不同泪道硅胶引流管留置时间对慢性泪囊炎患者视力、生活质量及复发率的影响

目的:探讨不同泪道硅胶引流管留置时间对慢性泪囊炎患者的生活质量、视力及复发率的影响。方法:回顾性选取2018年1月2019年12月期间于我院就诊的慢性泪囊炎患者91例(128眼),根据术后泪道硅胶引流管留置时间分为A、B两组,其中A组泪道硅胶引流管留置时间6周,44例(61眼),B组泪道硅胶引流管留置时间12周,47例(67眼)。对比两组疗效、视力、并发症发生率、主诉溢泪发生率、生活质量及复发率。结果:A组拔管当天的总有效率高于B组(P<0.05),两组拔管后3个月总有效率对比无明显差异(P>0.05)。拔管后6个月两组社会功能、躯体疼痛、精神健康、生理功能、精力、情感职能、生理职能、总体健康维度评分均较术前升高(P<0.05),但两组组间对比未见统计学差异(P>0.05)。两组患者术前、拔管后3个月视力组间及组内比较均未见统计学差异(P>0.05)。两组患者主诉溢泪发生率比较未见统计学差异(P>0.05)。A组并发症发生率、复发率低于B组(P<0.05)。结论:泪道硅胶引流管留置时间的长短对慢性泪囊炎患者疗效、视力、生活质量、主诉溢泪发生率无明显影响,但留置6周者并发症发生率、复发率低于留置12周者,提示临床应视患者具体情况尽量缩短泪道硅胶引流管留置时间。     

体视感觉“崩溃”的阀值

视差是产生体视感觉的主要因素.但视差过大时这种体视感觉也不能存在.这时随着双眼视差的增大从融合为单一像到成复像,而引起体视“崩溃”.本文对正常人和体视欠缺者用心理物理试验方法结合视觉诱发电位(VEP)分析,测量了人眼体视“崩溃”的视差上限阈值.并在改变刺激图形亮度和面积时加以比较.我们的结果表明正常人体视上限阈值,其视差高于2度,在某些情况下这个“崩溃”阈值达到3度.体视欠缺者的“崩溃”阈值约为1.5度.亮度和面积变小会使体视“崩溃”阈值下降,但在这种情况下体视欠缺者的“崩溃”阈值不会下降.可以认为1.5度是人的最低上限阈值·体视存在时VEP的N峰潜伏期约为220—300ms,P_3峰在280—340ms之间.无体视现象(视差为零和过大)这两个峰的潜伏期明显加大.     

视力与视觉诱发电位的相关分析

对104例病人的图形翻转VEP的瞬态波形各参数,以及9例正常或近视学生的稳态曲线功率谱与视力之间的关系进行了多元相关统计分析,旨在探讨VEP的哪些参数可客观地评估视力.结果表明,瞬态VEP的波形参数中以13’格诱发的N_1P_1、P_1N_2的峰峰值及P_(100)潜伏期与视力的相关系数最大,故认为,分析视力时以平均P_(100)波的波幅值和P_(100)波潜伏期作指标较为灵敏;而稳态、VEP能谱曲线则显示,视力与平均相叶能谱或刺激频率点的能谱相关性较大,与二次谐波的相关性则小.     

大熊猫视力的定量化

有大量的研究提出,大熊猫具有发达的嗅觉和听觉系统但是视力很差。 虽然有些关于大熊猫视力和色觉方面的研究,但是至今我们对大熊猫的具体视力值方面的内容知之甚少。为了定量化大熊猫的视力值,我们观察并记录了8只圈养大熊猫（雌:雄=4:4）对于移动不同水平黑白相间条纹宽度的纸片的行为反应。我们发现,在测量距离为50 cm的情况下,大熊猫能够区分大约为0.46mm宽的黑白相间条纹。这个研究结果为大熊猫视网膜结构的解剖学研究提供了行为学支持,也为今后研究大熊猫的通讯和认知提供一定的参考。     

端粒长度及端粒酶活性与儿童先天性心脏病发病机制的相关性研究

目的:探讨不同年龄儿童外周血白细胞端粒长度及端粒酶活性与儿童先心病发病机制的相关性.方法:采用实时荧光定量PCR检测先天性心脏病2个年龄组及健康受试者外周血白细胞的端粒长度及hTERT mRNA(端粒酶催化亚基).比较相同年龄的先天性心脏病与健康受试者外周血白细胞的端粒长度及hTERT mRNA差异,并比较不同年龄组间外周血白细胞的端粒长度及hTERT mRNA差异.结果:先天性心脏组3-6岁组的受检者及健康受试者3-6岁组平均外周血白细胞端粒(1.63± 0.61)长于先天性心脏组7-10岁组的受检者及健康受试者7-10岁组(1.36± 0.46)(t=1 1.37,P＜0.05);各组均无端粒酶表达.结论:外周血白细胞的端粒长度随着年龄的增长而缩短.端粒酶活性与先天性心脏病发病并无直接相关性.     

用于立体视检测的微机软件包的设计

为了快速、方便、准确地检测人的立体视功能,根据双眼视差原理,设计了用于立体视检测的微机软件包称为立体视检测(SVT).利用该软件可在彩色屏幕(VGA)上产生静态等视差图(图中各部分的视差不随空间位置的变化而改变)、变视差图、以及在深度上的正弦波状起伏图形.叙述了设计原理和程序框图;报导了用SVT软件包对视力正常和异常儿童的立体视检测结果并讨论了其临床应用价值．     

新疆伊犁锡伯族和蒙古族的苯硫脲尝味能力测定

用阈值法对新疆伊犁的锡伯族1121人和蒙古族679人的苯硫脲尝味能力进行了测定,结果表明,锡伯族中味盲率为19.98％,味盲基因频率为0.4470,平均尝味阈值为8.53±1.25;蒙古族中味盲率为15.17％,味盲基因频率为0.3895,平均尝味阈值为8.10±1.49。味盲率、平均尝味阈值和味盲基因频率在锡伯族男女间无明显差异(P>0.05),而在蒙古族中,味盲率与味盲基因频率分布男女间差异显著(P<0.01)。在上述这两个民族中,少年组的味盲率高于成年组。对同一受试者的ABO血型与卷舌能力也进行了观察和分析。     

大熊猫视力的定量化（英文）

有大量的研究提出,大熊猫具有发达的嗅觉和听觉系统但是视力很差。虽然有些关于大熊猫视力和色觉方面的研究,但是至今我们对大熊猫的具体视力值方面的内容知之甚少。为了定量化大熊猫的视力值,我们观察并记录了8只圈养大熊猫(雌:雄=4:4)对于移动不同水平黑白相间条纹宽度的纸片的行为反应。我们发现,在测量距离为50 cm的情况下,大熊猫能够区分大约为0.46 mm宽的黑白相间条纹。这个研究结果为大熊猫视网膜结构的解剖学研究提供了行为学支持,也为今后研究大熊猫的通讯和认知提供一定的参考。     

马来酸噻吗洛尔联合拉坦前列腺素治疗高眼压型开角型青光眼的效果

目的:探讨马来酸噻吗洛尔联合拉坦前列腺素治疗高眼压型开角型青光眼的临床效果。方法:选取高眼压型开角型青光眼患者210例,随机分为治疗组和对照组,每组各105例。对照组患者给予马来酸噻吗洛尔治疗,治疗组患者给予马来酸噻吗洛尔联合拉坦前列腺素治疗。观察并比较两组患者治疗前后视力改善情况,眼压、视乳头杯盘比值变化情况,眼结膜充血、眼内干涩、角膜点状浸润以及一过性视觉模糊等不良反应的发生情况等。结果:治疗组患者视力改善率为85.7%,对照组为71.4%,治疗组高于对照组,差异具有统计学意义(P0.05);治疗后两组患者眼压、视乳头杯盘比值均明显下降,且治疗组明显低于对照组,差异具有统计学意义(P0.05)。治疗组患者眼结膜充血、眼内干涩、角膜点状浸润以及一过性视觉模糊等不良反应明显低于对照组,差异具有统计学意义(P0.05)。结论:马来酸噻吗洛尔联合拉坦前列腺素治疗高眼压型开角型青光眼能够改善患者视力水平,值得临床推广应用。此外,我们分析其作用可能与降低视乳头杯盘比值有关。     

遗传性盲疾经基因治疗恢复视力

一种罕见的遗传性盲人现在可较易重见光明了.一项对盲小鼠的研究为眼丧失全部光加工细胞的人复明提供了希望.有3个患有一种遗传性盲疾,称为勒伯尔先天性黑蒙的人,经基因治疗恢复了视力,研究者报道于2008年4月27日New England Journal of Medicine上.该盲疾是由基因RPE65突变引起,该基因编码一种蛋白质,可帮助视杆细胞中的光采集色素的再循环.视锥细胞可以在一段时期中起作用,但也开始衰退,通常使40岁以下的人致盲.美国有2 000～3 000人罹患此眼疾.研究者将含有RPE65正常拷贝的工程病毒注射到罹患该退行性眼疾的3个人右眼中.所有3个人在数周后改善了右眼的视力,2个人在术前仅能辨清手的移动,而术后所有病人都能读出视力表的3行字.当光照在病人治疗后的眼时,病人的瞳孔收缩,说明病人的视网膜察觉出光线.无一病人视力恢复到20/20,但是所有这3个病人均汇报在暗淡光线下的视力有改善,并加强了驾驶能力.另一个研究组用不同的方法恢复了小鼠的视力,这些小鼠丧失了所有察觉光线的视杆细胞与视锥细胞.除了这些小鼠以外,其他动物,包括人,都会因此失明.该研究结果发表在2008年4月27日Nature Neuroscience上.一旦这些光感受器细胞死亡,如原发性色素性视网膜炎或是黄斑变性,可选择的恢复方法甚少.有些研究者试图用电刺激视网膜来治疗.在2006年,科学家报道,他们用来自绿藻Chlamydomonas reinharditic的一种光采集蛋白的基因插入到类似原发性色素性视网膜炎的小鼠视网膜中去.当小鼠受光刺激时,该蛋白质能将小鼠眼受损伤的信息传递到大脑.但是不管用绿藻蛋白还是用电刺激法,是否确实能使整个视网膜恢复视力尚不清楚.现在研究者将光采集藻蛋白(ChR2)插入到视网膜的第二层称为ON双极细胞中去,该细胞对亮光有反应;相类似的细胞称为OFF双极细胞则对暗淡光线起反应.ON与OFF细胞正常时将来自视杆细胞与视锥细胞的信号传递给大脑视觉中心,故而若直接刺激这些细胞可以恢复视力.研究者用电流将载有ChR2基因的DNA片段灌注到ON双极细胞中去,该基因受DNA片段的调控而只允许其在ON双极细胞中开启.该技术产生的蛋白质只是一时的,故而人的治疗需要更为持久的方法.用工程化方法在ON细胞中制造蛋白质ChR2的盲小鼠当暴露于亮光时,如正常小鼠一样急忙遮住眼睛.未经治疗的盲小鼠则无此对光反应. (李潇摘译自Tina Hesman Saey:Science News, May 24,2008,p.8)     

Screening for Significant Refractive Error Using a Combination of Distance Visual Acuity and Near Visual Acuity

PurposeTo explore the effectiveness of using a series of tests combining near visual acuity (NVA) and distance visual acuity (DVA) for large-scale screenings for significant refractive error (SRE) in primary school children.MethodEach participant underwent DVA, NVA and cycloplegic autorefraction measurements. SREs, including high myopia, high hyperopia and high astigmatism were analyzed. Cycloplegic refraction results were considered to be the gold standard for the comparison of different screening measurements. Receiver-operating characteristic (ROC) curves were constructed to compare the area under the curve (AUC) and the Youden index among DVA, NVA and the series combined tests of DVA and NVA. The efficacies (including sensitivity, specificity, positive predictive value, and negative predictive value) of each test were evaluated. Only the right eye data of each participant were analysed for statistical purpose.ResultA total of 4416 children aged 6 to 12 years completed the study, among which 486 students had right eye SRE (SRE prevalence rate = 11.01%). There was no difference in the prevalence of high hyperopia and high astigmatism among different age groups. However, the prevalence of high myopia significantly increased with the age (χ² = 381.81, p<0.01). High hyperopia was the biggest SRE factor associated with amblyopia（p＜0.01，OR = 167.40, 95% CI: 75.14∼372.94). The DVA test was better than the NVA test for detecting high myopia (Z = 2.71, p<0.01), but the NVA test was better for detecting high hyperopia (Z = 2.35, p = 0.02) and high astigmatism (Z = 4.45, p<0.01). The series combined DVA and NVA test had the biggest AUC and the highest Youden Index for detecting high hyperopia, myopia, astigmatism, as well as all of the SREs (all p<0.01).ConclusionThe series combined DVA and NVA test was more accurate for detecting SREs than either of the two tests alone. This new method could be applied to large-scale SRE screening of children, aged 6 to 12, in areas that are less developed.     

Functional Visual Acuity of Early Presbyopia

Purpose

To evaluate visual function in patients with early presbyopia using the functional visual acuity (FVA) test.

Methods

This study included 27 eyes of 27 healthy older volunteers (mean age, 44.1 ± 2.6 years) and 14 eyes of 14 healthy young volunteers (mean age, 28.4±4.8 years). The distance-corrected visual acuity (DCVA), distance-corrected near VA (DCNVA), subjective amplitude of accommodation (AA), and distance and near pupillary diameters were measured. The distance FVA and distance-corrected near FVA (DCNFVA) were measured using the FVA Measurement System. The standard Schirmer test and standard tear break-up time measurement also were performed.

Results

The logarithm of the minimum angle of resolution (logMAR) DCVA was better than 0 in all subjects. The percentages of subjects with logMAR DCNVA below 0 was significantly lower in the presbyopia group than in the young group. The DCNFVA in the presbyopia group was significantly (P < 0.001) poorer than the DCNVA in that group. Significant linear negative correlations were seen between the DCNVA and AA (r = -0.507, P < 0.001) and the DCNFVA and AA (r = -0.681, P < 0.001) in the older subjects. Stepwise regression analysis showed that only the AA was a significant factor predictive of the DCNFVA in the presbyopia group. Tear function parameters were not adopted in the regression model.

Conclusions

Measurement of the DCNFVA can detect decreased AA in early presbyopia better than measurement of the conventional near VA. The DCNFVA is a good index for early presbyopia.     

Photometric Compliance of Tablet Screens and Retro-Illuminated Acuity Charts As Visual Acuity Measurement Devices

Mobile technology is increasingly used to measure visual acuity. Standards for chart-based acuity tests specify photometric requirements for luminance, optotype contrast and luminance uniformity. Manufacturers provide some photometric data but little is known about tablet performance for visual acuity testing. This study photometrically characterised seven tablet computers (iPad, Apple inc.) and three ETDRS (Early Treatment Diabetic Retinopathy Study) visual acuity charts with room lights on and off, and compared findings with visual acuity measurement standards. Tablet screen luminance and contrast were measured using nine points across a black and white checkerboard test screen at five arbitrary brightness levels. ETDRS optotypes and adjacent white background luminance and contrast were measured. All seven tablets (room lights off) exceeded the most stringent requirement for mean luminance (≥ 120 cd/m²) providing the nominal brightness setting was above 50%. All exceeded contrast requirement (Weber ≥ 90%) regardless of brightness setting, and five were marginally below the required luminance uniformity threshold (L_min/L_max ≥ 80%). Re-assessing three tablets with room lights on made little difference to mean luminance or contrast, and improved luminance uniformity to exceed the threshold. The three EDTRS charts (room lights off) had adequate mean luminance (≥ 120 cd/m²) and Weber contrast (≥ 90%), but all three charts failed to meet the luminance uniformity standard (L_min/L_max ≥ 80%). Two charts were operating beyond manufacturer’s recommended lamp replacement schedule. With room lights on, chart mean luminance and Weber contrast increased, but two charts still had inadequate luminance uniformity. Tablet computers showed less inter-device variability, higher contrast, and better luminance uniformity than charts in both lights-on and lights-off environments, providing brightness setting was >50%. Overall, iPad tablets matched or marginally out-performed ETDRS charts in terms of photometric compliance with high contrast acuity standards.     

Normal Monocular and Binocular Visual Acuity in Seven-Year-Old Children

The purpose of this study was to obtain age-specific normative data for visual acuity (VA) in sevenyear- old children. The sample included a total of 127 healthy children (mean age 7.53 ± 0.025 years) without ophthalmic disorders. Monocular and binocular VAs were determined to the threshold level at two distances, 5 m and 0.5 m, using eye charts with eight intermediate levels between 1.0 and 2.4 (in the decimal notation system) with widely spaced tumbling Snellen’s E optotypes randomly distributed in four orientations. Since the optotypes were located in lines at intervals that were twice as large as the size of the optotype itself, they could be considered as single stimuli. The normal monocular and binocular VAs were 1.279 ± 0.025 and 1.491 ± 0.028 at 5 m and 1.256 ± 0.024 and 1.388 ± 0.025 m at 0.5 m, respectively (mean ± standard error of mean). Interocular differences in VA are also discussed. Our findings show that the normal VA in seven-yearold children is higher than the clinically accepted norm of 1.0; therefore, VA measurement to the threshold level is necessary for earlier visual disorders to be detected.     

The Visual Acuity of the Frog (Rana pipiens )

The frog's visual acuity for gratings was tested with a two-choice prey-dummy setup. The two dummies had a constant position in the visual field, but in one of them a striped pattern was constantly drifting, while the other was a potentially less attention arousing dummy with non-moving stripes. The acuity was tested in bright white light and with different brightness levels of green light (500 nm). The highest acuity 2.8 cycles per degree was achieved with the maximum level of green light. When the brightness was lowered by six orders of magnitude the acuity fell to 0.7 cycles per degree. These behavioural acuities are compared with a theoretically calculated resolving power of the retinal ganglion cell array.     

The Effect of Zeaxanthin on the Visual Acuity of Zebrafish

Oral supplementation of carotenoids such as zeaxanthin or lutein which naturally occur in human retina have been shown to improve vision and prevent progression of damage to advanced AMD in some studies. The zebrafish eye shares many physiological similarities with the human eye and is increasingly being used as model for vision research. We hypothesized that injection of zeaxanthin into the zebrafish eye would improve the visual acuity of the zebrafish over time. Visual acuity, calculated in cycles per degree, was measured in adult zebrafish to establish a consistent baseline using the optokinetic response. Zeaxanthin dissolved into phosphate buffered saline (PBS) or PBS only was injected into the anterior chamber of the right and left eyes of the Zebrafish. Visual acuities were measured at 1 week and 3, 8 and 12 weeks post-injection to compare to baseline values. Repeated measures ANOVA was used to compare visual acuities between fish injected with PBS and zeaxanthin. A significant improvement in visual acuity, 14% better than before the injection (baseline levels), was observed one week after injection with zeaxanthin (p = 0.04). This improvement peaked at more than 30% for some fish a few weeks after the injection and improvement in vision persisted at 3 weeks after injection (p = 0.006). The enhanced visual function was not significantly better than baseline at 8 weeks (p = 0.19) and returned to baseline levels 12 weeks after the initial injection (p = 0.50). Zeaxanthin can improve visual acuity in zebrafish eyes. Further studies are required to develop a better understanding of the role zeaxanthin and other carotenoids play during normal visual function.