Background/Aim Long-term assessments of the impact of strabismus surgery in adults are rare and very limited in focus. Consequently, this study was designed to consider the psychosocial status of adults a minimum of 1 year after surgery.
Methods A repeated measures design, 25 participants were seen at 6-week pre-operative (T1), 3-month (T2) and 18-month (T3) post-operative appointments. Participants completed a battery of psychological scales comprising: Hospital Anxiety and Depression scale, the World Health Organisation Quality of Life assessment (short form), the Derriford Appearance Scale, and visual analogue scales to measure the impact of strabismus and its treatment on psychological adjustment and daily functioning.
Results At T2, all scores on all study measures had significantly improved. At T3, some study measures were showing continued improvement: World Health Organisation Quality of Life Assessment - short form (WHOQoL-Bref) social and environment domains; DAS-24; VAS scales for coping, postoperative satisfaction, strabismus noticeability and strabismus severity. A one-way Analysis of Variance (ANOVA) showed significant effects across time for DAS-24 and all VAS scales. Post hoc tests indicated that significant changes occurred between T1 and T2 and between T1 and T3.
Conclusions This study suggests that adjustment is a long-term process with improvements on some study measures being greater at 18 months than at 3 months postoperatively raising the possibility that some psychosocial goals are more appropriately measured in the longer term.
- Treatment Surgery
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Research assessing the impact of surgery on the psychosocial functioning of adults with strabismus has mostly focused on benefits identified at short-term (3-month) follow-up.1–3 In Menon et al's1 study, 95% of the participants reported positive postoperative changes in the areas of appearance, relationships with friends, self-confidence and self-esteem, as well as being willing to try activities that they had previously avoided. Burke et al2 reported that women with strabismus viewed corrective surgery as having a more profound positive effect than did men, and individuals with an esotropia had significantly greater appreciation of the effects of surgery than did those with an exotropia. Jackson et al3 reported that while strabismus surgery resulted in significant improvements in psychosocial adjustment, individuals with diplopia had poorer psychosocial adjustment than those without.
Longer term assessments of the psychosocial impact of strabismus surgery in adults are rare and limited in focus.4 ,5 Satterfield et al4 reported a retrospective study of 39 adults (average age 41 years) assessing the psychosocial implications of growing up and living with a socially noticeable strabismus. To be included in the study, participants had to have an uncorrected or incompletely corrected eye misalignment of more than 15 prism dioptres (PD). For the majority of participants (85%) while surgery had been traumatic, it had also had positive effects on their lives, although no specific examples were provided.
In contrast, Hertle5 suggested that clinical success should not merely focus on postoperative ocular alignment. Instead he proposed a three part definition; sensory, motor and subjective success. Sensory and motor success related to aspects of visual functioning, while subjective success comprised the patient's interpretation of the improvement in their eyes as a result of the surgery. Unfortunately, the measure of subjective success was limited to recording whether the patient was ‘happy’ or ‘unhappy’ with various aspects of their visual functioning.
These studies have a number of methodological weaknesses. For example, in the Satterfield et al4 study, seven participants had received no surgical treatment for their strabismus; and the time since surgical intervention is not stated but has to be inferred as being greater than 6 months. Hertle's5 study included data from teenage participants, and the reader must assume that the reported data on surgical outcomes relates to the final postoperative assessment.
There seems to be a strong suggestion that longer term surgical outcomes are positive in terms of function, but only very limited suggestions as to what that means for patients in terms of other (psychosocial) benefits. Consequently this study was designed to consider the psychosocial status of adults a minimum of 1 year after strabismus surgery.
Validated questionnaires employed in a previous study reported by Jackson et al3 were used in this follow-up study. These comprised the Derriford Appearance Scale (DAS-24), a measure of social anxiety and social avoidance (the higher the score on the DAS-24 the more the person is experiencing social anxiety and is using social avoidance as a coping strategy);6 the Hospital Anxiety and Depression Scale, comprising two subscales measuring anxiety and depression and where higher scores indicate greater distress7; and the World Health Organisation Quality of Life Assessment - short form (WHOQoL-Bref), measuring four quality of life domains: physical, psychological, social and environmental, where higher scores indicate greater satisfaction with quality of life.8
Visual analogue scales (VAS) were also included (see appendix 1 a web only file for details of wording and scoring). Scored on a scale from 0 to 10, these allowed participants to rate a variety of factors related to daily functioning (eg, coping and impact of the strabismus on lifestyle) and psychological adjustment (ie, postoperative satisfaction, the noticeability and severity of the strabismus and its impact on levels of worry).
An objective measure of eye misalignment, the 1/3 m measurement obtained on the prism cover test (PCT) was recorded preoperatively and postoperatively. This was chosen because of the two measures routinely taken (the other being 6 m) it is closest to the standard measure of distance for communication in Western culture (ie, within 45 cm for communication with intimate friends and family members, and between 50 cm and 1.2 m for other normal conversations).9
A repeated measures design was employed with data collected from participants at three time points (T1=preoperative, T2=3 months postoperative, T3=between 1 year and 3 years after surgery. The modal point of 18 months is used as the descriptor for the long-term, T3, data point). Quantitative measures (in the form of standardised questionnaires and VAS scales) and a qualitative element (a structured interview) were used. Data from the qualitative element are not reported in this paper. A control group was not used as adjustment to visible difference and changes to appearance comprises a whole myriad of factors that cannot adequately be matched in treatment and control groups.10
Participants who had already been seen twice as part of the previously reported study at the Bristol Eye Hospital and Swindon's Great Western Hospital at 6-week preoperative assessment (T1) and 3-month postoperative outpatients appointment (T2) between May 2003 and May 2005, and who had undergone surgery a minimum of 1 year previously were invited to take part.3 All potential participants were sent an invitation letter, a patient information sheet and consent form. Prior to contact, and with approval from the relevant Local Research Ethics Committees and the University of the West of England, Bristol, the notes for the patient population were reviewed to check current treatment status and to ascertain what treatment, if any, participants had received since their operation as part of the previous study.
Twenty-five (54%) of 46 patients invited to take part agreed to participate. Demographic information on this study cohort is shown in table 1. Two invitation mailings were undertaken. In all 17 patients did not respond to either mailing (an attrition rate of 37%). Four of the participants completed questionnaires but declined to be interviewed.
Where reference is made to statistical analyses being undertaken they were conducted using SPSS V.19.0.
Exploring selection bias
Independent sample t tests were undertaken to examine group differences for all study variables between those who took part in the follow-on study (n=25) and those who chose not to participate (n=21). Preoperatively (T1) those who took part reported significantly less social anxiety and social avoidance (DAS-24, t=2.419, df=44, p<0.02), better quality of life (WHOQoL-Bref physical domain, t=−2.108, df=44, p<0.04) and psychological domain (t=−2.264, df=44, p<0.03) than those who did not take part. They also reported a greater degree of coping, more social support and less impact of the more negative aspects of having a strabismus, as measured by the VAS scales.
Data comparisons for 3 months postoperatively (T2) again showed better psychosocial adjustment for those who chose to take part in the follow-on study; specifically, significantly better physical quality of life (WHOQoL-Bref, t=−2.848, df=44, p<0.007) and significantly lower levels of depression (Hospital Anxiety and Depression Scale, t=2.265, df=44, p<0.028). Additionally those taking part in the longer term follow-up had a smaller measured eye misalignment at T2 (7.56 PD) compared with those not taking part (9.67 PD). Descriptive statistics for both groups at T1 and T2 are shown in table 2.
The n=25 sample at the three data collection points
Means and SDs were calculated for those individuals (n=25) who took part in the follow-on study across all data collection time points for all measures (see table 3). At T2, scores on all study variables had improved. At T3, while none of the study variables had returned to their preoperative levels, scores on some of the variables had started to reduce. A one-way Analysis of Variance (ANOVA), with time as a three level factor (T1, T2 and T3), was carried out to determine which of the observed changes in the data were significant. Significant effects were recorded for only one of the standardised questionnaires (DAS-24), while all VAS scales recorded significant effects across time.
Tukey's post hoc tests indicated that significant changes occurred between T1 and T2, and between T1 and T3 (see table 4). The changes observed on study variables between T2 and T3 may be indicative of general trends, but at non-significant levels.
Strabismus characteristics and psychosocial factors
It was not possible to explore the influence of diplopia on the psychosocial factors as only eight of the 25 participants experienced preoperative diplopia. Similarly, further investigation of the direction of eye misalignment was not possible as only seven study participants had an esotropia. Pearson's correlation calculations carried out between the objective measure of eye misalignment (PCT score) and the psychological measures employed in this study for the follow-up cohort (n=25) showed only one significant result. This was at T1, where smaller measures of eye misalignment (PCT results) were significantly correlated with participants’ increased ratings of worry in relation to the strabismus (VAS C5 worry; r=−0.467, p<0.019). This could be related to fear that the strabismus might be made worse (ie, more noticeable) by the surgery.
Exploring age and gender differences
Pearson's correlation calculations revealed no associations between age and the outcome variables for the follow-up cohort (n=25) at T1 or at T3. One significant correlation was recorded at T2, that is, with increasing age, lower ratings of social anxiety and social avoidance were recorded (DAS-24; r=−0.426 p<0.034). This correlation may be linked to the after-effects of surgery. It is possible that the younger participants were more distressed by the postoperative bloodshot eyes and swelling than the older participants, avoiding social situations until such time as the more obvious side effects of surgery had reduced.
A 2×3 ANOVA calculation returned no evidence for gender differences in the postoperative effects of corrective surgery over an extended time period. Similarly, no interaction effects were recorded between gender and time of data collection.
Twenty-five (54%) participants from an original cohort of 46 completed this longer term follow-up study. There were some indications of selection bias evident in the group who chose to be part of the follow-up study. The general trend was for those who took part to have generally better psychosocial functioning (ie, reportedly less psychosocial distress) as recorded by the standardised questionnaires employed in the study. In particular, the small number of participants with diplopia in the follow-on cohort may have contributed to this (diplopia being associated with increased levels of depression and decreased scores for physical quality of life as noted by Jackson et al).3
As a result of the fact that ocular deviation is known to recur over time, the Japanese Association of Strabismus and Amblyopia treatment standard requires that the results of strabismus surgery are evaluated 4 years after the treatment has been carried out.11 Maruo et al (1988) carried out an evaluation of 1031 surgical corrections for strabismus comparing postoperative eye alignment at 1-month and 4 years in a sample consisting largely of children.12 Their results suggested that 39% of their study sample required further treatment during the 4 year period. No such long-term study has been carried out with adults, but it was clear from Hertle's5 study that adult individuals with strabismus seem to get caught in a cycle of diagnosis and treatment where the eye misalignment is diagnosed and treated, with symptoms reduced but not eliminated. Forty-five percent of the participants in Hertle's (1998) study had already undergone surgical correction for a strabismus prior to taking part in his study. In this study, 16 of the 25 participants (64%) had already received at least one surgical correction prior to study participation. While during Hertle's (1998) study six participants required two operations, and one participant required three corrective procedures, in this study three participants required one further surgical correction.
While the recruitment of participants from a previous study in a longitudinal design allowed issues of long-term adjustment to be considered, using such a postal survey design resulted in problems related to patient uptake. Given that the original study patient population comprised 46 participants, it was perhaps not surprising that the follow-on study patient population was small (n=25). A mixed method design where longitudinal and cross-sectional data were considered at each time point might have produced a more rounded picture of the issues relating to long-term adjustment for adults undergoing corrective surgery for strabismus. Further consideration of the follow-up study participants showed that those who had persistent diplopia following surgery were less likely to take part in this study of long-term adjustment. The sample population therefore consisted of three substantive groups of white British participants: (1) those for whom diplopia was never a problem; (2) those who had experienced a marked improvement in their diplopia; and (3) those whose double vision had been eradicated. The authors would recommend caution in relation to the results and conclusions that can be drawn from this study and would strongly recommend that a properly powered audit study of the longer term impact of strabismus surgery in adults be undertaken to properly understand the issues associated with adjustment to changed ocular alignment.
Satterfield et al4 arguably focused on the long-term issues of living with a strabismus, rather than on studying the processes involved in adjusting to a changed appearance. With the majority of participants taking part in this follow-up study appearing to be those who were adjusting well, this study provided an opportunity to consider a population of adults with more successfully corrected strabismus than that studied by Satterfield et al albeit over a shorter time frame. Data from the current study suggest that adjustment may be a long-term process, with some study measures showing greater improvements at 18 months than at 3 months postoperatively. Satterfield et al suggested that the problems of adults with strabismus increase with age, but this study found no evidence of a relationship between age and psychosocial outcomes at any of the data collection points. Similarly no evidence was found for gender differences in the benefits of corrective surgery, suggested by Burke et al.2 However, it should be noted that all research studies to date (including the author's own) exploring issues for adults with a strabismus have used small sample sizes and therefore these conclusions regarding the relationships between age, gender and strabismus effects should be regarded as tentative at best and requiring further research.
With few reports on the long-term effectiveness of strabismus surgery this study was designed to consider the psychosocial status of adults a minimum of 1 year after surgery. With the majority of participants taking part in this follow-up study appearing to be those who were adjusting well, a positive picture of adjustment was observed. Results from this study suggest that adjustment is a long-term process with improvements on some study measures being greater at 18 months than at 3 months postoperatively suggesting that some psychosocial goals are more appropriately measured in the longer term.
The authors would like to thank Dr Paul White, University of the West of England and staff at the Bristol Eye Hospital and Great Western Hospital Swindon for their assistance in this project. The material in this publication is the result of use of the WHOQOL-UK and the assistance of the University of Bath and the World Health Organisation is acknowledged.
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Files in this Data Supplement:
- Data supplement 1 - Online appendix
Contributors This work was undertaken as part of the work for SJ PhD studies. Her Director of Studies was Nichola Rumsey, Director of the Centre for Appearance Research at the University of the West of England, Bristol. Her second supervisor was MM, Principal Lecturer at the University of the West of England. She was also supervised by RA Harrad, Clinical Director at Bristol Eye Hospital.
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.
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