Do prisms according to Hans-Joachim Haase influence ocular prevalence?

BACKGROUND: Ocular prevalence is defined as an unequal weighting of the eyes in the directional perception of stereo objects. Opinions differ as to the cause and relevance of ocular prevalence. Hans-Joachim Haase suggested that ocular prevalence is due to fixation disparity, brought about by incomplete compensation of heterophoria. He further suggested that prismatic spectacles determined by his "measuring and correcting methodology" (MKH) could restore bicentral fixation and thus establish a perceptual balance between both eyes. METHODS: We examined 10 non-strabismic subjects with a visual acuity of > or = 1.0 in both eyes. It turned out that all 10 had a "fixation disparity type II", characterised according to Haase by a "disparate retinal correspondence". All subjects underwent the automatic Freiburg Ocular Prevalence Test, without and with MKH prisms. In addition we examined ocular prevalence under forced vergence and compared ocular prevalence with stereoacuity. RESULTS: Spontaneous ocular prevalence ranged between 1 and 69 %. Averaged over all 10 subjects, ocular prevalence without and with the MKH prisms were not significantly different. Statistical evaluation of single subjects revealed only in one of the 10 a significant difference (Bonferroni-corrected p = 0.001). In the subgroup of 5 subjects who underwent forced vergence, ocular prevalence remained unaltered between 0 and 18 Delta base out. The stereoscopic threshold of all 10 subjects ranged between 1.5 and 14.5 arcsec. There was no correlation between ocular prevalence and stereoscopic threshold (r = - 0.2, p = 0.5). CONCLUSION: Our results indicate that ocular prevalence is largely independent of phoria correction and vergence stress. The excellent stereoacuity of all subjects suggests that ocular prevalence is abandoned for the sake of optimal resolution when very small differences in depth have to be judged.     

Feasibility of prismatic correction of microesotropia using the measuring and correcting methodology by H.-J. Haase

BACKGROUND: The "Measuring and Correcting Methodology after H.-J. Haase" is based on the assumption that a minute deviation from the orthovergence position (fixation disparity) indicates a difficulty to overcome a larger "vergence angle of rest". Objective recordings have, however, revealed that the subjective tests applied in the "Measuring and Correcting Methodology after H.-J. Haase" can mislead to the assumption of a fixation disparity, although both eyes are aligned exactly to the fixation point. Question: How do patients with an inconspicuously small, yet objectively verified strabismus react to the "Measuring and Correcting Methodology by H.-J. Haase"? METHODS: Eight patients with a microesotropia between 0.5 and 3 degrees were subjected to the "Measuring and Correcting Methodology after H.-J. Haase. RESULTS: In all 8 patients, the prisms determined with the Cross-, Pointer- and Rectangle Tests increased the angle of squint, without reaching a full correction: the original angle prevailed. In the Stereobalance Test, prisms did not reduce the 100 % preponderance of the non-squinting eye. The stereoscopic threshold was between 36 and 1170 arcsec in 7 out of the 8 subjects, and above 4000 arcsec in 1 subject. CONCLUSIONS: (1) In all 8 patients, prisms determined with the "Measuring and Correcting Methodology by H.-J. Haase" increased the angle of strabismus, without reaching bifoveal vision. This uniform result suggests that primary microesotropia cannot be corrected with the "Measuring and Correcting Methodology after H.-J. Haase" (2) A lacking contribution of the strabismic eye to the recognition of a lateral offset between stereo objects, as determined with the Stereobalance Test, does not imply a lack of binocular stereopsis.     

Ocular prevalence and stereoacuity.

Background: Most people attribute a higher weight to the input from one eye than to that from the other eye when they have to align stereodisparate objects in the same visual direction. This preference for visual directions has been termed ‘ocular prevalence’, according to the Latin praevalentia = superior power. Questions: (1) Is ocular prevalence of one eye (or its correlate, partial suppression of the other eye in the prevalence task) restricted to large stereodisparities, close to Panum's limit, or does it occur also at small stereodisparities, near the stereoscopic threshold? (2) Is ocular prevalence a handicap for stereoacuity? Methods: Six non‐strabismic observers with equal visual acuity of their two eyes were examined. To determine their ocular prevalence, they were presented with vertical vernier lines at stereodisparities ranging between 30 and 430 arcsec. They had to judge whether the lower, anterior line was located on the right‐ or left‐hand side of the upper, posterior line. Their stereoscopic threshold was measured with an adaptive staircase procedure, using the Freiburg Stereoacuity Test. Results: All six observers exhibited some ocular prevalence. It changed considerably on repeated measurements. In three observers, it even switched from one eye to the other. Ocular prevalence occurred not only at large stereodisparities, close to Panum's limit, but also at small stereodisparities. The stereoscopic threshold of the six observers ranged between 1.7 and 12.3 arcsec. Conclusion: Ocular prevalence is common, intra‐individually variable and occurs even at small stereodisparities close to the stereoscopic threshold. It is compatible with ‘optimal’ stereoacuity. Hence, ocular prevalence appears to be a harmless feature of normal binocular vision.     

Association between Ocular Dominance and Spherical/Astigmatic Anisometropia, Age, and Sex: Analysis of 1274 Hyperopic Individuals

Purpose. To determine the association between ocular dominance and spherical/astigmatic anisometropia, age, and sex in hyperopic subjects. Methods. The medical records of 1274 hyperopic refractive surgery candidates were filtered. Ocular dominance was assessed with the hole-in-the-card test. Refractive error (manifest and cycloplegic) was measured in each subject and correlated to ocular dominance. Only subjects with corrected distance visual acuity of >20/22 in each eye were enrolled, to exclude amblyopia. Associations between ocular dominance and refractive state were analyzed by means of t-test, χ(2) test, Spearman correlation, and multivariate logistic regression analysis. Results. Right and left eye ocular dominance was noted in 57.4 and 40.5% of the individuals. Nondominant eyes were more hyperopic (2.6 ± 1.27 diopters [D] vs. 2.35 ± 1.16 D; P < 0.001) and more astigmatic (-1.3 ± 1.3 D vs. -1.2 ± 1.2 D; P = 0.003) compared to dominant eyes. For spherical equivalent (SE) anisometropia of >2.5 D (n = 21), the nondominant eye was more hyperopic in 95.2% (SE 4.7 ± 1.4 D) compared to 4.8% (1.8 ± 0.94 D; P < 0.001) for the dominant eye being more hyperopic. For astigmatic anisometropia of >2.5 D (n = 27), the nondominant eye was more astigmatic in 89% (mean astigmatism -3.8 ± 1.1 D) compared to 11.1% (-1.4 ± 1.4 D; P < 0.001) for the dominant eye being more astigmatic. Conclusions. The present study is the first to show that the nondominant eye has a greater degree of hyperopia and astigmatism than the dominant eye in hyperopic subjects. The prevalence of the nondominant eye being more hyperopic and more astigmatic increases with increasing anisometropia.     

Ocular Dominance in Open-angle Glaucoma: The Shifting Trend Depending on Stage of the Disease

PurposeTo investigate the characteristics and distribution of ocular dominance in primary open-angle glaucoma eyes. In addition, we tried to catch any trend of ocular dominance according to the stage of disease.MethodsTwo hundred participants with bilateral open-angle glaucoma underwent ocular dominant testing by “the hole-in-a-card” test. Using optical coherence tomography, macular ganglion cell-inner plexiform layer, as well as circumpapillary retinal nerve fiber layer thickness were measured and compared according to ocular dominance. Of the two eyes of one subject, the eye with less glaucomatous damage based on mean deviation was considered to be the “better eye” in our study.ResultsOcular dominance was in the right eye in 66% of the population and ocular dominance was positioned in the better eye in 70% of the population (p = 0.001 and p = 0.002, respectively). In conditional logistic regression analyses, right eye and better mean deviation were significantly associated with ocular dominance (p = 0.001 and p = 0.002, respectively). Ocular dominance tends to be present in the better eye and this trend was more apparent as the severity of glaucoma increased. Intereye comparison of visual field indices and retinal nerve fiber layer thickness between dominant versus nondominant eye become apparent in moderate and advanced glaucoma whereas it was not as apparent in early glaucoma.ConclusionsIn glaucomatous eyes, laterality and severity of glaucoma determined ocular dominance. Intereye difference between nondominant and dominant eyes increased with the severity of glaucoma. Our findings suggest the existence of potential reciprocal interactions between ocular dominance and glaucoma.     

Association of ocular dominance and anisometropic myopia

PURPOSE: To determine the association between ocular dominance and degree of myopia in patients with anisometropia. METHODS: Fifty-five subjects with anisometropic myopia were recruited. None of them had amblyopia. Refractive error and axial length were measured in each subject. Ocular dominance was determined using the hole-in-the-card test and convergence near-point test. RESULTS: There was a threshold level of anisometropia (1.75 D) beyond which the dominant eye was always more myopic than the nondominant eye. Of the 33 subjects with anisometropia of < or =1.75 D, the dominant eye was more myopic in 17 (51.5%) subjects. Dominant eyes, determined by the hole-in-the-card test, had a significantly greater myopic spherical equivalent (-5.27 +/- 2.45 D) than nondominant eyes (-3.94 +/- 3.10 D; P < 0.001). Dominant eyes also had a longer axial length than nondominant eyes (25.15 +/- 0.96 mm vs. 24.69 +/- 1.17 mm, respectively; P < 0.001). The difference was more evident in those subjects with higher anisometropia (>1.75 D), but was not significant in those with lower anisometropia (< or =1.75 D). Similar results were obtained using the convergence near-point test. CONCLUSIONS: The present study shows that the dominant eye has a greater degree of myopia than the nondominant eye in subjects with anisometropic myopia. Taking ocular dominance into account in the design of randomized clinical trails to assess the efficacy of myopia interventions may provide useful information.     

Hand-eye dominance in a population with mental handicaps: prevalence and a comparison of methods.

BACKGROUND: The primary purpose of this study was to investigate hand-eye dominance in a population with mental handicaps and how the distribution compared with the general population. In addition, this study investigated the correlation between two methods of hand-eye dominance testing. METHODS: Two methods were used to determine eye dominance: the hole-in-the-hand method and the eye dominance wand. Hand dominance was determined by the subject's choice of accepting hand. The sample was comprised of a population of 421 athletes participating in the 1997 Special Olympic Games in Toronto. All subjects unable to give a dominant hand or unable to perform either of the ocular dominance tests were eliminated from analysis. Athletes who demonstrated strabismus or a difference in visual acuity between the two eyes of greater than 1 line were separated in the analysis, reducing the sample population to 191. RESULTS: The hole-in-the-hand method of eye dominance showed that 40.3% of this population exhibited crossed dominance. The eye dominance wand found crossed dominance in 36.6% of this population. The eye dominance wand demonstrated moderate agreement with the hole-in-the-hand method; however, there was some crossover of eye dominance between tests, when the tests were compared on a case-by-case basis. CONCLUSIONS: The prevalence rate of this population of persons with mental handicaps agrees with the prevalence rates found by Robison et al., in which 41% of a general nonhandicapped population demonstrated crossed dominance. The results suggest that persons with mental handicaps have prevalence rates of crossed dominance similar to those found in the general population.     

The effect of ocular dominance on visual field testing.

PURPOSE: During standard automated perimetry (SAP), some patients experience visual disturbances in the tested eye while the other eye is covered with an opaque occluder. It is possible that a binocular interaction producing an inhibitory response in the nonoccluded eye, such as rivalry or Ganzfeld blankout, may be the causative factor, particularly when the dominant eye is occluded. The objective of this experiment was to determine whether subjective visual disturbances occurring during conventional perimetric test conditions were related to ocular dominance and to investigate the effect of these disturbances on measurements made during threshold visual field analysis. METHOD: Ocular dominance was determined by questioning and objective testing on 55 normal subjects. Each subject underwent program 24-2 Full Threshold SAP on a Humphrey Field Analyzer, and an opaque black patch was used to occlude the nontested eye. After testing, patients were asked to report symptoms of visual disturbance characteristic of rivalry or blankout, and the relationship between ocular dominance and visual disturbances was investigated. To determine whether symptoms of rivalry or blankout had affected visual field quantification, comparisons of short-term fluctuation, mean deviation, and false-negative errors were performed between eyes with and without visual disturbances. RESULTS: A total of 24 of 55 subjects reported visual disturbances consistent with rivalry or blankout (44%). Sixteen subjects complained of the phenomenon in one eye, and eight complained of the phenomenon in both eyes. Of the 16 experiencing disturbances in one eye only, nine cases occurred during occlusion of the dominant eye. The association between ocular dominance and visual disturbances was not found to be significant (p > 0.10). No significant differences in short-term fluctuation (p = 0.78), mean deviation (p = 0.64), or false-negative errors (p = 0.10) were found between eyes with and without visual disturbances. CONCLUSIONS: Patients undergoing standard automated perimetry with opaque patch occlusion of the nontested eye often experience visual disturbances consistent with rivalry or blankout, although these disturbances do not cause increased within-test variability or reduced sensitivity as quantified by visual field global indices. In terms of summary visual field indices, ocular dominance does not appear to affect visual field test results.     

Ocular Prevalence: Difference Between Crossed and Uncrossed Disparities of Stereo Objects

Background: Many observers perceive a horizontal offset between a stereoscopically viewed object and a reference object in the fixation plane, although both objects are presented along a single line that projects through the midpoint between both eyes. These observers weigh one eye more than the other when determining the visual directions of stereo objects. This unequal weighting has been called ocular prevalence. We considered that ocular prevalence might be asymmetric, that is, different for crossed and uncrossed stereo disparities. Methods: We examined 11 subjects with normal eyes and a stereo resolution of less than 100 sec arc. A vertical line was dichoptically presented for 100 ms at crossed or uncrossed stereo disparities of 1, 2, 3, 4, 5, 6, or 7 min arc; this stereo object was judged in relation to a reference line in the fixation plane. Results: Ten of the 11 subjects had ocular prevalence, but only 3 of the 10 showed a significant difference between crossed and uncrossed disparities. Conclusions: Ocular prevalence occurs frequently among observers with normal binocular vision, but only a minority of these observers show a difference between crossed and uncrossed disparities of the stereo object. It is unclear whether this difference bears clinical importance.     

Ocular dominance reverses as a function of horizontal gaze angle

Ocular dominance is the tendency to prefer visual input from one eye to the other [e.g. Porac, C. & Coren, S. (1976). The dominant eye. Psychological Bulletin 83(5), 880-897]. In standard sighting tests, most people consistently fall into either the left- or right eye-dominant category [Miles, W. R. (1930). Ocular dominance in human adults. Journal of General Psychology 3, 412-420]. Here we show this static concept to be flawed, being based on the limited results of sighting with gaze pointed straight ahead. In a reach-grasp task for targets within the binocular visual field, subjects switched between left and right eye dominance depending on horizontal gaze angle. On average, ocular dominance switched at gaze angles of only 15.5 degrees off center.     

Ocular dominance, laterality, and refraction in Singaporean children

PURPOSE: To explore the effect of dominance and laterality on refractive error and axial length. METHODS: Ocular dominance was assessed with the hole-in-the-card test in 543 children during their 2006 follow-up visits for the Singapore Cohort study Of the Risk factors for Myopia (SCORM). Data were compared to cycloplegic refractions and axial lengths measured by ultrasound. RESULTS: The spherical equivalent refraction was essentially the same between the right and left eyes, although there was a small but statistically significant longer axial length in the right eyes. Right and left ocular dominance was noted in 58% and 30% of the subjects, respectively, with 12% having no eye preference. There was no significant difference in spherical equivalent refraction (2.56 +/- 2.46 D [mean +/- SD] vs. -2.45 +/- 2.52 D, P = 0.22) or axial length (24.36 +/- 1.19 mm vs. 24.32 +/- 1.18 mm, P = 0.05) between dominant and nondominant eyes. In subjects with anisometropia >or=0.5 D, dominant eyes were more myopic in 52%. Dominant eyes, however, had less astigmatic power (-0.88 +/- 0.80 D versus -1.00 +/- 0.92 D; P < 0.001). CONCLUSIONS: Ocular laterality and dominance have no significant effect on spherical equivalent. All axial length and astigmatic differences were small and clinically insignificant. The study findings suggest that in Singaporean children, bias is not present in those investigations that restrict analyses to right or left eyes. Although there is no apparent association between refraction and ocular dominance in young Singaporean children, more research is needed to resolve the disparate results in existing reports.     

干眼病患者结膜损害的观察研究

目的 探讨干眼病患者结膜损害的观察方法.方法 选择2006年6月至2007年10月在我院门诊确诊的47例(94只眼)干眼病患者,对其94只眼用荧光素染色后分别用钴蓝光和蓝光滤过片观察眼表结构的改变情况.结果 在眼表上皮细胞方面,钴蓝光观察94只眼中有85只眼染色有异常,其中染色累及睑裂部角结膜有75只眼,染色累及下方结膜有10只眼;而用蓝光滤过片观察后,发现染色有异常的有90只眼,其中染色累及睑裂部角结膜有25只眼,染色累及下方结膜46只眼,染色累及上方结膜19只眼,Kappa一致性检验,二者有差异;染色累及上方结膜19只眼的干眼病患者泪膜破裂时间为均值4.07 s,标准差0.14 s;与正常眼泪膜破裂时间至少5 s相比有统计学差异.结论 眼表结构荧光染色后的的蓝光滤过片观察方法简便、特异性、敏感性高,尤其是在结膜上皮的损害观察方面优势明显.所有上方结膜损害的干眼病患者的泪膜稳定性差,主观症状中异物感症状重.     

LASIK术后主导眼对视功能影响的临床研究

目的:评价LASIK术前近视眼患者主导眼的分布及术后主导眼的变化与视力和视功能的关系。方法:选择拟行LASIK手术的近视眼患者235例470眼,分别于LASIK术前、术后1,3,6,12mo应用卡洞法行主导眼检查眼别,主导眼与非主导眼的术前的矫正视力和术后的视力进行比较,并接受视功能量表调查。结果:LASIK术前近视眼患者主导眼分布以右眼为主(67.2%);术前主导眼眼别与最佳矫正视力眼别一致性好,两者符合率为81.1%;235例近视患者LASIK术后主导眼眼别220例没有发生变化;15例患者眼别发生调换,其中5例有15°左右外斜。结论:主导眼分布以右眼为主,主导眼大多是患者最佳矫正视力眼;主导眼视力下降或低于非主导眼和主导眼调换患者在术后早期对视觉舒适度产生影响,但晚期影响降低患者逐渐适应。     

准分子激光角膜原位磨镶术后主导眼改变及其影响的研究

目的 观察准分子激光原位角膜磨镶术（LASIK）后主导眼分布特点及其影响.方法 前瞻性病例对照研究.选取行LASIK的近视患者190例（380眼）,按屈光参差度数及主导眼眼别分为3组：A组,两眼等效球镜度差异＜1.75 D,共154例;B组,两眼等效球镜差异≥1.75 D,且主导眼为近视度数较高眼,共19例;C组,两眼等效球镜差异≥1.75 D,且主导眼为近视度数较低眼,共17例.术前和术后1个月分别检查裸眼视力、屈光度及确定主导眼（卡洞法）,术后1个月接受远、近视觉满意度问卷调查.组间率的比较采用卡方检验,计量资料采用独立样本t检验.结果 LASIK术前右眼为主导眼125例（65.8%）,左眼65例（34.2%）;术后右眼为主导眼92例（48.4%）,左眼98例（51.6%）.59例（31.1%）患者在术后发生主导眼转变.B组患者中主导眼转变率（47%）高于A组（29%）和C组（29%）（x2=5.38,P＜0.05）.屈光参差患者术前主导眼与非主导眼等效球镜度差异无统计学意义.术后主导眼的等效球镜度为（-0.29±0.89）D,较非主导眼[（-0.42±0.91）D]低,差异存在统计学意义（t=2.448,P=0.015）.主导眼改变和未改变患者的远、近视觉满意度分别为2.33、2.40和3.62、3.95,差异均无统计学意义.结论 LASIK术后存在主导眼的改变,即关键期后,眼优势具有可塑性,尤其在术前有屈光参差且主导眼为近视度数较高眼的患者中发生率更高.术后非主导眼较主导眼更偏近视.但主导眼改变与否对术后视觉满意度无显著影响.     

Ocular dominance diagnosis and its influence in monovision

PURPOSE: To analyze the response of normal emmetropic subjects to different ocular dominance tests and to analyze the influence of this response in surgically induced monovision. DESIGN: A prospective study of diagnostic accuracy was carried out to analyze the different tests to determine ocular dominance, without a gold standard test. METHODS: Nine different tests were carried out in a group of 51 emmetropic subjects to determine both motor and sensory ocular dominance. For analysis, patients were divided into two groups according to age. Normal ophthalmologic examination results were the inclusion requirement, with normal binocular vision and good stereoacuity. RESULTS: A significant percentage of uncertain or ambiguous results in all tests performed was found, except in the hole-in-card and kaleidoscope tests. When the tests were compared, two by two, the correlation or equivalence found was low and was much lower if tests were compared three by three. CONCLUSIONS: No clear ocular dominance was found in most studied subjects; instead, there must be a constant alternating balance between both eyes in most emmetropic persons, but not in those with pathologic features. This fact would explain the great variability both between and within different kinds of tests. Also, it would establish that the monovision technique is well tolerated in most patients, with unsuccessful results only in those patients with strong or clear dominance. Consequently, it seems appropriate to evaluate patient's dominance before monovision surgery to exclude those individuals with clear dominance.     

Associated heterophoria and the asymmetry of ocular prevalence for stereo images in front of or behind a reference plane

BACKGROUND: An unequal weighting of the eyes in the directional perception of stereodisparate objects, is referred to as ocular prevalence of the right or left eye, respectively. Between 1962 and 1964 H.-J. Haase developed a valence test for the prismatic correction of heterophoria. He suggested that there would be less prevalence for stereo images presented in front of or behind a reference plane, and that this asymmetry of prevalence may be related to the direction of the associated heterophoria (eso- or exophoria). According to H.-J. Haase, the asymmetry may indicate a fixation disparity with a corresponding shift in retinal correspondence. Hence, the valence test could be an indicator for the prismatic correction of heterophoria. Methods: Prevalence was tested in 37 subjects, using three methods: The subjects were asked to describe their perception (1), to make a paper drawing of their perception (2), and to align the position of the stereo images to the central fusion target with a computer-controlled device (3). Methods 2 and 3 were used to reduce a possible suggestive influence on part of the investigator. The associated heterophoria was determined with the cross test by H.-J. Haase. RESULTS: Depending on whether the triangular stereo images were presented behind or in front of the reference plane, more or less prevalence was measured (mean values) in the group with exophoria than in the group with esophoria. These results were confirmed with all three methods. The asymmetry of prevalence was correlated with the direction of the associated heterophoria with r = 0.5. CONCLUSION: Statistically, these results confirm Haase's hypothesis of a relation between the asymmetry of ocular prevalence and the direction (eso- or exophoria) of the associated heterophoria. Since this relation holds true only for the group mean value, but not for each individual, the valence test cannot be generally recommended as an adjunct for the prismatic correction of heterophoria.     

Ocular trauma in an urban population in southern India: the Andhra Pradesh Eye Disease Study

Purpose : To assess the cumulative prevalence of ocular trauma and presence of vision loss due to ocular trauma in an urban population in southern India. Methods : As part of the population‐based Andhra Pradesh Eye Disease Study, 2522 people of all ages from 24 clusters representative of the population of Hyderabad city in southern India, underwent a detailed interview and standardized dilated ocular evaluation. An eye was considered to be blind due to trauma if best corrected distance visual acuity was worse than 6/60 due to trauma. Results : One hundred and thirteen subjects gave a history of ocular trauma and another two had evidence of ocular trauma by examination, a combined age–sex‐adjusted rate of 3.97% (95% CI 2.52–5.42%). Blindness in one eye due to trauma was present in 17 subjects, and in both eyes in one subject, a combined age–sex‐adjusted prevalence of 0.60% (95% CI 0.23–1.04%). Visual acuity in all the blind eyes except one was worse than 3/60. With multiple logistic regression, the odds of blindness in at least one eye due to trauma were highest for current age range of 30–39 years (odds ratio 6.33, 95% CI 1.69–23.77 compared with a current age of less than 30 years), were significantly higher for lower socioeconomic status (3.74, 95% CI 1.18–11.84), and were higher for males (2.48, 95% CI 0.91–6.82) though this did not reach statistical significance. Trauma resulting in blindness had occurred by the age of 15 years in 55% of subjects, and before the age of 40 years in 92.1% of subjects; this had occurred most commonly while playing (53.6% of the cases). With multiple logistic regression, the odds ratios for any ocular trauma were significantly higher for males (2.10, 95% CI 1.40–3.15), and for labourers than for other occupations (2.50, 95% CI 1.62–3.86). Conclusions : Ocular trauma affects one in 25 people in this urban population in India, and one in 167 people in this population are estimated to be blind in at least one eye due to trauma. The majority of the trauma resulting in blindness occurs during childhood and young adulthood, and slightly more than half occurs while playing. Targeting mothers and children of lower socioeconomic strata in eye health awareness strategies to reduce blindness due to trauma needs to be considered in urban India. Key words : blindness, India, population‐based, trauma, urban.     

Quantitative measurement of ocular dominance using binocular rivalry induced by retinometers

PURPOSE: To develop a new method using binocular rivalry and retinometers to quantitatively examine ocular dominance and to investigate the magnitude of ocular dominance in cataract patients preoperatively and postoperatively. SETTING: Eye Clinic, Kitasato University School of Medicine Hospital, Sagamihara, Kanagawa, Japan. METHODS: The duration of exclusive visibility of the dominant and nondominant eye target in binocular rivalry were measured in 60 healthy volunteers (study 1) and preoperatively and postoperatively in 10 cataract patients (study 2). Rivalry targets were presented directly to the retina of each eye using 2 retinometers. Subjects reported the exclusive visibility of 1 eye target, and the total duration of exclusive visibility for each eye in dominant and nondominant eye trials was evaluated. RESULTS: In study 1, the magnitude of ocular dominance was quantitatively assessed with 4 grades based on differences in total duration of exclusive visibility between dominant and nondominant eyes. In study 2, magnitude of ocular dominance could be evaluated in all cataract patients regardless of refractive and cataract conditions. Magnitude of ocular dominance displayed significant correlations between preoperative and postoperative conditions (simple regression, P<.001). CONCLUSIONS: Ocular dominance can be quantitatively evaluated using this new method based on binocular rivalry and retinometers, particularly in cataract patients. Magnitude of ocular dominance may indicate preoperatively whether a patient with cataracts will have sufficient ocular dominance to adjust to monovision correction.     

在屈光习惯矫正与全矫状态下用Worth四点法与卡洞法测量优势眼的结果比较

目的研究Worth四点法测量优势眼与卡洞法测量优势眼的相关性,并分别研究这两种方法在习惯矫正情况下与屈光全矫状况下测量优势眼眼别的差异。方法429例受试者,其中部分受试者采用两种方法(卡洞法与Worth四点法)测量优势眼,部分受试者接受了在两种条件下(习惯矫正方式与屈光全矫下)测量优势眼,使用SPSS11.5统计软件包的卡方检验及Spearman非参数两两相关分析计算各组数据的差异与相关性。结果Worth四点法和卡洞法测得优势眼在习惯屈光矫正下差异无显著性(n=61,P>0.05),也无显著相关性(P>0.05);在屈光全矫下两种方法的差异有显著性(n=140,P=0.001),但无显著相关(P>0.05);而卡洞法在两种条件下测量的优势眼眼别差异有显著性(n=61,P<0.0001),并且存在显著相关(r=0.782,P<0.0001);Worth四点法在两种条件下测量的优势眼眼别差异有显著性(n=62,P<0.0001),并且两者显著相关(n=62,r=0.517,P<0.0001)。结论Worth四点法与卡洞法是两种测量优势眼的方法,在习惯屈光矫正下与屈光全矫状态下测得的优势眼差异有显著性。医学验光时采用Worth四点法测量在习惯矫正下的优势眼的方法尚需进一步研究以确定其可靠性。