远用光学助视器在视力残疾患者康复中的临床应用

目的:观察远用助视器在视力残疾患者的临床应用效果。方法:对32例视力残疾患者进行屈光矫正后,然后再运用单筒望远镜式助视器或眼镜式助视器提高和改善患者远用视力。结果:配用远用助视器平均视力(logMAR视力)为0.24±0.23;而在屈光矫正的基础上再应用助视器矫正的患者平均视力(logMAR视力)为0.11±0.25,即戴镜后使用远用助视器后视力好于未戴镜患者(t=4.56,P<0.05)。试戴远用助视器后25例远视力≥0.3,脱残率为78%;进行屈光矫正后,该组病例脱残率为94%(P<0.05)。结论:远用光学助视器在视力残疾患者康复有着重要作用,它可提高患者的远用视力,尤其强调在屈光矫正的基础上应用光学助视器临床疗效更为明显。     

An algorithm for visual fields

The authors present an algorithm, or sequential strategy, for the performance and interpretation of visual fields. Based on the principle that particular areas of the visual field are relatively vulnerable and that particular defect configurations are relatively more diagnostic, the strategy proposes certain “core maneuvers” for all initial examinations, followed by selective exploration of the vertical meridian “rectangle” and central “keyhole”. This constitutes the “qualitative” portion of perimetry and combines threshold kinetic and suprathreshold static techniques. If time and patience permit, qualitative perimetry is followed by quantitative definition of defect size, depth and slope, using the requisite number of stimuli. This approach may be adapted to all visual field instruments. The interpretation of the field defects is based on assessing their localizing features.     

Spatial configurations for visual hyperacuity

The threshold for discrimination of relative position of two features in the fovea is lowest—a few sec of arc—when the two features are separated by 2–5′ arc. and is not significantly changed when the features are reduced to dots. Discrimination for lateral displacement, e.g. vernier acuity, is as good as for spatial intervals, e.g. the separation of two lines, dots or edges. Two widely-held concepts are thus found to lack validity: that averaging of local signs along lines or contours is a prerequisite to hyperacuity and that the detection is necessarily performed according to the criterion of explicit or implicit orientation.     

视野缺损患者视觉康复训练方法研究进展

临床中多数黄斑病变和神经性眼部疾病所致的视野缺损一旦形成,多不可逆,治疗与康复均陷入瓶颈。随着医学模式的转变及人们对康复需求的增加,这些疾病所致视野缺损的视觉康复训练方法不断涌现。目前视野缺损视觉康复训练主要针对中央视野缺损、偏盲及周边视野缺损两方面。中央视野缺损主要影响患者的精细视觉,其视觉康复训练分为三大类,即旁中心注视训练、眼动控制训练及知觉学习训练。偏盲及周边视野缺损主要影响患者的视觉探索、定向、步行和阅读,其视觉康复训练分为两大类,即视觉恢复策略和眼动代偿策略。本文就视野缺损视觉康复训练的研究进展进行综述。（中华眼科杂志,2015,51：552-556）     

Two modes of processing visual information: implications for assessing visual impairment

The recognition of visual detail and the ability to orient spatially to visual stimuli are apparently subserved by distinct modes of processing, termed "focal" and "ambient," respectively. Current clinical techniques are well suited to evaluate aspects of focal vision, but do little to evaluate ambient visual functions. As a result, the impairment of ambient functions may be difficult to specify or may be overestimated. Implications for the development of assessment techniques for ambient functions are discussed.     

Plasticity in the adult visual cortex: implications for the diagnosis of visual field defects and visual rehabilitation

It has recently been shown that, contrary to long-held beliefs, sensory and motor maps are not stable in the adult cerebral cortex. Alteration of input from the periphery results in changes in topography in the cortex, including the primary visual cortex. Mechanisms involved consist mainly of reshaping the receptive field of cortical cells and increasing the sensitivity of deprived cells in the visual cortex. Cortical plasticity allows the brain to adapt to background modifications or to damage of the nervous system. It also underlies learning and attention processes. Cortical changes occurring after focal visual differentiation modify visual perception by filling in visual field defects with information from the area surrounding the scotoma. This modification causes affected subjects to ignore or underestimate their defects. With visual field defects, cortical plasticity also causes distortion in spatial perception. Although the effects of cortical plasticity are prominent in neuro-ophthalmological daily practice, they are usually unrecognized or greatly underestimated. These effects cause delay in recognizing visual field defects, and hence in receiving therapy, while affecting the results of some procedures for testing the visual field. Affected individuals who are unaware of their defects may have increased difficulty in coping with activities in everyday life. Up to now, phenomena related to plasticity in the visual system have been investigated mainly by psychophysicists and neurophysiologists. It is essential to start considering the various effects of cortical reorganization in clinical practice. It is especially important to introduce into clinics the concept of dissociation between actual and perceived defects in the visual field, resulting from the filling-in process, and the need to measure it. This dissociation should also be demonstrated to the affected subjects.     

Minimum procedures for visual electrodiagnostic testing

A set of procedures for the electroretinogram, electrooculogram, and pattern and luminance visual evoked cortical potentials was defined by representatives from all Dutch University Eye Clinics in order to promote standardization of procedures for routine diagnostic testing.The procedures have been selected to obtain an answer to most electrodiagnostic questions of frequent occurrence with a minimum of equipment and examination time. An individual examiner may add other procedures to the proposed program to extend and diagnostic possibilities.     

Efficient bubbles for visual categorization tasks

Bubbles is a classification image technique that randomly samples visual information from input stimuli to derive the diagnostic features that observers use in visual categorization tasks. To reach statistical significance, Bubbles performs an exhaustive and repetitive search in the stimulus space. To reduce the search trials, we developed an adaptive method that uses reinforcement learning techniques to optimize sampling by exploiting the observer’s history of categorization. We compared the performance of the original and the adaptive Bubbles algorithms in a model observer and eight human adults who all resolved the same visual categorization task (i.e., five facial expressions of emotion). We demonstrate the feasibility of a substantial reduction (by a factor of ∼2) in the number of search trials required to locate the same diagnostic features with the adaptive method, but only when the observer reaches a performance threshold of 50% correct for each expression category. When this threshold is not reached, both the original and adaptive algorithms converge in the same number of trials.     

多焦视皮质诱发电位检查对白内障患者术后视力的预测(英文)

目的:评价术前多焦视皮质诱发电位(multifocal visual evoked potential,mVEP)检查对白内障术后视力的预测价值。方法:随机选取白内障患者共52例60眼,其中老年性白内障27例30眼,合并青光眼的白内障25例30眼(青光眼均为慢性闭角型缓解期或慢性进行期),术前对其行mVEP检查,另取正常对照组30眼。所有患者均行超声乳化联合折叠人工晶状体植入术。患者于术后1wk;1,3mo复查最佳矫正视力(best corrected visual acuity,BCVA)。结果:正常对照组mVEP检测平均主波振幅和潜伏期分别是183±11nV、95±8ms,老年性白内障组平均主波振幅和潜伏期分别是177±10nV、96±8ms,2组在统计学上无显著性差异(P>0.05);合并青光眼的白内障组平均主波振幅和潜伏期分别是138±7nV、99±6ms,与正常对照组及老年性白内障组均存在显著性差异(P<0.05);白内障超声乳化联合人工晶状体植入术后BCVA≥0.8者,无明显眼底视功能改变,其mVEP中心位点主波振幅276±11nV和潜伏期93±8ms与正常对照组无显著性差异(P>0.05);而术后BCVA<0.3者,眼底视功能检查有明显改变(术后检查证实),其mVEP中心位点主波振幅221±6nV,潜伏期105±7ms,与正常对照组差异显著(P<0.05)。结论:白内障术前mVEP振幅和潜伏期的改变可用来客观判断眼底视功能损害及预测术后视力。术前mVEP正常者高度提示术后视力预后良好,而mVEP检查结果变化显著,提示伴有眼底视功能损害,术后BCVA差。因此术前mVEP检查可作为预测白内障术后视力的一种有效、客观的检查方法。     

Distance doubling visual acuity test: A reliable test for nonorganic visual loss

Background  To determine the value of the distance doubling visual acuity test in the diagnosis of nonorganic visual loss in a comparative observational case series. Methods  Twenty-one consecutive patients with nonorganic visual acuity loss and 21 subjects with organic visual loss as controls were included. Best corrected visual acuity was tested at the normal distance of 5 meters using Landolt Cs. The patient was then repositioned and best corrected visual acuity was tested with the previous optotypes at double the distance via a mirror. Results  Nonorganic visual acuity loss was identified in 21 of 21 patients. Sensitivity and specificity of distance-doubling visual acuity test in functional visual loss were found to be 100% (CI; 83%–100%) and 100% (CI; 82%–100%), respectively. Conclusion  Distance doubling visual acuity test is widely used to detect nonorganic visual loss. Our results show that this test has a high specificity and sensitivity to detect nonorganic visual impairment.     

Perceived length in the central visual field: evidence for visual field asymmetries

Visual performance for judging the length of a simultaneously presented pair of radial lines, reciprocally opposed by 180 degrees at a central fixation point, was assessed for 24 radial positions of test lines, for three viewing conditions (binocular, left and right monocular) and five different standard line sizes (1.43-7.13 degrees ). Generally, the results showed underestimation of the test line. Furthermore, clear visual field asymmetries were observed between the upper versus lower visual fields and the left versus right visual fields with greater underestimation for test lines presented in the lower and right visual fields. Also, asymmetries tended to be strongest along the 30 and 150 degrees radial orientations. Fourier analysis indicated that these asymmetries are mainly described by summing up the f0, f1, f2 and f5 components.