Impaired functional visual acuity of dry eye patients.

PURPOSE: To report dry eye patients' functional visual acuity, which was measured after sustained eye opening for 10-20 seconds, as a simulation of visual function of daily acts of gazing, which is defined as looking at an object with involuntary blink suppression. METHODS: Interventional clinical nonrandomized comparative trial. We measured ordinary best-corrected visual acuity and functional visual acuity in non-Sj?gren's syndrome (non-SS, N = 10) and Sj?gren's syndrome (SS, N = 12) patients and in normal controls (N = 8), prospectively. Surface regularity index (SRI) of corneal topography was also measured under routine circumstances and after sustained eye opening. Blink rates while gazing were measured during reading in another 28 dry eye patients and during driving in another 8 normal controls. RESULTS: Functional visual acuity did not change (1.27-1.16) in normal controls, but decreased significantly from 1.18-0.336 in non-SS patients (P = .0007) and from 1.15-0.228 (P < .00001) in SS patients. SRI after sustained eye opening increased in non-SS (P = .032) and SS patients (P = .0007), but not in the normal controls. Blink rates during reading (P < .001) and driving (P = .012) were significantly decreased from baseline blink rates. CONCLUSIONS: This study shows that the visual function of dry eye patients becomes abnormal with ocular surface irregularity when the eye is kept open for 10-20 seconds. Our data indicate impaired visual function in dry eye patients while gazing. Functional visual acuity may be important in daily activities.     

干眼症患者功能视力初探

目的观察干眼症患者持续睁眼10～20s时其功能视力的变化,以模拟日常生活中因凝视物体瞬目减少情况下的视功能情况,即功能视力。方法观察正常对照组(非干眼症组10人)和干眼症组(非sjogren’s综合征患者10人)日常最好矫正视力和功能视力,并观察他们专注时如阅读和行视野检查时的瞬目频率。结果正常对照组功能视力没有改变(P=0.098),干眼症组由1.15±0.15减少为0.69±0.08,专注时的自然瞬目频率亦减少(P<0.01)。结论干眼症患者持续睁眼10～20s时其功能视力会下降,推测日常从事专注性工作时干眼症患者的视功能会受损,对干眼症患者功能视力的测试更有使用意义。     

Improved functional visual acuity after punctal occlusion in dry eye patients

PURPOSE: To report an increased functional visual acuity, which was recently reported as a simulation of visual function of daily acts of gazing, in dry eye patients after punctal occlusion. DESIGN: Prospective comparative interventional study. METHODS: We measured ordinary best-corrected visual acuity and functional visual acuity in eight eyes of eight dry eye patients after punctal occlusion, and compared the results with those of 22 eyes of 22 dry eye patients without punctal occlusion. RESULTS: Functional visual acuity in dry eye patients after punctal occlusion was 0.962 in decimal notation, which was significantly higher than that of patients without punctal occlusion, 0.283 (P <.0001). CONCLUSIONS: This study shows that punctal occlusion can improve the impaired functional visual acuity of dry eye patients.     

Variability of measurements of visual acuity in a large eye clinic

PURPOSE: The aim of this study was to determine the variability of visual acuity in a large eye clinic. METHODS: A cross-sectional study using 50, consecutively presenting adult patients with visual acuity of at least 6/60 and aged between 18 and 75 years was performed. Measurements of visual acuity obtained under normal clinical conditions were compared to measurements obtained using standard clinical research protocols. The variability of visual acuity was assessed by determining the 95% limits of agreement between test and retest measures. RESULTS: There were no significant differences between test-retest measurements of visual acuity, either aided or unaided. Pearson r correlation coefficients between test and retest measurements were high for both aided and unaided visual acuity. The 95% limits of agreement revealed repeatability of about +/-1.5 logMAR or 1.5 lines on a standard logMAR chart. CONCLUSION: In large eye clinics, in order to be confident that a real change in visual acuity has occurred between measurements, a difference of at least 0.15 logMAR (8 letters on a standard logMAR visual acuity chart) is required.     

Physiological basis of visual acuity measurement

The paper presents information about types of acuity tasks, visual acuity limitations and contrast sensitivity function. Measurements of resolution acuity may be interpreted as estimates of spatial density of the mosaic of photoreceptors and ganglion cells of the living human eye. Physiological basis such as Raleigh's criteria, sampling theory and filtering theory of visual resolution are described.     

连续性功能性视力在眼科的应用进展

连续性功能性视力（FVA）被认为是一种可以较好体现自然状态下视功能的功能性视力检查方法,它的概念与测量方法随着技术的进步得到了不断的更新.FVA检查最初应用于干眼患者的评估,并在屈光不正、白内障、眼底病变、药物使用效果评估等领域逐渐得到推广,为一些眼病的早期诊断、治疗效果评价等提供了理论依据.就FVA的概念与方法、FVA的测量系统以及FVA在干眼、屈光不正、白内障和眼底病变患者中的应用和研究进展进行综述.     

新型纳米材料在干眼中的应用进展

局部点药是眼部用药最常见的方式,但一般药物通过角膜困难,药物生物利用度低.纳米载体药物于80年代开始用于眼部,脂质体和类脂质囊泡(niosomes)与眼表的黏蛋白相互作用,延长药物在眼表的停留时间.纳米乳剂(nanoemulsion)的表面活性剂可以松解角膜上皮细胞紧密连接,形成转运开口,抑制细胞表面糖蛋白酶P(gly...     

The relation of functional visual acuity measurement methodology to tear functions and ocular surface status

Purpose  

To investigate the relation of functional visual acuity (FVA) measurements with dry eye test parameters and to compare the testing methods with and without blink suppression and anesthetic instillation.     

Random measurement error in visual acuity measurement in clinical settings

PURPOSE: To estimate the random measurement error in visual acuity (VA) determination in the clinical environment in cataractous, pseudophakic and healthy eyes. METHODS: The VAs of patients referred for cataract surgery or consultation by ophthalmic professionals were re-examined and the VA results for distance using projector acuity charts were compared. Refractive errors were also remeasured. A total of 99 eyes (41 cataractous, 36 pseudophakic and 22 healthy eyes) were examined. The healthy comparison group consisted of hospital staff. Only one eye of each person and eyes with Snellen VAs of 0.3-1.3 (logMAR 0.52 to - 0.11) were included. The mean time interval between the first and second examinations was 45 days. RESULTS: The estimated standard deviation of measurement error (SDME) of repeated VA measurements of all eyes was logMAR 0.06. Eyes with the lowest VA (0.3-0.45) had the largest variability (SDME logMAR 0.09), and eyes with VA > or = 0.7 had the smallest (SDME logMAR 0.04). The variability may be partly explained by the line size progression in lower VAs, partly by the difference in the remeasurement of the refractive error. The difference in the average VA between examinations 1 and 2 (logMAR 0.15 versus 0.12) was considered to be of some interest because it indicates that some learning effect is possible. CONCLUSION: Visual acuity results in clinical settings have a certain degree of inherent variability. In this series variability ranged from SDME logMAR 0.04 (eyes with good vision) to logMAR 0.09 (in the lower vision group) in the Snellen VA range of 0.3-1.3. Changes should be judged with caution, especially in cases of decreased VA.     

噪声视力表在儿童视力检查中的可重复性分析

目的探讨噪声视力表对儿童视力检查的可重复性及其相关影响因素。方法在门诊首诊患儿中,随机选择无理解障碍及除屈光不正外无其他器质性眼病儿童200例,使用噪声视力表进行噪声视力重复检查。采用配对t检验进行统计学分析。结果两次视力测量之间差异的均数为O.03行,（P=0.515）;两次视力测量结果按性别分组无明显差异（P=1.0,P=0.262）;按年龄分组亦无明显差异（P=0.159,P=0.786）;按屈光不正分组,其中近视组两次视力测量结果有明显差异（P=0.010）。近视儿童视力检查一致性较差,而正视及远视儿童的视力检查一致性较好（P=0.133,P=0.083）。结论结果提示噪声视力表适合儿童视力检查,建议推广使用。