Adaptation of the resting states of accommodation

Without an adequate stimulus to focus, the eyes accommodate for a "resting state" that averages about 1.6 diopter (D) (62 cm). The resting state can be made more "myopic" by adaptation to a near accommodative or vergence stimulus. In the present experiment, 21 subjects were tested for adaptation to both types of stimuli. Resting state was measured before and after adaptation in the dark (dark focus) and in the presence of an illuminated empty field. The authors found that preadaptation resting states were more myopic in the light field than in the dark test conditions; accommodative and vergence stimuli produce myopic shifts in dark and light field resting states; and a subset of the subjects show much larger aftereffects in the light field conditions. These subjects also show the largest difference between preadaptation dark- and light-field measures. Differences between dark- and light-field measures of resting state in these and other experiments may require a re-examination of the hypothesis that there is a single resting state for each subject.     

The interocular light adaptation effect at varying retinal locations

The interocular light adaptation effect can be demonstrated in the fovea and in nonfoveal areas up to 10° temporal to the fovea but not 15° from the fovea. These results substantiate the existence of both cone and rod components in the effect. The effect is similar whether determined in the dominant eye or the non-dominant eye. The interocular light adaptation effect is significant for considerations of cone-rod interactions and binocular vision. The differential effects of monocular and dichoptic preadaptation are considered to be due to afterimages which provide different equivalent backgrounds.     

Studies on the stability of the clinical electro-oculogram

The electro-oculogram is variable as a clinical test, but the recording technique has not been standardized, and differences in the protocols for adaptation and stimulation among laboratories may contribute to the variability. To analyze some of these factors, we performed more than 100 electro-oculograms on a single subject under different conditions. Both the Arden ratio and the ratio of light peak amplitude to a stable dark-adapted baseline were independent of pupillary dilation but linearly related to retinal illumination measured in trolands. Between 3.0 and 4.0 log trolands, the values began to level off, but they were difficult to interpret because of subject discomfort above 3.5 log trolands. The Arden ratios were influenced by preadaptation light levels and were roughly 20% higher above 90 cd/m² than below 45 cd/m². There was a circadian rhythm in dark trough, baseline and light peak values, but the composite Arden ratio and light peak/baseline ratio showed little circadian effect. The light peak/baseline ratios were slightly more stable than the Arden ratios; the variability (defined as [standard deviation × 100]/mean) was 6.6% and 12.5%, respectively. Our results suggest that stimulus intensities for clinical electro-oculographic testing should be between 3.0 and 3.5 log trolands; pupil dilation is optional. This translates into light levels of 141–447 cd/m² for a 3-mm pupil and 20–63 cd/m² for an 8-mm pupil. The reduction in variability and independence from preadaptation achieved by using the light peak/baseline ratio instead of the Arden ratio must be weighed against the time required to achieve a stable dark baseline.     

Toward a general theory of visual adaptation

Summary The problem of visual adaptation has been reconsidered in the light of the electrophysiologic data on photoreceptors that has become available in the last few years. Four phenomena are particularly important : a) Photoreceptors show typical response adaptation (i.e., response decay in the presence of maintained stimuli); b) The intensity-voltage transformation is similar for most if not all photoreceptors thus far studied and it is characterized by saturation effects analogous to endplate potentials; c) The primary visual cells are characterized by dark and light adaptation functions analogous to those observed in central neurons and psychophysically; d) Desensitization during dark adaptation is accompanied by sizeable D.C. offsets in membrane resting potential. In studies of adaptation the response to the test stimulus is always superimposed upon a steady-state or slowly decaying response. Due to saturation the summation of the background and test responses is nonlinear with a resulting loss in gain or sensitivity to the test stimulus. Desensitizations observed in the presence of an adapting light and in its aftermath compare favorably with those predicted from the accompanying D.C. shift and the gain of the intensity-voltage function at that D.C. level.HoustonDepartment of Biology Rice University Houston, Texas 77001 U.S.A.Supported by Health Sciences Advancement Award, 5-SO4-FR-06136 General Research Support Branch Bureau of Health Professions Education and Manpower Training, National Institutes of Health.     

Orientation-based texture segmentation in strabismic amblyopia.

Texture segmentation of 'target' Gabors from an array of 'background' Gabors was measured in terms of the difference in orientation between the two regions, as well as the difference in orientation within each region. Segmentation was shown to occur on the basis of local orientation differences at the boundary between the target and background regions (Nothdurft, H.C. (1992). Feature analysis and the role of similarity in preattentive vision. Perception and Psychophysics, 52, 355-375.). We obtained similar results for both the amblyopic and non-amblyopic eye of three strabismic amblyopes, and showed also that the effects of texture undersampling and positional jitter were similar for the two eyes. This pattern of results is consistent with intact mechanisms of texture perception in amblyopic cortex, and suggests also that any amblyopic deficits in first-order cortical units (undersampling and/or positional uncertainty) do not limit higher-order texture segmentation processes. Therefore, first- and second-order processes involved in perceptual grouping of oriented elements (that appear to be abnormal in amblyopic cortex; Kovács, I., Polat, U., Norcia, A.M. (1996). Breakdown of binding mechanisms in amblyopia. Association for Research in Vision and Ophthalmology Abstracts; Mussap, A.J., Levi, D.M. (1995). Amblyopic deficits in perception of second-order orientation. Investigative Ophthalmology and Visual Science (Supplement), 36, S634; Mussap, A.J., Levi, D.M. (1998). Amblyopic deficits in perceptual grouping. Vision Research, submitted) do not contribute to texture perception based on orientation contrast.     

Light adaptation of the human photopic oscillatory potentials: Influence of the length of the dark adaptation period

Photopic electroretinograms recorded immediately after a period of dark adaptation show a regular increase in amplitude with time spent in light. The retinal mechanisms at the origin of this light adaptation effect remain obscure. The purpose of this study was to investigate the duration of the dark adaptation period needed to produce an optimal light adaptation effect as demonstrated by photopic oscillatory potential recordings. Our results indicate that the light adaptation effect can be separated into two distinct processes. The first one, activated early in the dark adaptation process, reduces the amplitude of the fourth oscillatory potential to 32% of control after less than 5 min of dark adaptation, while the second process, activated after more than 10 min of dark adaptation, appears to impact solely the amplitude of the earlier oscillatory potentials 2 and 3. Our results suggest that the light adaptation effect is mediated by two distinct retinal pathways or mechanisms.Abbreviations DA dark adaptation - LAE light adaptation effect     

已治愈与未治愈屈光参差性弱视患者双眼间的波前像差特点

目的　探讨已治愈与未治愈屈光参差性弱视患者双眼间的波前像差特点。方法　收集在广西视光中心就诊并自愿参加本研究的屈光参差患者共91例，根据病史和矫正视力将所有患者分成两组:对照组（已治愈的屈光参差性弱视）31例、弱视组（未治愈的屈光参差性弱视）60例。对照组按照等效离焦度的高低，将每例患者双眼的数据分别归入原弱视眼组和原对侧眼组；弱视组按照矫正视力是否正常，将每例患者双眼的数据分别列入弱视眼组和对侧眼组。弱视组患者按年龄分为成年弱视22例、未成年弱视38例。所有患者均接受iDesign^?波前像差仪（美国AMO公司）检测，以均方根值（root mean square，RMS）形式表示总像差和各项高阶像差（RMS3~6）。配对t检验用于分析各组内双眼间的参数差异；独立样本t检验比较两组间的参数差异；Spearman相关分析和线性回归分析各亚组内变量间的相互关系。结果　对照组原弱视眼等效离焦度高于原对侧眼，差异有统计学意义（P<0.01）；弱视组弱视眼等效离焦度、总像差RMS均高于对侧眼，差异均有统计学意义（均为P<0.01）；其余参数如总高阶像差、三阶像差、四阶像差、五阶像差、六阶像差RMS，在两组内双眼间的差异均无统计学意义（均为P>0.05）。散瞳状态下成年弱视组、未成年弱视组双眼间等效离焦度、总像差RMS差异均有统计学意义（均为P<0.01），弱视眼均大于对侧眼。波前像差图像显示:对照组和弱视组双眼间总像差均呈非对称性、总高阶像差均呈相似性与对称性。将对照组、弱视组双眼间波前像差各参数差值进行组间比较，独立样本t检验结果提示:△等效离焦度以及△总像差RMS在两组之间的差异均有统计学意义（均为P<0.01），弱视组均大于对照组；其余参数在两组间的差异均无统计学意义（均为P>0.05）。对照组、弱视组内双眼的等效离焦度均与其自身总像差RMS呈正相关；等效离焦度与其他波前像差参数之间无相关性。线性回归分析结果显示:对照组内原弱视眼的等效离焦度与总像差RMS的回归方程为Y=0.16+0.798X(R²=0.633，F=50.031，P=0.000)，原对侧眼的等效离焦度与总像差RMS的回归方程为Y=1.278+0.611X(R²=0.522，F=31.613，P=0.000)；弱视组内弱视眼的等效离焦度与总像差RMS的回归方程为Y=-1.466+1.149X(R²=0.825，F=272.675，P=0.000)，对侧眼的等效离焦度与总像差RMS的回归方程为Y=1.101+0.832X(R²=0.632，F=99.561，P=0.000)。结论　散瞳状态下已治愈和未治愈的屈光参差性弱视患者等效离焦度和总像差形态在双眼间存在明显差异，但高阶像差在双眼间具有相似性和对称性。     

LASCER Bode plots for normal,amblyopic, and stereoanomalous observers

Indices of laterality, interocular response latency difference, and binocular summation derived from Bode plots (amplitude-versus-temporal frequency and phase lag-versus-temporal frequency) of cortical responses evoked by laser speckle (LASCER) are correlated with common tests used in clinical refraction. We evaluated eight normal observers and eleven observers with histories of amblyopia and/or stereoanomalies. We find that: (1) LASCER amplitude is reduced in the amblyopic eyes relative to the unaffected fellow eyes, (2) LASCER response latency is increased in the amblyopic eyes relative to the unaffected fellow eyes, and (3) binocular LASCER summation is reduced in stereoanomalous observers. The phenomenal appearance of laser speckle is different for amblyopic eyes than unaffected fellow eyes. Neural disturbances in pattern perception may account for these results.This research was supported by U.S. Public Health Service Grants l F32 EY05180 and 1 R01 EY02985-01 and U.S. National Science Foundation Grant BNS 75-20147-A02.     

远视性单眼弱视患者黄斑区视网膜厚度的研究

目的通过检测远视性单眼弱视者弱视眼黄斑区视网膜厚度（MRT）,研究弱视眼视网膜神经上皮层厚度的特征。方法远视性单眼弱视患者42例,正常组单眼远视但无弱视者20例。采用光学相干断层扫描仪（OCT）测量弱视眼和正常眼的MRT。结果弱视眼黄斑中心凹厚度比正常眼厚（P=0．005）,对于黄斑部位的分区测量,黄斑中心区厚度弱视眼比正常眼厚（P=0．010）,而黄斑周围外环及内环各象限弱视眼和正常眼相比差异均无统计学意义（P〉0．05）。不同程度弱视患者问黄斑中心凹及黄斑各分区的视网膜厚度差异均无统计学意义（P〉0．05）。结论远视性单眼弱视眼黄斑中心区视网膜厚度增厚,不同程度弱视眼间的视网膜厚度差异无统计学意义。     

Normal values in clinical electrooculography. 1. Material, method, methodological investigations and distribution of the potential and time parameters.

For the evaluation of normal EOG potential and time parameters a case series (142 eyes) is presented. An EOG technique aiming at the largest possible amplitude between the dark trough and the light peak is described. It is shown that the light-induced response following a 20 min period of adaptation to a very low degree of illumination (about 1/10 lx, allowing a rough orientation on the displayed trace) does not differ from that produced after 20 min of total darkness. Also, the independence of the pupillary area for the light-induced response is demonstrated, which means that the light stimulus employed (2500-4000 lx) is supramaximal. Furthermore, the good quality of the gaze fixation in the actual test situation with respect to the recording of equidistant saccades is proven. A DC amplification of the signal is used, which secures independency of inter- and intra-individual differences in the saccadic velocity and makes possible accurate measurements of deflections disfigured by correcting movements. The following EOG parameters are recorded: A base value after 10 min of preadaptation with the light stimulus, the dark trough and the light peak potentials. Also the periods between the beginning of the dark adaptation and the dark trough and between the dark trough and the light peak are noted. The frequency distribution and the general level of the various parameters are discussed in the light of comparable figures of previous publications.     

Retinal adaptation effects on the patterned VEP and ERG

The patterned visually evoked potential (pVEP) and patterned electroretinogram (pERG) after light and dark adaptation were investigated in 10 visually normal human observers. The influence of retinal preadaptation on the pVEP appeared to be dependent on the stimulus field size. With a 6 degree field size retinal adaptation effects were not apparent, but with a 12 degree field size the amplitudes of the dark-adapted steady-state pVEP (ssVEP) and transient pVEP (tVEP) were significantly larger than the light-adapted amplitudes. Similarly pERG's elicited by a 12 degree field size produced larger amplitude dark-adapted results. The implications of these findings are discussed. Monitoring the temporal changes in the pVEP subsequent to different retinal preadaptation levels proved to be inconclusive for the conditions studied.     

Effect of light exposure on the accumulation and depletion of retinyl ester in the chicken retina

A previous study has shown that in the cone-rich chicken retina, 11-cis retinyl ester increases with light exposure and decreases in subsequent dark adaptation. The purpose of this research is to study how light exposure (intensity and duration) determine the rate of accumulation and utilization as well as the size of this 11-cis retinyl ester pool in the chicken retina. Chickens were dark-adapted overnight before exposure to different light intensities and durations. Animals were sampled at regular time intervals. 11-cis retinal and 11-cis retinyl ester were extracted from the retina and analyzed by HPLC. An increase in light intensity from 1,000 and 2,000 Lux (for a 20 min exposure) increased the amount of 11-cis retinyl ester from 0.38 to 0.75 nmol/mg. An increase in the duration of light exposure from 10 to 20 min (at 2,000 Lux) also increased the amount of 11-cis retinyl ester in the chicken retina (from 0.37 to 0.75 nmol/mg). This 11-cis retinyl ester pool in the chicken retina was rapidly reduced to baseline level ( approximately 0.20 nmol/mg) upon dark adaptation. The rate of accumulation of 11-cis retinyl ester was dependent on light intensity and duration of exposure and the maximum rate was approximately 0.03 nmol/mg/min. In comparison, dark adaptation was associated with a significantly higher rate of 11-cis retinyl ester depletion (approximately 0.05), indicating that light exposure and dark adaptation were associated with different biochemical steps of retinoid storage and utilization. Results from this study are the first to show that the size of the 11-cis retinyl ester pool, as well as the rate of its accumulation and depletion in the cone-rich chicken retina, are determined by the intensity and duration of light exposure. These data support the suggestion that a light-driven cone cycle exists in the chicken retina.     

Technical Note: A Problem with the Clinical Measurement of Dark Adaptation by the Friedmann Visual Field Analyser

ABSTRACT The measurement of the dark adaptation function is possible in private practice with the Friedmann Visual Field Analyser. However errors are introduced by internal stray light in some of the early Mark 1 instruments. A method of overcoming this problem is described.     

Contrast masking in strabismic amblyopia: attenuation, noise, interocular suppression and binocular summation

To investigate amblyopic contrast vision at threshold and above we performed pedestal-masking (contrast discrimination) experiments with a group of eight strabismic amblyopes using horizontal sinusoidal gratings (mainly 3c/deg) in monocular, binocular and dichoptic configurations balanced across eye (i.e. five conditions). With some exceptions in some observers, the four main results were as follows. (1) For the monocular and dichoptic conditions, sensitivity was less in the amblyopic eye than in the good eye at all mask contrasts. (2) Binocular and monocular dipper functions superimposed in the good eye. (3) Monocular masking functions had a normal dipper shape in the good eye, but facilitation was diminished in the amblyopic eye. (4) A less consistent result was normal facilitation in dichoptic masking when testing the good eye, but a loss of this when testing the amblyopic eye. This pattern of amblyopic results was replicated in a normal observer by placing a neutral density filter in front of one eye. The two-stage model of binocular contrast gain control [Meese, T.S., Georgeson, M.A. & Baker, D.H. (2006). Binocular contrast vision at and above threshold. Journal of Vision 6, 1224-1243.] was 'lesioned' in several ways to assess the form of the amblyopic deficit. The most successful model involves attenuation of signal and an increase in noise in the amblyopic eye, and intact stages of interocular suppression and binocular summation. This implies a behavioural influence from monocular noise in the amblyopic visual system as well as in normal observers with an ND filter over one eye.     

基于功能性近红外光谱技术的屈光不正性弱视患儿视皮层功能研究

目的　应用功能性近红外光谱技术（fNIRS）比较屈光不正性弱视患儿与正常儿童视皮层血红蛋白含量的差异,探讨屈光不正性弱视患儿视皮层功能是否存在异常。方法　选取在山东中医药大学附属眼科医院2019年至2020年就诊的19例（38眼）临床确诊为双眼屈光不正性弱视的患儿作为弱视组,年龄为6～12周岁;另选19例（38眼）年龄相似视力正常的健康儿童作为正常组。在给予最佳矫正视力的情况下,对受试者进行单眼棋盘格翻转刺激的fNIRS检测。采用上海心果光电科技有限公司针对 Polhemus 公司的三维定位仪研发的可视化头部三维定位信息实时记录系统（VPen 1.0）对受试者各通道测量点位置进行定位记录,依据3D定位仪的解剖标记和重叠比例可得第11、12、15、16、17、20、21号通道为fNIRS感兴趣区域通道。将单眼注视黑白棋盘格翻转刺激时段作为刺激期,将此时段fNIRS感兴趣区域通道的β均值用于表示双侧视皮层血红蛋白的含量变化。记录两组受试者年龄、性别、最佳矫正视力、血红蛋白β均值等指标,采用SPSS 23.0软件对所得数据进行统计学分析。结果　弱视组患儿与正常组儿童最佳矫正视力（logMAR）分别为0.20±0.14和-0.02±0.04,两组间差异有统计学意义（t=-8.990,P<0.001）。弱视组患儿氧合血红蛋白β均值低于正常组,差异有统计学意义（P<0.05）;脱氧血红蛋白β均值高于正常组,但差异无统计学意义（P>0.05）。弱视组患儿受试眼同侧视皮层氧合血红蛋白β均值较正常组儿童受试眼同侧视皮层、对侧视皮层β均值均显著减小,差异均有统计学意义（P=0.009、0.003）;弱视组患儿受试眼对侧视皮层氧合血红蛋白β均值较正常组儿童受试眼同侧视皮层、对侧视皮层亦均显著减小,差异均有统计学意义（P=0.016、0.005）。弱视组患儿的最佳矫正视力与其视皮层氧合血红蛋白含量的相关系数r=-0.039（P=0.815）,二者无线性相关关系。结论　fNIRS可以作为测量弱视患者初级视皮层血红蛋白含量的新方法,屈光不正性弱视患儿视皮层存在功能异常。     

The effect of long-term light and dark adaptation and stimulus intensity on the receptor potential of theLimulus lateral eye

Intracellular recordings of the receptor potential of the lateral eye ofLimulus were made following white light stimuli, to test intensity-dependence and long-term light and dark adaptation.The plot of the peak amplitude of the receptor potential (h_max) versus logI is S-shaped. The linear phase coversca. 2 log units. The plateau-value (h_e) obviously saturates at higher intensities thanh_max.The long-term adaptation was tested during sustained background light (10 min) with superimposed test flashes, and subsequently in the dark (64 min). The adaptation was fully reversible; 30 sec after turning off the background lighth_max has already reached 80% of the reference value.The results are discussed on the basis of the concept that the opening of channels in the cell membrane causes the receptor potential. The observed membrane adaptation effects can be explained by assuming, among other factors, a light-dependent variable amplification of the mechanisms producing the receptor potential.The influence of active and electrogenic transport on adaptation is discussed.     

Central and peripheral contrast sensitivity in amblyopia with varying field size

The purpose of the present study was to establish the extent of the amblyopic deficit at 0°, 10°, and 20° retinal eccentricity using contrast sensitivity measures for sine wave gratings subtending various field sizes. Contrast sensitivity functions were shown to vary with stimulus field size, retinal location and degree of amblyopia. Foveally, peak contrast sensitivity of amblyopic eyes increased markedly with increasing field size, to reach the same magnitude as that of the contralateral non-amblyopic eyes for large fields. Peripherally, peak contrast sensitivity remained lower in the amblyopic eyes for all field sizes examined. High spatial frequency cut-offs were reduced both centrally and peripherally with all field sizes in the amblyopic eyes. The effect of increasing field size on the cut-off acuity was found to be smaller than the effect on-peak contrast sensitivity.The most significant conclusions drawn from the results are that: (1) The amblyopic deficit in terms of both peak contrast sensitivity and acuity isnot restricted to the central foveal region; and (2) amblyopic eyes benefit to a greater extent from increased stimulus field size than non-amblyopic eyes in terms of peak contrast sensitivity.A model is proposed which suggests that the results obtained are due to fewer and/or less sensitive cortical neurons being driven by the amblyopic eye in humans with naturally occurring amblyopia.Supported in part by NEI grant R01EY01728 from the National Eye Institute, NIH, Bethesda, Maryland     

Effects of light and dark adaptation of rods on specific-hue threshold

Specific-hue threshold as a function of absolute rod threshold was measured with long-, middle-, and short-wavelength monochromatic test lights presented 17 deg extrafoveally. The measurements were obtained both during the rod phase of long-term dark adaptation and under conditions where the rod receptor system was gradually light adapted from a dark-adapted state by a scotopic background field of increasing retinal illumination. The results show that change in specific-hue threshold with change in absolute rod threshold is not, in general, identical for light and dark adaptation of the rod receptor system. Thus, in the long- and middle-wavelength test regions, the specific-hue threshold could be obtained at higher intensities under the light- as compared to the dark-adaptation condition when absolute rod thresholds were the same. Just the opposite was found for the short-wavelength tests. It is concluded that change in specific-hue threshold with light and dark adaptation of the rod receptor system is not, in general, controlled by the same mechanism.     

弱视治疗前后对比敏感度的分析

目的：分析弱视患者治疗前后的对比敏感度的变化。方法随机选取40例（80眼）健康体检儿童（视力≥1.0）为正常对照组,47（79眼）例弱视儿童为病人组。利用美国 STEREO 公司生产的 OPTEC 6500视功能测试仪分别测量正常对照组和病人组治疗前、综合治疗5个月时5种空间频率[1.5、3、6、12和18周/度（cycles/degree, c/d）]的对比敏感度（contrast sensitivity , CS）。所有检查对象在正常光线下,采用自然瞳孔测试,病人组先检查患者视力较好的眼,后检查视力较差的眼,将测试结果存储,通过相应软件处理,自动生成资料,即时呈现出对比敏感度函数（contrast sensitivity function, CSF）曲线图。用 SPSS17.0统计软件对比正常组、弱视组治疗前后不同空间频率对比敏感度数值有无差异。结果（1）正常儿童的 CSF 曲线其峰值位于空间频率6 c/d 附近,在较低、较高空间频率,CSF均降低,曲线呈一倒“ U“字形。曲线向高空间频率端外推,得截止率为25c/d。（2）轻度弱视组：治疗前 CS 在高空间频率时,振幅比正常对照组降低明显,,两组差异有统计学意义（P ＜0.05）。治疗后 CS 较治疗前升高,治疗前后差异有统计学意义（P＜0.05）,治疗后 CS 与正常对照组差异无统计学意义。（3）中度弱视组：治疗前 CS 在中、高空间频率比正常对照组降低,和正常对照组之间差异有统计学意义（P ＜0.05）。治疗后 CS 较治疗前升高,差异有统计学意义（P＜0.05）,治疗后 CS 与正常对照组差异无统计学意义。（4）重度弱视组：治疗前 CS 在低、中、高空间频率均比正常对照组降低,在中、高空间频率和正常对照组之间差异有统计学意义,但在低空间频率差异无统计学意义。治疗后CS 较治疗前升高,差异无统计学意义,和正常对照组差异亦无统计学意义。（5）弱视程度与疗效：弱视越重,疗效     

三类弱视患者的视觉噪声差异研究

目的探讨三类弱视患者之间视觉噪声的差异。方法选取2010年1月至8月在我科就诊的149例(298眼)患者,分为屈光参差性弱视组(71例)、斜视性弱视组(38例)和屈光不正性弱视组(40例)。各组分别进行视觉噪声双视力表检测。使用SPSS13.0统计软件比较3组患者的年龄、性别、最佳矫正视力、视觉噪声差异。结果年龄:方差分析结果显示3组患者的年龄差异无统计学意义(F=2.032,P=0.135);性别:χ2检验显示3组间的性别差异无统计学意义(χ2=2.785,P=0.248);最佳矫正视力:方差分析结果显示3组间差异无统计学意义(F=1.697,P=0.185)。视觉噪声:视觉噪声双视力表检测结果显示3组患者在无、有噪声条件下表现出的视觉噪声分别为:屈光参差性弱视组(1.42±0.81)行,斜视性弱视组(1.82±1.00)行,屈光不正性弱视组(2.06±0.94)行。方差分析显示3组患者间的视觉噪声差异有统计学意义(F=14.220,P<0.001);LSD法进行组间两两比较显示:屈光参差性弱视组的视觉噪声低于其他两组,差异均有显著统计学意义(均为P<0.01);斜视性弱视组与屈光不正性弱视组比较差异无统计学意义(P>0.05)。结论弱视患者视觉系统存在着内部噪声,不同弱视类型之间的视觉噪声水平存在差异;屈光参差性弱视的视觉噪声最低,屈光不正性弱视的视觉噪声最高。