Importance of pathological intraocular light scatter for visual disability

For healthy eyes intraocular light scatter was investigated several decades ago. For pathological eyes, however, little is known. As clinical test several techniques have been proposed but none has gained general acceptance. A disadvantage of these tests was that quantities were estimated that related only indirectly to the amount of light scatter. We propose a method that gives a direct estimate of the light scatter.We studied patients with cataract, corneal dystrophy, iris and fundus hypopigmentation, etc. A remarkable finding was that visual acuity correlates rather weakly with the amount of scatter. Since, however, the amount of scatter causes a considerable loss of visual function, the results show that for these patients the visual acuity test gives a rather limited impression of their visual handicap. More attention to the problems associated with intraocular light scatter is needed.     

正常人中心视野视网膜光敏感度的定量分析

目的：为了解我国正常人群中央３０度视野视网膜光敏感度的定量值,并对研究青光眼的视野损害提供有益的经验。方法：应用北京市眼科研究所和航空航天部一０二所联合研制的ＱＺＳ－２型全自动静态视野分析仪,采用全阈值程序对４８例９６只正常眼进行中央３０度视野光敏度的测定。结果：９６只正常眼中央及鼻上、下,颞上、下视野的平均光敏度均随着年龄的增加而降低,其降低的幅度及变异均随着年龄的增加而增大,年龄（ｘ）与平均光     

Variability of visual field measurements is correlated with the gradient of visual sensitivity

Conventional static automated perimetry provides important clinical information, but its utility is limited by considerable test-retest variability. Fixational eye movements during testing could contribute to variability. To assess this possibility, it is important to know how much sensitivity change would be caused by a given eye movement. To investigate this, we have evaluated the gradient, the rate at which sensitivity changes with location. We tested one eye each, twice within 3 weeks, of 29 patients with glaucoma, 17 young normal subjects and 13 older normal subjects. The 10-2 test pattern with the SITA Standard algorithm was used to assess sensitivity at locations with 2 degrees spacing. Variability and gradient were calculated at individual test locations. Matrix correlations were determined between variability and gradient, and were substantial for the patients with glaucoma. The results were consistent with a substantial contribution to test-retest variability from small fixational eye movements interacting with visual field gradient. Successful characterization of the gradient of sensitivity appears to require sampling at relatively close spacing, as in the 10-2 test pattern.     

The influence of forward light scatter on the visual field indices in glaucoma

Light scatter was induced in 15 glaucoma patients, exhibiting clear media and moderate field loss, using cells containing varying concentrations of 0.5 m diameter latex beads in distilled water. The right eye was examined with program G1 on the Octopus 201, and with a 45° threshold profile on the Dicon AP3000, with and without a given cell. Forward light scatter due to the cell was assessed by measuring the depression of contrast sensitivity, with the Nicolet CS2000, under glare conditions. Perimetric mean sensitivity decreased linearly and loss variance decreased curvilinearly with increase in forward scatter. Threshold values for 26 glaucoma patients, determined in the absence of induced scatter, were then corrected for the effects of naturally occurring intraocular light scatter [44]. The recalculated mean defect decreased linearly while loss variance remained essentially unchanged. Forward light scatter therefore predominantly exaggerates diffuse loss; the apparent underestimation of focal defects caused by induced scatter is partly a computational artefact resulting from inapplicable age-matched normal reference data.Presented in part at the Annual Spring Meeting of the Association for Research in Vision and Ophthalmology, Sarasota, Florida, May 1989     

The relation between visual sensitivity and intraocular pressure in normal eyes

Intraocular pressure and flicker modulation sensitivity at 25 and 40 Hz were measured in 22 normal observers, with an age range from 20-71 years. Significant correlations up to 0.67 were found between intraocular pressure and flicker sensitivity at several points in the visual field. There was no correlation between flicker sensitivity and age of the observers. Thus intraocular pressure may affect neuronal function in the normal eye.     

正常眼压性青光眼中眼压与视野间的关系

目的 :探讨正常眼压性青光眼 (normalpressureglaucoma ,NPG)的眼压、视野和相互关系。方法 :分析 98例新诊断NPG患者的眼压曲线和视野状态。结果 :眼压曲线呈单峰式波动 ,双眼对称 ,总体平均水平位于 16mmHg上下 ,波动幅度 <2mmHg。患者男性眼压均值右眼为15 70± 2 5 7mmHg、左眼为 15 46± 2 %41mmHg ,女性右眼为 16 5 2± 1 97mmHg、左眼为 16 45± 2 0 1mmHg ,眼压与年龄相关不显著 (P >0 0 5 )。患者各相应年龄组的眼压均高于正常老年人 (分别P <0 0 2 ,P <0 0 1,P <0 0 0 1)。在 98例患者 196眼的视野中 ,5 2例患者为单眼损害 ,14 4眼的视野损害在损害形态和部位上与眼压升高的原发性开角型青光眼 (hp -POAG)相符合 ,但旁中心损害侵入中心固视区者约占 2 2 2 2 %。在两眼视野损害相对轻重的划分中 ,视野损害不同分级状态下眼压的平均值、最高值和波动差二者间差异不显著 (P >0 0 2 ) ,单侧视野损害患者患眼与对侧眼眼压差异不显著 (P >0 0 5 ) ,但同侧视野损害较重且眼压较高眼数的构成比最大 ,约占 5 5 1%(P <0 0 1)。结论 :NPG患者的眼压状态在单值水平、波动幅度和双眼对称性上均与一般群体生理眼压相一致 ,但平均眼压高于年龄可比的正常老年人。视野损害特征与hp -POAG相符合 ,     

The contrast sensitivity gradient across the major oblique meridians of the human visual field

The contrast sensitivity gradient across the major oblique meridians of the visual field is compared with previous estimates of the horizontal and vertical meridians.     

Contrast sensitivity versus static visual field testing during experimental elevation of intraocular pressure

Contrast sensitivity testing has been recommended as a more sensitive indicator of early visual loss than visual field testing. Using gravity inversion to induce an intraocular pressure rise, we performed contrast sensitivity testing on each eye of 10 normal subjects in the upright and inverted positions. Contrast sensitivity results were not altered in the head-down position, even though in 5 of the 10 subjects (7 of 20 eyes), visual field alterations on static perimetry were elicited during inversion. In both of these evaluations, the subject's results in the upright position served as the control, freeing us from reliance upon age-matched populations. We conclude that precise measurement of static thresholds with automated perimetry is more sensitive than routine contrast sensitivity testing in detecting visual dysfunction related to transient acute elevations of intraocular pressure.     

早期正常眼压性青光眼的弥漫性视敏度缺失

目的 :研究早期正常眼压性青光眼 (normaltensionglaucoma ,NTG)的中心视野是否存在视敏度的弥漫性缺失。方法 :对临床确诊的 3 0例 (5 2只眼 )早期NTG病人 ,与 3 5例 (60只眼 )正常人群进行年龄匹配 ,比较两组人群之间 3 0°视野的中心 2 4°范围内的 10个最敏感点视敏度的差别。视敏度检测采用Humphrey自动视野仪 3 0 -2程序。结果 :早期NTG组与正常人群年龄匹配组之间年龄平均差别为 11天 (P =0 992 ) ,两组视力平均差别为 0 0 4(P =0 65 8) ,瞳孔大小平均差别为 0 11mm (P =0 2 93 ) ,眼压平均差别为 2 0 9mmHg (1mmHg =0 13 3kPa) (P =0 15 8)。通过对两组 10个最敏感点对比研究后发现早期NTG组病人比正常人群年龄匹配组平均低 1 0到 2 0dB (P <0 0 0 1) ,并且每组有 78 5 7%～92 86%的正常人群年龄匹配组的视敏度值要高于早期NTG组。结论 :早期NTG病人的视敏度显著下降 ,下降视敏度区域累及视野中最敏感位点 ,并且在局限性视野缺损的基础上伴有弥漫性的缺失。     

Detection sensitivity to light offsets is abnormal in glaucomatous visual field

The detection thresholds in the central visual fields of glaucomatous (n=21), ocular hypertensive (n=21) and normal (n=13) individuals were tested with both light decrements (offsets=dark spots) on a cathode ray tube (CRT) and light increments (onsets=bright spots) on a bowl projection perimeter. Both types of stimuli were of equal surface area (Goldmann size IV=16 mm²) and duration (200 milliseconds) on a 10 cd/m² background intensity. Computerized threshold testing with light offsets on CRT could document the glaucomatous visual field loss with high accuracy and might indicate early glaucomatous visual field loss missed by the conventional light onset stimuli.     

Effects of yellow filters on visual acuity,contrast sensitivity and reading under conditions of forward light scatter

Background  

Yellow filters are sometimes recommended to people with low vision. Our aim was investigate the effects of three commercial yellow filters on visual acuity and contrast sensitivity (with and without glare) and reading (without glare) under conditions of forward light scatter (FLS).     

眼内散射光及对比敏感度检查在白内障患者真实视觉质量评估中的意义

目的:分析眼内散射光及对比敏感度检查在白内障患者真实视觉质量评估中的意义。方法:选取我科2012-01/2014-01的白内障患者共73例120眼,其中皮质性白内障32例52眼,核性白内障18例33眼,后囊下白内障23例35眼,同时选取同期正常人40例40眼。观察所有入选者的角膜散光和全眼总散光;采用自动眩光对比敏感度检查仪检查不同视角的对比敏感度。结果:皮质性白内障组、核性白内障组和后囊下白内障组的角膜散光和全眼总散光显著高于正常组(P<0.05);白内障三组患者的角膜散光和全眼总散光无显著差异(P>0.05)。皮质性白内障组、核性白内障组和后囊下白内障组的对比敏感度在全频段均显著低于正常组(P<0.05);后囊下白内障组的对比敏感度在全频段均显著低于皮质性白内障组和核性白内障组(P<0.05)。结论:采用眼内散射光及对比敏感度联合检查,可有效评价白内障患者的视觉质量,进而早期治疗。     

Psychophysical determination of intraocular light scatter as a function of wavelength

Intraocular scatter of monochromatic light was assessed in three subjects (ages 21, 38, and 43) using the equivalent veil technique. For an annular stimulus of 3 deg inner and 8 deg outer diameter, the scattered illuminance at the center averaged 1.2% of the surround and was independent of wavelength from 420 to 650 nm. These results are inconsistent with predictions of wavelength dependence inherent in recent theories of ocular scatter. We conclude that intraocular scatter is produced by particles or cellular structures substantially larger than the wavelength of light.     

Short-term fluctuation of light discrimination sensitivity at the borders of glaucomatous visual field defects

Using profile program F-4 of the Octopus 201 computerized perimeter, retinal light sensitivity and threshold short-term fluctuations were studied in 15 eyes of 15 patients with glaucomatous field defects, with a resolution of 1.5 degrees. The scotomata were verified with programs 33 and 34 of the Octopus 201. Control profiles, either at identical locations in the healthy fellow eye or in areas showing no glaucomatous changes, were used to compare focal fluctuation in the vicinity of the scotoma. At the borders of the scotomata, between 20 degrees and 30 degrees eccentricity, a significant increase in short-term fluctuation of retinal sensitivity was found. This change in short-term fluctuation decreased with increasing distance from the field defect. Significantly greater short-term fluctuations were also detected in border-area measurements of scotomata located between 0 and 10 or 10 and 20 degrees of eccentricity.     

Stimulus configuration and the format of the normal sensitivity gradient

The study investigated the effect of three distinct types of stimulus configuration on the format of the normal sensitivity gradient derived by computer assisted perimetry namely: projected stimuli; light emitting diodes (LED) with the same luminance as the perimeter bowl; and black hole LED stimuli. The study comprised two separate parts: 22 age matched subjects were examined with the Dicon AP3000 and with the Topcon SBP-1000 along the 15°–195° meridian of the visual field of the right eye; a further 22 subjects matched for age and gender were examined along the same meridian in an identical manner with the Dicon AP2025 and with the Humphrey Field Analyser 620. The various stimulus parameters were chosen in order to provide uniformity as far as possible between the instruments. The Topcon evoked greater relative sensitivity than the Dicon at all eccentricities although the rate of change of sensitivity with increase in peripheral angle varied between the two instruments at different locations. Centrally the Dicon profile followed more closely that of Humphrey stimulus size II and beyond 5° that of stimulus size I. The Topcon profile followed that of the Humphrey stimulus size II both centrally and peripherally in spite of being geometrically closer to the size III stimulus. It is proposed that the variations in the sensitivity gradient are not exclusively related to stimulus size and spatial summation; the accommodative stimulus of the black hole LED stimuli, stimulus colour and thresholding strategy may all be contributing factors.