Quality of life in adult intermittent exotropia and the risk factors

Bo-Wen Zhao, Jing Fu, Jing-Hui Wang, Hai-Xia Bai, Pei-Pei Liu, Ya-Nan Guo, Rong-Han Zhang, Han Su

1Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing 100730, China

2Eye Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, Zhejiang Province, China

Abstract

INTRODUCTION

Intermittent exotropia (IXT) is a kind of strabismus in which the eye position either tends to outside or to the positive position. IXT is a common condition that affects patients of all ages[1]. The prevalence of IXT is high, about 1%-5% in the population, and it ranks the first among exotropia of all ages in China[2]. It not only affects the appearance of patients, but also leads to the impairment of binocular vision function and eye movement abnormality[3], which causes different degrees of psychosocial problems and affects the quality of life of patients. The influence of strabismus on quality of life has generally been informal in clinical assessment and is mostly focused in children[4-5]. Adults with strabismus have also been reported to suffer from low self-esteem and have problems with inter-personal relationships, especially social anxiety. There were also reports pointing that strabismus affected the quality of life of Chinese Han teenagers[6]. The strabismus surgery can effectively improve the life quality of children with IXT and their parents after surgical treatment[7].

Although IXT is always found in children, IXT may finally progress to constant exotropia and has a serious influence on quality of life in adults[8]. The Chinese version of the adult strabismus quality of life assessment scale (CAS-20) was translated and improved on the basis of the CAS-20 version of AS-20, which has good reliability and validity[9-11]. This study used the CAS-20 to evaluate the impact of IXT on the quality of life of adult patients in comparison with normal subjects and other strabismus patients (except IXT), to explore the factors affecting the quality of life of patients with IXT, so as to provide a basis for the clinical diagnosis and treatment of IXT.

SUBJECTS AND METHODS

Ethical ApprovalIn accordance with the Helsinki Declaration, all participants were informed before the study and signed the informed consent. The study protocol was approved by the Ethics Committee of Beijing Tongren Hospital.

PopulationsFrom July 2018 to June 2019, 77 adult patients with IXT from Beijing Tongren Hospital were enrolled as the disease group; 115 patients with other type of strabismus (except IXT) were enrolled as strabismus control group; additional 109 subjects with normal eyes were enrolled as the normal control group.

Inclusion criteria include: definite diagnosis by specialist examination as strabismus or IXT as previously described[12]; age above 18 years old; comprehensible and complete questionnaire survey. Exclusion criteria include: combined with obvious facial scars and defects; combined with other eye appearance abnormalities (such as blepharoptosis, thyroidrelated ophthalmopathy, orbital deformity, etc.) and other eye or body diseases; reading and cognitive impairment; unable to understand and complete the questionnaire after explanation.

CAS-20 QuestionnaireCAS-20 questionnaire includes two dimensions of social psychology and visual function. Each dimension contains 10 items. Each item has five levels of response. The grades are divided into never, rarely, sometimes, often and always, which correspond to 100, 75, 50, 25 and 0 points, respectively. The average score is obtained in statistics, and the scores of social psychology dimension and vision function dimension are obtained. The higher the score of functional dimensions, the better the quality of life.

All questionnaires were conducted by the same researcher. The subjects completed the quality of life questionnaire. If the subjects did not understand individual items, they could be explained by the researcher. After the completion of the questionnaire, the researcher checked its completeness.

General InformationAll participants completed individual information collection, including age, gender, family history of strabismus, occupation, marital status, diplopia and strabismus course. Compound tropicamide is used for mydriatic optometry in patients between 18 and 40 years old and no dilation optometry is used in patients above 40 years old to check best corrected visual acuity (BCVA). Anterior segment and fundus were routinely checked to exclude other eye diseases besides strabismus and amblyopia. Stereoscopic stereogram was used to examine near stereopsis (normal: less than or equal to 60 arc seconds). Far stereopsis was detected by synoptophore. Horizontal and vertical strabismus degree was measured with prism + alternating occlusion or prism + corneal reflection.

Statistical AnalysisAll data were input and checked by Excel table and analyzed by SPSS 16.0 software. Chi-square test and Kruskal-Wallis test were used to analyze the differences of general characteristics, visual function and scores between normal control group, IXT group and other types of strabismus control group; independent sample t-test was used to analyze the difference of course of disease between two strabismus groups; Wilcoxon test was used to analyze strabismus degree between two strabismus groups and to analyze the influence of individual factors on the quality of life of patients with IXT (Kruskal-Wallis test was used to analyze the influence of age on the quality of life of patients with strabismus). P＜0.05 was taken as statistical significance, when pairwise comparison variables in multiple samples. The test level was corrected to 0.017, that is, when P＜0.017, the difference between the two groups was considered to be significant.

RESULTS

General InformationAs indicated in Table 1, no significant difference was observed among groups regarding the age and gender.

Outcomes of Social DataAs shown in Table 1, there was no significant difference in the composition of marital status (χ2=3.725, P=0.155). Among strabismus patients, the proportion of patients with family history in IXT group was higher than that of strabismus control group (χ2=5.901, P=0.015). There were significant differences in occupational composition among the three groups (χ2=8.064, P=0.018). Further comparisons showed that the employed in strabismus control group was significantly lower than that in the normal control group (χ2=7.706, P=0.005). There was no significant difference between IXT group and normal control group, IXT group and strabismus control group (χ2=0.865, P=0.352; χ2= 2.488, P=0.115).

Visual Function DataThe proportion of patients with amblyopia in IXT group was significantly lower than that in strabismus control group (χ2=22.973, P＜0.001); the proportion of patients with diplopia in IXT group was not significantly different from that in strabismus control group (χ2=1.156, P=0.282). The proportion of patients with vertical strabismus in IXT group was not significantly different from that in strabismus control group (χ2=0.354, P=0.551; Table 1). The proportion of people with normal near stereopsis was different among the three groups (χ2=180.275, P＜0.001). The results of pairwise comparison showed that the proportion of normal near stereopsis in the IXT group and strabismus control group was lower than that in the normal control group (χ2=37.153, P＜0.001; χ2=165.982, P＜0.001; Table 1). the proportion of normal near stereopsis in the IXT group was higher than that in the strabismus control group (P＜0.001).

Table 1 General and clinical information of the participants in three groups

The proportion of people with normal far stereopsis was different among the three groups (P＜0.001). The results of pairwise comparison showed that the proportion of patients with normal far stereopsis in IXT group and strabismus control group was lower than that in normal control group (P＜0.001). There was no significant difference between IXT and other types of strabismus (P=0.186; Table 1).

There were significant differences in the overall comparison of BCVA among the three groups (Hright=39.315, P＜0.001; Hleft=24.045, P＜0.001). BCVA of the IXT group and strabismus control group was lower than that of the normal control group (P＜0.01), and the BCVA of the IXT group was higher than that of strabismus control group (P＜0.001). The median level of strabismus degree in IXT group was higher than that in strabismus control group (Zright=8.401, P=0.003; Zleft=5.342, P=0.02; Table 1).

Quality of Life in Patients with Intermittent ExotropiaThe scores of social psychology in the three groups were significantly different (Z=187.886, P＜0.001; Table 1). The median psychosocial score of IXT group was 475.00 (375.00, 600.00), lower than that of normal control group [950.00 (900.00, 975.00)] (Z=-11.098, P＜0.001); the median psychosocial score of strabismus control group was 500.00 (325.00, 650.00), also lower than that of normal control group (Z=12.306, P＜0.001). However, there was no significant difference between IXT and strabismus control groups (Z= -0.111, P=0.911).

The scores of visual functions in the three groups were significantly different (Z=178.071, P＜0.001). The median visual function score of IXT group was 525.00 (400.00, 650.00), lower than that of normal control group [900.00 (875.00, 975.00)] (Z=-10.909, P＜0.001); the median visual function score of strabismus control group was 575.00 (450.00, 725.00), also lower than that of normal control group (Z=11.785, P＜0.001). However, there was no significant difference between IXT and strabismus control groups.

Influencing Factors of Quality of Life in Patients with Intermittent ExotropiaAs shown in Table 2, there was no significant difference in psychosocial scores between the practitioners and the unemployed (including students/unemployment/retirement; Z=1.168, P=0.243), but the visual function scores of the practitioners were lower than those of the unemployed (Z=2.559, P=0.009). The visual function scores were higher in those with normal near stereopsis (Z= -2.072, P=0.038) and with normal far stereopsis (Z=3.027, P=0.003). The psychosocial scores of strabismus patients with a course of more than five years were lower than those with a course of less than five years (Z=7.037, P=0.008). Sex, age, marital status, vertical strabismus, diplopia, amblyopia, and family history had no significant effect on the psychosocial scores and visual function scores of patients with IXT.

DISCUSSION

Our present study demonstrated that IXT patients had a higher family history, lower rates of amblyopia compared with other types of strabismus. BCVA of IXT group was better than that of strabismus control group.

Satterfield[13]found that the main psychosocial problems of strabismus patients included impaired self-esteem and selfconfidence, sensitive interpersonal relationships, fewer job opportunities, and inactive exercise. This study found that there was no significant difference in occupational composition between the IXT group and the normal control group, while the proportion of employees in other strabismus control group was lower than that in the normal control group. There are two possible reasons. First, other strabismus affects the appearance of patients, thus affecting employment[14]. Second, since patients do not have normal binocular vision function (stereopsis), many jobs are limited, and the employment rate is low. IXT patients might have normal eye position, and nearstereopsis function is relatively good. Thus, the employment situation is better than other strabismus patients.

Table 2 Influencing factors of quality of life in patients with intermittent exotropia

The BCVA of the two strabismus groups were lower than that of the normal control group. The BCVA of strabismus control group was lower than that of the IXT group, and the proportion of amblyopia was higher than that of the IXT group. On the one hand, strabismic amblyopia was not easy to be caused in the patients with IXT. On the other hand, other type strabismus patients including disused strabismus and strabismic amblyopia own poor vision, resulting in the lower BCVA[15].

This study found that the proportion of people with near and far stereopsis in IXT group and strabismus control group was lower than that in normal control group. The proportion of people with near and far stereopsis in strabismus control group was lower than that in IXT group. IXT is characterized by damage of far stereopsis, similar to other types of strabismus[16-17]. The proportion of patients with family history in IXT group is higher than that in other types of strabismus control group. At present, the reasons have not been reported. Therefore, we should pay more attention to related genetic research in future research[18-19].

Hatt et al[20-21]showed that the social psychological health of strabismus patients was lower than that of normal people, and the quality of life was reduced accordingly, especially in adult strabismus patients who had participated in social activities. In this study, the quality of life of adult strabismus patients was assessed by CAS-20 scale. It was found that the psychosocial score and visual function score of IXT group and strabismus control group were lower than those of the normal control group, which was consistent with the results of Hatt et al[20-21].Other studies have found that strabismus has a certain relationship with gender, among which female patients are more easily affected[20,22], especially in the workplace[23-24]. With the increase of age, the influence of strabismus on patients’ social psychology is more obvious[25]. In addition, race, region, economic status and other factors also have a significant impact on the quality of life of strabismus patients[26]. However, the effects of deviation types such as esotropia and exotropia on the quality of life of patients are still unclear[27-28]. Our results showed that gender, age and marital status had no significant effect on the quality of life of patients with IXT.

Strabismus not only causing the damage of patients’ visual function, but also influencing the appearance. At present, all clinical examinations (vision, binocular vision, eye position) can only reflect the damage of patients’ visual function, but not the psychological problems. The results of this study show that there is no significant difference in psychosocial scores between the employed and the unemployed in patients with IXT, but the visual function score of the employed is lower than that of the unemployed, presumably because the employed have higher requirements for visual function and more stringent evaluation of self-stereopsis. The visual function scorse of IXT patients with normal near/far stereopsis is higher than that of patients without normal near/far stereopsis. These indicators show that patients’ perception of their visual function is relatively consistent with the results of objective examination.

The purpose of this study is to study the quality of life of Chinese patients with IXT. In this study, we analyzed the quality of life of patients with IXT compared with that of normal people and other type strabismus people and provided potential implications whether surgery can improve the quality of life. In addition, the doctors and society should pay more attention to the quality of life of patients with IXT.

There are still some limitations in this study. The age of the subjects was concentrated between 20 to 40. Therefore, the research results mainly reflected the quality of life of young people. The data of middle-aged and old people were required to collected in the future to evaluate the quality of life of all adult patients with IXT.

In conclusion, the quality of life of adult patients with IXT in China was significantly decreased. Stereopsis, course of disease and occupation status were the main factors affecting the quality of life of IXT patients, which could provide some basis for clinical diagnosis and treatment of IXT.

ACKNOWLEDGEMENTS

Foundations:Supported by the Beijing Talent Youth Training Program and Beijing Municipal Administration of Hospitals Incubating Program (No.PX2017045); Beijing Municipal Science & Technology Commission (No.Z171100001017066); Beijing Municipal Science & Technology Commission (No.Z201100005520044).

Conflicts of Interest:Zhao BW,None;Fu J,None;Wang JH,None;Bai HX,None;Liu PP,None;Guo YN,None;Zhang RH,None;Su H,None.