An Evaluation of the Amblyopia and Strabismus Questionnaire Using Rasch Analysis

Protective Effect of Allyl Isothiocyanate in an Experimentally Induced Rat Model for Dry Eye Syndrome

PURPOSE/AIM OF THE STUDY

Growing evidence emphasizes the role of inflammation and oxidative stress in the pathogenesis of Dry Eye Syndrome (DES). Concordantly, the importance of agents targeting the inflammatory cascade and oxidative stress in the treatment is also progressively increasing. Herein, the study has investigated the protective effects and underlying mechanism of allyl isothiocyanate (AITC) on the ocular surface in a benzalkonium chloride (BAC)-induced dry eye rat model.

MATERIALS AND METHODS

A total of twenty-one Wistar albino rats were used to form the following three groups: Control, BAC, BAC + AITC. DES was established by topical application of BAC (four times daily for two weeks) in two groups, of which one group was treated with AITC (10 mg/kg BW daily oral dosage) for four weeks. Rats were monitored by dry eye diagnostic tests during the study period, and eventually, corneal tissues were used to evaluate for histopathologic analyzes and inflammatory and oxidative status.

RESULTS

A significant improvement was observed in various histopathologic and ophthalmologic findings, including tear volume, tear film integrity, ocular surface damage, ocular inflammatory signs, corneal thickness, and edema through AITC supplementation. AITC prominently balanced the inflammatory status and oxidative stress by lowering key proinflammatory mediators (NF-κB, TNF-α, IL-1β, IL-6, and IL-8) and increasing the activities of antioxidant enzymes (SOD, GSH-Px). Also, levels of protective tear proteins, including Muc1, Muc4, and Muc5 were recovered with AITC supplementation.

CONCLUSION

AITC alleviates clinical and histopathologic signs related to DES. Antioxidative and anti-inflammatory properties of AITC play a significant role in the mechanism of action.

Egocentric Distance Perception Disorder in Amblyopia

Egocentric distance perception is a psychological process in which observers use various depth cues to estimate the distance between a target and themselves. The impairment of basic visual function and treatment of amblyopia have been well documented. However, the disorder of egocentric distance perception of amblyopes is poorly understood. In this review, we describe the cognitive mechanism of egocentric distance perception, and then, we focus on empirical evidence for disorders in egocentric distance perception for amblyopes in the whole visual space. In the personal space (within 2 m), it is difficult for amblyopes to show normal hand-eye coordination; in the action space (within 2 m~30 m), amblyopes cannot accurately judge the distance of a target suspended in the air. Few studies have focused on the performance of amblyopes in the vista space (more than 30 m). Finally, five critical topics for future research are discussed: 1) it is necessary to systematically explore the mechanism of egocentric distance perception in all three spaces; 2) the laws of egocentric distance perception in moving objects for amblyopes should be explored; and 3) the comparison of three subtypes of amblyopia is still insufficient; 4) study the perception of distance under another theoretical framework; 5) explore the mechanisms of amblyopia by Virtual Reality.

Measuring Anxiety in Patients With Early-Stage Parkinson's Disease: Rasch Analysis of the State-Trait Anxiety Inventory

The State-Trait Anxiety Inventory (STAI), composed of two 20-item subscales (STAI-state and STAI-trait), has been increasingly used to assess anxiety symptoms in patients with Parkinson's disease (PD). However, the clinimetric attributes of the STAI under the statistical framework of the item-response theory (IRT) have not been fully elucidated within this population to date. We performed an IRT-based Rasch analysis of the STAI outcomes of patients with de novo PD from the Parkinson's Progression Markers Initiative database. The unidimensionality, Rasch model fit, scale targeting, separation reliability, differential item functioning, and response category utility of the STAI were statistically evaluated. A total of 326 (209 males, 117 females) patients without cognitive dysfunction were enrolled in our study. The original versions of the STAI-state and STAI-trait had acceptable separation reliability but lacked appropriate response category functioning, exhibited scale off-targeting, and several items demonstrated poor fit to the Rasch model. The response categories were reduced from four to three, and the rescored three-point TASI-trait demonstrated a marked improvement in clinimetric properties without a significant impact on unidimensionality and separation reliability. The rescored three-point version of the STAI-state required the additional removal of four misfitting items in order to improve the Rasch model fit. To our knowledge, this is the first study to assess the measurement properties based on the IRT of the STAI in patients with PD. Our Rasch analysis identified the components requiring possible amendments in order to improve the clinimetric attributes of the STAI.

Development of a conceptual model regarding quality of life in Chinese adult patients with strabismus: a mixed method

Background

Substantial challenges have been reported in China in terms of the large number of adult patients with strabismus and their poor quality of life. Quality of life is a cultural concept that varies according to personal feelings and perceptions, and it is influenced by physical, psychological and social factors. However, to date, there has been no mixed-method research of the quality of life of Chinese adult patients with strabismus, and no conceptual model has been reported. This study aimed to utilize mixed methods to explore the influence of strabismus on health-related quality of life in Chinese adult patients and to develop a conceptual model.

Methods

Thirty adult patients with strabismus from three tertiary hospitals in China participated in the interview. In-depth one-to-one interviews were semi-structured and addressed strabismus-related symptoms and the impacts on the participants’ quality of life. Transcripts were analysed to identify themes. A self-designed questionnaire was distributed to 448 patients, 437 of whom returned valid questionnaires. Descriptive statistics and x² test were conducted.

Results

Five themes were revealed regarding the impact of strabismus on patient quality of life: appearance, daily activities, personal development, social interaction, and emotions. In the survey, the top three symptoms (n ≥ 70%) rated by the participants were monocular vision, eye fatigue and physical discomfort. Compared to those without diplopia, the patients who suffered diplopia more often reported experiencing the symptoms of blurred vision, monocular vision, physical discomfort, eye fatigue, cannot estimate depth well and increasing deviation size (all p < 0.05).

Conclusions

This study is the first to examine quality of life among Chinese strabismus patients using both qualitative and quantitative methods and proposing a conceptual model. Symptom burden and appearance were the two original reasons for the decreased quality of life, and they were also the triggers for strabismus patients to visit clinics and undergo surgery. The interventions to treat symptoms burden should be different between patients with and without diplopia.

Development and Validation of the Vision-Related Dizziness Questionnaire

Purpose

To develop and validate the first patient-reported outcome measure (PROM) to quantify vision-related dizziness. Dizziness is a common, multifactorial syndrome that causes reductions in quality of life and is a major risk factor for falls, but the role of vision is not well understood.

Methods

Potential domains and items were identified by literature review and discussions with experts and patients to form a pilot PROM, which was completed by 335 patients with dizziness. Rasch analysis was used to determine the items with good psychometric properties to include in a final PROM, to check undimensionality, differential item functioning, and to convert ordinal questionnaire data into continuous interval data. Validation of the final 25-item instrument was determined by its convergent validity, patient, and item-separation reliability and unidimensionality using data from 223 patients plus test–retest repeatability from 79 patients.

Results

120 items were originally identified, then subsequently reduced to 46 to form a pilot PROM. Rasch analysis was used to reduce the number of items to 25 to produce the vision-related dizziness or VRD-25. Two subscales of VRD-12-frequency and VRD-13-severity were shown to be unidimensional, with good psychometric properties. Convergent validity was shown by moderately good correlations with the Dizziness Handicap Inventory (r = 0.75) and good test–retest repeatability with intra-class correlation coefficients of 0.88.

Conclusion

VRD-25 is the only PROM developed to date to assess vision-related dizziness. It has been developed using Rasch analysis and provides a PROM for this under-researched area and for clinical trials of interventions to reduce vision-related dizziness.

Differences in quality-of-life dimensions of Adult Strabismus Quality of Life and Amblyopia & Strabismus Questionnaires

Purpose

The Adult Strabismus Quality of Life Questionnaire (AS-20) and the Amblyopia & Strabismus Questionnaire (A&SQ) both measure health-related quality of life in strabismus patients. We evaluated to what extent these instruments cover similar domains by identifying the underlying quality-of-life factors of the combined questionnaires.

Methods

Participants were adults from a historic cohort with available orthoptic childhood data documenting strabismus and/or amblyopia. They had previously completed the A&SQ and were now asked to complete the AS-20. Factor analysis was performed on the correlation-matrix of the combined AS-20 and A&SQ data to identify common underlying factors. The identified factors were correlated with the clinical variables of angle of strabismus, degree of binocular vision, and visual acuity of the worse eye.

Results

One hundred ten patients completed both questionnaires (mean age, 44 years; range, 38–51 years). Six factors were found that together explained 78% of the total variance. The factor structure was dominated by the first four factors. One factor contained psychosocial and social-contact items, and another factor depth-perception items from both questionnaires. A third factor contained seven items—only from the AS-20—on eye strain, stress, and difficulties with reading and with concentrating. A fourth factor contained seven items—only from the A&SQ—on fear of losing the better eye and visual disorientation, specific for amblyopia. Current visual acuity of the worse eye correlated with depth-perception items and vision-related items, whereas current binocular vision correlated with psychosocial and social-contact items, in 93 patients.

Conclusions

Factor analysis suggests that the AS-20 and A&SQ measure a similar psychosocial quality-of-life domain. However, functional problems like avoidance of reading, difficulty in concentrating, eye stress, reading problems, inability to enjoy hobbies, and need for frequent breaks when reading are represented only in the AS-20. During the development of the A&SQ, asthenopia items were considered insufficiently specific for strabismus and were excluded a priori. The patients who generated the items for the AS-20 had, in majority, adulthood-onset strabismus and diplopia and were, hence, more likely to develop such complaints than our adult patients with childhood-onset strabismus and/or amblyopia.

Evaluation of the Intermittent Exotropia Questionnaire using Rasch analysis

IMPORTANCE

The Intermittent Exotropia Questionnaire (IXTQ) is a patient, proxy, and parental report of quality of life specific to children with intermittent exotropia. We refine the IXTQ using Rasch analysis to improve reliability and validity.

OBSERVATION

Rasch analysis was performed on responses of 575 patients with intermittent exotropia enrolled from May 15, 2008, through July 24, 2013, and their parents from each of the 4 IXTQ health-related quality-of-life questionnaires (child 5 through 7 years of age and child 8 through 17 years of age, proxy, and parent questionnaires). Questionnaire performance and structure were confirmed in a separate cohort of 379 patients with intermittent exotropia. One item was removed from the 12-item child and proxy questionnaires, and response options in the 8- to 17-year-old child IXTQ and proxy IXTQ were combined into 3 response options for both questionnaires. Targeting was relatively poor for the child and proxy questionnaires. For the parent questionnaire, 3 subscales (psychosocial, function, and surgery) were evident. One item was removed from the psychosocial subscale. Resulting subscales had appropriate targeting.

CONCLUSIONS AND RELEVANCE

The Rasch-revised IXTQ may be a useful instrument for determining how intermittent exotropia affects health-related quality of life of children with intermittent exotropia and their parents, particularly for cohort studies.

Measuring Health-Related Quality of Life in Strabismus: A Modification of the Adult Strabismus-20 (AS-20) Questionnaire Using Rasch Analysis

Purpose

To evaluate the psychometric properties of the Adult Strabismus-20 (AS-20)- a health-related quality of life (HRQoL) questionnaire in adults with strabismus, and if flawed, to revise the AS-20 and its subscales creating valid measurement scales.

Methods

584 adults (meanage, 27.5 years) with strabismus were recruited from an outpatient clinic at a South Indian tertiary eye care centre and were administered the AS-20 questionnaire.The AS-20 was translated and back translated into two Indian languages. The AS-20 and its two 10-item subscales – ‘psychosocial’ and ‘function’were assessed separately for fit to the Rasch model, including an assessment of the rating scale, unidimensionality (by principal components analysis), measurement precision by person separation reliability, PSR, targeting, and differential item functioning (DIF; notable > 1.0 logits).

Results

Response categories were not used as intended, thereby, required re-organization and reducing their number from 5 to 3. The AS-20 had adequate measurement precision (PSR = 0.87) but lacked unidimensionality; however, deletion of the six multi-dimensionality causing items and an additional three misfitting items resulted in 11-item unidimensional questionnaire (AS-11). Two items failed to satisfy the model expectations in the ‘psychosocial’ subscale and were deleted – resulting in an 8-item unidimensional scale with adequate PSR (0.81) and targeting (0.23 logits). One item misfit in the ‘function’ subscale and was deleted—resulting in a 9 item Rasch-revised unidimensional subscale with acceptable PSR (0.80) and targeting (0.97 logits).None of the items displayed notable DIF by age, gender and level of education.

Conclusions

The AS-11 and its two Rasch-revised subscales – 8-item psychosocial and 9-item function subscale may be more appropriate than the original AS-20 and its two 10-item subscales for use as unidimensional measures of HRQoL in adults with strabismus in India. Further work is required to establish the validity of the revised rating scale.

The relationship between central visual field damage and motor vehicle collisions in primary open-angle glaucoma patients

Purpose

To investigate the relationship between visual field (VF) damage and history of motor vehicle collisions (MVCs) in subjects with primary open-angle glaucoma (POAG).

Methods

MVC history and driving habits were recorded using patient questionnaires in 247 POAG patients. Patients' driving attitudes (carefulness) were estimated using Rasch analysis. The relationship between MVC outcomes and 52 total deviation (TD) values of integrated binocular VF (IVF), better and worse visual acuities (VAs), age and gender was analyzed using principal component analysis and logistic regression.

Results

51 patients had the history of MVCs. Significant difference was observed between patients with and without history of MVCs only for: better VA, a single TD value in the superior-right VF, and the typical distance driven in a week (unpaired t-test, p = 0.002, 0.015 and 0.006, respectively). There was not a significant relationship between MVCs and mean deviation (MD) of IVF (p = 0.41, logistic regression). None of the principal components were significantly correlated with MVC outcome (p>0.05, polynomial logistic regression analysis). There was a significant relationship between IVF MD and Rasch derived Person parameter (R² = 0.023, p = 0.0095). There was also a significant positive relationship between MVCs and the distance driven in a week (p = 0.005, logistic regression).

Conclusions

In this study of POAG patients, MVCs were not related to central binocular VF damage. These results suggest the relationship between visual function and driving is not straightforward, and careful consideration should be given when predicting patients' driving ability using their VF.

Comparison of the Adult Strabismus Quality of Life Questionnaire (AS-20) with the Amblyopia and Strabismus Questionnaire (ASQE) among adults with strabismus who seek medical care in China

BACKGROUND

The impact of strabismus on visual function, self-image, self-esteem, and social interactions might decrease health-related quality of life (HRQoL). This study aimed to evaluate the psychometric properties and clinical applications of two strabismus-specific HRQoL questionnaires in the cultural context of China.

METHODS

The Chinese versions of the Adult Strabismus Quality of Life Questionnaire (AS-20) and the Amblyopia and Strabismus Questionnaire (ASQE) were self-administered to 304 adults with strabismus. The Cronbach's α coefficient was calculated to assess the internal consistency reliability. The criterion-related validity was identified by exploring Spearman's correlation with the most widely used vision-specific quality of life questionnaire NEI-VFQ-25. One-way ANOVA was employed to examine the differences in the quality of life of strabismus patients with visually normal adults and with other eye diseases patients.

RESULTS

Significantly positive correlations with NEI-VFQ-25 were shown in both scales (r = 0.21 - 0.44, p <0.05, p <0.01). Both scales could distinguish individuals with strabismus from visually normal adults (p <0.001) and adults with other eye diseases (p <0.001). The overall Cronbach's α value were 0.91 for the AS-20 and 0.89 for the ASQE; and for the subscales, the α value ranged from 0.68 to 0.90.

CONCLUSION

This was the first cross-sectional study to compare the psychometric properties of two strabismus-targeted questionnaires, AS-20 and ASQE in the context of Chinese culture. Both AS-20 and ASQE showed satisfactory and comparable properties for measuring HRQoL in strabismus patients.

Quality assessment of ophthalmic questionnaires: review and recommendations

PURPOSE

The aim of this article was to systematically review all the available ophthalmic patient-reported outcome (PRO) instruments (questionnaires) that demonstrated interval measurement properties to identify the instruments with the highest psychometric quality for use in different eye diseases and conditions.

METHODS

An extensive literature review was carried out to identify all existing ophthalmic PRO instruments. Instruments were then excluded if they did not have demonstrable interval measurement properties; the remaining instruments were reviewed. The quality of the following psychometric properties was assessed: content development (initial item development process), performance of the response scale, dimensionality (whether the instrument measures a single construct), measurement precision, validity (convergent, concurrent, discriminant, and known groups), reliability (test-retest), targeting (whether the items are appropriate [e.g., difficulty level] for the population), differential item functioning (whether subgroups of people respond differently to an item), and responsiveness.

RESULTS

The search identified 48 PRO instruments that demonstrated interval measurement properties, and these were relevant to nine applications: glaucoma, dry eye, refractive errors, cataract, amblyopia and strabismus, macular diseases, adult low vision, children low vision, and others. These instruments were evaluated against the psychometric property quality criteria and were rated for quality based on the number of criteria met.

CONCLUSIONS

This review provides a descriptive catalog of ophthalmic PRO instruments to inform researchers and clinicians on the choice of the highest-quality PRO instrument suitable for their purpose.

The impact of strabismus on quality of life in adults with and without diplopia: a systematic review

Strabismus affects approximately 4% of the adult population and can cause substantial physical disturbance and changes to appearance. This article aims to examine the impact of strabismus in adults both with and without diplopia, focusing primarily on quality of life (QoL). We highlight the value of measuring QoL, assess the ways in which it can be measured, and the impact the disease, diplopia, and surgery have on the patient. QoL differs for strabismus patients based on their diplopia status. Patients with diplopia tend to have more concerns relating to functional QoL, whereas patients without diplopia have primarily psychosocial concerns. Two diplopia-specific questionnaires have been designed to assess QoL and the perceived severity of symptoms. Further research is needed to identify the variables which influence QoL so that appropriate support can be given to all patients with strabismus to improve their QoL.

Levels of state and trait anxiety in patients referred to ophthalmology by primary care clinicians: a cross sectional study

Purpose

There is a high level of over-referral from primary eye care leading to significant numbers of people without ocular pathology (false positives) being referred to secondary eye care. The present study used a psychometric instrument to determine whether there is a psychological burden on patients due to referral to secondary eye care, and used Rasch analysis to convert the data from an ordinal to an interval scale.

Design

Cross sectional study.

Participants and Controls

322 participants and 80 control participants.

Methods

State (i.e. current) and trait (i.e. propensity to) anxiety were measured in a group of patients referred to a hospital eye department in the UK and in a control group who have had a sight test but were not referred. Response category analysis plus infit and outfit Rasch statistics and person separation indices were used to determine the usefulness of individual items and the response categories. Principal components analysis was used to determine dimensionality.

Main Outcome Measure

Levels of state and trait anxiety measured using the State-Trait Anxiety Inventory.

Results

State anxiety scores were significantly higher in the patients referred to secondary eye care than the controls (p<0.04), but similar for trait anxiety (p>0.1). Rasch analysis highlighted that the questionnaire results needed to be split into “anxiety-absent” and “anxiety-present” items for both state and trait anxiety, but both subscales showed the same profile of results between patients and controls.

Conclusions

State anxiety was shown to be higher in patients referred to secondary eye care than the controls, and at similar levels to people with moderate to high perceived susceptibility to breast cancer. This suggests that referral from primary to secondary eye care can result in a significant psychological burden on some patients.

Development and validation of the 21-item children's vision for living scale (CVLS) by Rasch analysis

BACKGROUND

The aim was to develop and validate an instrument called the 'Children's Vision for Living Scale' (CVLS) for the assessment of vision-related quality of life in Saudi Arabian children with and without amblyopia.

METHODS

A 43-item child self-report questionnaire was initially developed based on interviews with children with amblyopia, their parents and eye-care professionals, and a literature review. Following a process that involved the removal of redundant items, 28 items remained and were piloted on children aged five to 12 years with and without amblyopia (n = 48 amblyopic, n = 53 non-amblyopic) living in Saudi Arabia. Rasch analysis was applied to determine whether the 28-item questionnaire fitted the Rasch model. Rasch analysis was used to assess the validity and reliability of the questionnaire. Principal components analysis (PCA) was used to check dimensionality. A 21-item questionnaire resulting from this process was administered in children with (n = 81) and without (n = 82) amblyopia in Saudi Arabia for further validation.

RESULTS

The final 21-item questionnaire had good validity and reliability as demonstrated by person separation of 2.02, person reliability of 0.80 (mean square and standard deviation: infit = 1.01 ± 0.39; outfit = 1.01 ± 0.40) and item reliability of 0.93 (item infit range = 1.33 to 0.78; item outfit range = 0.78 to 1.30). The mean difference between person and item scores of 0.33 ± 0.53 logits (scale range, 2 to -2) indicates that the items are well targeted to the populations. The PCA (dimensionality measures) shows the percentage of variance explained by measures equal to 26.4 per cent (modelled 26.9 per cent) and an eigenvalue of the first contrast of 2.5, which demonstrated good stability.

CONCLUSION

The 21-item CVLS is a valid uni-dimensional child self-report instrument for the assessment of the impact of amblyopia on vision-related quality of life in children with and without amblyopia living in Saudi Arabia.

Evaluation of the Adult Strabismus-20 (AS-20) questionnaire using Rasch analysis

PURPOSE

To further refine the Adult Strabismus 20 (AS-20) health-related quality of life (HRQOL) questionnaire using Rasch analysis.

METHODS

Rasch analysis was performed independently on the original AS-20 using the following steps: dimensionality, response ordering, local dependence, infit and outfit analyses, differential item functioning, subject targeting, and confirmatory dimensionality.

RESULTS

Two subscales were present in each of the original AS-20 subscales, for a total of 4 subscales, which were labeled "self-perception," "interaction," "reading function," and "general function." Response ordering was appropriate for 3 of the subscales but required reduction to 4 response options for the fourth subscale. No notable local dependence was found for any subscale. As a result of fit analysis, 2 items were removed, 1 each from 2 subscales. No significant differential item functioning was seen for sex or age. The resulting 5-item self-perception subscale and 4-item reading function subscale are reliable and target the adult strabismus patient cohort appropriately. The resulting 5-item interaction subscale and 4-item general function subscale have less than optimal reliability.

CONCLUSIONS

The AS-20 benefits from reduction to 4 subscales (self-perception, interaction, reading function, and general function) and reducing the response options in the general function subscale from 5 to 4 options. The refined AS-20 may prove to be even more responsive to HRQOL changes in adult strabismus following treatment or changes over time.

Amblyopia and quality of life: a systematic review

Amblyopia is a common condition, which can affect up to 5% of the general population. Health-related quality-of-life (HRQoL) implications of amblyopia and/or its treatment have been explored in the literature. A systematic literature search was undertaken during the period of 7-14 May 2010 to identify the HRQoL implications of amblyopia and/or its treatment. A total of 35 papers were included in the literature review. The HRQoL implications of amblyopia related specifically to amblyopia treatment, rather than to the condition itself. These included impact on family life, social interactions, difficulties in undertaking daily activities, as well as feelings and behaviour. The identified studies adopted a number of methodologies. The study populations included children with the condition, parents of children with amblyopia, and adults who had undertaken amblyopia treatment as a child. Some studies developed their own measures of HRQoL, and others determined HRQoL through proxy measures. The reported findings of the HRQoL implications are of importance when considering the management of cases of amblyopia. The issues identified in the literature review are discussed with respect to how HRQoL is measured (treatment compliance vs proxy measures), and whether HRQoL is taken from a child's or a parent's perspective. Changing societal views over glasses and occlusion therapy are also discussed. Further research is required to assess the immediate and long-term effects of amblyopia and/or its treatment on HRQoL using a more standardised approach.