素钠注射后60 s背景荧光消失,需重复注射.至造模成功后12周,各组大鼠视网膜均未发现荧光素渗漏.OCT结果显示,正常SD大鼠的OCT图像与人类相似,共分为十层,与组织病理学检测的结果相吻合.距视盘2 DD处上方、下方、鼻侧、颞侧4个方向视网膜厚度及内外界膜间的厚度比较差异均无统计学意义（P＞0.05）.造模后4周、8周,与对照组大鼠比较,糖尿病组大鼠视网膜厚度无明显增加,差异均无统计学意义（P＞0.05）;造模后12周糖尿病组大鼠的视网膜厚度和内外界膜间厚度与对照组大鼠比较均明显增加,差异均有统计学意义（P＜0.05）.OCT测量的视网膜厚度和内外界膜间量化分析结果与组织病理学结果并不完全一致. 结论 SD-OCT联合FFA有助于活体观察糖尿病大鼠视网膜厚度的动态变化,评估血管渗漏情况,为糖尿病的发病机制研究、防治及病情监测提供依据.