Motion‐compensated b‐tensor encoding for in vivo cardiac diffusion‐weighted imaging

Motion is a major confound in diffusion‐weighted imaging (DWI) in the body, and it is a common cause of image artefacts. The effects are particularly severe in cardiac applications, due to the nonrigid cyclical deformation of the myocardium. Spin echo‐based DWI commonly employs gradient moment‐nulling techniques to desensitise the acquisition to velocity and acceleration, ie, nulling gradient moments up to the 2nd order (M2‐nulled). However, current M2‐nulled DWI scans are limited to encode diffusion along a single direction at a time. We propose a method for designing b‐tensors of arbitrary shapes, including planar, spherical, prolate and oblate tensors, while nulling gradient moments up to the 2nd order and beyond. The design strategy comprises initialising the diffusion encoding gradients in two encoding blocks about the refocusing pulse, followed by appropriate scaling and rotation, which further enables nulling undesired effects of concomitant gradients. Proof‐of‐concept assessment of in vivo mean diffusivity (MD) was performed using linear and spherical tensor encoding (LTE and STE, respectively) in the hearts of five healthy volunteers. The results of the M2‐nulled STE showed that (a) the sequence was robust to cardiac motion, and (b) MD was higher than that acquired using standard M2‐nulled LTE, where diffusion‐weighting was applied in three orthogonal directions, which may be attributed to the presence of restricted diffusion and microscopic diffusion anisotropy. Provided adequate signal‐to‐noise ratio, STE could significantly shorten estimation of MD compared with the conventional LTE approach. Importantly, our theoretical analysis and the proposed gradient waveform design may be useful in microstructure imaging beyond diffusion tensor imaging where the effects of motion must be suppressed.     

Cyclic exotropia associated with retinitis pigmentosa

Purpose To report the occurrence of cyclic exotropia in a patient with retinitis pigmentosa. Methods A 31-year-old man presented with cyclic exotropia of the left eye of 4 years duration that alternated every 24 h. A detailed ophthalmologic examination was performed. Results The patient showed an orthotropia and a comitant left exotropia of 30 prism diopters at distance and 25 prism diopters at near in the primary position on an exotropic day with a cycle of 48 h. A fundoscopic examination showed bone spicule formation and arteriolar narrowing, and electroretinography showed no response in either eye. A Goldmann visual field examination showed a central island in both eyes. Conclusions Cyclic exotropia may occur in patients with retinitis pigmentosa, an association that to the best of our knowledge has not been previously reported in the English ophthalmic literature. Cyclic exotropia is an unusual association with retinitis pigmentosa.     

Binocular Interactions in the Lateral Suprasylvian Visual Area of Strabismic Cats Following Section of the Corpus Callosum

Visually responsive neurons have been recorded in the lateral suprasylvian area (LSA) of cats raised with either a convergent or a divergent strabismus. In contrast to areas 17 and 18, where many studies have documented a profound loss of binocularly activated neurons following early strabismus, in the LSA the majority of cells could still be binocularly driven. Acute or chronic section of the splenium of the corpus callosum reduced but did not abolish binocularity in the LSA. We propose that the widespread callosal connections, the large size of the receptive fields and the peculiar internal circuitry of the LSA all concur in permitting the maintenance of binocular coding in spite of early misalignment of the eyes.     

眼球后退综合征的手术设计

目的 探讨眼球后退综合征(DRS)手术设计的特点。方法 11例眼球后退综合征患者，采用常规的方法检查眼位，单眼、双眼水平注视野，异常头位的偏斜角度。手术方式患眼外直肌不等量后徙。结果 原在位外斜，双眼注视野位于患眼颞侧，面部转向健眼一侧。手术后外斜视得到矫正，异常头位消失。结论 为了矫正原在位存在外斜视，即使外直肌力量不足，手术后外转进一步受限，也需减弱外直肌，以期获得良好效果。     

共同性内斜视手术的术后正位率

目的探讨共同性内斜视手术的术后正位率及其影响因素。方法统计和分析46例共同性内斜视的手术效果及术前诸多因素与术后正位率的关系。结果46例中手术后正位34例(73％)。发病年龄、手术年龄、病程、手术前双眼视力及手术前斜视是否交替性与术后双眼视功能的建立密切相关，而与眼位矫正无关，手术量是术后眼位的决定性因素。结论超常量内直肌徙后、以戴镜及裸眼视近斜视度的平均值作为目标角及以角膜缘为起点测量手术量都是提高手术正位率的重要因素。     

Clinical Features and Surgical Treatment of A-pattern Exotropia

IntroductionAnA鄄patternexotropiashowssignificantlymoreexodeviationindowngazeversusupgaze,inwhichthechangeofbinocularalignmentresemblesthealphaberA.Accordingtopublishedreports[1～4],A鄄patternexotropiaisviewedastheleasttypeofAandVpatterns.However,thepr鄄evalenceofA鄄patternexotropiaratherincreasedinourclinicalstudies[5],inwhichparticularattentionwaspaidtoobservethedeviationindownwardgazeandassesssuperiorobliquefunction.Accordingly,clinicalcharacteristics,surgicaltreatmentandtreatmentoutcome…     

间歇性外斜视的手术治疗

目的探讨间歇性外斜视手术治疗的疗效。方法回顾性分析30例间歇性外斜视患者的术前情况、手术情况及术后1～4周的随访情况,根据斜视的类型选择不同的手术方式并评价其治疗效果。结果30例间歇性外斜视患者术后临床治愈26例,占86．7%；欠矫4例,占13．3%。结论局麻手术时手术量的设计不应该因患者紧张而减小；正确选择间歇性外斜视的手术时机,发现双眼单视功能丧失或部分丧失时,应尽早手术矫正,可有利于双眼视功能的建立。     

单眼一退一缩术式矫正集合不足型间歇性外斜视短期效果分析

目的：观察一退一缩术式对集合不足型间歇性外斜视的效果和术后回退程度。

方法：对45例集合不足型间歇性外斜视患者由同一术者进行单眼一退一缩术式后,检查术后1d,2wk的斜视度,并进行统计分析。

结果：集合不足型间歇性外斜视患者45例进行单眼一退一缩术式后,术后1d,视远平均过矫8.27±7.17PD,视近平均过矫2.40±8.86PD,术后2wk视远平均欠矫1.18±6.98PD,视近平均欠矫4.36±7.83PD。术后2wk内,视远平均回退9.45±6.40PD,视近平均回退6.77±7.92PD。视远及视近回退呈正相关。术后2wk视远视近斜视度差异(3.18±5.60PD)较术前(7.65±6.55PD)明显减小,两者呈正相关。

结论：集合不足型间歇性外斜视患者适合一退一缩术式,适当加大内直肌手术量可减少术后远近斜视度的差异,且不改变患者内外直肌的张力状态。术后视远视近回退呈同步状态,视远约回退10PD,术后近期过矫10PD可有利于远期正位。     

新版美国眼科临床指南(PPP)对间歇性外斜视诊治的指导及解读

间歇性外斜视是临床最常见的外斜视类型。本文基于2017年版的美国眼科临床指南(PPP)《内斜视和外斜视》分册,从病史、斜视专科检查、分型、治疗4个方面对间歇性外斜视的规范化诊治进行解读。     

Comparison of contrast sensitivity based on the surgical results for intermittent exotropia

AIM: To compare contrast sensitivity (CS) based on the surgical results for intermittent exotropia (IXT) and to examine the relationship between CS and photophobia. METHODS: Medical records of the patients who underwent bilateral lateral rectus muscle recession for IXT between 4 and 12 years old were reviewed retrospectively. They were categorized based on the surgical results; successful correction group (n=36) and overcorrection group (esotropia ≥10 PD at 3mo postoperatively, n=18). Using CGT-2000 test for CS was performed binocularly, and subjective reports of photophobia was investigated preoperatively and at 3mo postoperatively. Objective photophobia was defined as a significant decrease in CS in the presence of glare. RESULTS: Preoperatively, there was no difference in CS between the groups. Postoperatively, under mesopic conditions, significant improvement of CS was observed at 6.3°, 4°, and 2.5° in the successful correction group and at 6.3° and 4° in the overcorrection group, regardless of glare. Under photopic conditions, at all visual angles except 0.64°, improvement in CS was noted in both groups while CS worsened significantly at 0.64° in the overcorrection group postoperatively. At all visual angles under photopic conditions postoperatively, regardless of glare, CS in the overcorrected group was significantly worse than that in the successful correction group, and CS was significantly decreased by addition of glare in both groups. All patients except one (96.4%) in the successful correction group and 8 patients (61.5%) in overcorrection group showed improvement of photophobia postoperatively, which correlated with CS under photopic conditions (P=0.001, 0.03). CONCLUSION: After surgery for IXT, CS under photopic conditions improve at all visual angles except 0.64°, while CS is significantly worse in the overcorrection group postoperatively at 0.64°. Subjective photophobia have significant correlation with CS under photopic conditions, and may be used as an objective indicator of photophobia.