2013

Ophthalmic Epidemiology, 2013; 20(4): 239–247! Informa Healthcare USA, Inc.

ISSN: 0928-6586 print / 1744-5086 online

DOI: 10.3109/09286586.2013.809771

ORIGINAL ARTICLE

Development and Evaluation of a Chinese Versionof the Adult Strabismus Questionnaire (AS-20)

Huanyun Yu1,*, Xinjun Yang2,*, Ting Ye1, Jie Chen1, Fang Zhang1, and Xinping Yu1

1Eye Hospital of Wenzhou Medical College and 2Department of Epidemiology,Wenzhou Medical College, Wenzhou, China

ABSTRACT

Purpose: The 20-item Adult Strabismus Quality of Life Questionnaire (AS-20) was developed in the UnitedStates to assess health-related quality of life (HRQOL) of adult patients with strabismus. At present,no questionnaire is available for assessing HRQOL specifically for adult patients with strabismus in China.A Chinese version of the AS-20 (CAS-20) was developed and its reliability and validity evaluated in adultpatients with strabismus in China.

Methods: The AS-20 was translated into Chinese. A total of 102 adults with strabismus and 102 visually healthyadult controls were recruited to answer the 5-level Likert items of the CAS-20. Demographic (age and sex) andclinical data of the recruited subjects were documented. Internal consistency, test-retest reliability, correlationsbetween items and their respective subscale, and construct validity were evaluated to assess questionnairereliability and validity.

Results: The number of responses for each item was calculated, as well as individual items’ correlation withtheir respective subscale. Cronbach’s a coefficient for the two subscales and the CAS-20 were satisfactory (0.846,0.819, 0.883, respectively). The intra-class correlation coefficient for test-retest reliability was 0.723–0.862.Patients with strabismus had significantly lower scores on the CAS-20 than controls. Factor analysis identifiedsix principal factors, and could be grouped into two subscales. The results supported the construct validityof the CAS-20.

Conclusion: The CAS-20 presented satisfactory reliability and validity in our study. It is suggested that thequestionnaire can be applied in clinical trials or research for Chinese patients with strabismus.

Keywords: Adult, chinese, quality of life, questionnaire, strabismus

INTRODUCTION

Strabismus is characterized by eye misalignment, andis one of the most common disorders of the visualsystem. The condition affects the health-related qual-ity of life (HRQOL) of adults and children to varyingdegrees.1–10 It has been increasingly recognized thatHRQOL evaluation is an important aspect of strabis-mus management.1,2,8–10 The HRQOL of patientswith strabismus can be assessed by using instrumentsthat are either generic or specific to strabismus.

However, there are very limited condition-specificquestionnaires for evaluating HRQOL in adults withstrabismus.1

The Amblyopia and Strabismus Questionnaire(A&SQ) is one of the established condition-specificquestionnaires with good reliability and validity,which was developed as a specific instrument foradult patients with amblyopia and strabismus.11–13

However, two of the final 26 items of the A&SQwere rated ‘‘not relevant’’ by 44% and 37% ofAmerican adults with strabismus.11 Furthermore, the

*Huanyun Yu and Xinjun Yang contributed equally to this study and should be regarded as first joint authors.

Correspondence: Xinping Yu, Eye Hospital of Wenzhou Medical College, 270# Xueyuan Xi Road, Wenzhou, 325027, China. Tel: +86 57788068831. Fax: +86 577 88824115. E-mail: yu-xinping@163.com

Received 17 May 2012; Revised 9 January 2013; Accepted 12 January 2013; Published online 11 July 2013

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A&SQ contains questions that are not univer-sally relevant in China, e.g. questions referring toparking cars and navigating through departmentstores.

A more recently described alternative question-naire is the Adult Strabismus-20 (AS-20), a patient-derived HRQOL questionnaire of 20 items that wasvalidated specifically for adults with strabismus.1

It can be used to assess HRQOL of individualstrabismus patients, and to analyze measured out-comes in clinical trials. It was reported that the AS-20is more sensitive than the 25-item Visual FunctionQuestionnaire (VFQ-25) of the National Eye Institute(NEI) in detecting HRQOL changes due to correctivesurgery in patients with strabismus.14,15 The AS-20excluded questions which may discriminate betweenindividuals based on differences in economic statusor cultural background.1 However, there is no suchspecific questionnaire in China for assessing HRQOLof patients with strabismus. Here we establish aChinese-language version of AS-20 (CAS-20), andpresent our findings in a series of adults withstrabismus.

METHODS

Translation and Development of theQuestionnaire

The original AS-20 with psychosocial and functionalsubscales is available free of charge throughthe website http://publicfiles.jaeb.org/pedig/Misc/AS-20%20Questionnaire.pdf (see Appendix 1). TheAS-20 was first translated into Chinese by two of theauthors (XPY, TY) and then discussed and modifiedby a panel which included ophthalmologists, statisti-cians, and adult patients with strabismus. When aconsensus was reached, a second draft was formedafter discussion with two foreign students (Chinese-American) who were familiar with both the Englishand Chinese languages. Back translation was com-pleted by an English teacher who was not famil-iar with the quality of life questionnaire, was notinvolved in the forward translation, and also wasblinded to the original questionnaire. The back-translated AS-20 was compared with the original

English version to identify any discrepancies, andthen revised by the panel (see Appendix 2).

Each of the 20 questionnaire items was scored(0, 25, 50, 75, or 100) according to a 5-point (always,often, sometimes, rarely, or never, respectively) Likert-type scale. For each patient, we calculated a meanoverall score (i.e. the mean of the 20 items), andalso mean scores for psychosocial and functionalsubscales (the mean of 10 items for each subscale).A score of zero indicated the least favorable and100 the most favorable HRQOL. The review panelconsidered that the items should be grouped andanalyzed in the same two subscales as those originallydescribed in the AS-20: the ‘‘psychosocial’’ scalefrom items 1–10 and the ‘‘functional’’ scale, fromitems 11–20.1

Subject Recruitment

The inclusion criteria in this study were as follows:aged �16 years with obvious strabismus and/ordiplopia for more than 1 month; and ability tounderstand and/or read Chinese. Patients unable toread or understand Chinese and patients with severecognitive impairment were excluded from the study.A total of 102 adults with strabismus, aged 16–63years, were recruited from the inpatient clinic atthe Eye Hospital of Wenzhou Medical College. Allpatients had had strabismus for �3 months. We asked21 of the 102 patients to answer the questions twice toevaluate test-retest reliability. The first questionnairewas taken when recruited to participate in the study,while the second questionnaire was obtained at thetime of hospital admission, during the first testing andre-testing time (10–14 days after recruitment), withoutany treatment for the strabismus. A control group of102 adults aged 17–58 years with no known visualdefects was also recruited. Of the 102 controls, 62 werecompanions or family members of the patients withstrabismus recruited into the study, and 40 werestudents of the college. Demographic and clinical dataon all subjects are summarized in Table 1.

The Medical Research Ethics Committee of theWenzhou Medical College Eye Hospital approvedthis study, and Institutional Review Board approvalwas granted. All procedures and data collection

TABLE 1. Main demographic and clinical characteristics of patients and controls, inpatient clinic, Eye Hospitalof Wenzhou Medical College, China.

Sex, nAge, years

Diplopia, n Strabismus type, n

Group Male Female mean� SD With Without Exotropia Esotropia Vertical

Strabismus 49 53 25.61� 8.23 13 89 59 29 14Re-tested 7 14 25.05� 4.00 2 19 12 8 1Control 58 44 32.46� 8.58 0 102 0 0 0

SD, standard deviation

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were performed according to the standards of theDeclaration of Helsinki.

Administration of the Questionnaire

The CAS-20 was administered to the 102 adultpatients with strabismus and the 102 normal controls.All participants answered the 20 5-level Likert itemsof the written questionnaire in the waiting room afterreceiving simple written and verbal instructions.

Statistical Analyses

Cronbach’s a coefficients were used to test the internalconsistency and reliability of the entire questionnaireand each subscale. Test-retest reliability was evalu-ated through intra-class correlation coefficient in 21patients by comparing scores of a second question-naire taken within 14 days (usually 10–14 days)with the first questionnaire. The item-internal con-sistency (the correlation between an item and itshypothesized subscale) were evaluated (Spearman’srank correlation). Item discrimination validity (thecorrelation between an item and other scales) andvarimax rotation factor analysis were used to estimateconstruct validity. The instrument’s discriminativevalidity was evaluated by comparing CAS-20 scoresof patients with strabismus with controls. Correlationbetween test score and the patient’s age was analyzedusing Spearman’s correlation analysis. All analyseswere performed using SPSS version 17.0 software(SPSS Inc, Chicago, IL, USA).

RESULTS

Most of the back translation, though different fromthe original, had a similar meaning. For example, theoriginal version of item 5 was ‘‘People don’t give meopportunities because of my eyes’’, while the backtranslation was ‘‘I lost some opportunities becauseof my eyes’’.

Table 1 shows the demographic (age and sex) andclinical (presence of diplopia and strabismus type)data of the patients with strabismus and controls.Five patients had previously undergone correctivesurgery but still presented with obvious deviationthat required further corrective surgery. For the29 patients with esodeviation, the median angle ofdeviation measured with prism and alternating covertest (PACT) at a distance was 50 prism diopters (PD;range 16–110). For the 59 patients with primaryexodeviation, the median PACT at distance was 54PD (range 14–160). For the 14 patients with verticaldeviation, the median PACT at distance was 27.5 PD(range 8–140). A total of 30 of the 102 patients had best

corrected visual acuity (BCVA) worse than 20/30in one eye because of strabismic (or mixed withanisometropic) amblypopia (22 eyes), congenital cata-ract (6 eyes), traumatic cataract (1 eye) or cornealleukoma (1 eye). Another 72 patients had BCVA betterthan 20/25 in both eyes. The 102 visually normaladults had no more than 10 PD of horizontal and 1 PDof vertical heterophoria measured with PACT. Forall normal subjects, stereoacuity was 60–80 secondsof arc using the TNO test, and BCVA was at least20/25 in each eye (median 20/20 in each eye).

The results of the survey showed that adultswith a primary education level could understandthe meaning of the items, and could successfullycomplete the questionnaire in 5–8 minutes, with orwithout the assistance of an investigator.

All respondents answered each of the items ofthe questionnaire. Figure 1 shows the distributionof responses to each 5-level Likert question, whichreflect the diversity of the patients’ experience of theircondition. The floor (responses as ‘‘always’’ – score 0)and ceiling effects (responses of ‘‘never’’ – score 100)on individual items, are also indicated in Figure 1.Several items resulted in 53.9–69.6% of responses atthe ceiling (most notably items 12, 13, and 16), whilefloor effects were minor.

Reliability

The acceptable minimum Cronbach’s a coefficientis 0.70, and �0.80 is considered good. Cronbach’s acoefficient was 40.8 for each subscale and for theCAS-20 as a whole (Table 2).

The intra-class correlation coefficient of the test-retest were 0.862 (95% confidence interval, CI,0.659–0.944) and 0.723 (95% CI 0.317–0.887) for thepsychosocial and functional subscales, respectively,

0

20

40

60

80 always often sometimesrarelynever

0

20

40

60

80 always often sometimesrarelynever

Patient responses to item 11-20

Patient responses to item 1-10

item 11

item 12

item 13

item 14

item 15

item 16

item 17

item 18

item 19

item 20

item 1

item 2

item 3

item 4

item 5

item 6

item 7

item 8

item 19

item 10

FIGURE 1. Distribution of strabismus patient responses toindividual items of the Chinese Adult Strabismus Quality ofLife Questionnaire (CAS-20); Items 1–10, psychosocial subscale,items 11–20, functional subscale (see Appendix 1for itemdetails).

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and 0.811 (95% CI 0.535–0.923) for the overall scale,indicating that test-retest reliability was good(p50.001 for all; Table 2).

Validity

The varimax rotation factor analysis of the CAS-20identified six principal factors (Eigen-values over 1),shown in Table 3. The six factors could be regroupedinto two factors, while all of the 20 items could beloaded on the two originally described subscales:psychosocial (item 1–10) and functional (item 11–20).The item-internal consistency and item-discriminationvalidity of the CAS-20 are displayed in Table 4.All of the item-internal consistencies were above0.5 and all item-discrimination validities, except foritem 17, were below 0.50.

TABLE 3. The varimax rotated component matrix of the Chinese Adult Strabismus Quality of Life Questionnaire (CAS-20).

ComponentFactor structures of

Item 1 2 3 4 5 6 CAS-20

Rotation sums of squaredloadings, % of variance

17.374 13.751 12.976 10.697 8.433 6.069

Total eigenvalues 6.480 2.484 1.574 1.193 1.102 1.028item1 0.795 �0.110 �0.028 0.172 0.228 0.248 1item2 0.717 0.005 0.293 0.227 0.063 �0.021 1item3 0.804 0.208 0.128 0.207 0.149 �0.067 1item4 0.717 0.227 0.190 0.102 �0.196 0.032 1item5 0.102 �0.089 0.751 0.293 0.047 0.133 1item6 0.677 �0.108 0.065 0.543 0.097 0.053 1item7 0.313 0.207 0.540 0.027 0.130 �0.582 1item8 0.337 0.223 0.321 0.002 0.000 0.700 1item9 0.375 0.130 0.657 �0.180 0.148 0.052 1item10 0.283 0.145 0.552 0.316 �0.242 0.149 1item11 0.300 0.119 �0.115 0.040 0.720 �0.147 2item12 0.072 0.755 0.211 0.015 0.207 0.098 2item13 �0.084 0.553 0.573 0.175 0.109 �0.072 2item14 �0.094 0.358 0.184 0.104 0.632 0.003 2item15 0.044 0.232 0.238 0.258 0.606 0.418 2item16 0.117 0.865 0.060 0.080 0.017 0.028 2item17 0.445 0.134 0.421 0.515 0.148 0.239 2item18 0.304 0.159 0.047 0.729 0.068 �0.051 2item19 0.016 0.368 0.304 0.619 0.162 0.013 2item20 0.110 0.756 �0.067 0.174 0.263 0.016 2

Structure of the CAS-20 is Factor 1: psychosocial; Factor 2: functional. Six principal factors could be identified and thefactors could be regrouped into two subscales, psychosocial (items 1–10) and functional (items 11–20). For item details seeAppendix 1.

TABLE 4. Item-internal consistency and item-discrimination validity of the Chinese AdultStrabismus Quality of Life Questionnaire(CAS-20).

ItemaPsychosocial

subscalebFunctionalsubscaleb

1 0.664 0.2912 0.756 0.3703 0.784 0.4784 0.710 0.3175 0.592 0.3236 0.658 0.4027 0.514 0.3688 0.567 0.3639 0.602 0.355

10 0.640 0.34311 0.216 0.50812 0.296 0.65513 0.328 0.60414 0.170 0.60015 0.332 0.67816 0.272 0.62817 0.732 0.63918 0.478 0.55219 0.419 0.69420 0.218 0.695

aItems 1–10 belong to the psychosocial subscaleand items 11–20 belong to the functionalsubscale. All 20 items had item-internal con-sistencies 40.5. All but item 17 had item-discrimination 50.50. For item details, seeAppendix 1.bStatistical analyses: Spearman rank correlation

TABLE 2. Tests for reliability of the Chinese Adult StrabismusQuality of Life Questionnaire (CAS-20).

Scale Items

Cronbach’s a forinternal consistency

(N = 102)

Test-retestreliability

(n = 21)

Psychosocial 10 0.846 0.862Functional 10 0.819 0.723Total 20 0.883 0.811

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As shown in Table 5, median scores were signifi-cantly lower for patients with strabismus than forcontrols in both subscales and the overall scale.Among the 72 patients with normal visual acuity,the overall scale scores and both subscales weresignificantly lower than for the controls (p50.0001).

Patient Factors and CAS-20 QuestionnaireResponses

No significant differences in scores were foundbetween the sexes, or between normal and impairedvisual acuity for either of the two subscales or theCAS-20 as a whole (Table 6). Patients with diplopiahad lower scores on the function subscale thanpatients without diplopia (p = 0.024; Table 6). Nosignificant correlation was found between scoresand age (two-tailed Spearman correlation coefficient�0.033; p = 0.74).

DISCUSSION

CAS-20 contains 20 items in two subscales (psycho-social and functional) and was developed specificallyfor Chinese adult patients with strabismus. We foundthat patients with strabismus, with or without diplo-pia, scored lower (i.e. experienced worse HRQOL)on the CAS-20 than did visually normal subjects.The data presented in this study indicates that the

CAS-20 has good psychometric properties thatinclude acceptable levels of floor and ceiling effects,good convergence validity, internal consistency, andtest-retest reliability.

HRQOL may be assessed using either generic orcondition-specific instruments. However, within thefield of ophthalmology, there are concerns that genericmeasures of HRQOL lack the required sensitivity torecognize symptoms of vision loss, or the emotionalaspects of a specific ophthalmic condition such asstrabismus.16 Other Chinese versions of conditioninstruments have been developed and used to assessHRQOL within ophthalmology. For example, theVisual Function and Quality of Life questionnairedeveloped by the NEI and World Health Organizationfor developing countries, is used to describe theimpact of cataract on HRQOL within a given popu-lation, and as a measure to determine the suitability orsuccess rate of cataract surgery.17,18 The NEI-VFQ25(Chinese version) has been administered as a proxymeasure to parents whose children have undergonestrabismus surgery.19 However, the use of patient-reported outcome measures within the specific fieldof strabismus is still not established well in China.Therefore, a Chinese version of a strabismus ques-tionnaire, targeted to Chinese patients, is urgentlyneeded.

In the present study we chose the AS-20 as atemplate for our questionnaire because this versiondoes not include questions that may have discrimi-nated against individuals with varying economicstatus or cultural background.1 For example, drivingquestions and questions related to ‘‘work’’ were notincluded in the final version of the original AS-20.1

Driving experience is not so common to adultsin most developing countries including China, whilereading books, computers or mobiles are universal.

We chose to adapt the AS-20, although there areother condition-specific instruments available, such asthe A&SQ. However, the A&SQ contains questions thatare not universally applicable to Chinese people (e.g.question 8: ‘‘I have difficulty parking my car’’, ques-tion 14: ‘‘I have difficulties finding my way in ashopping mall’’, question 15: ‘‘I have difficulties find-ing my way in a department store’’, and question 16:‘‘I have difficulties finding my way in a train station’’).

TABLE 6. Comparisons of mean scores of the Chinese Adult Strabismus Quality of Life Questionnaire (CAS-20) in 102 patients withstrabismus, by sex, visual acuity, and with or without diplopia.

ScaleMale, meanscore (SD)

Female, meanscore (SD) pa

Normal VA,mean score (SD)

Impaired VA,mean score (SD) pb

With diplopia,mean score (SD)

Without diplopia,mean score (SD) pc

Psychosocial 53.83 (15.87) 59.29 (18.38) 0.112 56.2 (16.4) 57.8 (17.7) 0.66 57.50 (19.44) 56.54 (17.14) 0.869Functional 65.88 (18.49) 71.65 (15.59) 0.090 69.5 (16.2) 67.2 (19.7) 0.52 58.84 (19.46) 70.34 (16.47) 0.024Total 59.85 (14.85) 65.47 (15.24) 0.062 62.9 (14.3) 62.5 (17.7) 0.91 58.17 (16.70) 63.44 (15.01) 0.247

aComparing male with female.bComparing patients with normal and impaired visual acuity (VA).cComparing patients with and without diplopia.

TABLE 5. Comparison of Chinese Adult Strabismus Quality ofLife Questionnaire (CAS-20) scores in patients with normalcontrols (Wilcoxon rank sum test).

Scale

Patients withstrabismus, mean

score (range)(N = 102)

Normalcontrols, meanscore (range)

(N = 102) pa

Psychosocial 55 (17–95) 100 (70–100) 50.001Functional 72 (20–97) 100 (52–100) 50.001Total 64 (25�92) 100 (61–100) 50.001

aMedian scores of the overall scale, and psychosocial andfunctional subscales were lower in patients than those incontrols.

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Furthermore, the A&SQ evaluates the HRQOL impactof both strabismus and amblyopia. Therefore, if adecreased HRQOL was found through use of theA&SQ, it may be uncertain whether the impact wasattributable to amblyopia, strabismus, or both. It wasthus reasonable to apply the AS-20 to investigate theimpact of only strabismus on HRQOL.16

The patients recruited in our study differed indiagnosis from the patient population on which theAS-20’s development and validation was based. Bothin the development and testing phases of the AS-20,62% and 69% of patients, respectively, had diplopia,and more than half were diagnosed with incomitantforms such as cranial nerve palsy and Graves eyedisease. In our study, most patients were diagnosedwith concomitant deviation and early age onset ofdeviation with absence of diplopia. In China, mostpatients who undergo corrective surgery for strabis-mus are concomitant. For example, in a 4-yearretrospective study of 8997 strabismus surgeriesperformed at an eye medical center in Beijing from2003 to 2006, 7110 (79%) were concomitant strabismussurgeries.20 The median score of patients was 64(range: 25–92), which was slightly higher than thatof the study by Hatt (56; range: 21–96).1 Our studyfurther confirmed that the CAS-20 can be usedto assess HRQOL of adults with strabismus, evenwithout diplopia.

We compared CAS-20 scores for strabismuspatients with scores for visually normal adults. Thequestionnaire showed good discriminative validitywith significantly lower overall and psychosocialand functional scores (indicating worse HRQOL) forstrabismus patients with or without diplopia, withnormal or impaired visual acuity. We recruited thenormal controls from companions or family membersof the strabismus patients enrolled in the study; thus,it is likely that differences in economic, education, andother living circumstances between the two groupswere minor.

Six principal factors extracted from factor analysiscould be identified into two subscales, and every itemascribed into a single subscale. Factors 1, 3 and 6,when combined, are the same as the psychosocialsubscale. Factors 2, 4 and 5, when combined, arethe same as the functional subscale. The results of thefactor analysis show that CAS-20 has good constructvalidity. Recently, the AS-20 was evaluated usingRasch analysis. Four subscales, which were labeled as‘‘self-perception’’, ‘‘interaction with others’’, ‘‘readingfunction’’ and ‘‘general function’’ were confirmed.21

The AS-20 could benefit by reduction to foursubscales and removing two questions.21 Our studyidentified six factors: Factors 1 and 2 are the same astwo of the Rasch subscales (self-perception andreading function); factors 3 and 6, when combined,are the same as the ‘‘interaction with others’’ subscale;and when factors 4 and 5 are combined, they

correspond to the ‘‘general function’’ subscale plusthe two questions eliminated in the Rasch-analysis.21

CAS-20 should be analyzed using Rasch-based meth-ods in future.

Just as in the study by Hatt,1 there was a ceilingeffect for visually normal adults, of whom a largeproportion had the maximum score of 100 on thepsychosocial and functional subscales. Such ceilingeffects may lead to reduced sensitivity when compar-ing strabismus patients to people with normal vision.1

However, it may not be a true limitation sinceall condition-specific instruments have ceilings fornormals.

In this study, the function scores of patients withdiplopia were significantly lower than the functionscores of patients without diplopia. We also foundthat some patients with diplopia had a greater level ofpsychosocial concerns. For example, 61% of patientswith diplopia rated question 3 (‘‘I feel uncomfortablewhen people are looking at me because of my eyes’’)‘‘always’’ or ‘‘often’’. Our results indicate that somepatients with diplopia also have a high level ofpsychosocial concerns, which further confirmed thespeculation by Hatt1 that the presence of diplopia maycause a patient to feel self-conscious of eye misalign-ment even when the strabismus is not particularlynoticeable.

There are potential weaknesses in this study.First, there were fewer patients with diplopia in ourstudy than there were in the study by Hatt on thedevelopment of AS-20.1 Nevertheless, the duration ofstrabismus in all patients in our study was more than3 months, and the effect of strabismus on their lifecould be evaluated reliably. Another potential weak-ness is that most of the patients in our study were20–50 years old, and there were few who were older.Thus the validity of CAS-20 to assess HRQOL inolder patients should be confirmed in more cases.In planned future studies, we will assess the reliabilityof the CAS-20 in older patients and compare theirHRQOL to younger people, before and after correctivesurgery.

In summary, our study suggests that the CAS-20is a useful instrument for assessing the impact ofstrabismus on HRQOL of adult Chinese patients.

DECLARATION OF INTEREST

The authors report no conflicts of interest. The authorsare responsible for the content and writing of thepaper.

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21. Leske DA, Hatt SR, Liebermann L, et al. Evaluationof the adult strabismus-20 (AS-20) questionnaireusing Rasch analysis. Invest Ophthalmol Vis Sci 2012;53:2630–2639.

APPENDIX 1

Attachment 1: Adult Strabismus Quality of Life Questionnaire (AS-20)

Psychosocial Aspect(1) I worry about what people will think about my eyes

Never Rarely Sometimes Often Always(2) I feel that people are thinking about my eyes even when they don’t say anything

Never Rarely Sometimes Often Always(3) I feel uncomfortable when people are looking at me because of my eyes

Never Rarely Sometimes Often Always(4) I wonder what people are thinking when they are looking at me because of my eyes

Never Rarely Sometimes Often Always(5) People don’t give me opportunities because of my eyes

Never Rarely Sometimes Often Always(6) I am self conscious about my eyes

Never Rarely Sometimes Often Always(7) People avoid looking at me because of my eyes

Never Rarely Sometimes Often Always(8) I feel inferior to others because of my eyes

Never Rarely Sometimes Often Always(9) People react differently to me because of my eyes

Never Rarely Sometimes Often Always(10) I find it hard to initiate contact with people I don’t know because of my eyes

Never Rarely Sometimes Often Always

Chinese Adult Strabismus Questionnaire 245

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Functional Aspect(11) I cover or close one eye to see things better

Never Rarely Sometimes Often Always(12) I avoid reading because of my eyes

Never Rarely Sometimes Often Always(13) I stop doing things because my eyes make it difficult to concentrate

Never Rarely Sometimes Often Always(14) I have problems with depth perception

Never Rarely Sometimes Often Always(15) My eyes feel strained

Never Rarely Sometimes Often Always(16) I have problems reading because of my eye condition

Never Rarely Sometimes Often Always(17) I feel stressed because of my eyes

Never Rarely Sometimes Often Always(18) I worry about my eyes

Never Rarely Sometimes Often Always(19) I can’t enjoy my hobbies because of my eyes

Never Rarely Sometimes Often Always(20) I need to take frequent breaks when reading because of my eyes

Never Rarely Sometimes Often Always

APPENDIX 2

246 H. Yu et al.

Ophthalmic Epidemiology

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