Comparison of alternate cover test reliability at near in non‐strabismus between experienced and novice examiners

Purpose: The purpose of this study was to determine the reliability of the prism neutralized alternate cover test (ACT) used to measure near phoria in non‐strabismic participants as measured by experienced and novice examiners and to compare the values to results obtained by eye tracking. Methods: Two experienced optometrists and two optometry students performed the ACT at 40 cm on 50 non‐strabismic participants. The ACT was then repeated with the subjects wearing an eye tracker. The saccade amplitude of the eye movement recordings was used to determine the phoria. The reliability was determined using Bland–Altman analysis to determine the mean of the differences in the groups and the 95% limits of agreement. Results: The phoria range determined by the eye tracker was between 6 pd eso and 19 pd exo. The mean of the difference in values and 95% limits of agreement between the experienced examiners was 0.7 ± 3.0 pd; between the novice examiners was ?0.1 ± 4.4 pd; between the experienced and novice examiners was 0.8 ± 3.5 pd; between the eye tracker and the experienced examiners was 0.6 ± 3.5 pd; between the eye tracker and novice examiners was 1.4 ± 3.6 pd. Conclusions: The mean differences of the ACT result between experienced examiners, novice examiners, and the eye tracker, were not clinically meaningful. However, the 95% limits of agreement were quite high (±3.0–4.4 pd). This information is useful for clinical decision making, student education and student evaluation.     

Comparison of near heterophoria tests under varying conditions on an adult sample

PURPOSE: This study compared the near phoria measurement using the Bernell muscle balance card with and without prism neutralization, using both trial frame and phoropter correction, and compared with the conventional Maddox rod method. METHODS: Forty young normal Chinese adults had their near phoria measured with trial frame correction using the conventional muscle balance card method (method 1). Any deviation was compensated with a prism bar as an alternative approach (method 2). The conventional Maddox rod method (method 3) was also carried out for comparison. These three methods were repeated with phoropter correction and considered as methods 4, 5 and 6. RESULTS: The phorias obtained from these six methods were not significantly different from each other (repeated measures anova, p > 0.05). More than half of the subjects were exophoric. Although the difference in phoria was not significant, phoria measurement using phoropter correction yielded a greater coefficient of variation. CONCLUSIONS: Near phoria measurement using the muscle balance card conducted with trial frame correction was less variable, and was also more natural and similar to a real reading situation. The use of prism for compensation did not affect the phoria results. Exophoria seems to be more common than esophoria in young Chinese adults.     

The influence of heterophoria measurements on subsequent associated phoria measurement in a refractive routine

The influence of measuring heterophoria on a subsequent associated phoria measurement was investigated in 50 subjects. After refraction, heterophoria was measured by either von Graefe's technique or Maddox rod and wing. The effect of these procedures was assessed by associated phoria measurements taken before and after the dissociated measures. It is shown that subjects with a history of unstable binocular vision are likely to have an associate phoria induced or changed by the previous dissociated phoria measurement, particularly if von Graefe's technique is employed. It is recommended that, especially for near, associated phoria should be assessed before the dissociated phoria in subjects who are regarded as having a history of unstable binocular vision.     

Relation between distance heterophoria and tonic vergence

The distance heterophoria was measured using both the von Graefe and Maddox rod clinic procedures under standard reduced illumination conditions and in total darkness. Tonic vergence was measured in total darkness. The phoria measures were more divergent than tonic vergence, with the von Graefe being the more divergent of the two measures. The difference between the phoria and tonic vergence position is believed to be due to accommodative divergence derived from the decrease of accommodation, relative to the tonic level, required to focus the distance phoria target. Equations were derived to predict tonic vergence from the phoria value.     

Convergence Insufficiency Neuro-Mechanism Adult Population Study: Phoria Adaptation Results

PurposeThe purpose of this study was to compare changes in phoria adaptation between young adult binocularly normal controls (BNCs) and participants with symptomatic convergence insufficiency (CI), who were randomized to either office-based vergence accommodative therapy (OBVAT) or office-based placebo therapy (OBPT).MethodsIn the double-masked randomized clinical trial, 50 BNC and 50 CI participants were randomized to the following therapeutic interventions: OBVAT or OBPT with home reinforcement for 12 one-hour office sessions. A 6∆ base-out and 6∆ base-in phoria adaptation experiment at near (40 cm) was conducted using the flashed Maddox rod technique at baseline and at outcome. Measurements included the rate and the magnitude of phoria adaptation.ResultsAt baseline, BNC and CI participants had significantly different rates and magnitudes of base-in and base-out phoria adaptation (P < 0.001). When comparing the outcome to baseline measurements, significant main effect differences in longitudinal measurements were observed for the magnitude and the rate of phoria adaptation for both base-out and base-in experiments (P < 0.05). For the magnitude and rate of phoria adaptation, post hoc analyses using paired t-tests revealed that the CI group administered the OBVAT intervention exhibited a significant increase in the magnitude and rate of phoria adaptation compared to baseline for both base-in and base-out phoria adaptation (P < 0.01) but not for those administered OBPT.ConclusionsPhoria adaptation is significantly different at baseline between those with normal binocular vision and symptomatic CI participants. OBVAT significantly improves the rate and magnitude of both base-out and base-in phoria adaptation at near compared to OBPT. Results have clinical implications for new therapeutic interventions.     

主视眼对民航招飞隐斜检查结果的影响

目的:探索便携式隐斜计放置眼别(主视眼或非主视眼)对民航招飞隐斜检查结果的影响。方法:南航2012年度广东地区招飞上站眼科第一轮通过650例学生,卡孔法判断被检者主视眼眼别,将便携式隐斜计分别放置在主视眼(主视眼组)与非主视眼(非主视眼组)前测量隐斜值,用Von Graefe法测量值作为对照,外隐斜为负值、内隐斜为正值,垂直隐斜取绝对值。分别对主视眼组与非主视眼组、主视眼与Von Graefe法组、非主视眼组与Von Graefe法组隐斜值进行统计学分析。结果:Von Graefe法组外隐斜平均为-2.21±0.35△,内隐斜平均为+3.87±1.20△,上隐斜为+0.44±0.12△;主视眼组外隐斜平均为-2.68±0.55△,内隐斜平均为+6.22±2.55△,上隐斜为+0.46±0.15△;非主视眼组外隐斜平均为-2.16±0.40△,内隐斜平均为+3.22±1.65△,上隐斜为+0.45±0.14△。水平隐斜(外隐斜和内隐斜):主视眼组与非主视眼组有统计学差异(P<0.05),主视眼组与Von Graefe法组有统计学差异(P<0.05),非主视眼组与Von Graefe法组无统计学差异(P>0.05);垂直隐斜:Von Graefe法组与主视眼组、非主视眼组无明显统计学差异(P>0.05)。结论:民航招飞隐斜检查时便携式隐斜计放置在被检者非主视眼前结果更为可靠。     

The forced vergence cover test and phoria adaptation

Phoria adaptation (PA) provides innervation to help maintain the correct vergence posture for binocularly viewing objects. Once fusion is disrupted, such as is required for measuring a (dissociated) phoria, this innervation is slowly depleted. Thus, extended periods of monocular occlusion can be required to dissipate PA and reveal the full extent of the phoria. Two versions of a forced vergence modification of the alternating cover test (CT) have been proposed to rapidly show the full phoria. We evaluated the ability of these forced vergence CTs (FVCT-1 and FVCT-2) to deplete the PA induced by a 15 min adaptation period to base out prism. In both experiments, the CT followed by the FVCT was performed before and after the adaptation period. In Experiment 1 (n = 13), the FVCT-1 was evaluated at 40 cm. Experiment 2 (n = 32) evaluated the FVCT-2 at 4 m. In Experiments 1 and 2, the difference between pre- and post-adaptation CTs showed significant PA occurred during the adaptation period (7.8(Delta), p < 0.0005, and 5.4(Delta), p < 0.0005 respectively). In Experiment 1, the FVCT-1 did not reveal a larger phoria than the CT before (mean difference: 0.4(Delta), p = 0.34) or after (no difference for all subjects) the adaptation period. Thus, the FVCT-1 did not alter PA. In Experiment 2, the FVCT-2 did show a shift in the phoria compared to the CT. However, this shift was found to be equivalent before and after the adaptation period (mean difference in shift: 0.22(Delta), 95% CI: -0.52 to 0.96(Delta)). Thus, the FVCT-2 shifts the phoria a constant amount independent of the amount of PA present. We conclude that neither FVCT's behaviour is dependent on the PA present. Thus, these procedures are unlikely to be effective clinical procedures for revealing the full magnitude of the phoria.     

The effects of varying examiner position on alternating cover test results.

BACKGROUND: Although the alternate cover test is a widely accepted test of ocular alignment, clinical ambiguity exists with regard to the specific location of the examiner. This study was an attempt to replicate the findings of a previous study that compared two examiner positions and their effect on heterophoria measurement at 40 cm. METHODS: Fifty-seven adult subjects (mean age, 24.0 +/- 2.88 years) with normal binocular vision were measured for heterophoria posture using the alternate cover test while the examiner position was varied between midline and offset 30 degrees to the right of patient midline. RESULTS: A significant difference between midline and offset position of 1.3delta was found (p < 0.0001). The results show that a greater exophoric measurement was seen when the examiner performed the test in the 30 degrees offset position. DISCUSSION: A 1.3delta difference in measured phoria associated with examiner position is consistent with, though smaller than previously reported. Why the examiner position should influence the phoria is possibly related to proximal awareness or prismatic measurement error. Given the small magnitude of the effect found in this study, its relevance for patients with normal binocular vision is slight, though examiner position may contribute to variability in cover test measures between examiners or on test-retest.     

The effect of saccades and brief fusional stimuli on phoria adaptation.

PURPOSE: The purpose of this experiment was to determine whether brief fusional stimuli and saccades similar to those seen in the alternate cover test affect phoria disadaptation. METHODS: Three cover test conditions were performed randomly. Before each test condition, subjects fused for 2 min at an angle convergent to the subjective phoria. In one test condition, subjects viewed monocularly. In another condition, subjects alternately fixated with each eye (no binocular time). In a third condition, subjects alternately fixated with each eye, and there was a 100-ms period of binocular viewing between alternations. The ocular vergence angle was monitored using scleral search coils. RESULTS: Vergence angle was plotted against time for each condition. The area under this plot was determined using a computer program. The area reflected the rate at which ocular vergence returned to the original phoria position. The mean area for the monocular condition was 300.9, the mean area for alternate fixation with no binocular time was 300.3, and the mean area for alternate fixation with binocular time was 205.2. CONCLUSIONS: Saccadic alternations do not affect phoria adaptation. However, short periods in which binocular disparate images are viewed significantly increase the rate at which phoria adaptation declines for some subjects.     

Repeated measures of horizontal heterophoria.

PURPOSE: To assess repeatability, horizontal heterophoria measurements were taken from 31 subjects on five occasions, each between 1 and 4 weeks apart. METHOD: Distance heterophoria was measured using a Maddox Rod, and near heterophoria was measured using a Maddox Wing. In addition, near measurements were repeated with a +3.00 D lens in front of each eye to place the targets at optical infinity. In each case, the standard deviation of the five values was taken as a metric of the test variability. RESULTS: On average, the variability of the Maddox Rod was half of the Maddox Wing, both with and without the lenses. CONCLUSION: This consistency suggests that the difference reflects the test conditions rather than optical differences in the target position.     

眼动参数变化与青年近视眼关系的分析

目的:分析相对调节力(正,负)、水平隐斜(远,近)及调节灵活度等眼动参数与青年近视发生发展的关系。方法:在知情同意的情况下,选择大学入校新生266例,平均年龄18.8±0.8岁。根据受检者屈光状态分为五组:正视组29例,低度近视组118例,中度近视组82例,高度近视组37例,屈光参差组26例(其中屈光参差组不纳入研究对象所有受试者)。在综合验光仪上测正、负相对调节力,VonGraefe法测量远、近距水平隐斜度,利用±2.00D蝴蝶镜测调节灵活度,不同组眼动参数进行统计学分析。结果:正相对调节力正视眼组均值4.87±1.47D,低、中、高度近视组正性对调节力均值分别为2.36±1.21,2.92±1.40,2.86±1.81D,差异有统计学意义(P<0.05);负相对调节力正视眼组与近视眼组无统计学差异(P>0.05);调节灵活度在正视眼组与近视眼组间无统计学差异(P>0.05);远、近水平隐斜正视组与近视组之间无统计学差异(P>0.05),但低度近视组与高度近视组间有统计学差异(P<0.05)。结论:正相对调节明显下降引起调节储备不足形成远视性离焦可能是青年近视发病病因之一,而负相对调节力、调节灵活度及远、近水平隐斜等眼动参数与青年近视发生无关。     

Vertical heterophoria and susceptibility to visually induced motion sickness

Motion sickness is reported to be a common symptom in patients with vertical heterophoria. The goal of this study was to assess the relationship between vertical phoria and susceptibility to motion sickness in a nonclinical sample of 43 subjects. Vertical phoria was measured with a Maddox rod after 30 s of occlusion. To evaluate susceptibility to motion sickness, subjects read text while sitting inside a rotating optokinetic drum for 10 min. Subjects rated their level of motion sickness at 1 min intervals during drum rotation and the magnitude of 13 motion sickness symptoms after drum rotation ended. The magnitude of vertical phoria ranged from 0 to 2.13 prism diopters (pd) with a mean of 0.46 pd and correlated significantly with both the maximum rating of motion sickness during drum rotation and the summed symptom score following rotation. A vertical phoria of 0.75 pd discriminated best between subjects with low vs high summed motion sickness symptom scores (p < 0.0001). Introducing a prism to artificially increase the phoria of 12 subjects with vertical phorias <0.75 pd increased motion sickness symptoms in only 1 subject. Prisms that reduced the phoria of subjects with vertical phorias > 0.75 pd reduced motion sickness symptoms in 2 of the 4 subjects tested. The results confirm an association between vertical phoria and motion sickness, but suggest the relationship may not be causal.     

近视儿童调节滞后与隐斜状态及相关因素研究

目的 研究近视儿童近距注视下的调节滞后和隐斜量,分析近视儿童调节滞后与近隐斜的关系及相关因素.方法 受试者为250名近视儿童,等效球镜屈光力范围为-0.50～-5.25D.采用MEM动态检影法测量受试者右眼近距的调节滞后;分别采用Howell测量法(HT)和改良Thorington测量法(MTT)测量近隐斜;通过问卷调查受试者父母的屈光状态.各重复测量三次,取均值.结果 受试者近距调节滞后为(+0.97±0.43)D,近隐斜为(-0.94±4.55)△(外隐斜,HT)和(-1.71±4.85)△(外隐斜,MTT).伴近内隐斜者占28.0％(HT)和22.8％(MTT).伴近内隐斜者的调节滞后和内隐斜呈正相关(r=0.353,P=0.003,HT;r =0.461,P＜0.001,MTT);受试者调节滞后和近视程度呈负相关(r=-0.241,P＜0.001).23％近视者父母均为近视,其调节滞后显著大于其父母组儿童(F =4.90,P=0.009).结论 近视儿童在近距注视状态下调节滞后较高.近隐斜状态和遗传因素都可能影响近视儿童的调节滞后,调节滞后量与近视程度可能存在相互作用.临床上应将近距调节反应和隐斜测量纳入儿童的常规视功能检查项目.     

The Prevalence of Strabismus,Heterophorias, and Their Associated Factors in Underserved Rural Areas of Iran

Purpose: To determine the prevalence of different types of strabismus and heterophoria and their associated factors in underserved rural areas of Iran. Methods: Two rural areas in the north and southwest of Iran were randomly sampled using multistage cluster sampling. Individuals aged over 1 year, totaling 3851, were invited to participate in the study. In addition to collecting demographic data, optometric examinations were performed for each participant. Unilateral and alternating cover tests were performed at far (6 m) and near (40 cm) to detect tropia and phoria, respectively, and the magnitude of the deviation was measured using alternating cover test and prism bar. Tropia was defined as the presence of constant unilateral or alternating horizontal strabismus (exotropia or esotropia) at either far or near fixation distances. Far and near exophoria were defined as more than 3 prism diopters (PD) and 9 PD of exophoria at far and near fixation distances, respectively. Far esophoria was defined as more than 1 PD of esophoria at far. Near esophoria was defined as any amount of esophoria at near. Results: Of 3851 selected individuals, 3314 (86.5%) participated in the study. After excluding those who met the exclusion criteria or had missing data, eventually there were 3248 subjects available for this analysis. The prevalence of tropia and phoria was 4.3% (95% CI: 3.28-5.33) and 28.37% (95% CI: 19.12 -37.61), respectively. The prevalence of exotropia and esotropia was 3.87% (95% CI: 2.77-4.98) and 0.43% (95% CI: 0.19-0.67), respectively. The prevalence of near exophoria, far exophoria, near esophoria, and far esophoria was 25.96 (95% CI: 16.71-35.2), 4.82% (95% CI: 0.23-9.41), 0.47% (95% CI: 0.2-0.75), and 0.34% (95% CI: 0.06-0.63), respectively. In this study, the prevalence of tropia had no significant association with age, sex, living place, and refractive errors (all P values >0.05), while the prevalence of phoria increased significantly with increasing age (P<0.001) and was also significantly associated with living place (P<0.001). Conclusion: The prevalence of tropia and phoria was high in our study. Moreover, the prevalence of exotropia and exophoria was higher than esotropia and esophoria. The prevalence of phoria was significantly higher in older age groups and in the participants living in the southern villages.     

LATERAL SHORT-TERM PRISM ADAPTATION IN CLINICAL EVALUATION

Data were obtained from a normal clinical population regarding heterophoria, associated phoria and short-term prism adaptation in an attempt to differentiate between those subjects with symptoms and those without. Correlation between heterophoria, associated phoria, prism adaptation and symptoms was low. A short prism-adaptation test was found to be of little value in diagnosing decompensated heterophoria in the general population. Subjects diagnosed as having decompensated heterophoria did not have an abnormal short-term prism-adaptation system. The clinical implications of these findings are discussed in relation to the diagnosis of decompensated heterophoria and the prescribing of prismatic corrections.     

The effect of vergence adaptation on convergent accommodation

This study investigates whether, during a sustained near-vision task, the convergent accommodation (CA) derived initially from the fast (reflex) vergence response is subsequently maintained by tonic (adaptive) vergence. CA was examined during the course of a 3 min near-vision task (viewing distance 33 cm) in 10 emmetropic subjects. Vergence was stimulated by the introduction of a 6 delta base-out prism before the right eye while the open-loop accommodative response of the left eye was measured at approximately 1 s intervals using an objective infra-red optometer. In a control condition the subject viewed the target through a plano lens (0 delta). The accommodation loop was opened by the subject viewing near-type through 0.5 mm diameter pinholes. Pre- and post-task measurement of heterophoria was made using a Maddox rod and prism bar. Regression of post-task heterophoria to the pre-task value indicated that adaptation to the vergence stimulus had occurred. However, there was no significant reduction in induced CA during the task. As the onset of adaptation does not produce any fall in CA, it is concluded that both reflex and adaptive vergence act as a stimulus to CA. This finding is discussed with regard to models of accommodation-vergence interaction.     

Heterophoria measured with white, dark-grey and dark-red Maddox rods

BACKGROUND: Heterophoria is defined as a deviation from orthovergence position when no fusional contours are provided. It has been suggested that darkening one eye effects the phoric angle between the two eyes. We tested this assumption by comparing the phoric angles with white, dark-grey and dark-red Maddox rods. METHODS: In a first group of 14 subjects horizontal heterophoria was measured with white, dark-grey and dark-red Maddox rods. In a second group of 43 different subjects horizontal heterophoria was measured with white and dark-red Maddox rods. Subjects were asked to continually correct any perceived deviation, using Herschel prisms. Readings were taken after 1 min. RESULTS: Group 1 (n=14): No significant difference between white, dark-grey and dark-red Maddox rods (Friedmann test). Correlation between white and dark-grey Maddox rods r=0.97 (P<0.0001), slope of regression line 0.92 (95% confidence interval 0.78-1.06). Correlation between white and dark-red Maddox rods r=0.94 (P<0.0001), slope of regression line 0.67 (95% confidence interval 0.53-0.82). Group 2 (n=43): No significant difference between white and dark-red Maddox rods (Wilcoxon signed rank tests). Correlation r=0.96 (P<0.0001), slope of regression line 0.95 (95% confidence interval 0.87-1.03). CONCLUSION: Our study revealed no significant difference and a high correlation among the phoric angles obtained with white, dark-grey and dark-red Maddox rods. The close match suggests that darkening one eye does not effect the phoric angle between the two eyes.     

The anti-inflammatory regulation of calcitonin gene-related peptide in mouse Aspergillus fumigatus keratitis

AIM: To analyze the impact of calcitonin gene-related peptide (CGRP) in mouse keratitis after Aspergillus fumigatus (A. fumigatus) infection. METHODS: C57BL/6 mice were treated subconjunctivally with different concentrations of exogenous CGRP, and BALB/c mice were treated with CGRP8-37 (a CGRP antagonist) before corneas were infected with A. fumigatus. The cornea was assessed under the slit-lamp and the clinical score was recorded. The mRNA levels of IL-1β, TNF-α, IL-6, and MIP-2 were detected by quantitative real-time polymerase chain reaction (PCR), while the protein level of IL-1β was determined by Western blotting. In vitro, RAW264.7 cells were used to investigate NLRP3 and IL-1β expression induced by A. fumigatus after the pretreatment of exogenous CGRP or CGRP8-37. Cytokines expression in RAW264.7 cells was evaluated by real-time PCR and Western blotting. RESULTS: Using exogenous CGRP resulted in down-regulated synthesis of IL-1β and MIP-2 stimulated by A. fumigatus in C57BL/6 mice keratitis, and the synthesis of IL-1β, MIP-2 and IL-6 was up-regulated in BALB/c mice corneas after the pretreatment with CGRP8-37. Pretreatment with exogenous CGRP and CGRP8-37 did not influence TNF-α mRNA levels either in BALB/c or C57BL/6 mice keratitis. The levels of NLRP3 and IL-1β were both reduced in A. fumigatus stimulated-macrophages after treatment with exogenous CGRP. And CGRP8-37 pretreatment would increase NLRP3 and IL-1β levels. CONCLUSION: CGRP may alleviate the inflammatory reaction in mice keratitis after infection with A. fumigatus. The anti-inflammatory effect may be related to the inhibition of NLRP3 expression by CGRP.     

Comparison between dissociated and associated heterophoria

Background. Since Ogle (1949) dissociated heterophoria is distinguished from associa-ted heterophoria. Dissociated heterophoria is defined as a deviation from the orthovergence position that occurs when no fusional contours are provided. Associated heterophoria is a deviation that occurs under prism correction of fixation disparity, i. e. under a viewing condition in which fusional contours are absent only in the centre of the visual field. Both dissociated and associated heterophoria have been used as indications for prismatic correction. It has been controversially discussed to what extent dissociated and associated heterophoria are comparable. Methods. A total of 43 subjects were investigated using the white Maddox rod test for horizontal dissociated heterophoria and the cross test of Hans-Joachim Haase (a test si-milar to the fixation disparity test described by Ogle 1949) for horizontal associated heterophoria. In both tests subjects were asked to continually correct any deviation using Herschel prisms. Readings were taken after 1 min. Results. The correlation between the results obtained with the white Maddox rod test and the cross test was r=0.89 (p<<0.0001) and the slope of the regression line was 0.92 (95% confidence interval from 0.77 to 1.07). One subject was unable to reach a match in the cross test because she had an “obligate” fixation disparity due to a staphyloma posticum. Conclusions. Our study revealed a high correlation between dissociated and associated heterophoria. This result appears plausible since the feedback loop for fusion is disconnected in both cases, although in a different manner: When dissociated heterophoria is measured, fusionable contours are absent. When associated heterophoria is measured, any disparity of peripheral contours that could serve as an error signal is nullified by instantaneous prism correction. The high concordence of dissociated and associated heterophoria suggests that both measures are of equal value as an indication for prismatic spectacle correction. In rare cases of an “obligate” fixation disparity, however, associated heterophoria cannot be determined so that dissociated heterophoria remains as the only indication.     

Prevalence of heterophoria in a population of school children in central China:the Anyang Childhood Eye Study

AIM:To investigate the prevalence of heterophoria and the relationship between heterophoria and refractive error in a school-based study conducted in central China.METHODS:A total of 23637 th-grade children were recruited into the cross-sectional school-based Anyang Childhood Eye Study(ACES)by cluster sampling method.Heterophoria was examined using alternate cover and cover-uncover testing.The Maddox rod and prism test were conducted at 33 cm and 6 m distance fixation.Uncorrected viual acuity(UCVA)and best-corrected viual acuity(BCVA)were recorded as logarithm of the minimum angle of resolution(logM AR)with cycloplegic autorefraction by administrating of Mydrin-P and 1.0%cyclopentolate.Hyperopia was defined as the spherical equivalent(SE)refraction of+0.50 D or greater,and higher hyperopia was defined as+2.00 D or greater.Emmetropia was defined as the SE refraction in the range of-0.49 to+0.49 D,and myopia was in the SE refraction range from-0.50 D to less.RESULTS:Totally 2260 students in grade 7 were examined.Response rate among eligible children was 95.64%.Totally 486 children,22.66%of the population,were diagnosed with heterophoria in which 479 were diagnosed with exophoria at near distance,and 6 with esophoria.Totally 89(4.15%)children were diagnosed with heterophoria in which 82 had exophoria,and 7 had esophoria at far distance.Exophoria was common at near fixation(22.33%).Myopia was examined to be related to exophoria at near distance(OR 3.03,95%CI 2.33-3.95)and far distance fixation(OR 1.90,95%CI 1.09-3.32).CONCLUSION:Exophoria is a predominant heterophoria for 7 th-grade junior school in central China.Significant associations are discovered between heterophoria and refractive error.Hyperopia is associated with esophoria,and myopia is associated with exophoria.