Development of a Keratoconus-Specific Questionnaire Using Rasch Analysis

Rasch validation of the Keratoconus End-Points Assessment Questionnaire in a Spanish population with keratoconus

OBJECTIVE

To carry out a methodologically complete validation of the Spanish version of the Keratoconus End-Points Assessment Questionnaire (KEPAQ) in a Spanish population with keratoconus.

METHODS

Analytical, prospective study, including patients with keratoconus without previous surgical history, in which a measurement of quality of life was performed using the KEPAQ questionnaire, a complete exploration of the anterior pole and a corneal elevation topography with the Galilei G6 topographer. The evaluation of the psychometric characteristics of the scale in the studied population was carried out using Rasch modeling.

RESULTS

A total of 140 patients with keratoconus were included, with a median age of 26.0 years, the majority (57.6%) being men. For the KEPAQ-E subscale, the median score was 69.3, with a reliability of 0.85 and an eigenvalue of the first contrast of 2.34. For the KEPAQ-F, the median score was 56.4, with a reliability of 0.88 and an eigenvalue of 2.00. All infit and outfit parameters were within normal limits for both subscales. A significant evaluation was found between the evaluations of both subscales (rho = 0.696; p < 0.001). The evaluations of the subscales and various clinical and tomographic characteristics showed a significant classification between them (p value between 0.048 y 0.001).

CONCLUSION

The KEPAQ is a psychometrically robust and valid scale to evaluate quality of life in the Spanish population with keratoconus. This questionnaire can be easily used for both clinical and research aims.

Evaluation of the German Version of the Keratoconus Outcomes Research Questionnaire

PURPOSE

To translate, validate, and evaluate the psychometric properties of the German version of Keratoconus Outcomes Research Questionnaire (KORQ).

METHODS

This prospective study included 3 phases. In phase 1, the KORQ was translated in a standardized way; in phase 2, Rasch validation was performed; in phase 3, the validated questionnaire was evaluated in a separate patient cohort. All patients answered the German KORQ. Scheimpflug imaging (Pentacam) and optical coherence tomography scans (MS-39) were conducted. Corneal imaging measurements were correlated with patient-reported outcome measures.

RESULTS

After standardized translation, 100 patients self-administered the German KORQ. Rasch analysis was conducted for psychometric testing of the KORQ. Based on the results of the Rasch analysis, the original German version of the KORQ was modified and any items showing a misfit were excluded. This resulted in a new shortened version of the KORQ, which was evaluated in 30 patients. The revised German KORQ met the criteria of Rasch analysis and showed excellent internal consistency reliability and convergent validity. The correlation between the KORQ score and various clinical measurements was examined using Spearman correlation. A significant moderate correlation was observed between the D (r = 0.237; P = 0.006) and Kmax (r = 0.162; P = 0.065) values of Pentacam. Inverse correlations were observed for thinnest pachymetry measured with MS-39 (r = -0.167; P = 0.058) and best corrected visual acuity (r = -0.210; P = 0.016).

CONCLUSIONS

The shortened German KORQ met the assumptions of the Rasch model and displayed satisfactory psychometric properties. The German KORQ could be adopted as a powerful patient-reported outcome measures tool for German-speaking patients with keratoconus in the future.

Cross-Linking Improves the Quality of Life of People With Keratoconus: A Cross-Sectional and Longitudinal Study From the Save Sight Keratoconus Registry

PURPOSE

The purpose of this study was to comprehensively evaluate the patient-reported quality-of-life (QoL) outcomes after corneal cross-linking for keratoconus.

METHODS

This Save Sight Keratoconus Registry study used cross-sectional and longitudinal designs. For the cross-sectional study, 532 patients with keratoconus (mean age 30.9 ± 11.9 years; 31.6% female) completed the Keratoconus Outcomes Research Questionnaire (KORQ) and 343 patients with keratoconus (mean age 28.3 ± 10.7 years; 32.7% female) completed the Impact of Vision Impairment (IVI) questionnaires. Similarly, for the longitudinal study, 39 patients (mean age 24.2 ± 8.4 years; 23.1% female) completed the KORQ and 16 patients (mean age 27.9 ± 17.1 years; 50.0% female) completed the IVI questionnaire before and after 6 months of cross-linking. The QoL data were analyzed using the Andrich Rating Scale Model of Rasch analysis.

RESULTS

For both cross-sectional and longitudinal studies, the KORQ and IVI scales demonstrated satisfactory psychometric properties [ordered and well-spaced categories, variance explained by the measure 52%-73%, person separation index 2.4-3.9, and fit statistics <1.3 (most cases)]. The patients who had not undergone corneal cross-linking had worse mean activity limitation than those with cross-linking ( P = 0.008). However, the differences in symptoms and emotional scores between the groups were not statistically significant (both P > 0.05). The longitudinal study showed that cross-linking was associated with improved activity limitation, symptoms, and emotional scores.

CONCLUSIONS

The KORQ and IVI are psychometrically robust tools to evaluate the QoL outcomes of corneal cross-linking. Cross-linking is associated with improved activity limitation, symptoms, and emotional status.

Keratoconus and the Impact of Treatment on Patients' Quality of Life: A Qualitative Study

INTRODUCTION

Keratoconus has a significant impact on patients' quality of life (QoL), from diagnosis to the advanced stages of the disease. The aim of this research was to identify domains of QoL affected by this disease and its treatment.

METHODS

Phone interviews were conducted using a semi-structured interview guide, with patients with keratoconus stratified according to their current treatment. A board of keratoconus experts helped identify the guide's main themes.

RESULTS

Thirty-five patients (rigid contact lenses, n = 9; cross-linking, n = 9; corneal ring implants, n = 8; and corneal transplantation, n = 9) were interviewed by qualitative researchers. Phone interviews revealed several QoL domains affected by the disease and its treatments: "psychological", "social life", "professional life", "financial costs" and "student life". All domains were impacted, independently of the treatment history. Few differences were found between treatment regimens and keratoconus stages. Qualitative analysis enabled the development of a conceptual framework based on Wilson and Cleary's model for patient outcomes common to all patients. This conceptual model describes the relationship between patients' characteristics, their symptoms, their environment, their functional visual impairment and the impact on their QoL.

CONCLUSIONS

These qualitative findings supported the generation of a questionnaire to evaluate the impact of keratoconus and its treatment on patients' QoL. Cognitive debriefings confirmed its content validity. The questionnaire is applicable for all stages of keratoconus and treatments and may help tracking change over time in regular clinical settings. Psychometric validation is yet to be performed before its use in research and clinical practices.

Patient-Reported Outcomes in Keratoconus: A Save Sight Keratoconus Registry Study

PURPOSE

The aim of this study was to evaluate the quality-of-life (QoL) status in keratoconus severity subgroups using the Keratoconus Outcomes Research Questionnaire (KORQ) and to determine the relationship between the QoL scores and the standard clinical variables.

METHODS

A cross-sectional study was conducted using prospective, web-based Save Sight Keratoconus Registry data. Rasch analysis was conducted on the KORQ data using the Andrich Rating Scale Model. Comparative analysis included Welch t test and 1-way ANOVA. Associations between visual acuity, corneal curvature, and minimum corneal thickness with KORQ scores were evaluated with Pearson correlation and multiple regression adjusted for age and sex.

RESULTS

The KORQ was completed by 542 patients with keratoconus (male, 67.7%; mean age, 31.6 years). Keratoconus severity, based on Kmax, was mild [<48 diopter (D)], moderate (48-55 D), and severe (>55 D) in 26.3%, 45.0%, and 28.7% of patients, respectively. Activity limitation (AL) and symptoms (SY) scales of the KORQ had robust psychometric properties including well-functioning response categories, unidimensionality, excellent measurement precision, and satisfactory fit statistics. In a group-wise analysis, the female patients had significantly lower AL and SY scores. Similarly, the severe keratoconus group had the worst AL and SY scores. Contact lens wearers had worse KORQ scores than the spectacles wearers. Overall, statistically significant but weak correlations between KORQ scores and visual acuity and corneal curvature (Kmax and K2) (Pearson r, 0.11-0.35) were observed. The correlations for SY were weaker than for AL scores.

CONCLUSIONS

Female sex, contact lens wear, reduced visual acuity, and higher disease severity were associated with worse AL and SY scores in keratoconus. Although the correlations between clinical and QoL scores were statistically significant, the low magnitudes suggested a complex relationship between clinical parameters and patient-reported outcomes.

Quality of life and tomography indices in patients with keratoconus

OBJECTIVE

Keratoconus is a corneal ectasia that leads to thinning and steepening of the corneal surface. We aimed to assess the relationship between quality of life and corneal tomography indices, irrespective of visual acuity.

METHODS

This was a cross-sectional study using a translated and validated Keratoconus Outcomes Research Questionnaire (KORQ) in Arabic language. We screened patients with keratoconus using the Belin/Ambrósio D-Index. We included the best-seeing eye in each patient with keratoconus, with a best corrected visual acuity better than 0.5. We collected variables including KORQ scores, flattest meridian keratometry, steepest meridian keratometry, mean keratometry front, maximum simulated keratometry, astigmatism front, Q value front, and thickness at the thinnest location. We performed linear regression analysis to identify predictors of the visual function score and symptom score.

RESULTS

Sixty-nine patients were included in this study, 43 (62.3%) male and 26 (37.7%) female patients, with a mean age 34.0 ± 11.50 years. The only predictor for visual function score was sex (β = 11.64, 95% confidence interval: 3.50-19.78). None of the topographic indices were related to quality of life.

CONCLUSION

In this study, quality of life in patients with keratoconus was not related to specific tomography indices and might be related to visual acuity itself.

Impact of corneal collagen cross-linking on vision-related quality of life measured with the keratoconus outcomes research questionnaire (KORQ) in patients with keratoconus

PURPOSE

To assess the impact of corneal collagen cross-linking on self-reported vision-related quality of life (VR-QoL) in keratoconus patients by means of the Keratoconus Outcomes Research Questionnaire (KORQ), a new disease-specific patient reported outcomes measures (PROMs) tool.

METHODS

Patients with progressive keratoconus undergoing corneal collagen cross-linking were consecutively enrolled. Patients completed the KORQ before and after the treatment, at 1, 3 and 6 months. Data were collected regarding the visual acuity and the topographic, aberrometric and pachymetric parameters of both eyes. Patients were also asked to quantify their eye rubbing behavior on a Visual Analogue Scale (VAS) from 0 to 10, before and 6 months after treatment. The KORQ scores were associated with the visual acuity, topographic, aberrometric and pachymetric data by means of the Spearman correlation coefficient.

RESULTS

The Activity Limitation (AL) subscale score was higher after surgery. Preoperatively, negative correlations were observed between the KORQ AL score and Best Corrected Visual Acuity (logMAR), maximum keratometry, flattest keratometry, steepest keratometry, symmetry index front and higher order aberrations (HOA) of the treatment eye. Postoperatively, we observed a shift toward the fellow eye, with stronger correlation of the KORQ scores with the fellow eye parameters. The Symptoms subscale score correlated with the aberrometric parameters of both eyes at various time points. Statistically significant correlations were observed between the change in KORQ scores and the change in aberrometric parameters. A statistically significant reduction in the eye rubbing behavior was detected (p < 0,0001).

CONCLUSIONS

These results suggest that the corneal cross-linking treatment is effective both in improving the subjective perception of the disease by the patient and in stabilizing the objective indicators of disease progression. Keratometric, aberrometric and visual acuity values showed a significant impact on self-reported VR-QoL. Corneal cross-linking, by halting the worsening of these parameters, may bear a beneficial effect on VR-QoL.

What Are the Dry Eye Questionnaires Available in the Scientific Literature Used for? A Scoping Review

PURPOSE

Dry eye disease (DED) is a frequent chronic ophthalmic condition. Its diagnosis includes tests and patient reported outcomes (PRO) questionnaires. Although many PRO dry eye questionnaires (PRO-DEQs) are available, they differ greatly from each other and not all have been validated. The purpose of this study was to retrieve the PRO-DEQs present in the scientific literature by performing a descriptive analysis of them and identifying those with known validity and reliability characteristics and to perform a descriptive analysis of the geographic area, year of publication, and characteristics of the target population of the clinical studies that have used validated PRO-DEQs.

DESIGN

Scoping review of the literature.

METHODS

Searches were conducted in PubMed to retrieve PRO-DEQs published up to July 2018 and written in English, French, Italian or Spanish.

RESULTS

One thousand six hundred two records were identified and 973 were included in the final analysis. Of these, 56 provided information on the design and validation of PRO-DEQs and 49 PRO-DEQs were identified. Twenty-two PRO-DEQs were validated (17 original and 5 modified) and 27 had no associated design, validity, and reliability studies. Most of the validated PRO-DEQs were designed in English, the number of items varies from 1 to 57, the dimensions are generally not specified, and they are self-administered. The greatest use of validated PRO-DEQs in clinical studies has been in Asia since 2010, with the Ocular Surface Disease Index being the most used. These questionnaires have been used mostly in adults, retired professionals, and people with visual diseases to diagnose DED.

CONCLUSIONS

This study aims to encourage the use of validated PRO-DEQs to guarantee the quality of the results obtained and the comparability and replicability among studies.

Topical Review: Optometry in Nepal-Clinical Practice, Research Advances, and Challenges

SIGNIFICANCE

This article reviews educational standard, clinical practice, research advances, and challenges associated with optometry in Nepal and provides critical considerations for contemporary and new optometry programs in countries with similar socioeconomic status and health care systems.Optometry education started in Nepal in 1998 with the primary objective of addressing the unmet needs of eye health and vision care in the country. Over the last two decades, this program has made significant contributions to facilitating and improving the delivery of quality eye care and establishing the nation's eye health system as an exemplary model in South Asia. Despite the positive impact in a short time, optometry education and the profession continue to face several challenges, including a shortage of training resources and facilities, poor quality control and regulation of practice standards, lack of professional recognition, limited pathways for entry to governmental jobs via the national public service commission, and limited clinical and academic opportunities in existing eye care programs. This article reviews current education and clinical practice standards, highlights research advances, and discusses present and future challenges in sustaining and improving the quality of education and advancing the scope of practice of optometry in Nepal. Given the limited access to primary eye care services in Nepal, appropriate professional recognition and integration into the national health system, and initiatives targeted at improving the delivery of optometry education in alignment with successful international models may provide a long-sought solution to making eye care services accessible to all and lowering the burden of visual impairment in the country.

Standardizing the measurement and classification of quality of life using the Keratoconus End-Points Assessment Questionnaire (KEPAQ): the ABCDEF keratoconus classification

Background

Measuring quality of life is of importance in keratoconus. So far, the Keratoconus End-Points Assessment Questionnaire (KEPAQ) is the only keratoconus-specific scale to measure emotional well-being along with functional compromise in this population. Nevertheless, there is still a lack of clarity and standardization as to how KEPAQ scores should be computed and reported. There are also no guidelines for interpretation of classification of quality of life when using this instrument. The purpose of this study is to provide a specific framework on how to grade and classify keratoconus by using the KEPAQ and propose an extension of current classification to encompass subjective compromise.

Methods

A group of patients with a confirmed diagnosis of keratoconus underwent application of the KEPAQ. First, a Rasch modeling was performed to evaluate the psychometric characteristics of both sub-scales of the instrument. Then, a linear transformation was performed to turn data into a more relatable scale ranging from 0 to 100. Finally, by using Tukey’s Hinges, scores of the KEPAQ were divided in a 1-to-4 scale, allowing for an easy E&F classification system.

Results

A total of 386 applications of the KEPAQ were included. Analysis provided evidence of the KEPAQ being unidimensional, well-fitted to the Rasch Model, and provided adequate interval-level scores. Linear transformation resulted in a user-friendly final score ranging from 0 to 100, where a higher score translates to having a better quality of life. Two methods of easily computing final score, one by hand and the other one by an Excel file, were constructed. An E&F 1-to-4 classification was proposed, which may work well with the current ABCD classification of keratoconus.

Conclusions

The KEPAQ is a psychometrically robust scale, which confidently measures both emotional-related and functional-related quality of life in patients with keratoconus. It can be easily computed, and the results are interpretable and classified in a manner similar to that used in the ABCD keratoconus classification, by adding letters ‘E’ for emotional and ‘F’ for functional compromise.

Factors affecting quality of life in keratoconus

PURPOSE

To identify the factors affecting the quality of life (QoL) in adults with keratoconus, using the disease-specific Keratoconus Outcomes Research Questionnaire (KORQ).

METHODS

In this cross-sectional study, 574 patients with keratoconus completed the 29-item KORQ (18-item activity limitations and 11-item symptoms subscales) and demographic information. Based on mean corneal curvature to grade keratoconus severity, participants were categorised into four groups: mild <48 dioptres [D]; moderate: 48 to 53 D; advanced: 54 to 55 D and severe: >55D. Rasch analysis was used to assess the psychometric properties and to score the KORQ. Multivariable regression was performed to determine the independent impact of age, sex, laterality, severity and duration of keratoconus, education, employment status and mode of treatment for keratoconus on activity limitations and symptoms.

RESULTS

Mean (SD) age was 24.5 (5.1) years. 304 (53%), 160 (28%), 26 (4%) and 84 (15%) belonged to keratoconus groups 1, 2, 3 and 4, respectively. Rasch analysis demonstrated the 'activity limitations' and 'symptoms' KORQ subscales to possess good psychometric properties. Statistically significant associations were found between activity limitation score and the following measures: visual acuity (VA) in the better-seeing eye (r = -0.10, p = 0.01); VA in the worse-seeing eye (r = -0.09, p = 0.04) and ocular aberrations (r = -0.13, p = 0.008) in the worse-seeing eye. Statistically significant associations were also found between symptoms score and mean corneal curvature in the better-seeing eye (r = -0.10, p = 0.02). In regression models, female sex was associated with 21% worse symptom score than male (β = -0.33, 95% CI, -0.09, -0.59, p = 0.01) and working people experienced clinically and statistically significantly greater trouble from symptoms compared to those not working (β =0.44, 95% CI, 0.17, 0.70, p = 0.001).

CONCLUSIONS

People with keratoconus have poorer QoL in terms of activity limitations if they have poorer VA and greater wavefront aberrations, and in terms of symptoms if they are female and employed.

Comparing the measurement properties of visual analogue and verbal rating scales

PURPOSE

Utilising Rasch analysis on the Keratoconus Outcome Research Questionnaire (KORQ) data, we explored the hypothesis that the KORQ with discrete verbal rating scale (VRS) would demonstrate better psychometric properties and provide less noise in measurement than with a visual analogue scale (VAS).

METHODS

The KORQ is a keratoconus-specific patient-reported outcome measure; it has activity limitation and symptoms scales. The KORQ scales with two different rating scales (VAS and a discrete 4-response VRS) were completed by self-administration by people with keratoconus. For each KORQ scale, Rasch analysis-based psychometric properties were compared between the two versions. Rasch analysis was also used to optimise rating scale functioning when disordered thresholds were observed.

RESULTS

118 (mean age ± SD, 46.4 ± 0.4 years) and 169 (45.4 ± 14.7 years) people completed the KORQ with VAS and VRS, respectively. Both scales demonstrated high measurement precision. However, the VAS rating scale was disordered (6 out of 11 categories dysfunctional) and had two misfitting items. Conversely, the VRS had ordered categories and no misfitting items. For the disordered VAS, ordering was achieved only after collapsing 11 categories into four categories. In comparison to the KORQ with VRS, the repaired VAS had lower measurement precision, test information, variance explained by the measure, poor targeting, and reduced measurement range.

CONCLUSIONS

The KORQ demonstrated superior psychometric properties when measured using a VRS than with a VAS. This illustrates the advantages of verbal rating scales for a patient-reported outcome measurement over a visual analogue scale.

Both subscales of the Keratoconus End-Points Assessment Questionnaire have excellent test-retest reliability

Purpose:

The keratoconus end-points assessment questionnaire (KEPAQ) is a disease-specific scale designed to evaluate the quality of life in keratoconus patients and provides the measurement of both functional and emotional compromise in keratoconus. It was previously developed, tested, and validated and now we want to evaluate the test-retest reliability of the KEPAQ, in an effort to contribute evidence on its internal consistency and capability of measuring clinical state with minimal inference of random chance.

Methods:

This is a prospective analytical study, designed to evaluate the test-retest reliability of the KEPAQ through the repeated application of the questionnaire to a group of clinically stable individuals. A number of patients with a confirmed diagnosis of keratoconus underwent double application of the KEPAQ, seven days apart. Mean KEPAQ score was obtained through Rasch analysis, while test-retest reliability was evaluated through Spearman rank-order correlation and intraclass correlation coefficient. Rasch analysis was performed in JMetrik version 4.1.1 (Psychomeasurement Systems LLC; Charlottesville, VA, USA) in a MacBook Air computer running macOS Catalina version 10.15.2 (Apple Inc.; Cupertino, CA, USA).

Results:

A total of 100 patients were included. For KEPAQ-E, Spearman correlation was R = 0.963 while ICC was 0.981 (95% confidence interval 0.972–0.987). For KEPAQ-F, Spearman correlation was R = 0.921 while ICC was 0.952 (95% confidence interval 0.929–0.968).

Conclusion:

The KEPAQ is a robust, well-developed, extremely reliable scale which can be confidently used for clinical and research endeavors.

The Italian version of the Keratoconus Outcomes Research Questionnaire (KORQ): Translation and validation of psychometric properties

PURPOSE

To develop and validate the Italian version of the Keratoconus Outcomes Research Questionnaire (KORQ).

METHODS

Cross-sectional validation study. Keratoconus patients with routine appointments at the outpatient clinic were consecutively enrolled in conjunction with a sample of non-keratoconus controls for comparison. The Italian translation from the original English version of the KORQ was administered to the patients together with the Italian version of the 25-item version of the National Eye Institute Visual Function Questionnaire (NEI VFQ-25). The reliability and validity of the Italian KORQ were assessed using standardized internationally accepted methods for cultural adaptation and validation of health-related quality of life measures.

RESULTS

One hundred patients were deemed eligible and completed the questionnaires. The Cronbach's alpha coefficient for internal consistency ranged from 0.71 to 0.956 across the subscales. Spearman correlation coefficient and intraclass correlation coefficient of 0.98 showed excellent test-retest reliability. The control group had better scores on every subscale. Statistically significant correlations were found between the KORQ and analogous domain of the NEI VFQ-25 and with disease severity indicators, such as visual acuity, maximum keratometry, and steepest keratometry, thus demonstrating good construct and concurrent validity.

CONCLUSION

The Italian version of the KORQ exhibited excellent internal consistency, test-retest reliability, validity, discriminatory power, and psychometric properties comparable with those of the original English version, and thus may be adopted as a powerful vision-targeted quality of life assessment tool for Italian keratoconus patients.

Quality of life in keratoconus: evaluation with Keratoconus Outcomes Research Questionnaire (KORQ)

To assess the quality of life of keratoconus patients using the Keratoconus Outcomes Research Questionnaire (KORQ), translated and validated in Portuguese language. The KORQ is the only validated keratoconus specific questionnaire and has a high rating for its psychometric properties. This cross-sectional study enrolled 100 keratoconus patients from a tertiary referral eye hospital between April 2018 and June 2019. Associations between age, sex, allergic conjunctivitis, keratoconus stage, best-corrected visual acuity (BCVA), maximum simulated keratometry (Kmax), steep keratometry (K2), pachymetry, treatments performed, hydrops, and KORQ scores were evaluated using univariate (Wilcoxon test and the Kruskal Wallis test) and multivariate linear regression with stepwise backward modeling. Lower KORQ scores are associated with better quality of life, whereas, higher scores are associated with greater impairment of functional activities and symptoms. Among the 100 patients, mild, moderate, and severe keratoconus were observed in 15%, 46% and 39% of participants, respectively. Univariate analysis showed lower function scores values, with male sex (p < 0.05) and both functional and symptom scores were significantly associated with BCVA < 0.3 (LogMAR) (p < 0.05). Multivariate analysis indicated significantly lower functional scores in individuals with BCVA < 0.3 (LogMAR) (p < 0.001) and those with a history of crosslinking treatment (p = 0.022), while symptom scores were only significantly associated with only BCVA < 0.3 (LogMAR) (p < 0.001). In patients with keratoconus, BCVA in the better eye and history of crosslinkig were factors associated with better quality of life scores using the KORQ.

Translation and validation of the "Questionnaire for research on keratoconus results" (KORQ) in the Colombian population

OBJECTIVE

It is proposed to carry out a process of translation and adaptation of the "Questionnaire for Research on Keratoconus Results" (KORQ) into Spanish and its validation in a Spanish-speaking population, such as Colombia. This is intended to provide a tool for measuring and monitoring the commitment to quality of life of patients with this corneal ectasia.

MATERIAL AND METHODS

A prospective analytical study was carried out, in which 200 subjects diagnosed with keratoconus completed a translated version of the KORQ questionnaire. The internal validity of the questionnaire was evaluated using Cronbach's Alpha, while its construction was evaluated by an Exploratory Factor Analysis, including a Parallel Horn Analysis for the selection of the number of underlying factors. Subsequently, 50 patients were re-selected to complete the questionnaire one week later. The repeatability of the questionnaire was measured by the Spearman test.

RESULTS

The KORQ questionnaire in its Spanish version showed some internal validity in both sections. Both sections of the questionnaire showed an essentially unidimensional behaviour. The test-retest repeatability of the test was excellent (Spearman rho> 0.95).

CONCLUSIONS

The translated version of the KORQ is valid in Colombian population.

Both Subjective Emotional Distress and Visual Handicap Correlate with Belin ABCD Classification in the Worse Eye as Measured with the "Keratoconus End-Points Assessment Questionnaire" (KEPAQ)

BACKGROUND

Keratoconus is a disease characterized by progressive corneal distortion and quality of vision. So far, no study using disease-specific scales has evaluated whether different stages of the disease correlate with higher quality of life (QoL) compromise.

METHODS

A total of 114 patients with a confirmed diagnosis of Keratoconus were included in this retrospective study. All patients underwent a clinical and a Pentacam evaluation. They were also administered the "Keratoconus End-Points Assessment Questionnaire" (KEPAQ). Belin ABCD criteria were used for Keratoconus classification. "Better eye" was defined as the eye with the lowest maximum keratometry value. Spearman Rank Order Correlation was used to determine the correlation between the different Belin criteria and the KEPAQ scores in both subscales.

RESULTS

Mean age was 28.13 ± 11.57 years, with 39.47% of patients being male. Mean score for the KEPAQ-E was 2.33 ± 3.40 Logit, while for the KEPAQ-F, it was 1.85 ± 3.61 Logit. Criteria A (anterior elevation), B (posterior elevation) and D (visual acuity) in the worse eye correlated significantly with a greater decrease in QoL (p < 0.05 for all correlations). No correlation could be found regarding the better eye.

CONCLUSION

A greater corneal distortion in the worse eye, as determined by Belin ABCD, is associated with a greater decrease in patient's QoL. Surgical improvement of the worse eye should probably be performed before surgery of the better eye, as it may provide a better response regarding the quality of life improvement.

Both sub-scales of the "Keratoconus End-Points Assessment Questionnaire" (KEPAQ) are unidimensional and reliable

BACKGROUND

Measuring quality of life in keratoconus is important and demands for well-constructed instruments and scales. To date, the Keratoconus End-Points Assessment Questionnaire (KEPAQ) is the only disease-specific scale to measure both functional and emotional compromise due to disease. Nevertheless, not much information exists regarding whether both sub-scales of the test show unidimensionality, a necessary condition in well-functioning instruments.

METHODS

A sample of patients with a confirmed diagnosis of keratoconus were administered the full version of the KEPAQ. A Rasch analysis and principal component analysis were performed.

RESULTS

A total of 249 patients with keratoconus were included. Their average age was 29.19 ± 10.91 years, and 51.40% were male. Mean score for the KEPAQ-E was 2.51 ± 3.29 logit while it was 2.26 ± 3.70 logit for the KEPAQ-F. For both sub-scales, Kaiser Criterion, Scree Plot Criterion, and Variability Criterion demonstrated unidimensionality. Reliability as measured by Cronbach's alpha was 0.85 for the KEPAQ-E and 0.87 for the KEPAQ-F.

CONCLUSIONS

The KEPAQ is a robust, well-designed disease-specific questionnaire that shows unidimensionality. It can be reliably used to measure quality of life in keratoconus patients.

Development and Validation of the "Keratoconus End-Points Assessment Questionnaire" (KEPAQ), a Disease-Specific Instrument for Evaluating Subjective Emotional Distress and Visual Function Through Rasch Analysis

BACKGROUND

Keratoconus is a disease characterized by progressive distortion of the corneal anatomy, coupled with a decrease in vision. Assessing quality of life (QoL) in keratoconus is essential. So far, no instrument in the world has been designed to evaluate both visual function and emotional distress in this population. The purpose of the following study is to develop and validate the "Keratoconus End-Points Assessment Questionnaire" (KEPAQ) in a population of ectatic patients, the very first disease-specific scale to measure emotional latent traits in keratoconus.

METHODS

A last generation, Rasch analysis method was used for scale validation. First, a number of focus groups were carried out to create a pool of potential items. Then, a series of processes (such as "Content Validity Index") was carried out to develop a prior, 20-question version of the KEPAQ. Then, a study including 150 keratoconus patients was performed, followed by a careful Rasch analysis to validate and optimize both sub-scales (Emotional Compromise, KEPAQ-E, and Functional Compromise, KEPAQ-F).

RESULTS

Initially, 86 items were considered as potential elements. After test optimization, 20 items were retained. A total of 150 patients with a confirmed diagnosis of keratoconus were included for the Rasch analysis. The mean age was 29.84 ± 9.96 years. In 150 patients, 12.6% had a history of keratoplasty, 46.0% had corneal rings, and 31.3% had crosslinking. For both sub-scales, misfitting items were removed until no misfitting was determined by repetitive Rasch runs. For the final version of the KEPAQ-E sub-scale, variance explained by the model was 62.4% with a dimensional scale. Person Separation Index and Person Number of Strata were 2.43 and 3.57, respectively. For the final version of the KEPAQ-F sub-scale, variance explained by the model was 61.3% with a unidimensional scale. Person Separation Index and Person Number of Strata were 3.19 and 4.59, respectively. Both sub-scales showed excellent Person Reliability.

CONCLUSION

The KEPAQ is a robust scale, developed and validated through the latest theoretical models. It shows excellent psychometric properties, which render it extremely useful for both clinical and research use. To date, the KEPAQ is the only disease-specific scale worldwide to evaluate both functional and emotional compromise in keratoconus patients.

The impact of keratoconus treatment with the Athens Protocol (partial topography-guided photorefractive keratectomy combined with higher-fluence corneal collagen cross-linking) on quality of life: a long-term study

Purpose

The aim of this study was to evaluate the health-related quality of life (HRQoL) before and after the management of keratoconus (KCN) with Combined Topography-Guided Transepithelial partial photorefractive keratectomy (PRK) and corneal Cross-Linking: the Athens Protocol.

Patients and methods

Thirty-four consecutive patients treated for progressive KCN were selected for retrospective telephone interview and individual questionnaire submission. A disease-specific HRQoL questionnaire was administered before and after the Athens Protocol intervention, using the following administrative questionnaires: National Eye Institute Visual Function Questionnaire (NEI VFQ) 25/39 and IVI-28. The disease grade was ranked according to the Amsler–Krumeich classification (KCN severity). Reliability of collected data was evaluated with Cronbach’s α test.

Results

Patients’ age ranged from 15 to 51 years at the time of the operation. Mean time before the operation during which the questionnaires were administered was 52±6 months. General visual acuity, psychological well-being, and driving ability showed significant improvement. Younger keratoconic patients tend to have more enhanced psychological status and to cope better with difficulties in everyday activities (prior to operation) than older patients.

Conclusion

The Athens Protocol treatment has been proven to be beneficial to patients in a large number of aspects.

Refinement of the Child Amblyopia Treatment Questionnaire (CAT-QoL) using Rasch analysis

Aims or Purpose: The Child Amblyopia Treatment Questionnaire (CAT-QoL) was developed using a "bottom-up" methodological approach. Interviews with children with amblyopia identified items (questions) and response levels to be tested in a draft questionnaire consisting of 11 items (sad, feeling on face, hurt, doing schoolwork, cross, how other children treat you, doing things, worried, upset with family, playing with friends, happy). This study describes the refinement of the descriptive system for the CAT-QoL instrument using the application of Rasch analysis. Methods: A multi-centre pilot study was conducted, and data collected from 342 participants. Participants were asked to self-complete the appropriate treatment version of the CAT-QoL questionnaire socio-demographic and clinical data were collected by the clinician using a standardised proforma. A "measure" of child's health was obtained from the parent by asking how they would rate their child's health over the previous week. Rasch analysis techniques were applied to refine the questionnaire. Rasch was used to examine response categories and collapse item response levels, identify poorly performing items, and explore local dependency of items. Results: A total of 331 subjects were included in the study sample, however only 315 were accepted into the RUMM program as a number of subjects had missing questions responses on the CAT-QoL. RUMM also excluded a further 41 subjects as these demonstrated extreme responses. Disordered response categories were found for each item, requiring adjacent response levels to be combined. This was applied to all items, and the model fit was re-examined. Two items were found to have poor fit (cross and happy) and were removed from the measure and the model fit was re-examined. No statistically significant differential item functioning (DIF) was found for any item, using person factors of age, sex or general health. Two items showed some dependency (worried and upset with family), and the poorer fitting item was subsequently removed (upset with family). This resulted in a refined CAT-QoL instrument that consists of 8-items, each with three-level response scales. Conclusion: The refined CAT-QoL instrument includes the following items: sad, feeling on face, hurt, doing work at school, how other children treat you, doing things, worried and playing with friends. The CAT-QoL can be Rasch scored, with a range of 0-16 where a greater value indicates a worse quality of life (or greater impact of treatment on the individual). The CAT-QoL may be useful in determining how amblyopia treatment affects children, and offers an alternative to generic patient reported outcome measures.