The absence of lateral congruency between sighting dominance and the eye with better visual acuity

The notion that in subjects with normal binocular vision (i.e. non-strabismic cases) the eye showing sighting dominance will also most likely be that individual's better-sighted eye has proved to be persistent. A review and analysis of the literature has now demonstrated, across several population groups, the fallacy of this belief. In fact, the occurrence of lateral congruency between sighting dominance and the eye with better visual acuity is at a statistical level no greater than chance would predict. Some clinical implications of this outcome are considered.     

Sighting ocular dominance magnitude varies with test distance

Background

Ocular dominance can be defined as the preference of an individual for viewing with one eye over the other for particular visual tasks. It is relevant to monovision contact lens wear, cataract surgery and sports vision. Clinically, the measurement of ocular dominance is typically done at an arbitrary distance using a sighting test, such as the hole‐in‐card method that has a binary outcome. We investigated the effect of test distance on ocular dominance measured using a binocular sighting test that provided a continuous measurement of dominance.

Methods

Ten participants with normal binocular vision took part in this study. Their binocular sighting ocular dominance and phorias were measured at one, two, four, eight and 10 metres. During the dominance tests participants made a binocular alignment judgment and then were asked to indicate the relative alignment of each eye using a visual analogue scale as a reference.

Results

Eight participants had strong ocular dominance (five right, three left). For these participants, there was a significant increase in the magnitude of dominance with increasing test distance (p < 0.001). This could not be fully explained by changes in convergence demand. Two participants showed very weak ocular dominance across all test distances (p > 0.05), despite changes in convergence demand.

Conclusion

When ocular dominance is present, its magnitude varies significantly with test distance. This has significant implications for the accurate measurement of ocular dominance in the clinic and may reflect the neural processes that influence eye preference.

     

Contrast sensitivity and acuity of the goldfish.

Photopic contrast thresholds to sinusoidal gratings were measured in five goldfish by conditioning respiration in a Pavlovian paradigm. Vertical gratings were generated on an oscilloscope at a space-averaged luminance of 5 and 23 cd/m². The CSF (contrast sensitivity as a function of grating spatial frequence) peaked at about 0.3 c/deg, falling off at lower and higher spatial frequencies. CSF's were fitted by double exponential functions that were used to calculate acuity and point-spread functions. Acuity, defined as the half-period of a just resolvable unity contrast grating, ranged in different fish from 13′ to 22′, the smaller value agreeing with the acuity predicted from the intercone separation. The central region of the derived point-spread function subtended about 1.6°, which is smaller than both the smallest ganglion cell receptive field centers, and the limit of full summation previously found for the light-adapted goldfish.     

Development of spatial resolution, contrast sensitivity and binocularity in normal and strabismic kittens

The purpose of the present experiment was to evaluate visual acuity, contrast sensitivity and binocularity in teno-tomized, strabismic kittens of various ages.     

超常视力眼波前像差与对比度视力相关性研究

目的 分析超常视力眼波前像差与不同对比度视力的相关关系,探讨与视力相关的像差函数.方法 应用Snellcn视力表检测裸眼视力≥1.5者81例(81只眼),用WASCA波阵面像差仪测眼波前像差,用多功能电子视力测量仪测量、暗环境下对比度分别为100%、25%、10%和5%的视力.用多元线性相关与回归分析波前像差与不同对比度视力的相关关系.结果 总像差、各阶像差及各Zemike函数与亮、暗环境中对比度为100%和25%视力间的直线相关关系均无统计学意义(P＞0.05).总像差、2阶像差及离焦像差与亮、暗环境中对比度为10%和5%视力间直线相关关系均有统计学意义(P＜0.01)相关系数分别为-0.30、-0.35和-0.28、-0.35:-0.33、-0.38和-0.28、-0.39;-0.31、-0.39和-0.28、-0.39(P＜0.01).其余像差与对比度为10%利5%视力间直线相关关系均无统计学意义(P＞0.05).结论 超常视力眼波前像差与高对比度视力无直线相关关系,与低对比度视力有直线相关关系,总像差、2阶像差和离焦像差越小,低对比度视力越好.     

High contrast and low contrast visual acuity in age related macular degeneration*

Low contrast Bailey-Lovie visual acuity (LCBL) and high contrast Bailey-Lovie visual acuity (HCBL) were measured in subjects with age-related macular degeneration (ARM) and subjects with normal visual function. Low and high contrast visual acuities and the difference between low and high contrast acuities were significantly different for the ARM group compared with the normals, confirming previous findings of disruption to contrast discrimination in ARM. The high contrast Bailey-Lovie chart was found to be a useful screening device for macular degeneration using a pass/fail criterion of 6/7.5. Pre-ARM (PARM) subjects can be defined as those with drusen and/or pigmentary disturbance and high contrast acuity of better than 6/7.5. However, the low contrast chart used at normal clinical illuminances is of no additional diagnostic value in ARM.     

The contrast sensitivity of the squirrel monkey (Saimiri sciureus)

The contrast sensitivity of three squirrel monkeys and two human subjects was measured under similar conditions with a modified method of constant stimuli. Sensitivity was greatest for all subjects at 2–5c/deg and declined at higher and lower spatial frequencies. The high frequency limit of resolution was approx 35 c/deg for two monkeys and the human subjects and 17 c/deg for the other monkey. These results agree closely with previous visual acuity measurements for both species when luminance differences are taken into account. At the low photopic luminance used in the present study, the spatial vision of humans and squirrel monkeys appears very similar.     

Association of lens opacities,intraocular straylight,contrast sensitivity and visual acuity in European drivers

Purpose: To study the relationship between lens opacity and intraocular straylight, visual acuity and contrast sensitivity. Methods: We investigated 2422 drivers in five clinics in different European Union (EU) member states aged between 20 and 89 years as part of a European study into the prevalence of visual function disorders in drivers. We measured visual acuity [Early Treatment Diabetic Retinopathy Study (ETDRS) chart], contrast sensitivity (Pelli–Robson chart) and intraocular straylight (computerized straylight meter). Lens opacities were graded with the Lens Opacities Classification System III (LOCS) without pupillary dilation. Participants answered the National Eye Institute Visual Functioning Questionnaire – 25. Results: Intraocular straylight was related more strongly to LOCS score than to both visual acuity and contrast sensitivity. Visual acuity and contrast sensitivity were correlated to each other well, but to intraocular straylight to a much lesser extent. Self‐reported visual quality was best related to contrast sensitivity; night driving difficulty was best related to visual acuity. Conclusion: Straylight is found to have added value for visual function assessment in drivers, whereas if visual acuity is known contrast sensitivity has limited added value.     

正视眼波前像差与低对比度视力相关性研究

目的 分析正视眼波前像差与低对比度视力的相关性.方法 对95例(95眼)健康正视眼用WASCA(wavefront supported corneal ablation)波阵面像差仪测眼波前像差,对瞳孔6 mm时第2,3,4阶像差的各项Zernike函数(C3-C14)进行分析.用多功能电子视力测量仪检测亮、暗环境中对比度为10﹪和5﹪时的裸眼视力和最佳矫正视力.用多元线性回归分析眼波前像差与各低对比度视力间的相关关系.结果 离焦像差(C4)与亮、暗环境中对比度为10﹪和5﹪时的裸眼视力间的直线相关关系有统计学意义(P＜0.01);水平彗差(C8)与亮、暗环境中对比度为10﹪和5﹪时的最佳矫正视力间的直线相关关系有统计学意义(P＜0.01).其余Zernike 函数与各低对比度视力间的直线相关关系均无统计学意义(P＞0.05).结论 正视眼的波前像差与低对比度视力有关,其中离焦像差与裸眼视力有关,水平彗差与最佳矫正视力有关.     

屈光参差性弱视一阶光栅锐度和二阶纹理敏感度的感知能力

目的：研究单眼屈光参差性弱视患者对一阶光栅锐度和二阶纹理敏感度的感知能力。方法：收集2018-01/2022-12于我院确诊的单眼屈光参差性弱视儿童715例715眼作为弱视组，另选取矫正视力正常儿童745例745眼作为正常对照组。分别检测最佳矫正视力(BCVA)、一阶光栅锐度和(或)二阶纹理敏感度，并分析不同程度弱视患者对一阶光栅锐度和二阶纹理敏感度的感知能力。结果：弱视组与正常对照组一阶光栅锐度(11.58±6.10 vs 20.27±3.47，P&#x003C;0.001)、二阶纹理敏感度(0.33±0.16 vs 0.12±0.04，P&#x003C;0.001)均有明显差异，且轻中度弱视患者与重度弱视患者一阶光栅锐度(12.10±6.23 vs 8.13±3.70，P&#x003C;0.001)和二阶纹理敏感度(0.32±0.16 vs 0.37±0.17，P&#x003C;0.05)均有明显差异。结论：单眼屈光参差性弱视患者大脑皮层一阶视觉通路和二阶视觉通路均存在不同程度的损伤，重度弱视患者较轻中度弱视患者损伤更为严重。     

训练方式对共同性斜视术后患者眼位控制及立体视觉功能重建的影响

目的 比较不同训练方式对共同性斜视术后患者的眼位控制及立体视觉功能重建的效果。设计 前瞻性随机对照研究。研究对象 北京同仁眼科中心进行斜视矫正术的213例共同性斜视患者。方法 所有患者术后1周开始以训练方式不同随机分为观察组65例、传统双眼视觉训练组76例和视感知觉训练组72例,于术后1周,1、3、6个月进行随访,比较三组患者在术后不同时间点眼位控制情况及立体视觉功能变化。主要指标 斜视度、知觉眼位、扭曲度、正位率、立体视觉功能。结果 术后6个月时,观察组、传统训练组和视感知觉组眼位正位率分别为78.46%、86.84%、91.67%,其中视感知觉训练组正位率显著高于观察组（χ2=4.78,P=0.03）;三组患者远近斜视度均较术后1周时显著增加（F远=676.69,F近=794.65,P均=0.000）。视感知觉组术后3、6个月知觉眼位水平偏移数值较术后1周显著降低（F=98.34,P=0.000）,其他两组术后各时间点无显著性差异。传统训练组和视感知觉组扭曲度平均偏移较术后1周显著降低（F=90.37,P=0.000）,观察组术后各时间点差异无显著性。远立体视术后3、6个月时观察组和传统训练组远立体视较术后1周显著提升,视感知觉组术后1、3、6个月时较术后1周均有改善（F=86.70,P=0.000）。视感知觉组和传统训练组术后1、3、6个月近立体视功能较术后1周显著改善（F=25.90,P=0.000）,观察组术后各时间点差异无统计学意义。结论 共同性斜视患者术后立体视功能可以获得不同程度改善,其中传统训练组和视感知觉训练组近立体视功能重建效果更好。视感知觉组远立体视重建效果一定程度上优于其他两组,这可能与其可以获得更稳定的眼位控制相关。     

Age norms for grating acuity and contrast sensitivity measured by Lea tests in the first three years of life

AIM: To determine age norms in the first three years of life for grating visual acuity and contrast sensitivity obtained with Lea grating test and Hiding Heidi low contrast face test. METHODS: Lea grating test was used to estimate binocular grating acuity and Hiding Heidi low contrast face test was used to estimate contrast sensitivity in 600 healthy infants and children. Age ranged from 3 to 36mo subdivided into 12 groups subjected for full ophthalmologic and pediatric examinations. RESULTS: The grating acuity developed along the first three years of life. It ranged from 1.88±0.32 c/d at 3mo to 30.95±0.77 c/d at 36mo. The most rapid development was during the first 12mo and the slowest development was from 30 to 36mo. The contrast sensitivity showed rapid development in the first two years of life. Its mean value ranged from 4.23±1.17 at 3mo to 78.26±8.21 at 24mo. It was constant at the highest score (80) thereafter. CONCLUSION: Age norms for grating acuity along with contrast sensitivity offer a more comprehensive measure of spatial vision and should be incorporated in clinical practice for better visual assessment in preverbal and nonverbal children.     

Measuring contrast sensitivity in patients with Graves' ophthalmopathy complicated by ocular hypertension and suspect glaucoma or dysthyroid optic neuropathy

The present study compares contrast sensitivity functions of patients with uncomplicated Graves' ophthalmopathy, patients with ophthalmopathy and elevated intraocular pressure or suspect glaucoma, and patients with dysthyroid optic neuropathy (DON). Aim of the study was to investigate the clinical potential for the contrast sensitivity functions (CSF) in distinguish between the groups. Contrast sensitivity measurements were obtained from twenty-seven subjects with endocrine ophthalmopathy. Group I included patients with uncomplicated ophthalmopathy (n=20 eyes); group II included patients with ophthalmopathy, intraocular pressure 24 mmHg with and without early visual field defects, and no evidence of apical crowding on coronal computed tomography scan (n=14 eyes); group III included patients with DON (n=12 eyes). Contrast thresholds were determined for stationary and 6.87 Hz phase-alternating gratings at eight spatial frequencies from 0.18 to 15.7 c/deg. Data from each group was compared with data from age-matched normal subjects. Observers with uncomplicated ophthalmopathy had normal CSFs. Eyes affected with DON showed contrast sensitivity disruption at overall intermediate-high spatial frequencies. Eyes with elevated intraocular pressure or suspect glaucoma had pronounced sensitivity loss in the low frequency range (0.18-0.70 c/deg) as compared to eyes with DON. This study shows that CSF detects visual function abnormalities noninvasively in patients with complicated Graves' ophthalmopathy. Results also indicate that the clinical potential for CSF in distinguish between patients suffering from ophthalmopathy complicated by ocular hypertension or suspect glaucoma and patients with DON improves when a temporal modulation of 6.87 Hz and gratings of low spatial frequency (< 1 c/deg) are used.     

Comparison of preoperative 10-Hz visual evoked potentials to contrast sensitivity and visual acuity after cataract extraction

Cataract patients whose surgical outcomes were in question were referred for testing by visual evoked potentials, elicited through closed eyelids by a luminance stimulus (flash) that appeared 10 times per second. Visual evoked potentials were rated as normal (predicted acuity of 20/50 or better) or abnormal (predicted acuity of 20/60 or worse). Postoperative Arden and Optronix contrast sensitivities and visual acuities were determined in 37 patients who had no intraoperative or early postoperative complications. Arden grating scores of less than 100 were rated as normal. The optimal and cutoff spatial frequency values were determined for the Optronix scores. Optimal and cutoff values of greater or equal to 1 c/deg and 12 c/deg, respectively, were rated as normal. Visual acuities were considered normal at 20/50 or better. Preoperative visual evoked potentials were quantitatively compared to the postoperative contrast sensitivities and visual acuities by 2 × 2 contingency tables. The accuracy of prediction was 79% for the visual acuities, 62% for the Optronix optimal values, 70% for the Optronix cutoff values and 62% for the Arden gratings.     

中低度近视眼高阶像差与低对比度视力相关性研究

目的 探讨中低度近视眼高阶像差与低对比度视力的关系.方法 对65例65眼中低度近视患者,用WASCA波前像差仪测眼高阶像差,对瞳孔直径6 mm时总高阶像差、各阶像差和各项Zernike函数(C6～C14)的均方根进行分析.用多功能电子视力测量仪测量亮、暗环境中对比度为10%和5%的最佳矫正视力.用多元线性回归分析眼高阶像差与各低对比度视力间的相关关系.结果 眼总高阶像差与各低对比度视力间的直线相关关系均有显著统计学意义(P＜0.01).在第3、4阶像差中,第3阶像差与各低对比度视力间的直线相关关系有显著统计学意义(P＜0.01);第4阶像差与各低对比度视力间的直线相关关系无统计学意义(P＞0.05).在C6～C14项Zernike 函数中,水平慧差与各低对比度视力间的直线相关关系有显著统计学意义(P＜0.01),其余Zernike 函数(如球差、垂直慧差)与各低对比度视力间的直线相关关系均无统计学意义(P＞0.05).结论 中低度近视眼的水平慧差与低对比度最佳矫正视力有关.     

The effect of observation time and contrast on visual acuity

Background: Field studies of the duration of fixation during daytime driving find that it is about 0.2 seconds on average. Thus, the time available to read traffic signs is often limited. There are other circumstances where time to read alphanumeric messages is limited. Data relating time of observation are needed for purposes of ergonomic design as the data available in the literature are limited and uncertain. Method: Visual acuity was measured using Landolt rings in negative contrast, which were presented on a computer screen with a background luminance of 32 cd/m2 for durations that varied between two and 0.02 seconds at three different contrasts. Resulte: Visual acuity depends on the log of the light dose reduced by a factor that may be related to absorption of the light by the eye media. For young observers, it was found that: VA = 0.57 (log C t) + 1.705, where C is the contrast and is expressed as δL/L, where δL is the difference between target and background luminances in cd/m2 and t is the observation time in seconds. Conclusion: This formula or the functions fitted to the data obtained can be used to calculate the increase in target size needed to allow for short observation times.     

准分子激光原位角膜磨镶术后早期对比敏感度的研究

目的通过对低度、中度、高度近视眼行准分子激光原位角膜磨镶术术后早期对比敏感度的变化研究,完善对不同程度近视的术后视功能的评价。方法共85例(170只眼)。按等效球镜计算后分三组:低度(<3.00D)28例(56只眼);中度(≥3.00D～<6.00D)30例(60只眼);高度(≥6.00D)27例(54只眼)。患者在术前、术后1周、1个月、3个月时除常规检查外,用美国Stereooptical对比敏感度测试卡(F.A.C.T)检查对比敏感度视力,并分组内与组间比较三组患者对比敏感度视力变化的规律。结果1.术前各组间:三组在术前各频率段无明显差别。2.在各组内的结果:(1)在术后一周:三组的各频率段都有明显的下降,且以6,12cpd下降幅度最明显。(2)在术后1个月:低度组,在各频率段恢复到术前水平;而中、高度组在12,18cpd仍低于术前水平。(3)在术后3个月:低、中度组在各频率段均恢复到术前水平;高度组除12,18cpd都已达术前水平。3.在各组间的结果:(1)在术后1周:低、高度组在6,12,18cpd频率段下降程度差异有统计学意义,后者在三频率段下降更显著。(2)在术后1个月:低、中度组在恢复程度上12,18cpd差异有统计学意义(P<0.05),低、高度组在12,18cpd频率段恢复程度差异有统计学意义(P<0.01),后者较慢。(3)术后3个月:低、高度组在12,18cpd频率段恢复程度仍有差异有统计学意义(P<0.01),后者较慢。结论近视患者LASIK术后早期对比敏感度均有下降后回升,其变化特点与术前屈光状态有关。对比敏感度视力检查结合常规检查能更全面、客观地评价近视患者LASIK术后视功能的变化。     

Intermediate spatial frequency letter contrast sensitivity: its relation to visual resolution before and during amblyopia treatment

We examined the loss of letter contrast sensitivity (LCS) measured using the Pelli-Robson chart, and the extent to which any such loss was modulated by spectacle wear and occlusion therapy in children participating in an amblyopia treatment trial. Their initial mean interocular difference in logMAR acuity was approximately three times that of their LCS (0.45 vs 0.14 log units). Log LCS was weakly though significantly correlated with logMAR visual acuity (VA) for all VAs better than 0.90 (r = -0.19, 95% CI: -0.28 to -0.10) whereas for all VAs of 0.90 or poorer, log LCS was markedly and significantly correlated with VA (r = -0.72, 95% CI: -0.83 to -0.53). LCS in those children with a > or =0.1 log unit interocular difference on this test improved commensurately with VA during treatment. We conjecture that the spatial visual loss in all but the most severe amblyopes occurs in an area of resolution and contrast space that lies beyond that sampled by the Pelli-Robson chart.